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Role of the Posterior Left Atrium and Pulmonary Veins in Human Lone Atrial Fibrillation Electrophysiological and Pathological Data From Patients Undergoing Atrial Fibrillation Surgery
Abstract
Surgery can eliminate atrial fibrillation (AF), but data confirming the rationale for specific lesion sets are lacking. We used postoperative electrophysiological studies to test the rationale and effects of operative pulmonary venous isolation.
Fourteen patients undergoing surgical pulmonary venous isolation for drug-refractory lone AF were studied. Successful isolation was confirmed postoperatively in 13 of 14 patients. Spontaneous sustained AF was recorded from the isolated pulmonary venous region (PVR) in 4 and was induced by extrastimulus testing in another. The remaining atrial region (RAR) was in sinus rhythm in 13 patients and nonsustained AF in 1. Atrial extrastimulus testing and burst pacing in the RAR failed to induce sustained AF. In follow-up, 1 patient developed paroxysmal AF, and electrical continuity between the PVR and RAR was confirmed. Isolation was achieved with radiofrequency ablation with no further AF. Another patient developed typical atrial flutter that required ablation. AF has not recurred in any patient at 25.1+/-11.9 months (range, 6 to 56 months) after surgery. Atrial histopathology was consistent with tachycardia-induced changes.
Total electrical isolation of the PVR controlled AF with excellent clinical outcome and appeared necessary for success. The isolated PVR can sustain spontaneous or induced AF, whereas the considerably larger RAR does not. These data provide a sound rationale for PVR in eliminating AF.
... [1][2][3][4] Isolation of the PLA might be particularly useful in patients with non-paroxysmal AF (PAF) since it seems to be more dependent on activity in the PLA than the pulmonary veins (PV). [5][6][7][8] Since the path of the esophagus is invariably crossed perpendicularly while creating the floor line of the Box lesion, it is necessary to apply the radiofrequency (RF) energy adjacent to the esophagus to achieve the entire PLA isolation. Esophageal-related complications secondary to catheter ablation are rare but potentially life-threatening. ...
... Previous basic and clinical reports demonstrated that the PLA plays an important role in both the initiation 19,20 and maintenance of AF. [5][6][7][8] These findings suggest that ending in a partial isolation of the PLA may theoretically reduce the effect of eliminating the arrhythmogenecities localized in the PLA. However, the survival free rates from atrial arrhythmias were not affected by the size of the PLA isolation area in our study. ...
Introduction:
There are some cases with frequent luminal esophageal temperature (LET) rises despite titrating the radiofrequency energy while creating a linear lesion for the Box isolation of atrial fibrillation (AF). Little is known about the feasibility of redesigning the ablation lines for a modified Box isolation strategy to prevent fatal esophageal injury in those cases.
Methods and results:
Two hundred and seventeen patients who underwent a Box isolation of non-paroxysmal AF were evaluated. We divided them into two groups, patients in whom a box lesion set of the entire posterior left atrium had been achieved (Complete Box Isolation [CBI]; n = 157) and those in whom two additional peri-esophageal vertical lines were created at both the right and left ends of the esophagus, and those areas were left with an incomplete isolation when frequent rapid LET rises above 39.0°C were observed while creating the floor line (Partial Box Isolation [PBI]; n = 60). During 20.1 ± 13.9 months of follow-up, the arrhythmia-free rates were 54.1% in the CBI group versus 48.3% in the PBI group (p = 0.62). In the second session, a complete box isolation was highly achieved even in the PBI group (94.3% vs. 83.3%, respectively; p = 0.17) and after two procedures, the arrhythmia-free rates increased to 75.2% vs. 68.3%, respectively (P = 0.34). There was no symptomatic esophageal injury in the PBI group.
Conclusion:
In the case of frequent LET rises while creating the linear lesions for the Box isolation strategy for non-paroxysmal AF, shifting to the PBI strategy was feasible. This article is protected by copyright. All rights reserved.
... There is another method for an extensive substrate modification ablation targeting the isolation of the posterior left atrium (PLA), the so-called Box isolation [12,13]. This strategy arose from the concept that the PLA would play an Contents lists available at ScienceDirect important role in the maintenance of AF [14][15][16]. In the latest study, the PLA isolation with a PVI demonstrated a significantly high rate of sinus maintenance compared to PVI alone in patients with persistent AF [17]. ...
... Previous animal and human reports demonstrated that the PLA plays an important role in the maintenance of AF [14][15][16]. These results suggest that electrically isolating the PLA in addition to a PVI might result in a much better cure rate than a PVI alone in patients with non-PAF. ...
Background:
Catheter ablation of non-paroxysmal atrial fibrillation (non-PAF) is a therapeutic challenge especially in elderly patients. This study describes the feasibility of a posterior left atrium isolation as a substrate modification in addition to pulmonary vein isolation, the so-called Box isolation, for elderly patients with non-PAF.
Methods:
Two hundred twenty-nine consecutive patients who underwent Box isolations for drug-refractory non-PAF were divided into two groups according to their age; younger group comprising 175 patients aged <75 years and elderly group comprising 54 patients aged ≥75 years.
Results:
During 23.7±12.0 months of follow-up, the arrhythmia-free rates after one procedure were 53.1% in younger group versus 48.1% in elderly group (p=0.50). Following the second procedure, all patients had electrical conduction recoveries along the initial Box lesion. However, a complete Box re-isolation was highly established in both age groups (87.1% vs. 92.9%, respectively; p=1.00). Recurrence of macro-reentrant atrial tachycardia was mainly associated with the gaps through the initial Box lesion in both age groups (25.8% vs. 21.4%, p=1.00), but typical cavo-tricuspid isthmus (CTI) dependent atrial flutter was significantly observed in the elderly patients' group only (all events were observed within 6 months after the initial procedure; 3.2% vs. 28.6%, p=0.009). After two procedures, the arrhythmia-free rates increased to 73.1% in younger group versus 66.7% in elderly group (p=0.38). The occurrence rate of procedural-related complications did not differ between the two age groups, and there were no life-threatening complications even in elderly patients.
Conclusions:
Box isolation of non-PAF is effective and safe even in elderly patients. A prophylactic CTI ablation combined with Box isolation might be feasible to improve the long-term outcome.
... Ectopic foci arising from the pulmonary veins or other sites have been shown to promote persistent AF in the general population, with catheter ablation as the suggested therapy. 19,32 However, the real implication of ectopic foci to explain postoperative AF has not been yet clarified. Nevertheless, in support of this theory a relationship between AF and ventricular venting through the right superior pulmonary vein has been observed. ...
... Secondly, samples were only derived from the right atrial appendage and not the left atrial tissue. It is generally accepted that the pulmonary veins and the left atrial tissue are the most critical regions in initiating and maintaining AF. 32 However, the ethical aspects in terms of surgical sampling and inflicted risks directed the focus onto the right atrium only, a consideration shared with previous studies in this field of science. ...
... 28 Similarly, among patients in cluster 7 with "lone AF," we observed ablation to be the preferred treatment approach, which is also consistent with prior clinical trials showing favorability of AF ablation in this subtype of patient. 58,59 Additional inferences could be inferred in other clusters; for example, cluster 5, which corresponded with patients having coronary artery disease, in which use of an additional rhythm-control modality beyond external cardioversion did not seem as preferable. One could infer validation of this finding from the extensive body of literature supporting lack of benefit from rhythmcontrol agents among early studies before the ablation era. ...
Background
Rhythm management is a complex decision for patients with atrial fibrillation (AF). Although clinical trials have identified subsets of patients who might benefit from a given rhythm‐management strategy, for individual patients it is not always clear which strategy is expected to have the greatest mortality benefit or durability.
Methods and Results
In this investigation 52 547 patients with a new atrial fibrillation diagnosis between 2010 and 2020 were retrospectively identified. We applied a type of artificial intelligence called tabular Q‐learning to identify the optimal initial rhythm‐management strategy, based on a composite outcome of mortality, change in treatment, and sustainability of the given treatment, termed the reward function. We first applied an unsupervised learning algorithm using a variational autoencoder with K‐means clustering to cluster atrial fibrillation patients into 8 distinct phenotypes. We then fit a Q‐learning algorithm to predict the best outcome for each cluster. Although rate‐control strategy was most frequently selected by treating providers, the outcome was superior for rhythm‐control strategies across all clusters. Subjects in whom provider‐selected treatment matched the Q‐table recommendation had fewer total deaths (4 [8.5%] versus 473 [22.4%], odds ratio=0.32, P =0.02) and a greater reward ( P =4.8×10 ⁻⁶ ). We then demonstrated application of dynamic learning by updating the Q‐table prospectively using batch gradient descent, in which the optimal strategy in some clusters changed from cardioversion to ablation.
Conclusions
Tabular Q‐learning provides a dynamic and interpretable approach to apply artificial intelligence to clinical decision‐making for atrial fibrillation. Further work is needed to examine application of Q‐learning prospectively in clinical patients.
... The arrhythmogenicity of the posterior LA wall may reflect the fact that the myocardium in this part of the atrium arises from the same embryological origin as the pulmonary veins [16]. When isolation of the left atrial posterior wall incorporating the pulmonary veins is confirmed, atrial fibrillation has been observed to be inducible in the isolated posterior wall region whereas atrial fibrillation could not be induced in the larger surface area of the remainder of the atrial chambers [17]. ...
The management of non-paroxysmal atrial fibrillation (AF) remains controversial. We examined the efficacy and safety of the 2 stage Hybrid AF ablation approach by analysing the largest series of this technique reported so far.
Methods:
The approach aims to electrically isolate the left atrial posterior wall incorporating the pulmonary veins ('box-set'pattern). An initial video-assisted thoracoscopic (VATS) epicardial ablation is followed after a minimum of 8 weeks by endocardial radiofrequency catheter ablation.
Results:
Of 175 patients from 4 European cardiothoracic centers, who underwent the surgical (COBRA Fusion, AtriCure Inc) 1st stage ablation, 166 went on to complete 2nd stage catheter ablation. At median follow up of 18 months post 2nd stage procedure 93/166 (56%) had remained free of AF or atrial tachycardia (AT) recurrence off antiarrhythmic drugs. 110/175 62.9% were in sinus rhythm off all antiarrhythmic drugs at last clinic follow-up (132/175 75.4% including those on antiarrhythmic drugs). 18 patients (10.8%) underwent a further re-do ablation (mean of 1.1 ablations per patient) 105/166 (63%) remained free of AF/AT recurrence off antiarrhythmic drugs following last ablation procedure.Latterly, ILRs have been implanted in patients (n = 56); 60% have remained fully arrhythmia free and 80% have shown AF burden < 5% at a median 14 months follow-up [IQR: 13.5 (8-21.5)]. Only 10.9% have reverted to persistent AF. 5 patients (2.9%) had a perioperative stroke and 4 patients (2.3%) exhibited persistent weakness of the right hemidiaphragm following stage 1 VATS epicardial ablation. One patient died following stroke (overall mortality 0.6%).
Conclusions:
In patients with non-paroxysmal AF with unfavourable characteristics for catheter ablation, the staged hybrid approach results in acceptable levels of freedom from recurrent atrial arrhythmia, however, complication rates are higher than with catheter ablation alone.
... 8 When isolated en bloc in patients with persistent AF, it has been found that the posterior LA can still sustain AF in some patients, while the remaining atria cannot. 9 These observations have motivated the development of catheter-based techniques to achieve complete posterior wall isolation in an effort to improve ablation outcomes. ...
Catheter ablation is widely utilized for the management of atrial fibrillation (AF), particularly in patients who are refractory to medical therapy. The left atrium appears to play a dominant role in the condition of most patients with AF and, in particular, the posterior wall and pulmonary veins frequently harbor sources of fibrillation. Currently, the role of posterior wall isolation during catheter ablation of AF is controversial. In this review, we will examine the mechanistic role of the posterior left atrium, discuss the technical challenges of ablating in the posterior wall and the evolution of strategies to achieve isolation with catheter approaches, and review the relevant literature to date.
... The rest are classified as non-PV triggers. The main trigger areas in both lone and nonlone AF are believed to be similarly derived from the PV and the posterior wall of the left atrium 14 . However, non-PV triggers were more prominent in patients with lone AF than all comers with ordinary AF 15 . ...
Characterized by lack of evidence of structural heart disease or any secondary causes of atrial fibrillation (AF), “lone AF” is used to represent a unique subtype of AF among young individuals aged less than 60 years. Although the longstanding definition has been proposed for years, the diagnostic criteria for “lone AF” remain ambiguous. As more contributing factors causing AF are recognized gradually, the validity of the term “lone AF” is in question. Despite advances in the past few decades, the mechanism of AF remains poorly understood, particularly in the absence of other structural changes. It is generally accepted that three essential electrophysiological elements (trigger, substrate, and modulators)contribute to the initiation and maintenance of lone AF. In addition, the role of microRNAs and genomic variations in the pathogenesis of lone AF has been also gaining attention. Some changes in relevant biomarker levels have also been proven to correlate with lone AF. Accumulating insights into the pathogenesis of lone AF strongly suggest coexistent disorders in patients with lone AF. Consequently, the growing evidence of these numerous and diverse pathogenic mechanisms and factors related to lone AF inevitably raises the question of whether the term “lone AF” is a meaningful category. The classification of lone AF as a separate identity has not lead to any unique clinical management. In this review, we update knowledge of definition, mechanisms, genetics, biomarkers, and clinical management of “lone AF.” With this comprehensive review, we suggest that the term “lone AF” should be abandoned for its futility.
... The LA posterior wall often contains electrophysiological substrate(s) required for the maintenance of PRAF. The PVs and posterior LA (PV region) have been shown to sustain spontaneous and induced AF. 11 Microreentrant and macroreentrant rotors important for AF perpetuation were observed in the posterior wall of the LA in animal studies. 12 Furthermore, in animal studies using Langendorff-perfused sheep hearts, wherein 35 AF episodes were analyzed, the highest dominant frequency was most often (80%) localized to the posterior LA, near the PV ostium. ...
Atrial fibrillation (AF) is the most common heart rhythm disorder and a growing major public health burden. AF ablation is considered to be the preferred rhythm control strategy for symptomatic drug-refractory paroxysmal and persistent AF (PRAF). To date, the long-term ablation success rates of pulmonary vein isolation (PVI) for PRAF and longstanding PRAF (LS-PRAF) have not paralleled those of paroxysmal AF. Additional concomitant ablation strategies such as linear ablation lesions in the left and right atria; autonomic ganglionic plexi ablation; ablation directed by complex fractionated atrial electrograms; ablation of nonpulmonary vein (PV) triggers; radiofrequency ablation of the vein of Marshall; and, most recently, focal impulse and rotor ablation/modulation have shown modest improvement in terms of efficacy, but no reproducible outcomes. Here, we describe the critical role of the posterior left atrium (LA) and PV region in the development and progression of PRAF and LS-PRAF. We discuss the results of single-center outcomes data for convergent or hybrid AF ablation of the posterior LA and PV region (endocar-dial PVI + minimally invasive epicardial posterior LA ablation). This epicardial ablation approach, combined with endocardial ablation, is an option for patients with PRAF and LS-PRAF. More definitive clinical trials are needed.
... demonstrated of additional ablation beyond PVI(18). Studies reporting on favourable outcome after isolation of the posterior wall are not in direct contradiction with the STAR AF II trial as this trial did not include a group undergoing isolation of a part of the left atrium in addition to PVI. Isolation of a part of the posterior left atrium may be a promising strategy, as there is evidence that the LA posterior wall harbours triggers and substrate for AF: animal studies have demonstrated that 80% of AF triggers are located in the posterior wall including the PV region, based on electrophysiological and molecular findings(19)(20)(21). In addition, imaging studies could demonstrate that fibrotic areas (atrial delayed enhancement) are mainly located in the posterior wall(6)(7)(8). ...
Background
The posterior wall of the left atrium (LA) is a well‐known substrate for atrial fibrillation (AF) maintenance. Isolation of the posterior wall between the pulmonary veins (box lesion) may improve ablation success. Box lesion surface area size varies depending on the individual anatomy. This retrospective study evaluates the influence of box lesion surface area as a ratio of total LA surface area (box surface ratio) on arrhythmia recurrence.
Methods
Seventy consecutive patients with persistent AF (63±11 years, 53 men) undergoing CT imaging and ablation procedure consisting of a first box lesion were included in this study. Box lesion surface area was measured on electroanatomical maps and total LA surface area was derived from CT. Patients were followed with 24‐hour electrocardiography and exercise tests at 3, 6 and 12 months after AF ablation. Arrhythmia recurrence was defined as any AF/atrial tachycardia (AT) beyond 3 months without anti‐arrhythmic drugs.
Results
During a median follow‐up of 13 (IQR 10–17) months, 42 (60%) patients had AF/AT recurrence. Multivariate Cox proportional regression analysis showed that a larger box surface ratio protected against recurrence (Hazard Ratio (HR) 0.81; 95% confidence interval (CI) (0.690–0.955); p = 0.012). Left atrial volume index (HR 1.01 (0.990‐1.024, p = 0.427) and a history of mitral valve surgery (HR 2.90; 95% CI 0.970–8.693; p = 0.057) were not associated with AF recurrence in multivariate analysis.
Conclusion
A larger box lesion surface area as a ratio of total LA surface area is protective for AF/AT recurrence after ablation for persistent AF.
This article is protected by copyright. All rights reserved
... 44 Over the years, many surgical and transcatheter ablation studies have shown that effective PW isolation improve outcomes both in paroxysmal and non-paroxysmal AF patients. [45][46][47][48][49][50][51][52] Therefore, empirical isolation of the left atrial PW should be performed in all patients undergoing AF ablation. ...
Ablation of non-pulmonary vein (PV) triggers is an important step to improve outcomes in atrial fibrillation ablation. Non-pulmonary vein triggers typically originates from predictable sites (such as the left atrial posterior wall, superior vena cava, coronary sinus, interatrial septum, and crest terminalis), and these areas can be ablated either empirically or after observing significant ectopy (with or without drug challenge). In this review, we will focus on ablation of non-PV triggers, summarizing the existing evidence and our current approach for their mapping and ablation.
... Several authors have noted that fibrosis in the LAA and LA body is similar to that observved in patients with chronic AF (2,4,21,22). In contrast, however, Agmon et al. reported that the LAA function does not always parallel the LA function (23). ...
Objective The neutrophil-to-lymphocyte ratio (NLR) is an inflammation marker that can be used to detect atrial inflammatory changes, which may contribute to a reduced left atrial (LA) function and thrombosis. Our study aimed to determine whether or not the association of NLR with the LA appendage (LAA) function in relation to thrombogenesis differs from the association with the LA body function in paroxysmal atrial fibrillation (PAF) patients.
Methods A total of 183 PAF patients were studied. The LA volume index, mitral flow velocity (A), and mitral annular motion velocity (A′) were examined using transthoracic echocardiography. The LAA area, LAA wall motion velocity, and presence of spontaneous echo contrast (SEC) were examined using transesophageal echocardiography.
Results The NLR of patients with cerebral embolism was significantly greater than in patients without the disorder. A cut-off point of 2.5 for the NLR had a sensitivity of 71% and a specificity of 74% in predicting cerebral embolism. The patients with an NLR ≥2.5 had a higher CHADS2 score and greater LA volume index or LAA area than those with an NLR <2.5. The NLR was an independent risk factor for SEC and was significantly correlated with the LAA wall motion velocity (r=-0.409) in 153 patients without SEC and with the LAA wall motion velocity and LAA area (r=-0.583, r=0.654, respectively) in 30 patients with SEC, but not with the LA volume index, A, or A′ in either group.
Conclusion In PAF patients, a high NLR indicates thrombogenesis with a high degree of certainty and is associated with reduced LAA contraction rather than with the LA body function.
... In several studies was demonstrated the association of inflammation markers and AF occurrence [9,42,43]. Conversely, other investigators failed to show inflammatory changes in left atrium histological specimens from lone AF patients [44]. In this study myocarditis in RV was histologically verified in 14.2 % of patients with idiopathic AF, while the inflammatory substrate in atria was not directly proved. ...
Objective:
Aim was to study the performance of single-photon emission computed tomography (SPECT) with (99m)Tc-pyrophosphate ((99m)Tc-PYP) in diagnostics of chronic latent inflammation in myocardium of patients with atrial fibrillation (AF).
Methods:
The research included 70 patients (the average age of 49.3 ± 10.2 years) with persistent form of idiopathic AF. All patients underwent myocardium SPECT with (99m)Tc-PYP and cardiac magnetic resonance imaging (CMR) before the ablation. During the ablation endomyocardium sampling for histological and immunohistochemical verification of myocarditis was performed.
Results:
Sensitivity of SPECT with (99m)Tc-PYP in diagnoses of chronic latent myocarditis in patients with AF in relation to endomyocardial biopsy was 80 %, specificity-83 % and diagnostic accuracy-82 %. Sensitivity, specificity and diagnostic accuracy of myocardium perfusion scintigraphy for diagnostics of latent myocarditis in relation to endomyocardial biopsy was 30, 50 and 50 % correspondingly. Also the close correlation between the size of the perfusion defect and the severity of myocardial fibrosis in patients with AF was revealed. Specificity of the Lake Louise criteria for diagnostics of latent myocarditis in relation to endomyocardial biopsy was 77.6 %, sensitivity-60 % and diagnostic accuracy-74.5 %. For only LGE specificity was 16 %, sensitivity-90 % and diagnostic accuracy-28 %.
Conclusions:
The study showed the possibility of successful application of radionuclide methods for diagnoses of chronic latent myocarditis at AF. Taking into account high informative values the results of scintigraphy can be also considered as a promising additional criteria for selecting patients with AF of unexplained etiology for non-invasive endomyocardial biopsy procedure.
... The incorporated PVs form the smooth posterior wall of the LA, while the trabeculated portion of the LA comes to occupy a more ventral aspect [7,8]. Anatomically, there is an abrupt change in LA subendocardial fiber orientation as this bundle traverses the posterior LA between the PVs, which create a basis of reentry [9,10]. Indeed, previous work using noncontact mapping has demonstrated significant conduction abnormalities in the posterior LA during sinus rhythm in patients with PAF [9]. ...
... The posterior wall has proven to be an important site initiating and maintaining AF [15,16]. Satisfactory clinical results have been achieved by ablation strategies with PWI in both catheter ablation and surgical treatment for AF [17][18][19][20]. Our metaanalysis further demonstrated the benefit of PWI(+) ablation in patients with AF compared with PWI(−) ablation. ...
Purpose
The posterior wall of left atrium plays an important role in atrial fibrillation (AF) recurrence, but the benefit of left atrial posterior wall isolation (PWI) remains still unclear. The objective was to evaluate the benefit of PWI in radiofrequency ablation.
Methods
PubMed and the Web of Science were searched in September 2015. Studies comparing catheter ablation with PWI [PWI(+)] vs. ablation without PWI [PWI(−)] were included. We performed a meta-analysis to assess atrial arrhythmia recurrence, procedure-related complications, and procedural time.
Results
Five studies with 594 AF patients were included. Compared with PWI(−), PWI(+) resulted in a significantly lower atrial arrhythmia recurrence rate (relative risk [RR] 0.81, 95 % confidence interval [CI] 0.68–0.97, p = 0.02), which was largely driven by the decreased AF recurrence (RR 0.55, 95 % CI 0.35–0.86, p = 0.009). Recurrence rates of atrial tachycardia/flutter (AT/AFL) were comparable between two groups (RR 1.16, 95 % CI 0.85–1.58, p = 0.34). There were no significant differences in procedure-related complications (RR 1.07, 95 % CI 0.45–2.53, p = 0.89) and procedural times (weight mean difference 0.88, 95 % CI −7.29–9.06, p = 0.83).
Conclusions
This meta-analysis shows that with comparable procedure-related complications and procedural time, ablation with PWI reduces AF recurrence.
... Pulmonary vein isolation (PVI) is an stablished procedure to treat paroxysmal atrial fibrillation (AF), reaching success rates of up to 80%. 1 However, as the ablation techniques evolved, other left atrial structures proved to play a significant role in maintaining atrial fibrillation, especially in longstanding AF. 2,3 Fragmented potentials originated from left atrial (LA) roof, posterior wall (figure 1), and atrial septum became targets for ablation. Linear radiofrequency (RF) lesions in left atrial roof proved to be effective both in paroxysmal and persistent AF. 4 However, the alternative approach to eliminate fragmented potentials in the posterior wall still depends on extensive mapping and point-by-point RF lesions, leading to a longer procedure with no proof of complete posterior wall isolation and possibly creating new substrates to macroreentry. ...
Introduction:
The left atrial posterior wall has been shown to play na important role in AF pathophysiology.
Objective:
Evaluate the efficacy of an ablation strategy designed to completely isolate the LA posterior wall, on top of PV isolation. Methods and Results: 25 pts (72% male age 65 ± 12 years) undergoing AF ablation for persistent or long term persistent AF. Mean AF duration was 11 ± 3 months and mean LA diameter was 4.8 ± 0.4 mm. After complete PVI, a "Roof Line" was created between the top of each contralateral set of lesions and a "floor line" closed the posterior wall in a "Box" fashion, connecting the bottom of each set of contralateral lesions. After an average follow-up of 16 ± 2 months, 20 patients (80%) were free of any atrial arrhythmia recurrences (18 of whom off drugs). Five patients (20%) had sustained atypical flutter and required a new ablation procedure. All these patients had mitral isthmus dependent flutters and no electrical conduction in the PVs or posterior wall were detected.
Conclusions:
Complete LA posterior wall isolation on top of PV is associated with good outcomes in patients with persistent and long-standing persistent AF when performed using meticulous bidirectional isolation criteria and adenosine infusion. Recurrences occur predominately as perimitral flutter, without gaps in the posterior wall.
... It has been previously shown by Haisseguerre et al that the main trigger for paroxysmal atrial fibrillation (PAF) is ectopy arising from within the pulmonary veins. 1 Ablation therapy for PAF has therefore focused on the electrical isolation of the pulmonary veins. 2 This has traditionally been performed using radiofrequency (RF) catheter ablation with a point-by-point technique. 3 Cryoballoon ablation has more recently become available as a method to achieve pulmonary vein isolation (PVI) en bloc. ...
Background:
Cryoballoon pulmonary vein isolation (PVI) is an alternative to radiofrequency (RF) PVI for the treatment of paroxysmal atrial fibrillation (AF). Treatment effect, complication rates, and hospital length of stay are not well established with early use of cryoballoon PVI as compared to more experienced performance of RF PVI.
Purpose:
We reviewed the early experience of cryoballoon PVIs for paroxysmal AF performed by 3 operators at our institution compared to their most recent RF PVIs. All repeat procedures were excluded. Patients were assessed for recurrence of AF at 6 months after the procedure, including a 3-month blanking period. Complications, procedure time, and hospital length of stay were recorded.
Methods:
Consecutive patients presenting to the ER with ECG-documented AF at an urban teaching hospital were treated according to a guideline-based care protocol, including a patient toolkit at ER discharge, and systematic referral to a rapid access AF clinic. Consenting patients received questionnaires on AF knowledge, patient satisfaction, and the AFEQT questionnaire at first visit and three-month follow-up.
Results:
Final analysis included 50 cryoballoon PVIs and 50 RF PVIs. There was no significant difference in baseline characteristics or percentage of patients wearing a home monitor (80% for cryoballoon vs 80% for RF). Symptomatic improvement was experienced by 96% of cryoballoon PVI as compared to 86% of RF PVI patients (p=0.08). Freedom from AF at 6 months was similar between the two groups (70% for cryoballoon and 70% for RF, p=1). Complications were seen in 6% of cryoballoon procedures as compared to 10% of RF procedures (p=0.46). Hospital length of stay was significantly shorter in the cryoballoon group (1.6 vs 3.4 nights, p=0.003).
Conclusion:
At the time of its adoption, cryoballoon PVI is associated with shorter procedure times and hospital length of stay as compared to RF PVI in experienced operators while maintaining similar efficacy outcomes and complication rates.
... 25 The results of this study could not be confirmed by others. 51 Many other studies searched for a correlation between markers of inflammation and LAF. Especially C-reactive protein (CRP) has been related to arrhythmia development, recurrences and persistence. ...
BACKGROUND: Since its introduction in 1953, lone atrial fibrillation (LAF) has not been defined with any consistency, resulting in an enormous variation in the way the term is used. Inherent to this, results from studies vary considerably. Many predisposing factors and pathogenic influences have been discovered over the past years, which raise the question if the term LAF should still be used and if the treatment should be different from non-lone atrial fibrillation (non-LAF). Therefore this systematic review on LAF provides an overview of risk factors and triggers, the second part focuses on the application of catheter and surgical ablation techniques.
METHODS: A systematic literature search was performed in the PubMed database. All identified articles were screened and checked for eligibility by the two authors. Additional literature was sought by screening the references of eligible articles.
RESULTS: The term LAF is used very variably and inconsistently, and results concerning etiology in different studies are often contradictory. Overall finding is that LAF has many risk factors (e.g. subclinical atherosclerosis, enlarged left atrial volume, left ventricular dysfunction, occult hypertension, arterial stiffness, systemic inflammation and genetic factors) and can be induced by many different triggers (e.g. use of substances, endurance sports, mental stress and sleeping). However, compared to non-LAF there are no unique mechanisms related to LAF. Concerning the therapy, catheter ablation is first or second choice after antiarrhythmic drugs, however surgical and hybrid approaches may be indicated in complex cases.
CONCLUSIONS: Insufficient evidence exists to consider LAF as a real, isolated and useful entity. A re-definition or even avoiding the use of the term LAF might be appropriate.
... The left atrial posterior wall should be considered as an extension of the PVs from an embryologic, anatomic and electrophysiological perspective (16). The surgical experience with AF ablation has confirmed a significant role of the posterior wall for triggering and maintaining the arrhythmia (17), with reports documenting AF localized only to the posterior wall (18,19). ...
Atrial fibrillation (AF) is the most common sustained arrhythmia. Recent guidelines recommend pulmonary vein isolation (PVI) as the main procedural endpoint to control recurrent AF in symptomatic patients resistant to antiarrhythmic drugs. The efficacy of such procedure is higher in paroxysmal AF while is still unsatisfactory in persistent and long-standing persistent AF. This review will summarize the state-of-the-art of AF ablation techniques in patients with persistent AF, discussing the evidence underlying different approaches with a particular focus on adjunctive ablation strategies beyond PVI including linear ablation, ablation of complex fractionated atrial electrograms (CFAE), ablation of ganglionated plexi, dominant frequency, rotors and other anatomical sites frequently involved in AF triggers.
... Durable transmurality of the ablation lines is considered the gold standard for the current treatment of atrial fibrillation (AF). One of the key aspects of AF treatment consists in ablating the pulmonary vein (PV) ostia, generally one of the thickest areas of the left atrium, obtaining their electrical disconnection [1][2][3]. Many technological refinements were introduced in recent years to ameliorate the efficacy of ablative energy sources, in particular bipolar radiofrequency (RF) lesions proved to be reproducibly transmural and contiguous on the cardiac muscle [4,5]. ...
Clinical success of atrial fibrillation (AF) ablation depends on persistent block of electrical conduction across the ablation lines. The fate of ablations performed with temperature-controlled bipolar radiofrequency (RF) is unknown. The purpose of this study was to validate the electrophysiological (EP) efficacy of these lesions, recording pulmonary vein isolation (PVI) after open chest ablation, in the human being.
Ten consecutive mitral patients (mean age: 53 ± 12 years) with concomitant AF were treated with the Cobra Revolution (Estech, San Ramon, CA, USA) bipolar RF device were enrolled for EP assessment. During surgery, pairs of additional temporary wires were positioned on the right PVs (RPV) and on the roof of the left atrium (RLA), before ablation. Pacing thresholds (PTs) were assessed before, after a single encircling ablation and at chest's closure. EP study was repeated before discharge and at 3 weeks. RLA wires served as control.
Baseline PTs were 0.83 ± 0.81 mA (range 0.2-3 mA) from RPV and 1.13 ± 0.78 mA (range 0.3-3 mA) from RLA. PVI was reached in all patients acutely, and was maintained at 1 week. At 3 weeks, the PTs were 14.3 ± 4.3 mA from RPV (range 7-20 mA) and 3.1 ± 1.3 mA (range 1.5-7 mA) from RLA. All patients were discharged in sinus rhythm.
Cobra Revolution temperature-controlled bipolar RF provides complete PVI after a single ablation up to 1 week. This notwithstanding, only 30% of patients were completely isolated (exit block validation) at 3 weeks.
© The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
... This and previous studies in the atrially burst-paced goat model have shown that the development of significant atrial fibrosis does not occur in this model, 29 even when AF is maintained for several months, 22 and that the absence of fibrotic change is consistent with many studies of human AF. 20,30 The model used in the present study can be considered as a model of "lone" AF, 1 distinct from models in which there is ventricular dysfunction and fibrosis. 31 A study by Dosdall et al 32 evaluated left ventricular function using cardiac MRI after 6 months of maintained AF in different animal models and found no significant change in left ventricular function in the goat model (in comparison to other animal models of AF). ...
Electrogram fractionation and atrial fibrosis are both thought to be pathophysiological hallmarks of evolving persistence of atrial fibrillation (AF), but recent studies in humans have shown that they do not colocalize. The interrelationship and relative roles of fractionation and fibrotic change in AF persistence therefore remain unclear.
The aim of the study was to examine the hypothesis that electrogram fractionation with increasing persistence of AF results from localized conduction slowing or block due to changes in atrial connexin distribution in the absence of fibrotic change.
Of 12 goats, atrial burst pacemakers maintained AF in 9 goats for up to 3 consecutive 4-week periods. After each 4-week period, 3 goats underwent epicardial mapping studies of the right atrium and examination of the atrial myocardium for immunodetection of connexins 43 and 40 (Cx43 and Cx40) and quantification of connective tissue.
Despite refractoriness returning to normal in between each 4-week period of AF, there was a cumulative increase in the prevalence of fractionated atrial electrograms during both atrial pacing (control and 1, 2, and 3 months period of AF 0.3%, 1.3% ± 1.5%, 10.6% ± 2%, and 17% ± 5%, respectively; analysis of variance, P < .05) and AF (0.3% ± 0.1%, 2.3% ± 1.2%, 14% ± 2%, and 23% ± 3%; P < .05) caused by colocalized areas of conduction block during both pacing (local conduction velocity <10 cm/s: 0.1% ± 0.1%, 0.3% ± 0.6%, 6.5% ± 3%, and 6.9% ± 4%; P < .05) and AF (1.5% ± 0.5%, 2.7% ± 1.1%, 10.1% ± 1.2%, and 13.6% ± 0.4%; P < .05), associated with an increase in the heterogeneity of Cx40 and lateralization of Cx43 (lateralization scores: 1.75 ± 0.89, 1.44 ± 0.31, 2.85 ± 0.96, and 2.94 ± 0.31; P < .02), but no associated change in connective tissue content or net conduction velocity.
Electrogram fractionation with increasing persistence of AF results from slow localized conduction or block associated with changes in atrial connexin distribution in the absence of fibrotic change.
Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
... Extrapulmonary vein locations of triggering foci have been found in the superior vena cava, crista terminalis, ostium of the coronary sinus, interatrial septum and atrial free wall [20,21,22,23]. In postoperative electrophysiology studies after surgical isolation of the posterior left atrium and pulmonary veins in humans, the pulmonary venous region was still able to sustain spontaneous or induced AF, whereas the rest of left atrium (LA) and right atrium (RA) were not [24]. ...
... Existen múltiples zonas generadoras de actividad ectópica que puede resultar en FA: aurícula derecha (incluida la cresta terminal), aurícula izquierda y el denominado "sistema venoso" (desembocadura de venas pulmonares, vena cava superior, vena cava inferior, ligamento de Marshall). [22][23][24] Apenas en la década pasada Haïssaguerre y su grupo establecieron que la presencia de actividad eléctrica en las venas pulmonares (VP) se asociaba con la génesis y el mantenimiento de algunas formas de FA idiopática 25 (Figura 5). Ello constituyó un avance fundamental en el tratamiento de la FA debido a que permitió el desarrollo de la ablación con catéter para el tratamiento de esta arritmia. ...
This review is a summary of the pathophysiology of atrial fibrillation (AF) and the progress in the understanding of this arrhythmia. The following factors should be considered in the genesis and maintenance of AF. The genetic factor is involved in cases of familial AF. Predisposing structural factors: atrial dilation, structural feature that allows the development of AF. Predisposing structural factors: the role of the Bachmann s bundle and frequency gradients between the left and right atrium. Electrophysiological factors: heterogeneous refractory periods favor the fibrillatory conduction. Triggers: abnormal electrical activity (ectopic foci). Modulating factors: autonomic nervous system. Increased vagal tone shortens atrial refractory periods, creating a greater dispersion of the refractory periods and the generation of reentries in the context of triggered activity. Finally, there are three types of atrial remodeling secondary to AF: structural, contractile, electrical. They are interrelated and contribute to maintaining the AF ("AF begets AF").
Esophageal perforation and fistula formation are rare but serious complications following atrial fibrillation ablation. In this review article, we outline the incidence, pathophysiology, predictors, and preventative strategies of this dreaded complication.
We conducted an electronic search in 10 databases/electronic search engines to access relevant publications. All articles reporting complications following atrial fibrillation ablation, including esophageal injury and fistula formation, were included for systematic review.
A total of 130 manuscripts were identified for the final review process. The overall incidence of esophageal injury following atrial fibrillation ablation was significantly higher with thermal ablation modalities (radiofrequency 5–40%, cryoballoon 3–25%, high-intensity focused ultrasound < 10%) as opposed to non-thermal ablation modalities (no cases reported to date). The incidence of esophageal perforation and fistula formation with the use of thermal ablation modalities is estimated to occur in less than 0.25% of all atrial fibrillation ablation procedures. The use of luminal esophageal temperature monitoring probe and mechanical esophageal deviation showed protective effect toward reducing the incidence of this complication. The prognosis is very poor for patients who develop atrioesophageal fistula, and the condition is rapidly fatal without surgical intervention.
Esophageal perforation and fistula formation following atrial fibrillation ablation are rare complications with poor prognosis. Various strategies have been proposed to protect the esophagus and reduce the incidence of this fearful complication. Pulsed field ablation is a promising new ablation technology that may be the future answer toward reducing the incidence of esophageal complications.
The recognition of risk factors and preventative strategies of esophageal injury, perforation, and fistula formation following atrial fibrillation ablation is essential to reduce the incidence of this dreaded complication (online abstract figure).
Background
Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation of atrial fibrillation (AF); however, the results are suboptimal for persistent AF. The left atrial posterior wall (LAPW) is thought to be a major additional area in initiation and perpetuation of persistent AF. Therefore, adjunctive ablation of the posterior wall may reduce AF recurrence in patients with persistent AF.
Objective
The objective of this study was to compare outcomes of catheter ablation in patients with persistent AF using PVI alone versus a combination of PVI and LAPW isolation.
Methods
Literature search was conducted in PubMed, PubMed Central, Scopus, and Embase since inception to February 2023. Screening of studies was done via Covidence software. Risk of bias assessment was done using appropriate tools. Data extraction and a narrative synthesis were carried out accordingly.
Results
Ten studies were included, of which five were randomized controlled trials. PVI with LAPW ablation group had significantly lower recurrence of overall atrial tachyarrhythmia (OR 0.47, CI 0.32–0.70) and AF (OR 0.39, CI 0.23–0.69). In sensitivity analysis, freedom from atrial arrhythmias was noted to be significantly higher in the PVI with LAPW ablation group (OR 2.22, CI 1.36–3.64). However, there was no significant difference in occurrence of atrial flutter (OR 1.36, CI 0.86–2.14) or with periprocedural adverse events (OR 1.10, CI 0.60–1.99).
Conclusion
LAPW ablation, in addition to PVI, significantly improves the rates of arrhythmia freedom and reduces the recurrence of overall atrial tachyarrhythmia. There was no significant difference in atrial flutter or periprocedural adverse events.
Focal activity is one of the dominant triggers of atrial fibrillation. Its activity is revealed in paroxysmal as well as in persistent patterns of arrhythmia. Starting as a trigger of atrial fibrillation in pulmonary veins, over time with increasing of burden of atrial fibrillation, focal activity is more and more revealed out of pulmonary veins: anterior and posterior left atrial walls, interatrial septum, coronary sinus, ligament of Marshal and right atrium. Diagnostics of focal activity is a challenging clinical task despite implementation of mathematical algorithms of electrogram analysis because of its spatial instability and activation direction of the mapping electrode. All these items are discussed in the article.
Background: Thoracoscopic ablation is an effective treatment of patients with atrial fibrillation. Nowadays, 2 types of ablative devices are available in clinical practice allowing one to perform the thoracoscopic procedure Medtronic and AtriCure. However, the contemporary clinical literature does not have enough data that would compare these two approaches. Aims: to perform a comparative analysis of the short-term results of two minimally invasive strategies in thoracoscopic ablation for atrial fibrillation. Methods: 232 patients underwent thoracoscopic ablation for atrial fibrillation in two clinical centers for the period from 2016 to August 2021. The patients were divided into 2 groups. The first group was represented by those patients to whom a Medtronic device was applied (n=140), the second group was treated with an AtriCure device (n=92). The patients were comparable in their age, gender, initial severity of the condition. The follow-up consisted of laboratory tests, chest Х-ray, electrocardiography, 24-hour Holter monitor, echocardiography. The structure and prevalence of postoperative and intraoperative complications, specifics of the postoperative period were compared between the two groups. Results: According to the structure and prevalence of intraoperative complications the 2 groups are comparable to each other: 4.3% and 1.1% for the 1st group and 2nd group, respectively (p 0.05). The postoperative complications had developed in 6 (4.3%) and 5 (5.4%) patients in groups 1 and 2, respectively (p 0.05). At the time of discharge from hospital, a sinus rhythm was registered in 93.6% of patients (1st group), and 85.9% (2nd group) (p 0.05). Conclusions: Both strategies have demonstrated comparable short-term results in patients with lone atrial fibrillation. A further research is needed to evaluate the effectiveness of this strategy in a long-term period.
Atrial fibrillation (AF) is associated with profound structural and functional changes in the atrium. Inflammation mediated atrial fibrosis is one of the key mechanisms in the pathogenesis of AF. The collagen deposition in extracellular matrix (ECM) is mainly mediated by transforming growth factor β1 (TGF-β1) which promotes AF via controlling smads mediated-collagen gene transcription and regulating the balance of metalloproteinases (MMPs)/ tissue inhibitor of metalloproteinases (TIMPs). Although many processes can alter atrial properties and promote AF, animal models and clinical studies have provided insights into two major forms of atrial remodeling: Atrial tachycardia remodeling (ATR), which occurs with rapid atrial tachyarrhythmia's such as AF and atrial flutter, and atrial structural remodeling (ASR), which is associated with CHF and other fibrosis-promoting conditions. The mechanism of atrial remodeling such as atrial enlargement, ultra structural changes of atrial muscle tissue and myocardial interstitial fibrosis in AF is still unclear. At present, many studies focus on calcium overload, renin angiotensin aldosterone system and transforming growth factor β1, that effect on atrial structural remodeling. Recent experimental studies and clinical investigations have provided structural remodeling is important contributor to the AF. This paper reviews the current understanding of the progresses about mechanism of atrial structural remodeling, and highlights the potential therapeutic approaches aimed at attenuating structural remodeling to prevent AF. Now some recent advancements of this area are reviewed in this paper.
Objectives
The aim of this study was to assess the safety and efficacy of a new subxiphoid hybrid epicardial-endocardial atrial fibrillation (AF) ablation and left atrial appendage (LAA) ligation approach for the treatment of persistent AF.
Background
Surgical hybrid ablation procedures have shown promise for maintaining sinus rhythm versus catheter ablation but are associated with increased periprocedural adverse events.
Methods
Patients with symptomatic persistent AF (n = 33, mean age 64 ± 9 years, 25 men) who had antiarrhythmic drug therapy or prior catheter ablation was unsuccessful were referred for hybrid epicardial-endocardial AF ablation and LAA exclusion. LAA closure was confirmed by transesophageal echocardiographic Doppler flow and/or computed tomographic angiography 1 to 3 months post-ligation. The incidence of atrial tachycardia or AF recurrence, LAA closure, thromboembolic events, and post-operative complications were assessed.
Results
All 33 patients underwent successful LAA ligation with epicardial ablation of the posterior left atrial wall, as well as endocardial pulmonary vein isolation and cavotricuspid isthmus ablation. Freedom from atrial tachycardia or AF was 91% (20 of 22 patients) at 6 months, 90% (18 of 20 patients) at 12 months, 92% (11 of 12 patients) at 18 months, and 92% (11 of 12) at 24 months. There were no acute periprocedural complications (<7 days). Thirty-day adverse events included 2 patients with pericardial effusion requiring pericardiocentesis and 1 incisional hernia repair. There were no long-term complications, strokes, or deaths. LAA ligation was complete in 27 of 33 subjects (82%), with 6 subjects having leaks of <5 mm.
Conclusions
Subxiphoid hybrid epicardial-endocardial ablation with LAA ligation is feasible, safe, and effective. Future prospective studies are needed to validate these initial findings.
This chapter reviews the technological advances in catheter ablation of atrial fibrillation (AF). Pulmonary veins isolation (PVI) and electroanatomical mapping (EAM) remain the mainstays of AF ablation. The chapter summarizes the advantages, disadvantages, and potential complications of energy source and catheter during AF ablation. Based on randomized controlled trials, AF ablation is considered an important part of management as a class I level of evidence A in patients with paroxysmal AF, particularly in those refractory to antiarrhythmic therapy. Furthermore, randomized controlled trials have shown that catheter ablation is superior to medical rate control. New mapping and imaging systems and catheters have improved the success rate of AF ablation procedures. The goal of the strategies for catheter ablation of atrial fibrillation is to maintain sinus rhythm and prevent AF recurrence without significant damage to collateral tissue.
The importance of the pulmonary veins as a source of triggers for atrial fibrillation (AF) is well accepted and the pulmonary veins may also play a role in sustaining persistent AF. The presence of multiple simultaneously present wavefronts and apparent focal activations emanating from within the mapped field has frequently been reported, with evidence of spatiotemporal organization consistently noted, at least over short timeframes and within spatially limited regions. Despite the previous demonstration of differences in activation timing between endocardium and epicardium during organized rhythms in animal studies, the complex and non‐uniform three‐dimensionality of the atrial walls has traditionally received little attention. By providing a constant source of independent fibrillation waves over the entire atrial epicardial surface, it is argued that the breakthrough activations offer an adequate explanation for the persistence of AF in the setting of structural heart disease, without the need to implicate specific focal sources.
This chapter discusses electrogram‐guided mapping and ablation of atrial fibrillation (AF) and pertains primarily to radiofrequency ablation. The strategy described in the chapter has the advantage of direct visualization in real time of the Lasso and ablation catheters with intracardiac echocardiography, which is theoretically more reliable than magnetor impedance‐based mapping systems. Multiple ablation strategies have been proposed to modify the atrial substrate, including empirical anatomy‐based ablations, ablation of complex fractionated atrial electrograms, dominant frequency (DF) analysis, spectral analysis guided mapping and ablation of AF nests and, more recently, rotor mapping and ablation. Substrate ablation guided by DF analysis has been proposed as a more specific strategy for targeting critical areas for AF maintenance. Nonetheless, observations from studies which assessed DF in AF suggest that with advancement of technology and better understanding of the pathophysiology, targeting DF sites may become a practical option in AF ablation.
Introduction
The left atrial (LA) posterior wall (LAPW) has been targeted to improve clinical outcomes in patients with persistent atrial fibrillation (PersAF). This study aimed to investigate the feasibility, safety, and clinical implications of CB applications on the LAPW to accomplish electrical isolation (EI) of the LAPW with cryoballoon (CB).
Methods
A total of 100 patients (males: 84, mean age: 64±10 years) with PersAF were enrolled. The first 50 patients underwent only pulmonary vein isolation (PVI) (PVI‐only group), and remaining 50 patients underwent PVI and EI of the LAPW with CB (EI‐LAPW group).
Results
One‐year sinus rhythm maintenance probability was significantly higher in the EI‐LAPW group than in PVI‐only group (80.0 vs. 55.1% p= 0.01). The success rate of constructing an LA roof block line (LA‐RB), bottom block line, and EI of the LAPW was 92%, 60%, and 58%, respectively. The nadir CB temperature (‐45±4 vs. ‐39±5 °C, p=0.005) and anatomical angle of the left atrial roof (106±30 vs. 144±17 °, p<0.001) significantly predicted the successful LA‐RB construction. The left ventricular ejection fraction was significantly higher in unsuccessful cases than in successful cases of an EI of the LAPW (64±8 vs. 58±11%, p=0.041). Even if unsuccess of the EI of the LAPW, CB freezing in LAPW significantly debulked non‐scar area (≥0.1 mV) in LAPW (18.1±5.6 vs. 2.2±3.1 cm², p<0.001) and provided the equivalent one‐year outcome to that of successful cases (79.3 vs. 81.0% p= 0.90).
Conclusion
The combination of PVI and EI of the LAPW with CB provide better clinical outcomes than conventional PVI procedure for patients with PersAF.
This article is protected by copyright. All rights reserved.
Background
Left atrial posterior wall isolation (LAPWI) via catheter, surgical and hybrid techniques is a promising treatment for persistent atrial fibrillation (PersAF). We investigated whether confirmation of LAPWI can be achieved using an esophageal pacing and recording electrode.
Methods
Patients undergoing PersAF ablation with the intention to achieve LAPWI were enrolled. Two approaches to LAPWI were tested: 1) ablation using endocardial catheter ablation only, 2) ‘Staged Hybrid’ ablation with thoracoscopic epicardial ablation, followed by endocardial left atrial electrophysiological study and catheter ablation where necessary. Patients enrolled in the study all required further catheter ablation to achieve LAPWI in this group.
In both groups, esophageal recording and esophageal pacing was performed at the start of mapping and electrophysiological study and compared with endocardial electrophysiological findings. This was repeated at the end of the procedure.
Results
Twenty patients (16 M, 4F) were studied. Endocardial electrophysiological study showed that in none of the cases was the posterior left atrial wall electrically isolated at the start of the study. One patient with Barretts esophagus failed to sense or pace from the oesophagus at any point in the study. In the remaining 19/19 esophageal pacing captured the atrial rhythm at the start of the procedure. LAPWI was then achieved in 17/19 using endocardial catheter ablation; retesting at this point showed sensing and capture of the atrium from the esophagus was abolished. In the remainder sensing and capture persisted.
Conclusions
Esophageal pacing can be used to confirm or refute electrical isolation of the left atrial posterior wall.
This article is protected by copyright. All rights reserved
Background
Atrial fibrillation (AF) is one of the widest spread forms of arrhythmia, which is associated with the increased mortality and thromboembolic complications. To date, the involvement of renin‐angiotensin‐aldosterone system and immunomediators of inflammation into the mechanisms of development and maintenance of isolated AF is not clear. Specificity of their changes with respect to the latent myocarditis at AF is not proved.
Methods
In 96 patients with persistent isolated atrial fibrillation (IsAF), scheduled for radiofrequency ablation and endomyocardial biopsy (EMB), and in 20 healthy volunteers (HVT), levels of plasma tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐1β, IL‐6, IL‐8, IL‐10, fatty acid‐binding protein (FABP), neopterin, C‐reactive protein (CRP) were determined by ELISA, level of aldosterone and the renin activity were determined by radioimmunoassay. Results were compared between the study and HVT groups and related to the EMB data.
Results
Endomyocardial biopsy revealed lymphocytic myocarditis in 29%, immunohistochemical signs of viruses' persistence in the myocardium—in 43.8% of patient. We formed 4 subgroups: «myocarditis», «fibrosis», «virus positive», «virus negative». In the group «myocarditis», level of IL‐6 was significantly higher than in group «fibrosis» (P < .01). ROC analysis showed its sensitivity 75%, specificity 75% (AUC = 0.759, Cutoff Value > 1.6 pg/mL, P < .01). In the group «virus positive», level of neopterin was significantly higher than in group «virus negative» (P < .01), with sensitivity 51%, specificity 84% (AUC = 0.675, Cutoff Value > 13.2 nmol/L, P < .01).
Conclusion
Levels of plasma IL‐6 and neopterin may serve as a marker of latent viral myocarditis in IsAF.
Anatomically based procedures to ablate atrial fibrillation (AF) are often successful in terminating paroxysmal AF. However, the ability to terminate persistent AF remains disappointing. New mechanistic approaches use multiple-electrode basket catheter mapping to localize and target AF drivers in the form of rotors but significant concerns remain about their accuracy. We aimed to evaluate how electrode-endocardium distance, far-field sources and inter-electrode distance affect the accuracy of localizing rotors. Sustained rotor activation of the atria was simulated numerically and mapped using a virtual basket catheter with varying electrode densities placed at different positions within the atrial cavity. Unipolar electrograms were calculated on the entire endocardial surface and at each of the electrodes. Rotors were tracked on the interpolated basket phase maps and compared with the respective atrial voltage and endocardial phase maps, which served as references. Rotor detection by the basket maps varied between 35–94% of the simulation time, depending on the basket’s position and the electrode-to-endocardial wall distance. However, two different types of phantom rotors appeared also on the basket maps. The first type was due to the far-field sources and the second type was due to interpolation between the electrodes; increasing electrode density decreased the incidence of the second but not the first type of phantom rotors. In the simulations study, basket catheter-based phase mapping detected rotors even when the basket was not in full contact with the endocardial wall, but always generated a number of phantom rotors in the presence of only a single real rotor, which would be the desired ablation target. Phantom rotors may mislead and contribute to failure in AF ablation procedures.
Both pulmonary veins (PVs) and the posterior left atrium (LA) are developed from the sinus venosus, where there are many pacemaker cells with spontaneous rhythmic activity. Non-PV foci originated mainly from the PV ostium or the posterior LA, and the posterior LA and the LA roof serve as a substrate for maintenance of AF in the patients with AF. It has been proposed that the surgical procedures for isolating the posterior LA and PVs could cure AF in 93% of patients with lone AF. These findings support that isolation of not only PVs but also the whole posterior LA can result in a much better cure rate in the patients with paroxysmal and persistent AF. Therefore, we developed a new approach for complete isolation of the posterior LA including all PVs, namely Box isolation. In the posterior LA, there are many arrhythmogenic substrates for AF, including the ganglionated plexi, reentries, triggers, and low-voltage areas. Box isolation can contain these abnormal substrates in the posterior LA and reduce the critical mass for maintenance of AF. Additional posterior LA isolation to PV isolation facilitates AF termination and non-inducibility. Previous studies reported that box isolation is an effective and safe treatment for paroxysmal or persistent AF. A meta-analysis showed that box isolation reduced AF recurrence with comparable recurrence rates of atrial tachycardia/flutter, complications, and procedure time compared with PV isolation alone.
Background:
Minimally invasive surgical AF ablation delivers RF energy via a thoracoscopic approach to perform pulmonary vein isolation and LA ganglionic plexi ablation. Data on long term outcomes of MISAA is lacking.
Objective:
We report 5 year follow-up data from a prospective cohort of patients who underwent MISAA at a single center.
Methods:
One hundred nine consecutive patients (60 paroxysmal, 49 persistent, mean age 62.7±9.3 years) underwent MISAA with left atrial appendage exclusion by a single surgeon between 2006 and 2012. Patients were followed with trans-telephonic monitoring at 1, 6 and 12 months and annually thereafter for up to 5 years. Recurrence was defined as any atrial tachyarrhythmia lasting ≥30 seconds after 90 days from surgery.
Results:
Mean follow-up duration was 1738.5 ± 661.5 days. Single procedure success rate was 38% (37 of 98 patients). Atrial arrhythmias occurred in 22%, 42%, 55%, 59% and 62% patients by 1,2,3,4 and 5 years. Seventy eight (79.6%) patients remained AF free with or without additional interventions including catheter ablation (CA), antiarrhythmic drugs or cardioversion. There was no significant difference in AF free survival between paroxysmal and persistent AF groups (p = 0.725). Multivariate analyses showed hypertension to be a significant predictor of AF recurrence (OR 6.6, CI 1.41-30.80 p = 0.016). Five (5.1%) patients had a stroke or TIA during follow-up.
Conclusions:
AF free survival was 38% at 5 years after MISAA. 79.6% remained AF free with or without additional intervention. Patients may have an ongoing risk of stroke even in absence of AF recurrences.
Background:
The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood.
Objectives:
This study sought to investigate the complexity and distribution of AF drivers in PsAF of varying durations.
Methods:
Of 135 consecutive patients with PsAF, 105 patients referred for de novo ablation of PsAF were prospectively recruited. Patients were divided into 3 groups according to AF duration: PsAF presenting in sinus rhythm (AF induced), PsAF <12 months, and PsAF >12 months. Patients wore a 252-electrode vest for body surface mapping. Localized drivers (re-entrant or focal) were identified using phase-mapping algorithms.
Results:
In this patient cohort, the most prominent re-entrant driver regions included the pulmonary vein (PV) regions and inferoposterior left atrial wall. Focal drivers were observed in 1 or both PV regions in 75% of patients. Comparing between the 3 groups, with longer AF duration AF complexity increased, reflected by increased number of re-entrant rotations (p < 0.05), number of re-entrant rotations and focal events (p < 0.05), and number of regions harboring re-entrant (p < 0.01) and focal (p < 0.05) drivers. With increased AF duration, a higher proportion of patients had multiple extra-PV driver regions, specifically in the inferoposterior left atrium (p < 0.01), superior right atrium (p < 0.05), and inferior right atrium (p < 0.05). Procedural AF termination was achieved in 70% of patients, but decreased with longer AF duration.
Conclusions:
The complexity of AF drivers increases with prolonged AF duration. Re-entrant and focal drivers are predominantly located in the PV antral and adjacent regions. However, with longer AF duration, multiple drivers are distributed at extra-PV sites. AF termination rate declines as patients progress to longstanding PsAF, underscoring the importance of early intervention.
Previously confined to the management of rare inherited arrhythmia syndromes, a role for genetics within cardiac electrophysiology has begun to emerge for more common arrhythmias, including atrial fibrillation (AF). Catheter ablation for AF is an invasive procedure effective for restoring normal rhythm, however, fails in up to 40% of those undergoing their first procedure and carries a risk for serious adverse events. Recent studies have suggested that a common genetic variant within chromosome 4q25 may be a powerful predictor of procedural success, highlighting the potential of an 'ablatogenomic' strategy. Although still in its infancy, an ablatogenomic approach for AF may facilitate delivery of ablation to those most likely to benefit, while sparing those prone to fail from its risks.
ntroduction
There are many different lesion sets that are used for the surgical ablation of atrial fibrillation (AF). One such pattern is the ‘box set’, a single ring of scar delivered anterior to the pulmonary veins, which aims to electrically isolate the posterior wall from the rest of the heart. However it remains unclear whether posterior wall isolation (PWI) is an effective lesion set for maintenance of sinus rhythm and whether it is necessary to achieve complete bidirectional block. We investigated the long-term integrity of the ‘box set’ lesion created during surgical AF ablation by epicardial High Intensity Focussed Ultrasound (HIFU). All patients had documented persistent or recurrent paroxysmal AF prior to surgery. We correlated this with subsequent success or failure in the abolition of atrial fibrillation.
Methods
With regional ethical and R&D approval, 101 patients who had previously undergone HIFU AF ablation greater than 4 years ago were screened for inclusion in the study. 17 patients agreed to late electrophysiological study: 11 with on-going AF and 6 in normal sinus rhythm.
Clinical history and 7-day holters were used to define the NSR group. We performed a diagnostic EP study using a transseptal approach in fully anticoagulated patients (INR>2.0 and ACT maintained at >300s). A catheter was placed in the coronary sinus (CS) and a circular multipolar mapping catheter was used to map the left atrium and pulmonary veins. Patients in atrial fibrillation were cardioverted. We recorded whether posterior wall (PW) and pulmonary vein (PV) isolation had been achieved at the surgical procedure. In selected cases we recorded a voltage map using either CARTO (Biosense- Webster) or NavX (St Jude Medical) to identify areas of ablation scar.
Results
All 11 patients with AF had absence of PW+PV isolation with fractionated electrograms recorded across the PW. In the 6 patients with long-term freedom from AF, PW+PV isolation was confirmed in 4 (67%) and in 1 there was prolonged conduction across the box-set lesion with CS to PW activation time of around 200ms versus 45ms from mid-CS to left atrial appendage. Of the 4 patients with confirmed PW+PV isolation, 1 had dissociated spontaneous atrial potentials within the box set area and the other 3 had electrical silence throughout with inability to capture the posterior wall pacing at 10mA at multiple sites.
Conclusions
There appears to be a clear correlation between the successful restoration of long-term sinus rhythm and isolation / delayed conduction from the pulmonary veins and posterior wall. Given the advent of hybrid atrial fibrillation ablation techniques designed to deliver this lesion set, these findings are timely and highly relevant.
Variant pulmonary venous anatomy is common and its pre-procedural recognition through cardiac imaging facilitates a personalized approach to ablation tailored to the individual patient. Close juxtaposition of the right and left pulmonary veins is an anatomic variation that serves as an ideal substrate for creation of a single box lesion set that concomitantly isolates the pulmonary veins and posterior wall. Isolation of the posterior wall may be an effective adjunctive ablative therapy among patients with persistent atrial fibrillation. Routine assessment for dormant conduction with adenosine serves as a valuable tool to assess for durability of ablation lesions and may improve clinical outcomes.
Atrial fibrillation (AF) is common in patients presenting for mitral valve surgery. Routine ablation of AF in such patients, although still not applied universally, is a recent phenomenon. This may be attributable to new data clarifying the pathogenesis of AF, the dangers of leaving it untreated, and development of new technologies that facilitate ablation. With a more comprehensive approach toward treating both the arrhythmia and the structural heart disease, it is estimated that surgeons could perform more than 10,000 ablation procedures annually. The purposes of this review are to (1) present the rationale for surgical ablation of AF in mitral valve patients, (2) describe the classic Maze procedure and its results, (3) detail new approaches to surgical ablation of AF, (4) emphasize the importance of the left atrial appendage, and (5) consider challenges and future directions in the ablation of AF in cardiac surgical patients.
The development of atrial fibrillation (AF) is one of the most common occurrences during follow-up after cardiac surgery. AF is a well recognized risk factor for increased postoperative complications and mortality. Preoperative use of antiarrhythmic medications has also been associated with a higher rate of postoperative AF. To enhance postoperative recovery of sinus rhythm in these patients, various perioperative antiarrhythmic drug regimens, including amiodarone, and repeated DC shock cardioversion have been adopted. Despite such strategies, AF tends to re-establish itself after surgery in over 75% of patients, with patients having mitral surgery faring worse than those undergoing aortic valve operations. The development of surgical ablation enables sinus rhythm to be restored in as many as 70% of patients. However, the large scale adoption of such techniques has also raised the issue of post-ablation arrhythmias. Although relapsing atrial fibrillation is generally addressed conservatively, most automatic arrhythmias require electrophysiological assessment and ablation, frequently transseptal. Completeness of the lesion sets and durable transmurality of the ablations are key to preventing most postoperative dysrhythmias.
Isolation of the pulmonary veins alone (PVI) is associated with a 50 to 70 % success rate in paroxysmal atrial fibrillation (AF) but is significantly lower for persistent AF. We sought to evaluate patient outcomes in terms of safety and efficacy when posterior left atrial box isolation is included as a catheter ablation strategy in patients with mainly persistent AF.
We performed an audit of 100 patients undergoing left atrial (LA) box isolation. Recurrence of arrhythmia was detected by evaluating symptoms and continuous 24 h ECG monitoring at 2, 6 and 12 months post procedure.
Seventy-two patients had persistent AF prior to procedure. Average duration of AF was 5.4 ± 5.2 years. All patients underwent circumferential PVI plus linear posterior LA lines to complete box isolation. At a mean follow-up of 12.5 ± 4.2 months, 75 patients were free from atrial fibrillation, 50.6 % of these were taking no antiarrhythmic medication. Twenty-five patients had recurrence of AF, 84 % of whom had previous persistent AF. The average time to recurrence post procedure was 5.9 ± 4.4 months. Thirteen patients underwent repeat procedures for recurrent AF. There were no adverse events relating to the procedure.
These results suggest that the strategy of left atrial box isolation is safe and effective, worthy of further evaluation in a multicentre registry.
Atrial fibrillation (AF) is the most common clinical arrhythmia and one of the most important factors for embolic stroke. In recent years, a tremendous amount has been learned about the pathophysiology and molecular biology of AF. Thus, pharmacologic interference with specific signal transduction pathways appears promising as a novel antiarrhythmic approach to maintain sinus rhythm and to prevent atrial clot formation. This review highlights the underlying molecular biology of atrial fibrillation, which may also be relevant for AF therapy.
Although posterior wall of left atrium (LA) is known to be arrhythmogenic focus, little is known about the effect of posterior wall isolation (PWI) in patients who undergo radiofrequency catheter ablation (RFCA) for persistent atrial fibrillation (PeAF).
We randomly assigned 120 consecutive PeAF patients to additional PWI [PWI (+), n=60] or control [PWI (-), n=60] groups. In all patients, linear ablation was performed after circumferential pulmonary vein isolation (PVI). Linear lesions included roof, anterior perimitral, and cavotricuspid isthmus lines with conduction block. In PWI (+) group, posterior inferior linear lesion was also conducted. Creatine kinase-MB (CK-MB) and troponin-T levels were measured 1day after RFCA. LA emptying fraction (LAEF) was assessed before and 12months after RFCA.
A total of 120 subjects were followed for 12months after RFCA. There were no significant differences between two groups in baseline demographics and LA volume (LAV). The levels of CK-MB and troponin-T and procedure time were not significantly different between the groups. AF termination during RFCA was more frequently observed in PWI (+) than control (P=0.035). During follow-up period, recurrence occurred in 10 (16.7%) patients in PWI (+) and 22 (36.7%) in control (P=0.02). The change in LAEF was not significantly different between the groups. On multivariate analysis, smaller LAV and additional PWI were independently associated with procedure outcome.
PWI in addition to PVI plus linear lesions was an efficient strategy without deterioration of LA pump function in patients who underwent RFCA for PeAF.
Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Atrial fibrillation is the most common sustained arrhythmia in clinical practice, associated with increased mortality, risk of stroke and heart failure, as well as the reduction of the quality of life. Atrial fibrillation may be encountered in young otherwise healthy individuals, due to the isolated electrophysiological disorder limited mostly to the pulmonary veins and posterior left atrial wall, or associated with the presence of advanced underlying heart disease and numerous cardiac and non-cardiac comorbidities with significant structural remodeling of the atrial myocardium. Due to limited efficacy and serious side effects of antiarrhythmic drugs, catheter ablation of atrial fibrillation, based on the pulmonary vein isolation for paroxysmal atrial fibrillation and adjunctive substrate modification for persistent atrial fibrillation, has emerged as an attractive and promissing alternative therapeutic option for selected patients with atrial fibrillation. In this review article, we discuss the electrophysiological left atrial abnormalities underlying lone atrial fibrillation and the role of pulmonary veins in pathophysiology of arrhythmia, and we summarize results of the studies on the long term outcome of catheter ablation of atrial fibrillation, as well as the studies on comparison of antiarrhythmic drugs with catheter ablation for treatment of atrial fibrillation. In addition, we present available data that provide better understanding of mechanisms, diagnosis, prevention and treatment of specific procedure-related complications and discuss current periprocedural anticoagulation strategies and their impact on the thromboembolic risk reduction.
Atrial fibrillation occurring in the absence of cardiovascular disease in individuals younger than 60 years is known as lone atrial fibrillation. Nearly 1-12% of atrial fibrillation is considered to be lone atrial fibrillation. As our understanding of atrial fibrillation grows, we wonder as to whether there is such as thing as "lone" atrial fibrillation? We know that male sex, obesity, obstructive sleep apnea, alcohol consumption and endurance sports increase the risk of developing lone atrial fibrillation. Family history of atrial fibrillation increases the risk strongly and there are several recognized mutations that are causative of lone atrial fibrillation. Common triggers for origin of atrial fibrillation are the pulmonary veins. The atrial substrate provides the reentry circuits for perpetuating the arrhythmia. The autonomic nervous system is a key modulator and allows the continuation of the atrial fibrillation. Catheter ablation has been very effective in the treatment of this condition. The ablation procedure involves isolation of the pulmonary veins, antrum, complex fractionated electrograms and other sites. Alternatively surgical techniques can be used to isolate the pulmonary veins and surgical techniques have evolved to minimally invasive procedures and these are as effective as catheter ablation. Early intervention improves the left atrial remodeling and may lead to fewer recurrences.
Despite the clinical importance of atrial fibrillation (AF), the development of chronic nonvalvular AF models has been difficult. Animal models of sustained AF have been developed primarily in the short-term setting. Recently, models of chronic ventricular myopathy and fibrillation have been developed after several weeks of continuous rapid ventricular pacing. We hypothesized that chronic rapid atrial pacing would lead to atrial myopathy, yielding a reproducible model of sustained AF.
Twenty-two halothane-anesthetized mongrel dogs underwent insertion of a transvenous lead at the right atrial appendage that was continuously paced at 400 beats per minute for 6 weeks. Two-dimensional echocardiography was performed in 11 dogs to assess the effects of rapid atrial pacing on atrial size. Atrial vulnerability was defined as the ability to induce sustained repetitive atrial responses during programmed electrical stimulation and was assessed by extrastimulus and burst-pacing techniques. Effective refractory period (ERP) was measured at two endocardial sites in the right atrium. Sustained AF was defined as AF > or = 15 minutes. In animals with sustained AF, 10 quadripolar epicardial electrodes were surgically attached to the right and left atria. The local atrial fibrillatory cycle length (AFCL) was measured in a 20-second window, and the mean AFCL was measured at each site. Marked biatrial enlargement was documented; after 6 weeks of continuous rapid atrial pacing, the left atrium was 7.8 +/- 1 cm2 at baseline versus 11.3 +/- 1 cm2 after pacing, and the right atrium was 4.3 +/- 0.7 cm2 at baseline versus 7.2 +/- 1.3 cm2 after pacing. An increase in atrial area of at least 40% was necessary to induce sustained AF and was strongly correlated with the inducibility of AF (r = .87). Electron microscopy of atrial tissue demonstrated structural changes that were characterized by an increase in mitochondrial size and number and by disruption of the sarcoplasmic reticulum. After 6 weeks of continuous rapid atrial pacing, sustained AF was induced in 18 dogs (82%) and nonsustained AF was induced in 2 dogs (9%). AF occurred spontaneously in 4 dogs (18%). Right atrial ERP, measured at cycle lengths of 400 and 300 milliseconds at baseline, was significantly shortened after pacing, from 150 +/- 8 to 127 +/- 10 milliseconds and from 147 +/- 11 to 123 +/- 12 milliseconds, respectively (P < .001). This finding was highly predictive of inducibility of AF (90%). Increased atrial area (40%) and ERP shortening were highly predictive for the induction of sustained AF (88%). Local epicardial ERP correlated well with local AFCL (R2 = .93). Mean AFCL was significantly shorter in the left atrium (81 +/- 8 milliseconds) compared with the right atrium 94 +/- 9 milliseconds (P < .05). An area in the posterior left atrium was consistently found to have a shorter AFCL (74 +/- 5 milliseconds). Cryoablation of this area was attempted in 11 dogs. In 9 dogs (82%; mean, 9.0 +/- 4.0; range, 5 to 14), AF was terminated and no longer induced after serial cryoablation.
Sustained AF was readily inducible in most dogs (82%) after rapid atrial pacing. This model was consistently associated with biatrial myopathy and marked changes in atrial vulnerability. An area in the posterior left atrium was uniformly shown to have the shortest AFCL. The results of restoration of sinus rhythm and prevention of inducibility of AF after cryoablation of this area of the left atrium suggest that this area may be critical in the maintenance of AF in this model.
Although atrial fibrillation (AF) is a common disease, there is relatively few publications on its associated pathology. Autopsy studies[1,2,3,4,5] report the lesions observed in a large variety of structural heart and systemic diseases causing multiple clinical presentations of AF (acute or chronic, permanent or paroxysmal). Others studies focuses on AF in rheumatic disease using autopsy examination[6] or biopsy studies[7,8] done during surgery for rheumatic mitral valve lesions. More recent works[9,10,11] address the problem of “lone” atrial fibrillation occurring in the absence of structural Heart Disease or of metabolic diseases. The pathological findings suggest that cardiomyopathic changes in the atria could be the anatomical substrate for the fibrillation. We report pathological findings in eleven cases of long-standing, drug-resistant AFs treated surgically with the Corridor operation[12–15].
Background:
The purpose of this study was to determine the feasibility and mechanistic implications of segmental pulmonary vein (PV) ostial ablation during atrial fibrillation (AF).
Methods and results:
Forty consecutive patients underwent PV isolation for AF. Among 125 PVs targeted for isolation, ablation was performed during AF in 70 veins and during sinus rhythm in 55 veins. A decapolar Lasso catheter was positioned near the ostium. During AF, ostial ablation was performed near the Lasso catheter electrodes that recorded a tachycardia with a cycle length shorter than in the adjacent left atrium. During sinus rhythm, ostial ablation was guided by PV potentials. Complete PV isolation was achieved in 70 PVs (100%) ablated during AF and in 53 PVs (96%) ablated during sinus rhythm (P=0.4). The mean durations of radiofrequency energy needed for isolation were 7.4+/-4.4 and 5.2+/-3.9 minutes during AF and sinus rhythm, respectively (P<0.01). Before ablation, an immediate recurrence of AF (IRAF), occurred after cardioversion in 18 of 40 patients, and IRAF was consistently abolished by PV isolation. The probability of AF termination during isolation of a PV was directly related to the extent of tachycardia in that vein. As more PVs were isolated, induction of persistent AF by rapid pacing became less likely.
Conclusions:
Segmental ostial ablation guided by PV tachycardia during AF is feasible and as efficacious as during sinus rhythm. The responses to cardioversion, ablation, and rapid pacing observed in this study imply that IRAF is triggered by the PVs and that PV tachycardias may play an important role in the perpetuation of AF.
The purpose of this study was to determine the feasibility and mechanistic implications of segmental pulmonary vein (PV) ostial ablation during atrial fibrillation (AF).
Forty consecutive patients underwent PV isolation for AF. Among 125 PVs targeted for isolation, ablation was performed during AF in 70 veins and during sinus rhythm in 55 veins. A decapolar Lasso catheter was positioned near the ostium. During AF, ostial ablation was performed near the Lasso catheter electrodes that recorded a tachycardia with a cycle length shorter than in the adjacent left atrium. During sinus rhythm, ostial ablation was guided by PV potentials. Complete PV isolation was achieved in 70 PVs (100%) ablated during AF and in 53 PVs (96%) ablated during sinus rhythm (P=0.4). The mean durations of radiofrequency energy needed for isolation were 7.4+/-4.4 and 5.2+/-3.9 minutes during AF and sinus rhythm, respectively (P<0.01). Before ablation, an immediate recurrence of AF (IRAF), occurred after cardioversion in 18 of 40 patients, and IRAF was consistently abolished by PV isolation. The probability of AF termination during isolation of a PV was directly related to the extent of tachycardia in that vein. As more PVs were isolated, induction of persistent AF by rapid pacing became less likely.
Segmental ostial ablation guided by PV tachycardia during AF is feasible and as efficacious as during sinus rhythm. The responses to cardioversion, ablation, and rapid pacing observed in this study imply that IRAF is triggered by the PVs and that PV tachycardias may play an important role in the perpetuation of AF.
Background-Circumferential radiofrequency ablation around pulmonary vein (PV) ostia has recently been described as a new anatomic approach for atrial fibrillation (AF). Methods and Results-We treated 251 consecutive patients with paroxysmal (n=179) or permanent (n=72) AF. Circular PV lesions were deployed transseptally during sinus rhythm (n=124) or AF (n=127) using 3D electroanatomic guidance. Procedures lasted 148±26 minutes. Among 980 lesions surrounding individual PVs (n=956) or 2 ipsilateral veins with close openings or common ostium (n=24), 75% were defined as complete by a bipolar electrogram amplitude 30 ms across the line. The amount of low-voltage encircled area was 3594±449 mm 2 , which accounted for 23±9% of the total left atrial (LA) map surface. Major complications (cardiac tamponade) occurred in 2 patients (0.8%). No PV stenoses were detected by transesophageal echocardiography. After 10.4±4.5 months, 152 patients with paroxysmal AF (85%) and 49 with permanent AF (68%) were AF-free. Patients with and without AF recurrence did not differ in age, AF duration, prevalence of heart disease, or ejection fraction, but the LA diameter was significantly higher (P<0.001) in permanent AF patients with recurrence. The proportion of PVs with complete lesions was similar between patients with and without recurrence, but the latter had larger low-voltage encircled areas after radiofrequency (expressed as percent of LA surface area; P<0.001). Conclusions-Circumferential PV ablation is a safe and effective treatment for AF. Its success is likely due to both PV trigger isolation and electroanatomic remodeling of the area encompassing the PV ostia.
ObjectivesA specific left atrial (LA) linear lesion concept for treatment of paroxysmal and permanent atrial fibrillation (AF) was tested using intraoperative ablation with minimally invasive surgical techniques.
Background:
We have devised a simple surgical procedure to be performed on the posterior wall of the left atrium for the treatment of chronic atrial fibrillation (AF) associated with mitral valve disease. The effectiveness of this procedure for serial mitral valve operations was then evaluated. We postulated that chronic AF associated with mitral valve disease could be attributable to a distended left atrium. The refractory period of the distended left atrium was significantly shorter in the left posterior atrial wall, especially at the base of the left atrial appendage and at the orifice of the left posterior pulmonary vein. We hypothesized that the left posterior atrial wall with its shorter fibrillatory cycle length would act as a driver for maintaining the AF, and therefore, surgical ablation of this critical area in the left atrium could terminate the chronic AF.
Methods:
The surgical patients were divided into two groups. In group 1 (control group), 15 patients with chronic AF were operated on by the mitral valve procedure only. In group 2, 36 patients underwent this procedure in combination with a concomitant mitral valve operation. The disappearance rate of the AF was estimated by electrocardiography, and atrial function was estimated by transthoracic and transesophageal echocardiography.
Results:
The chronic AF had been reduced significantly or eliminated at discharge in 4 of 15 patients (26.7%) in the group 1, versus 31 of 36 patients (86%) in group 2 (p < 0.05). In group 2, 29 of the 31 patients (94%) whose AF had disappeared recovered the atrial kick of their right atrium, and 21 patients (22/31; 71%) recovered the atrial kick of their left atrium.
Conclusions:
Surgical ablation of the posterior wall of the left atrium was effective in the treatment of chronic AF associated with mitral valve disease. This simple procedure could restore a sinus rhythm and also recovered atrial systolic function. We conclude that the left atrium may act as a driver for sustaining AF in mitral valve disease.
The "corridor" operation is designed to restore sinus rhythm to patients with atrial fibrillation by electrically isolating the sinus node, a band of atrial tissue and the atrioventricular (AV) node from the remaining atrial tissue. Nine patients with drug-refractory atrial fibrillation underwent this operation; four patients had chronic atrial fibrillation and five had paroxysmal atrial fibrillation; the mean duration of symptoms was 12 +/- 8 years. Patient ages ranged from 25 to 68 years (mean 48 +/- 12). At preoperative electrophysiologic study, no patient had evidence of an accessory AV pathway or AV node reentry. Sinus node recovery time could not be determined in five patients because of recurrent atrial fibrillation during or before programmed stimulation. At operation the corridor of atrial tissue connecting the sinus and AV nodes was successfully isolated from the remaining left and right atrial tissue in all patients. One patient required early reoperation for recurrent atrial fibrillation before hospital discharge. At the predischarge electrophysiologic study, the corridor remained isolated in all patients except for one patient who had intermittent conduction between the corridor and excluded right atrium. One patient had nonsustained atrial fibrillation and one had atrial tachycardia evident in the corridor. Atypical AV node reentry of uncertain significance was induced in one other patient. Over a total follow-up of 191 patient months (mean 21 +/- 20), seven patients remained free of atrial fibrillation. Two patients had recurrent atrial fibrillation, which in one patient was effectively controlled by a single antiarrhythmic agent. A permanent pacemaker was implanted in four patients for sinus node dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
In this study we tested the hypothesis that atrial fibrillation (AF) causes electrophysiological changes of the atrial myocardium which might explain the progressive nature of the arrhythmia.
Twelve goats were chronically instrumented with multiple electrodes sutured to the epicardium of both atria. Two to 3 Weeks after implantation, the animals were connected to a fibrillation pacemaker which artificially maintained AF. Whereas during control episodes of AF were short lasting (6 +/- 3 seconds), artificial maintenance of AF resulted in a progressive increase in the duration of AF to become sustained (> 24 hours) after 7.1 +/- 4.8 days (10 of 11 goats). During the first 24 hours of AF the median fibrillation interval shortened from 145 +/- 18 to 108 +/- 8 ms and the inducibility of AF by a single premature stimulus increased from 24% to 76%. The atrial effective refractory period (AERP) shortened from 146 +/- 19 to 95 +/- 20 ms (-35%) (S1S1, 400 ms). At high pacing rates the shortening was less (-12%), pointing to a reversion of the normal adaptation of the AERP to heart rate. In 5 goats, after 2 to 4 weeks of AF, sinus rhythm was restored and all electrophysiological changes were found to be reversible within 1 week.
Artificial maintenance of AF leads to a marked shortening of AERP, a reversion of its physiological rate adaptation, and an increase in rate, inducibility and stability of AF. All these changes were completely reversible within 1 week of sinus rhythm.
Lone atrial fibrillation (LAF) is a common clinical syndrome, but its origin remains unknown.
We performed endomyocardial biopsies of the right atrial septum (2 to 3 per patient; mean, 2.8) and of the two ventricles (6 per patient) in 12 patients (10 men, 2 women; mean age, 32 years) with paroxysmal LAF refractory to conventional antiarrhythmic treatment. As controls, we used endomyocardial biopsies (3 to 5 per patient; mean, 4.4) from the right atrial septum of 11 patients with Wolff-Parkinson-White syndrome (WPW) undergoing resection of the abnormal AV pathway. The weight of the biopsies ranged from 2.8 to 4.5 mg. Biopsy samples were processed for histology and electron microscopy and were read by a pathologist blinded to clinical data. All patients underwent two-dimensional Doppler echocardiography; cardiac catheterization; coronary angiography; and hormonal, virologic, and electrophysiological studies. All tests and WPW biopsies were normal, but all LAF atrial biopsy specimens (average, 2.8 per patient) showed abnormalities (P<.0001). The type of abnormalities varied: Two patients had a severe hypertrophy with vacuolar degeneration of the atrial myocytes and ultrastructural evidence of fibrillolysis occupying >50% of the areas assessed morphometrically (P=.50), 8 had lymphomononuclear infiltrates with necrosis of the adjacent myocytes (5 with fibrosis and 3 without; P<.003), and 2 had only nonspecific patchy fibrosis (P=.50). Biventricular biopsies were abnormal in only 3 patients and showed inflammatory infiltrates similar to those found in atrial biopsies.
Abnormal atrial histology was uniformly found in multiple biopsy specimens in all patients with LAF. It was compatible with a diagnosis of myocarditis in 66% of patients (active in 25%) and of noninflammatory localized cardiomyopathy in 17% and was represented by patchy fibrosis in 17%. The cause of the pathological changes, which were found only in atrial septal biopsies but not in biventricular biopsies, in 75% of patients remains unknown.
After cardioversion of sustained atrial fibrillation (AF), the electrical and contractile functions of the atria are impaired, and recurrences of AF frequently occur. Whether remodeling of the structure of atrial myocardium is the basis for this problem is not known.
Sustained AF was induced by electrical pacing in 13 goats instrumented long-term. The goats were killed after 9 to 23 weeks, and the atrial myocardium was examined by light and electron microscopy. The changes were quantified in left and right atrial free walls, appendages, trabeculae, the interatrial septum, and the bundle of Bachmann. A substantial proportion of the atrial myocytes (up to 92%) revealed marked changes in their cellular substructures, such as loss of myofibrils, accumulation of glycogen, changes in mitochondrial shape and size, fragmentation of sarcoplasmic reticulum, and dispersion of nuclear chromatin. These changes were accompanied by an increase in size of the myocytes (up to 195%). There were virtually no signs of cellular degeneration, and the interstitial space remained unaltered. The duration of sustained AF did not significantly affect the degree of myolytic cell changes.
Sustained AF in goats leads to predominantly structural changes in the atrial myocytes similar to those seen in ventricular myocytes from chronic hibernating myocardium. These structural changes may explain the depressed contractile function of atrial myocardium after cardioversion. This goat model of AF offers a new approach to study the cascade of events leading to sustained AF and its maintenance.
Atrial fibrillation, the most common sustained cardiac arrhythmia and a major cause of stroke, results from simultaneous reentrant wavelets. Its spontaneous initiation has not been studied.
We studied 45 patients with frequent episodes of atrial fibrillation (mean [+/-SD] duration, 344+/-326 minutes per 24 hours) refractory to drug therapy. The spontaneous initiation of atrial fibrillation was mapped with the use of multielectrode catheters designed to record the earliest electrical activity preceding the onset of atrial fibrillation and associated atrial ectopic beats. The accuracy of the mapping was confirmed by the abrupt disappearance of triggering atrial ectopic beats after ablation with local radio-frequency energy.
A single point of origin of atrial ectopic beats was identified in 29 patients, two points of origin were identified in 9 patients, and three or four points of origin were identified in 7 patients, for a total of 69 ectopic foci. Three foci were in the right atrium, 1 in the posterior left atrium, and 65 (94 percent) in the pulmonary veins (31 in the left superior, 17 in the right superior, 11 in the left inferior, and 6 in the right inferior pulmonary vein). The earliest activation was found to have occurred 2 to 4 cm inside the veins, marked by a local depolarization preceding the atrial ectopic beats on the surface electrocardiogram by 106+/-24 msec. Atrial fibrillation was initiated by a sudden burst of rapid depolarizations (340 per minute). A local depolarization could also be recognized during sinus rhythm and abolished by radiofrequency ablation. During a follow-up period of 8+/-6 months after ablation, 28 patients (62 percent) had no recurrence of atrial fibrillation.
The pulmonary veins are an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. These foci respond to treatment with radio-frequency ablation.
The activation patterns that underlie the irregular electrical activity during atrial fibrillation (AF) have traditionally been described as disorganized or random. Recent studies, based predominantly on statistical methods, have provided evidence that AF is spatially organized. The objective of this study was to demonstrate the presence of spatial and temporal periodicity during AF.
We used a combination of high-resolution video imaging, ECG recordings, and spectral analysis to identify sequential wave fronts with temporal periodicity and similar spatial patterns of propagation during 20 episodes of AF in 6 Langendorff-perfused sheep hearts. Spectral analysis of AF demonstrated multiple narrow-band peaks with a single dominant peak in all cases (mean, 9.4+/-2.6 Hz; cycle length, 112+/-26 ms). Evidence of spatiotemporal periodicity was found in 12 of 20 optical recordings of the right atrium (RA) and in all (n=19) recordings of the left atrium (LA). The cycle length of spatiotemporal periodic waves correlated with the dominant frequency of their respective optical pseudo-ECGs (LA: R2=0.99, slope=0.94 [95% CI, 0.88 to 0.99]; RA: R2=0.97, slope=0.92 [95% CI, 0.80 to 1.03]). The dominant frequency of the LA pseudo-ECG alone correlated with the global bipolar atrial EG (R2=0.76, slope=0.75 [95% CI, 0.52 to 0.99]). In specific examples, sources of periodic activity were seen as rotors in the epicardial sheet or as periodic breakthroughs that most likely represented transmural pectinate muscle reentry. However, in the majority of cases, periodic waves were seen to enter the mapping area from the edge of the field of view.
Reentry in anatomically or functionally determined circuits forms the basis of spatiotemporal periodic activity during AF. The cycle length of sources in the LA determines the dominant peak in the frequency spectra in this experimental model of AF.
The percutaneous approach to radiofrequency (RF) catheter ablation for curative treatment of atrial fibrillation (AF) is an investigational technique, and the optimal composition of lesion lines is unknown. We tested an intraoperative RF ablation concept with elimination of left atrial anatomic "anchor" reentrant circuits.
In 12 patients with an indication for valve surgery and chronic AF, a right atrial-transseptal approach was chosen for access to the left atrium. AF had been present for 4.3 +/- 3.9 years; the left atria measured 56 +/- 7 mm. Under direct vision, contiguous lesion lines were placed endocardially with temperature-guided RF energy applications for treatment of AF with a specially designed probe. The lesion lines were placed between the mitral annulus and the left lower pulmonary vein, further to the left upper pulmonary vein, from there to the right upper pulmonary vein, and finally to the right lower pulmonary vein. The antiarrhythmic ablation procedure lasted 19 +/- 4 minutes. One patient died postoperatively of low cardiac output. During follow-up of 11 +/- 6 months, chronic AF was ablated successfully in 9 of 11 patients (82%). Six patients were in stable sinus rhythm or intermittent pacemaker rhythm, and three patients were in sinus rhythm with intermittent atypical atrial flutter.
Intraoperative RF energy application for induction of contiguous lesion lines is feasible. Elimination of anatomically defined "anchor" reentrant circuits within the left atrium prevented chronic AF in > 80% of the patients treated. Intraoperative validation of lesion line concepts for curative treatment of AF may be transferred to percutaneous ablation techniques.
Studies of atrial fibrillation (AF) due to atrial tachycardia have provided insights into the remodeling mechanisms by which "AF begets AF" but have not elucidated the substrate that initially supports AF before remodeling occurs. We studied the effects of congestive heart failure (CHF), an entity strongly associated with clinical AF, on atrial electrophysiology in the dog and compared the results with those in dogs subjected to rapid atrial pacing (RAP; 400 bpm) with a controlled ventricular rate (AV block plus ventricular pacemaker at 80 bpm).
CHF induced by 5 weeks of rapid ventricular pacing (220 to 240 bpm) increased the duration of AF induced by burst pacing (from 8+/-4 seconds in control dogs to 535+/-82 seconds; P<0.01), similar to the effect of 1 week of RAP (713+/-300 seconds). In contrast to RAP, CHF did not alter atrial refractory period, refractoriness heterogeneity, or conduction velocity at a cycle length of 360 ms; however, CHF dogs had a substantial increase in the heterogeneity of conduction during atrial pacing (heterogeneity index in CHF dogs, 2. 76+/-0.16 versus 1.46+/-0.10 for control and 1.51+/-0.06 for RAP dogs; P<0.01) owing to discrete regions of slow conduction. Histological examination revealed extensive interstitial fibrosis (connective tissue occupying 12.8+/-1.9% of the cross-sectional area) in CHF dogs compared with control (0.8+/-0.3%) and RAP (0. 9+/-0.2%) dogs.
Experimental CHF strongly promotes the induction of sustained AF by causing interstitial fibrosis that interferes with local conduction. The substrates of AF in CHF are very different from those of atrial tachycardia-related AF, with important potential implications for understanding, treating, and preventing AF related to CHF.
Concomitant microwave ablation for curative treatment of atrial fibrillation (AF) was performed in 18 patients with history of chronic atrial fibrillation and indication for open heart surgery, 11 patients with mitral valve replacement and 7 patients with coronary artery bypass grafting. There were no perioperative complications. During the postoperative period most of the patients had intermittent AF, they received low dose Sotalol therapy and electric cardioversions. Up to now seven patients have reached follow-up day 90. One patient has persistent AF. Two patients had typical atrial flutter that was electrically converted to sinus rhythm (SR), isthmus ablation is planned. The other four patients have SR, one patient without cardioversions. These four patients show recovered atrial function with observed A-wave for transmitral flow. Under visual guidance the continuous atrial lesion lines could be induced effectively and safely by the intraoperative device Lynx.
The aim of the present study was to determine if myocytes can die by apoptosis in fibrillating and dilated human atria.
The cellular remodeling that occurs during atrial fibrillation (AF) may reflect a degree of dedifferentiation of the atrial myocardium, a process that may be reversible.
We examined human right atrial myocardium specimens (n = 50) for the presence of apoptotic myocytes. We used immunohistochemical and Western blotting analysis to examine the expression of a final effector of programmed cell death, caspase-3 (CASP-3) and of regulatory proteins from the BCL-2 family.
Sections from atria in AF contained a high percentage of large myocytes with a disrupted sarcomeric apparatus replaced by glycogen granules (64.4 +/- 6.3% vs. 12.2 +/- 5.8%). These abnormal myocytes, which also predominated in atria from hearts with decreased left ventricular ejection fraction (42.3 +/- 10.1%), contained large nuclei, most of which were TUNEL positive, indicating a degree of DNA breakage. None of these abnormal myocytes expressed the proliferative antigen Ki-67. A small percentage of the enlarged nuclei (4.2 +/- 0.8%) contained condensed chromatin and were strongly TUNEL positive. Both the pro- and activated forms of CASP-3 were detected in diseased myocardial samples, which also showed stronger CASP-3 expression than controls. Expression of the antiapoptotic BCL-2 protein was decreased in diseased atria, whereas that of the proapoptotic BAX protein remained unchanged.
In fibrillating and dilated atria, apoptotic death of myocytes with myolysis contributes to cellular remodeling, which may not be entirely reversible.
Atrial fibrillation (AF) has traditionally been described as aperiodic or random. Yet, ongoing sources of high-frequency periodic activity have recently been suggested to underlie AF in the sheep heart. Our objective was to use a combination of optical and bipolar electrode recordings to identify sites of periodic activity during AF and elucidate their mechanism.
AF was induced by rapid pacing in the presence of 0.1 to 0.5 micromol/L acetylcholine in 7 Langendorff-perfused sheep hearts. We used simultaneous optical mapping of the right and left atria (RA and LA) and frequency sampling of optical and bipolar electrode recordings (including a roving electrode) to identify sites having the highest dominant frequency (DF). Rotors were identified from optical recordings, and their rotation period, core area, and perimeter were measured. In all, 35 AF episodes were analyzed. Mean LA and RA DFs were 14.7+/-3.8 and 10.3+/-2.1 Hz, respectively. Spatiotemporal periodicity was seen in the LA during all episodes. In 5 of 7 experiments, a single site having periodic activity at the highest DF was localized. The highest DF was most often (80%) localized to the posterior LA, near or at the pulmonary vein ostium. Rotors (n=14) were localized on the LA. The mean core perimeter and area were 10.4+/-2.8 mm and 3.8+/-2.8 mm(2), respectively.
Frequency sampling allows rapid identification of discrete sites of high-frequency periodic activity during AF. Stable microreentrant sources are the most likely underlying mechanism of AF in this model.
This study was designed to determine if intraoperative atrial activation mapping facilitates operations for chronic atrial fibrillation associated with mitral valve disease.
Surgical treatment guided by intraoperative electrophysiologic mapping was performed in 12 patients with chronic atrial fibrillation associated with isolated mitral valve disease. In 10 of 12 patients, regular and repetitive activation (cycle length ranged from 118 to 210 msec) originated in the left atrial appendage and/or orifice of the left pulmonary vein. In the remaining 2 patients, dominant repetitive activation and sporadic complex activation were alternately observed in the left atrium. However, the activation sequence of the right atrium was extremely complex and chaotic.
On the basis of intraoperative mapping, surgical procedures, including resection of the left atrial appendage and/or cryoablation of the orifice of the left pulmonary vein, were applied on the breakthrough site of the repetitive activation. No surgical procedure was performed on the right atrium in 11 patients. Ten of 12 patients (83%) have maintained sinus rhythm for 6 to 40 months (average 24.8 months) after operation.
In the majority of the patients with isolated mitral valve disease, the left atrium acts as an electrical driving chamber for chronic atrial fibrillation. Computerized intraoperative mapping should guide surgeons in determining the appropriate surgical procedure for chronic atrial fibrillation.
Since the first patient underwent the Maze procedure on September 25, 1987, 346 patients have undergone this operation for the treatment of atrial fibrillation. The procedure was designed as an open-heart operation performed through a median sternotomy. It underwent 2 major modifications relatively early in the series, evolving into the so-called Maze-III procedure, which has been used exclusively since April 16, 1992. Since that time, the Maze-III procedure has been adapted to allow it to be done by minimally invasive techniques. In addition, we recently performed the entire procedure in 2 patients without the use of cardiopulmonary bypass. The operative mortality rate has remained at 2% to 3%. This includes patients undergoing concomitant high-risk cardiac surgical procedures and all re-do cases. The overall success rate in curing atrial fibrillation has been 99%. The procedure itself has been shown to cause no permanent damage to the sinus node. The left atrium has been documented to function long-term postoperatively in 93% of patients and the right atrium functions in 99% of patients. The Maze-III procedure remains the surgical procedure of choice for the treatment of medically refractory atrial fibrillation.
We describe an original radiofrequency ablation technique to treat chronic atrial fibrillation in patients undergoing mitral valve surgery. Most of the procedure is carried out epicardially, in order to avoid an undue increase of surgical time and trauma.
The ablations are performed using a temperature-controlled multipolar radiofrequency catheter. Two encircling lesions around the ostia of the right and of the left pulmonary veins are carried out epicardially, usually before cardiopulmonary bypass. Through a conventional left atriotomy the ablation procedure is completed with two endocardial lesions connecting the two encirclings between them and to the mitral valve annulus. After the mitral valve procedure is performed, the left appendage is sutured.
From February 1998 to May 1999, 40 patients with chronic atrial fibrillation (43. 1+/-51.9 months) underwent combined radiofrequency ablation and mitral valve surgery. Mean left atrial diameter was 56.8+/-10.7 mm. Mean cardiopulmonary bypass and aortic cross-clamp time were, respectively, 119.1+/-26.3 and 76.7+/-21.0 min. Mean postoperative blood loss was 287.2+/-186.6 ml. No reexploration for bleeding occurred. One patient died of pneumonia 12 days after operation. No patient needed permanent pacemaker implantation. Mean postoperative hospital stay was 7.3+/-5.6 days. At follow-up (mean 11.6+/-4.7 months), 30/39 (76.9%) of the patients were in stable sinus rhythm. All patients in sinus rhythm 3 months after operation recovered both left and right atrial contractility at echocardiographic control (mean 7.3+/-3.4 months). The left atrial diameter decreased significantly in patients recovering sinus rhythm.
Epicardial radiofrequency ablation is a safe means to achieve surgical ablation of atrial fibrillation with a high success rate. The simplicity of the technique and the low procedure-related risk should dictate combined treatment virtually in all patients with atrial fibrillation undergoing open heart operations.
Most episodes of focal atrial fibrillation (AF) can be initiated by premature beats originating from the pulmonary veins (PV). However, the role of rapid focal activation in the maintenance of AF is unclear. Thirty-two patients with focal AF who underwent focal ablation of triggering ectopic beats were studied. Bipolar electrograms from all four PVs were recorded simultaneously. The cycle length (CL) of RFA at sites that triggered AF was measured at AF onset, after 5 minutes of sustained AF, and just before the spontaneous termination of 32 episodes of nonsustained AF. Fifteen episodes of sustained AF (> 10 minutes) and 17 episodes of nonsustained AF (5-120 seconds, mean 56 +/- 59 seconds) were analyzed. In sustained AF, the mean CL of RFA in the PV from which it originated was not significantly different than in the other PVs, and RFA was continuously observed. In nonsustained AF, the mean CL of RFA in a PV from which it originated was significantly shorter than in other PVs and, when RFA disappeared, AF terminated. RFA in 1 PV induced RFA in another PV. In conclusion, widespread conduction of RFA from a PV at its source to the other sites may be necessary for the sustenance of AF. A PV interaction, a RFA triggering another, may be involved in the maintenance of AF. RFA arising from PVs is important not only as a trigger of onset, but also in the maintenance of AF.
Atrial fibrillation (AF) is commonly encountered in clinical practice and typically it is treated with pharmacological agents. Some patients whose arrhythmias are resistant to pharmacological therapy undergo the maze procedure, which is a surgical treatment. The atrial appendages are removed as part of the surgical procedure. These appendages often demonstrate mycocyte hypertrophy, vacuolar degeneration and other changes that may be seen in cardiomyopathies. We examined 19 of these appendages and compared them with 17 autopsy controls, 12 of whom had documented coronary atherosclerotic disease and 5 of whom did not. We semiquantitatively measured the amount of vacuolar degeneration, interstitial fibrosis, myocyte hypertrophy and intramyocardial adipose tissue. Univariate and multivariate analysis was performed and revealed that vacuolar degeneration were significantly more common in appendages of patients with arrhythmias than the autopsy controls (P<.0004). The other three histological features studied were not significantly different in the three groups. Ultrastructural studies on atrial tissue excised during the maze procedure, retrieved from the paraffin blocks, revealed degenerative changes similar to cardiomyopathic myocardial tissue. Vacuolar degeneration is commonly seen in atrial appendages removed in patients with chronic AF. Myocyte hypertrophy is a nonspecific finding and may occur in patients with arrhthymias and coronary artery disease.
Circumferential radiofrequency ablation around pulmonary vein (PV) ostia has recently been described as a new anatomic approach for atrial fibrillation (AF).
We treated 251 consecutive patients with paroxysmal (n=179) or permanent (n=72) AF. Circular PV lesions were deployed transseptally during sinus rhythm (n=124) or AF (n=127) using 3D electroanatomic guidance. Procedures lasted 148+/-26 minutes. Among 980 lesions surrounding individual PVs (n=956) or 2 ipsilateral veins with close openings or common ostium (n=24), 75% were defined as complete by a bipolar electrogram amplitude <0.1 mV inside the lesion and a delay >30 ms across the line. The amount of low-voltage encircled area was 3594+/-449 mm(2), which accounted for 23+/-9% of the total left atrial (LA) map surface. Major complications (cardiac tamponade) occurred in 2 patients (0.8%). No PV stenoses were detected by transesophageal echocardiography. After 10.4+/-4.5 months, 152 patients with paroxysmal AF (85%) and 49 with permanent AF (68%) were AF-free. Patients with and without AF recurrence did not differ in age, AF duration, prevalence of heart disease, or ejection fraction, but the LA diameter was significantly higher (P<0.001) in permanent AF patients with recurrence. The proportion of PVs with complete lesions was similar between patients with and without recurrence, but the latter had larger low-voltage encircled areas after radiofrequency (expressed as percent of LA surface area; P<0.001).
Circumferential PV ablation is a safe and effective treatment for AF. Its success is likely due to both PV trigger isolation and electroanatomic remodeling of the area encompassing the PV ostia.
The natural history of atrial fibrillation (AF) is characterized by a gradual worsening with time. The recent finding that AF itself produces changes in atrial function and structure has provided a possible explanation for the progressive nature of this arrhythmia. Electrical remodeling (shortening of atrial refractoriness) develops within the first days of AF and contributes to an increase in stability of AF. However, 'domestication of AF' must also depend on a 'second factor' since the persistence of AF continues to increase after electrical remodeling has been completed. Atrial contractile remodeling (loss of contractility) leads to a reduced atrial transport function after cardioversion of AF. An important clinical consequence is that during several days after restoration of sinus rhythm, the risk of atrial thrombus formation is still high. In addition, the reduction of atrial contractility during AF may enhance atrial dilatation which may add to the persistence of AF. Tachycardia-induced structural remodeling takes place in a different time domain (weeks to months). Myolysis probably contributes to the loss of atrial contractile force. Although it might explain the loss of efficacy of pharmacological cardioversion and the development of permanent AF, the role of structural remodeling in the progression of AF is still unclear. Atrial structural remodeling also occurs as a result of heart failure and other underlying cardiovascular diseases. The associated atrial fibrosis might explain intra-atrial conduction disturbances and the susceptibility for AF. Thus, both AF itself and the underlying heart disease are responsible for the development of the arrhythmogenic substrate. New strategies for prevention and termination of AF should be build on our knowledge of the mechanisms and time course of AF-induced atrial remodeling.
Activation patterns during permanent atrial fibrillation (AF) in patients with organic heart diseases are unclear.
We studied six patients with permanent AF and organic heart diseases undergoing surgery. The duration of AF averaged 4.9+/-7.6 years. Computerized epicardial mappings of the right atrial (RA) free wall and the left atrial (LA) posterior wall were simultaneously performed with 224 bipolar electrodes at 3-mm spatial resolution. In the RA, large wavefronts and conduction blocks were frequently observed. The lines of block correlated with the crista terminalis and large pectinate muscles. In contrast, the LA had rapid repetitive activities originated from corners of the electrode plaque, near the four pulmonary veins (PVs). On average, 2.8+/-1.2 sites of rapid repetitive activities were identified per patient. They activated continuously, intermittently, or alternately during AF. The mean activation cycle length in the RA (196+/-22 msec) was significantly longer than that in the LA (179+/-26 msec; P = 0.004). The maximum dominant frequency in the LA was higher than that in the RA (6.41+/-1.18 Hz vs 5.66+/-0.55 Hz; P = 0.049). The maximum dominant frequency was consistently located in areas with rapid repetitive activations near the PVs.
During human permanent AF associated with organic heart diseases, the activation cycle length was shorter in the LA posterior wall than in the RA free wall. Rapid repetitive activities are consistently observed in the LA posterior wall, at or near the PVs.
A specific left atrial (LA) linear lesion concept for treatment of paroxysmal and permanent atrial fibrillation (AF) was tested using intraoperative ablation with minimally invasive surgical techniques.
Curative treatment for patients with chronic AF is among the main challenges of interventional electrophysiology.
Seventy patients (mean age 53 +/- 10 years) with drug-refractory persistent (n = 28) or paroxysmal (n = 42) AF underwent intraoperative radiofrequency (RF) ablation using video-assisted minimally invasive techniques via a right anterolateral minithoracotomy. Contiguous lesion lines involving the mitral annulus and the orifices of the pulmonary veins were placed with RF energy application under direct vision to prevent anatomically defined LA re-entrant circuits.
Mean follow-up was 18 +/- 7 months in patients with permanent AF and 18 +/- 5 months in patients with paroxysmal AF. Antiarrhythmic drug treatment was instituted in patients with postoperative atrial arrhythmias to allow "reverse electrical remodeling" and was discontinued after three months. Six months following ablation, 93% of the patients were in sinus rhythm in both groups, and after 12 months, 95% and 97%, respectively. As major complications, one esophagus perforation and one circumflex coronary artery stenosis were observed.
A pure linear lesion line concept confined to the left atrium targeting specifically at elimination of anatomically defined LA "anchor" re-entrant circuits eliminated AF in >90% of the patients treated with intraoperative ablation using minimally invasive surgical techniques over a mean follow-up of 1.5 years.
The patterns of activation of the human left atrium (LA), how they relate to atrial myocardial architecture, and their role in arrhythmogenesis remain largely unknown.
Left atrial endocardial activation was mapped in 19 patients with a percutaneous noncontact mapping system. Earliest endocardial breakthrough during sinus rhythm (SR) occurred more frequently in the septal (63%, principally posteroseptal) than anterosuperior (37%) LA and varied little with isoproterenol or high right atrial pacing rate. Regardless of site of breakthrough, LA activation was characterized in all patients by propagation around a variably complete line of functional conduction block, descending on the posterior wall from the roof, passing between the ostia of the superior and then inferior pulmonary veins (PVs) before turning septally, passing below the oval fossa, and merging further anteriorly with the septal mitral annulus. Examination of the myocardial architecture in 10 normal adult postmortem hearts revealed an abrupt change in subendocardial fiber orientation along a line following the same course. During episodes of focal initiation of atrial fibrillation (AF), interaction was observed between wavefronts entering the LA from PVs and this functional line of conduction block that resulted in LA macroreentry or formation of daughter wavefronts.
The LA endocardium has complex but characteristic patterns of activation during sinus rhythm, pacing, and AF initiation by PV ectopy that are determined largely by the functional properties of atrial musculature. These findings have important implications for both pacing and ablative strategies for the prevention of initiation of AF.
Clinically, chronic atrial dilatation is associated with an increased incidence of atrial fibrillation (AF), but the underlying mechanism is not clear. We have investigated atrial electrophysiology and tissue structure in a canine model of chronic atrial dilatation due to mitral regurgitation (MR).
Thirteen control and 19 MR dogs (1 month after partial mitral valve avulsion) were studied. Dogs in the MR group were monitored using echocardiography and Holter recording. In open-chest follow-up experiments, electrode arrays were placed on the atria to investigate conduction patterns, effective refractory periods, and inducibility of AF. Alterations in tissue structure and ultrastructure were assessed in atrial tissue samples. At follow-up, left atrial length in MR dogs was 4.09+/-0.45 cm, compared with 3.25+/-0.28 at baseline (P<0.01), corresponding to a volume of 205+/-61% of baseline. At follow-up, no differences in atrial conduction pattern and conduction velocities were noted between control and MR dogs. Effective refractory periods were increased homogeneously throughout the left and right atrium. Sustained AF (>1 hour) was inducible in 10 of 19 MR dogs and none of 13 control dogs (P<0.01). In the dilated MR left atrium, areas of increased interstitial fibrosis and chronic inflammation were accompanied by increased glycogen ultrastructurally.
Chronic atrial dilatation in the absence of overt heart failure leads to an increased vulnerability to AF that is not based on a decrease in wavelength.
Most of the ectopic beats initiating paroxysmal atrial fibrillation (PAF) originate from the pulmonary vein (PV). However, only limited data are available on PAF originating from the non-PV areas.
Two hundred forty patients with a total of 358 ectopic foci initiating PAF were included. Sixty-eight (28%) patients had AF initiated by ectopic beats (73 foci, 20%) from the non-PV areas, including the left atrial posterior free wall (28, 38.3%), superior vena cava (27, 37.0%), crista terminalis (10, 3.7%), ligament of Marshall (6, 8.2%), coronary sinus ostium (1, 1.4%), and interatrial septum (1, 1.4%). Catheter ablation eliminated AF with acute success rates of 63%, 96%, 100%, 50%, 100%, and 0% in left atrial posterior free wall, superior vena cava, crista terminalis, ligament of Marshall, coronary sinus ostium, and interatrial septum, respectively. During a follow-up period of 22+/-11 months, 43 patients (63.2%) were free of antiarrhythmic drugs without AF recurrence.
Ectopic beats initiating PAF can originate from the non-PV areas, and catheter ablation of the non-PV ectopy has a moderate efficacy in treatment of PAF.
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Pathologie de la fibrillation auriculaire
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Guiraudon C. Pathologie de la fibrillation auriculaire. In: Anonymous. La
Fibrillation Auriculaire. Paris, France: Louis Pariente; 1997:52– 64.