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Twelve-lead ECG showing (A) pre-excited QRS complexes in Patient 1 with negative delta-wave in aVR and aVL, iso-electric in V1 and V2, and positive in other leads; (B) during AT the P-waves in lead I, aVL and V1, were negative, iso-electric or biphasic with an initial downward deflection in both left AT (LAT) cases contrasting to predominantly positive or biphasic with initial upward deflection in the right AT (RAT) case.
Source publication
Radiofrequency (RF) ablation near the AV node carries a significant risk of AV block. We report our initial experience of using cryomapping function to aid the safe cryoablation close to the compact atrioventricular (AV) node.
Five consecutive patients with para-Hisian accessory pathways (AP) ( n = 2), or focal atrial tachycardia (AT) originating n...
Contexts in source publication
Context 1
... ECGs during sinus rhythm revealed pre-excited QRS complexes in Patient 1 (Fig. 1A). The P-wave durations recorded during AT were shorter than that in sinus rhythm (457.3 ± 6.1 vs. 115.3 ± 8.1 ms, p = 0.0004), and the P-wave mor- phologies were summarized in Fig. ...
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Citations
... It should be considered as an interesting alternative to radiofrequency ablation in all these cases. 15,16 Fluoroless cryoablation guided by a 3D electroanatomical mapping system has also been shown to be feasible in all patients with atrioventricular nodal reentry tachycardia (AVNRT) without compromising the safety, efficacy, or duration of the procedure. 17 ...
Aims:
Although cryoenergy safety profile is appropriate for the ablation of arrhythmogenic foci near the conduction system, mapping using the cryoablation catheter is of limited precision. Combining the safety of cryoenergy and the high precision of a 3D mapping system therefore appears the most appropriate set-up for ablation in the vicinity of the His bundle.
Methods and results:
A 29-year-old woman with a 3-year history of increasing shortness of breath and palpitations refractory to medical treatment was sent to the electrophysiology (EP) laboratory for catheter ablation. Surface electrocardiogram showed sinus rhythm and frequent ectopic beats with narrow QRS complexes similar to those of the sinus beats. The left ventricular ejection fraction was impaired (38%) with no other aetiology found, apart from frequent ectopies. Detailed intracardiac mapping, using a 3D electroanatomical system, revealed that the ectopy originated from the distal His bundle, which was indicated by both antegrade and reversed His bundle activation sequence during ectopy compared to that during sinus rhythm. Due to the proximity of the conduction system, cryoenergy rather than radiofrequency was chosen to target this Hisian ectopy. A special set-up was made in order to allow the cryoablation catheter to be visualized into the 3D mapping system. Cryoenergy delivered to the site of earliest Hisian ectopy activation completely abolished it.
Conclusion:
Such a combined approach may help to improve the therapeutic strategy for ablation procedures with a high risk of injury to the conduction system. It could notably be extended to the ablation of para-Hisian ectopy or accessory pathways.
... Voraussetzung jeder Ablation von Herzrhythmusstörungen ist die präzise Lokalisation des Erregungsursprungs, einer für die Arrhythmie kritischen Anatomie im Herzen oder essenzieller morphologischer Strukturen. Dazu gab es vielfältige Analysen aus dem 12-Kanal-Oberflächen-EKG, aus zusätzlichen Ableitungen bis zum Surface-Mapping [9], aus EKGgetriggerter Radionuklidventrikulographie [10], Magnetresonanztomographie [11], Reaktion auf Elektrostimulation mit uni-und bipolaren Ableitungen oder Kryo-Mapping bei epikardialen Elektrogrammen im herzchirurgischen Operationssaal [12]. Letztlich musste mit Mapping-Kathetern ein Schwachpunkt der Arrhythmie lokalisiert werden. ...
Der Schritt von der invasiven elektrophysiologischen Diagnostik von Arrhythmien zur interventionellen Behandlung – zur Katheterablation – lag von den Anfängen der His-Bündel-Elektrographie im Jahr 1967 an nahe. Dabei war das Zeitintervall von 15 Jahren zwischen Diagnostik und Therapie bei Arrhythmien sogar kürzer, als die Zeit, die zwischen der ersten selektiven Koronarangiographie 1958 an der Cleveland-Klinik in den USA bis zur ersten perkutanen Koronartherapie 1977 in Zürich (19 Jahre) lag. In beiden Fällen wurden in diesem Zeitraum vielfältige Erfahrungen bei der kardiochirurgischen Behandlung gesammelt, die sich für die Entwicklung der interventionellen Therapie als sehr hilfreich erwiesen. Damit erinnert die Geschichte der endovaskulären Behandlung eindrucksvoll daran, dass die Weiterentwicklung der internistischen kardiologischen Therapie der Vorarbeit, Mithilfe, der Unterstützung und manchmal auch des Komplikationsmanagements der Kardiochirurgen bedurfte. Wenn man aus der Geschichte der Katheterablation etwas lernen kann, so sollte es die Erkenntnis sein, dass die gemeinsame Arbeit von Kardiologen und Kardiochirurgen im Herzteam nicht nur dem einzelnen Patienten die für ihn beste Behandlung gestattet, sondern auch die Therapie insgesamt weiterentwickeln hilft.
... Thus, depending on the type of catheters, temperatures down to −80 • C and even below are measured [4,13] , while tissue temperature is significantly warmer. For example, when using a catheter with a metallic tip for ablation near the AV-node, a temperature of −30 • C inside the tip is recommended for avoiding irreversible ablation of the AV-node (cryo-mapping [31] ). However, −30 • C inside the tip may correspond to a significantly warmer, positive temperature at the AV-node when considering temperature gradients from tip to tissue. ...
Increasing impedance during freezing might be a valuable marker for guiding cardiac cryo-ablation. We provide model based insights on how decreasing temperature below the freezing point of tissue relates to the percentage of frozen water. Furthermore, we provide experimental data for comparing this percentage with the increase in impedance. Measurements were performed on a bovine tissue sample at frequencies between 5 and 80 kHz. Slow cooling and heating rates were applied to minimize temperature gradients in the myocardial sample and to allow accurate assessment of the freezing point. Computer simulation was applied to link impedance with temperature dependent conductivities. The osmotic virial equation was used to estimate the percentage of frozen water. Measurements identified the freezing point at -0.6 ∘C. At -5 ∘C, impedance rose by more than a factor of ten compared to that at the freezing point and the percentage of frozen water was estimated as being 89%. At -49 ∘C impedance had increased by up to three orders of magnitude and ice formation was most pronounced in the extracellular space. Progressive ice formation in tissue is reflected by a large increase in impedance, and impedance increases monotonically with the percentage of frozen water. Its analysis allows for experimental assessment of factors relevant to cell death. Solid ice contributes to the rupture of the micro-vasculature, while phase shifts reflect concentration differences between extra- and intracellular space driving osmotic water transfer across cell membranes.
... Concomitant premature ventricular contractions (PVCs) were mapped to be of para-Hisian origin in one male patient with PACs of high CT origin. There were 18 distribution of atrial ectopic foci was shown in Figure 2. The most common sites of origin were PVs (n ¼ 7, 20.0%), CT (n ¼ 6, 17.1%), and para-Hisian area (n ¼ 6, 17.1%), followed by mitral annulus (n ¼ 4, 11.4%) and left atrial posterior wall (n ¼ 3, 8.6%). This was followed by cavo-tricuspid annulus (n ¼ 2, 5.7%) and ostium of left atrial appendage (n ¼ 2, 5.7%). ...
... It was advisable to map para-Hisian PACs in NCC via retrograde aortic approach, but unfortunately they could not be eliminated in NCC in any of the patients in group A. Cryomapping and ablation for para-Hisian PACs might be advantageous over radiofrequency energy for safety consideration. 17,18 Of note, the risk-benefit of para-Hisian PACs ablation should be considered. The prevalence of AV block was not neglectable if repeated RF ablation at this area was performed. ...
Aims
Frequent premature atrial contractions (PACs) are associated with increased risk of atrial fibrillation (AF), stroke, and death. This study aimed to explore the electrophysiological features of PACs with and without inducing AF and to evaluate the effectiveness of catheter ablation for PACs.
Methods and results
Thirty-five consecutive patients with symptomatic, frequent, and drug-refractory PACs in the absence of AF (group A) and 35 patients with PACs-induced AF (group B) were enrolled. Coupling intervals (CoIs) of PACs were compared. Premature atrial contractions were mapped by the point-by-point and/or circular mapping technique. Focal ablation or pulmonary vein/superior vena cava isolation was applied as appropriate. A total of 35 ectopic foci were identified in group A. The majority of them were at pulmonary vein (PV) ( n = 7), crista terminalis ( n = 6), and para-Hisian area ( n = 6). In group B, ectopic foci were in left-sided PVs in 21 patients, in right-sided PVs in 13 patients, and in SVC in 1 patient. There was significant difference in CoIs of PACs triggering AF and those from PVs and non-PV areas but without causing AF (362.8 ± 23.0 ms vs. 470.6 ± 60.1 ms vs. 515.6 ± 77.2 ms, P < 0.001). Premature atrial contractions were abolished in 32 of 35 patients from group A and in all patients from group B. At the end of follow-up, 29 patients in group A and 28 patients in group B were free of recurrence (off antiarrhythmic drugs) after the initial ablation ( P = 0.97).
Conclusions
Frequent PACs in the absence of AF were characterized as having their predilection sites and longer CoIs than those inducing AF. Catheter ablation was effective to eliminate symptomatic, frequent, and drug-refractory PACs.
... Thereby, complications seen with RFCA, like coronary artery occlusion [139] and AV-block [140], become less frequent with CA. Moreover, CA offers the potential of imitation of the post-ablation electric conduction pattern (cryomapping), by chilling cardiac tissue at -30°C to -20°C and causing a temporary electric alteration, before proceeding to definite tissue damage [141][142][143]. Although CA has been increasingly used during the last decade and has become the treatment of choice for specific arrhythmias [144,145], a recent retrospective study [146], which included 333 children undergoing RFCA, showed excellent outcomes, with 0.3% major complication rate (one pericardial hemorrhage), no reported AV-block and no deaths, suggesting that proper training and specializing may lead to better outcomes. ...
In an era when less invasive techniques are favored, therapeutic cardiac catheterization constantly evolves and widens its spectrum of usage in the pediatric population. The advent of sophisticated devices and well-designed equipment has made the management of many congenital cardiac lesions more efficient and safer, while providing more comfort to the patient. Nowadays, a large variety of heart diseases are managed with transcatheter techniques, such as patent foramen ovale, atrial and ventricular septal defects, valve stenosis, patent ductus arteriosus, aortic coarctation, pulmonary artery and vein stenosis and arteriovenous malformations. Moreover, hybrid procedures and catheter ablation have opened new paths in the treatment of complex cardiac lesions and arrhythmias, respectively. In this article, the main therapeutic utilities of cardiac catheterization in children are discussed.
... Cryothermal ablation may be an alternative to RF ablation to reduces the risk of permanent block in septal arrhythmia substrates [12][13][14][15][16] . Due to its safety profile, cryoablation is used increasingly in pediatric patients. ...
... Due to its safety profile, cryoablation is used increasingly in pediatric patients. The advantages of cryothermal energy is reversibility of lesions during cryomapping and increased catheter stability [12][13][14][15][16] . The target was usually identified using a steerable quadripolar electrophysiology catheter, marked as a point on the three-dimensional mapping system. ...
... Cryomapping usually was performed at -30°C at the previously marked location. If AP block was achieved, ablation was continued for 240-360 ms at -70°C to -80°C to achieve the freeze effect [12][13][14][15][16] . ...
Anteroseptal accessory pathways (APs) are located in the apex of the triangle of Koch's connecting the atrial and ventricular septum in the region of the His bundle. Ablation of anteroseptal pathway locations remains a challenge to the electrophysiologist due to a very high risk of transiet or permanent atrioventricular (AV) block.
A male, 18-year-old, patient was hospitalized due to radiofrequency (RF) ablation of APs. He was an active football player with frequent palpitations during efforts accompanied by dyspnea and lightheadedness, but without syncope. Electrocardiography on admission showed intermittent preexcitations. Intracardiac mapping showed the earliest ventricular activation that preceded surface electrocardiographic delta wave in anteroseptal region very close to the AV node and His bundle. Using a long vascular sheath for stabilization of the catheter tip, RF energy was delivered at the target site starting at very low energy levels and because of the absence of either PR prolongation, as well as accelerated junctional rhythm during the first 15 sec, the power was gradually increased to 40 W, so after application RF energy preexcitation was not registered.
Despite this proximity to the His bundle and very high risk of transiet or permanent AV block anteroseptal APs can still be ablated successfully.
... Data are limited to a small number of patients or case reports. 17,18 The high acute success rate in the present study is similar to that of RF ablation. 1 -7 We had a high long-term success rate (92%), with no permanent damage to the conduction system. ...
The purpose of this study was to evaluate the safety and efficacy of cryoablation as an alternative to radio frequency (RF) ablation in high-risk-located atrial tachycardia (AT).
Between 2004 and 2007, 164 patients underwent catheter ablation due to AT at our institution. Twenty-six of these patients (22 women and 4 men), median age 58 years (range 14-76), were considered having high-risk-located AT and were treated by cryoablation. Seven patients had failed prior RF ablation due to high risk of complications. The AT foci distribution was: close to the AV node (n = 14), vicinity of the sinus node (n = 7), and crista terminalis adjacent to the phrenic nerve (n = 5). Cryomapping, using a 6 mm tip catheter, at -30 degrees C was performed before ablation with a goal temperature of -80 degrees C for 240 s. Acute success rate was achieved in 25/26 patients (96%). During a follow-up of 493 +/- 258 days, three patients had recurrences. Two of these underwent a second successful cryoablation procedure. Long-term success rate was 92%. Phrenic nerve palsy occurred in two patients with complete recovery after 1 day and 5 months, respectively.
Cryoablation of high-risk-located AT foci is a safe and effective alternative to RF therapy.
... During this study, only one 4-minute freezethaw cycle was applied to each site. Since cryoadhesion-adherence of the catheter tip to the adjacent tissue during delivery of energyis a well-described feature of cryoablation, 6,14,15 catheters were only repositioned when the temperature recorded by the catheter was greater than or equal to 30 • C. ...
This study of a chronic porcine postinfarction model examined whether linear epicardial cryoablation was capable of creating large, homogenous lesions in regions of the myocardium including scarred ventricle. Endocardial and epicardial focal cryolesions were also compared to determine if there were significant differences in lesion characteristics.
Eighty focal endocardial and 28 focal epicardial cryoapplications were delivered to eight normal caprine and four normal porcine ventricular myocardium, and 21 linear cryolesions were applied along the border of infarcted epicardial tissue in a chronic porcine infarct model in six swines.
Focal endocardial cryolesions in normal animals measured 9.7+/-0.4 mm (length) by 7.3+/-1.4 mm (width) by 4.8+/-0.2 mm (depth), while epicardial lesions measured 10.2+/-1.4 mm (length) by 7.7+/-2 mm (width) by 4.6+/-0.9 mm (depth); P > 0.05. Linear epicardial cryolesions in the chronic porcine infarct model measured 36.5+/-7.8 mm (length) by 8.2+/-1.3 mm (width) by 6.0+/-1.2 mm (depth). The mean depth of linear cryolesions applied to the border of the infarct scar was 7+/-0.7 mm, as measured by magnetic resonance imaging.
Cryoablation can create deep lesions when delivered to the ventricular epicardium. Endocardial and epicardial cryolesions created by a focal cryoablation catheter are similar in size and depth. The ability to rapidly create deep linear cryolesions may prove to be beneficial in substrate-based catheter ablation of ventricular arrhythmias.
... Before applying a permanent cryoablation lesion (less than À70 C), the use of cryomapping (À30 C) to identify AT foci close to the AV node with monitoring the AV conduction is safe ablation procedure. 68) If AT origin is suspected as an epicardial focus, a large-tip (8 mm) electrode catheter or saline-irrigated catheter may be useful for making deep lesion. Atrio-esophageal fistulas as a fatal complication can occur after aggressive radiofrequency ablation at the posterior aspect of the left atrium. ...
Over the past decade most of the electrophysiologic mechanisms in patients with focal atrial tachycardias (ATs) have been well studied Recently advanced mapping systems have revealed the precise propagation and the relationship between non radial propagation pattern and substrate property of focal AT Non radial activation pattern of focal AT may mimic macrorentrant AT and may lead to inappropriate ablation strategy In this review we will focus on the current state of mapping and ablation techniques safety and efficacy associated with the catheter ablation for focal AT.
... The reversibility of conduction block in particular, via a technique known as cryomapping, is an especially useful safety benefit of cryo in clinical practice. Cryomapping allows for the evaluation of the acute effects of cryo on the structures to be ablated before creating a permanent lesion (21,22). This is probably the principal reason why no incidence of permanent AV block has yet been reported among the many cryo catheter ablation procedures that have been performed in the adult population (10,20,(22)(23)(24)(25). ...
We investigated the safety and efficacy of cryoablation in the treatment of pediatric patients with accessory pathways (APs) located near the atrioventricular junction and with atrioventricular nodal re-entrant tachycardia (AVNRT).
Few studies concern cryoablation in a significant number of pediatric patients involving treatment for supraventricular tachycardias (SVTs) with the reentry circuit located near the atrioventricular junction.
Twenty-six pediatric patients (age range: 5 to 20 years) were treated; 14 had AVNRT, 10 had Wolff-Parkinson-White syndrome, and 2 had re-entrant SVT due to a concealed AP. Electrophysiologic study was performed with diagnostic catheters, and cryoablations were performed with a 7-F 4-mm-tip catheter (Freezor, CryoCath Technologies Inc., Kirkland, Canada). Cryomapping, used to identify the tissue site for safe arrhythmia ablation, was performed at -30 degrees C for a maximum of 60 s. Cryoablations were from 4 to 8 min long at -75 degrees C. Acute end points were noninducibility of AVNRT by programmed atrial stimulation at baseline or during isoproterenol performed 30 min after procedure, as well as noninducibility and conduction block over the AP. The chronic end point was arrhythmia recurrence after intervention.
No permanent cryo-related complications or adverse outcomes were reported. Twenty-four (92%) patients were acutely successful. During follow-up (range: 1 to 22 months), seven (29%) acutely successful pediatric patients experienced arrhythmia recurrence.
Acute results demonstrate cryoablation of SVTs with the reentry circuit located near the atrioventricular junction to be safe and efficacious in pediatric patients. However, the etiology of recurrences reported after intervention need further investigation.
