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Paneth Suture Annuloplasty Abolishes Acute Ischemic Mitral Regurgitation but Preserves Annular and Leaflet Dynamics
Abstract
Ring annuloplasty, the standard treatment for ischemic mitral regurgitation (IMR), abolishes normal annular dynamics and freezes the posterior leaflet. We examined the impact of Paneth suture annuloplasty during acute IMR on motion of the mitral annulus and leaflets in an ovine model.
Eight sheep had radiopaque markers placed on the left ventricle, anterior mitral leaflet, posterior mitral leaflet, and mitral annulus. A Paneth suture annuloplasty that could be reversibly tightened was anchored to each fibrous trigone and externalized through the mid-lateral mitral annulus. Acute IMR was induced by proximal circumflex artery occlusion. Transesophageal echocardiography assessed the degree of IMR, and biplane cinefluoroscopy measured 3-dimensional marker coordinates before and during circumflex ischemia, and tightening of the Paneth suture. Paneth suture annuloplasty eliminated acute IMR, and reduced septal-lateral and commissure-commissure mitral annular dimensions. Tightening of the annuloplasty sutures, even beyond the degree necessary to eliminate mitral regurgitation (MR), did not reduce septal-lateral or commissure-commissure annular shortening, shortening of the muscular annular perimeter, annular flexion, or angular excursion of the anterior or posterior leaflets relative to ischemic conditions.
In contrast to ring annuloplasty, annular reduction sufficient to restore mitral competence during acute IMR can be achieved with a Paneth suture annuloplasty while simultaneously maintaining normal annular and leaflet dynamic motion. These findings should prompt additional investigation and design of repair methods that preserve the mobility of the mitral apparatus.
... Moreover, in ischemic mitral regurgitation the annuloplasty suture might help to restore and preserve the normal annular and leaflet dynamic motion. 3,4 ...
... Contrarily, the evidence that a prosthetic ring annuloplasty stabilizes the repair in a more durable fashion is accumulating. 3 In a well-constructed study, Cohn and coworkers were among ...
... Aikawa and Grande-Allen (2) proposed a vicious cycle of disadvantageous remodeling, wherein leaflet length-ening leads to increased leaflet tensile stress, resulting in further remodeling. Annular dilation in adult mitral valves has important functional and clinical consequences, such as mitral regurgitation and heart failure (42,43,47). Indeed, geometric changes in the annulus and leaflets similar in magnitude to those in the present study have been associated with functional mitral regurgitation in larger, adult sheep hearts (41). ...
While abnormal hemodynamic forces alter fetal myocardial growth, little is known about whether such insults dysregulate fetal cardiac valve development. We hypothesized that chronically elevated systolic load would detrimentally alter fetal valve growth. Sixteen chronically instrumented fetal sheep received either a continuous infusion of adult sheep plasma to increase fetal blood pressure (n=8), or a Lactated Ringers infusion as a volume control (n=8) beginning on day 126±4 of gestation. After 8 days, mean arterial pressure was higher in the plasma infusion group (63.0 mm Hg vs. 41.8 mm Hg, P < 0.01). Mitral annular septal-lateral diameter (11.9 mm vs. 9.1 mm, P < 0.05), anterior leaflet length (7.7mm vs. 6.4 mm, P < 0.05), and posterior leaflet length (4.0 mm vs. 3.0 mm, P < 0.05) were greater in the elevated load group. mRNA levels of Notch-1, TGF-β2, Wnt-2b, BMP-1, and versican were suppressed in aortic and mitral valve leaflets; elastin and alpha-1 type I collagen mRNA levels were suppressed in the aortic valves only. We conclude that sustained elevated pressure load on the fetal heart valve leads to anatomic remodeling and, surprisingly, suppression of signaling and extracellular matrix genes that are important to valve development. These novel findings have important implications on the developmental origins of valve disease and may have long term consequences on valve function and durability.
... Esse é um parâmetro de eficácia associado aos achados de ecocardiograma transesofágico, com redução da regurgitação da valva mitral de 3+ para 2+ imediatamente após o procedimento, que foi mantida durante a evolução. A redução de 50% da distância de P1-P3 (de 3 cm para 1,5 cm) foi essencial para reduzir a regurgitação da valva mitral, imitando o efeito da cirurgia descrito por Tibayan et al. 11 , em que a redução do diâmetro do anel posterior é eficiente quando a redução atinge no mínimo 20% da dimensão septolateral. ...
BACKGROUND: Untreated mitral regurgitation results in increased mortality in patients with congestive heart failure (CHF). The Mitralign Percutaneous Annuloplasty System provides a treatment option without surgery in selected cases with mitral annulus dilation. METHODS: The procedure is performed through a single 14 F femoral artery puncture; fluoroscopy and transesophageal echocardiography are both used for visualization. The guide catheter is maneuvered into the left ventricle and positioned at the posterior mitral annulus. A catheter system places sutured pledgets into the posterior mitral annulus and these implants are pulled together to remodel the mitral valve annulus. Once the desired effects are achieved, the suture is locked and cut. RESULTS: The procedure was performed in 6 patients and was well tolerated. Procedure times were generally < 2 hours and in most cases (4/6) immediate mitral regurgitation reduction was achieved. All patients were followed up to 12 months. There were no deaths and 4 patients were New York Heart Association class I, one was class II and one class III. There was a significant reduction of the left ventricular diameters, and left atrium size after the first 90 days of follow up. CONCLUSIONS: Direct percutaneous mitral annuloplasty is achievable and reproducible. This is a technique that can be performed safely and shows a considerable benefit for selected patients in whom surgery is not a good option. A higher number of patients treated with this new procedure will provide us with a better understanding of the limitations of percutaneous mitral annuloplasty approach.
... The lesser degree of annular reduction required by the Paneth suture annuloplasty may allow preservation of shortening of the mitral annular diameters. [14] In addition to this, annular growth has been reported after suture annuloplasty in the pediatric population. [15] This annular growth may be an advantage to rings, however, it may also be a disadvantage because of the potential for annular redilatation after annuloplasty. ...
Ring annuloplasty is the standard treatment of ischemic mitral regurgitation (MR), however, it has been associated with some drawbacks. It abolishes normal annular dynamics and freezes the posterior leaflet. In the present study, we evaluated Paneth suture annuloplasty in chronic ischemic MR and both early and mid-term outcomes of the technique on a selected population.
The study period was from June 2010 to June 2012. We operated on 21 patients who had the diagnosis of coronary artery disease and MR of grade 3 or 4. The patients had both a coronary artery bypass operation and the mitral semicircular reduction annuloplasty described by Paneth-Burr. The data on the patients were retrospectively collected. Patients were contacted by outpatient clinic controls for mid-term results.
The male/female ratio was 10/11. The mean age of the patients was 71.0 ± 6.4 years. Preoperative and postoperative left ventricular ejection fraction was statistically similar (P = 0.973). Early postoperative MR grade (mean, 0.57 ± 0.51) was statistically lower than the preoperative MR grades (mean, 3.38 ± 0.50) (P < 0.001). There was no revision for excess bleeding. Two patients had prolonged hospitalization, one for sternal infection and the other for severe chronic obstructive pulmonary disease. No hospital or late postoperative deaths occurred. The mean late postoperative MR grade was 0.66 ± 0.97 degrees. One patient had progression of MR in the later follow-up, which was treated by mitral valve replacement.
Semicircular reduction annuloplasty is an effective, inexpensive and easy surgical annuloplasty technique with low mortality and morbidity in severe symptomatic ischemic MR.
... Entre las entidades degenerativas se incluyen el prolapso valvular, el exceso tisular, la elongación de cuerdas y la dilatación del anillo. La IM funcional aparece como consecuencia de la dilatación del ventrículo izquierdo debido a isquemia o miocardiopatía 42,43 . ...
Structural heart disease interventions are the transcatheter techniques used for treating non-coronary heart disease. In recent years, these techniques have generated considerable interest even though they still comprise only a small percentage of the total volume of interventions performed in interventional cardiology departments. The level of interest in these techniques is high probably because their application is characterized by a number of special features: a) the need for multidisciplinary teams; b) the need for specialized education and training; c) the requirement for special skills developed through education and experience, and d) the limited number of referral centers at present. This article describes four specific techniques: a) percutaneous closure of perivalvular leaks; b) percutaneous left atrial appendage obliteration; c) percutaneous treatment of mitral regurgitation, and d) transcatheter implantation of prosthetic aortic valves. We explore the rationale for using the technique, the specific procedures involved and the results obtained.
... Surgical suture annuloplasty was developed to reduce the size of the annulus while maintaining physiological annular and leaflet motion. Evidence suggests that a 20% relative reduction of the septal-lateral dimensions of the mitral annulus can significantly reduce the severity of regurgitation (32). This approach has acceptable 7-year durability results, including an 82% rate of freedom from significant MR, a 95% rate for freedom from reoperation, and an actuarial survival rate of 87.2% at 6.4 years (33). ...
As the percentage of seniors continues to rise in many populations around the world, the already challenging burden of valvular heart disease will become even greater. Unfortunately, a significant proportion of patients with moderate-to-severe valve disease are refused or denied valve surgery based on age and/or accompanying comorbidities. Furthermore, because of advances in pediatric cardiology, the number of adult patients with congenital heart disease is on the rise and over time, these patients will likely require repeat high-risk surgical procedures. The aim of transcatheter valve therapies is to provide a minimally invasive treatment that is at least as effective as conventional valve surgery and is associated with less morbidity and mortality. The objective of this review was to provide an update on the clinical status, applicability, and limitations of transcatheter mitral and pulmonary valve therapies.
... Up to now, several novel surgical methods, focusing on either annular or subvalvular components, 8 were developed to correct for FMR. The methods include ring annuloplasty, Paneth suture annuloplasty, 23 cutting of the basal chords to relieve leaflet retraction, 24 use of a ventricular containment device to restrain left ventricular dilation, 25 imbrication of interpapillary myocardium during ventricular restoration operation, 26 and use of a papillary sling to bring both papillary muscles into close contact. 27 Poor LVEF was often considered a risk factor for late recurrence of FMR in patients after ring annuloplasty. ...
Patients with chronic coronary artery disease have double the mortality rate if the condition is combined with functional mitral regurgitation. An understanding based on geometric alterations of the mitral apparatus in functional mitral regurgitation is desirable.
Twenty-nine subjects were enrolled in the study, including 9 healthy volunteers (control group), 12 patients with chronic coronary artery disease without functional mitral regurgitation (CAD group), and 8 patients with chronic coronary artery disease with functional mitral regurgitation (CAD+FMR group). Cine magnetic resonance imaging was performed to acquire multiple short-axis cine images from base to apex. Left ventricular end-systolic volume, left ventricular ejection fraction, mitral area, and vertices of the mitral tetrahedron, defined by medial and lateral papillary muscle roots and anterior and posterior mitral annulus, were determined from reconstructed images at end-systole. Anterior-posterior annular distance, interpapillary distance, and annular-papillary distance (the distance from the anterior or posterior mitral annulus to the medial or lateral papillary muscle roots) were calculated.
Left ventricular end-systolic volume was inversely associated with left ventricular ejection fraction (R(2) = 0.778). Left ventricular end-systolic volume was highly associated with distances related to ventricular geometry (R(2) = 0.742 for interpapillary distance, 0.792 for the distance from the anterior mitral annulus to the medial papillary muscle root, and 0.769 for distance from the anterior mitral annulus to the lateral papillary muscle root) but was moderately associated with distances related to annular geometry (R(2) = 0.458 for anterior-posterior annular distance and 0.594 for mitral area, respectively). Moreover, interpapillary distance of greater than 32 mm and distance from the anterior mitral annulus to the medial papillary muscle root of greater than 64 mm readily distinguished the CAD+FMR group from the other groups.
In patients with coronary artery disease, an increase in left ventricular end-systolic volume is associated with inadequate approximation of the mitral tetrahedron during systole, which consequently leads to functional mitral regurgitation. Our study suggests that interpapillary distance and distance from the anterior mitral annulus to the medial papillary muscle root are sensitive to the increase in left ventricular end-systolic volume and reliably indicate the presence of functional mitral regurgitation.
... 11 In contrast, the potential advantages of suture annuloplasty over ring annuloplasty are believed to include better preservation of overall annular motion, as well as a lack of effect on posterior leaflet mobility. 25 It avoids the possibility of distortion of the anterior leaflet, as well as pushing up a commissure. The costs of the procedure are reduced by avoiding an implant, and the risk of infection or hemolysis might be decreased. ...
Our early experience with the mural annulus shortening suture procedure for mitral valve repair showed superior hemodynamic performance over ring annuloplasty. The aim of this study was to assess the durability of the mural annulus shortening suture procedure and evaluate our 7-year experience regarding valve function, hemodynamic performance, and clinical outcome.
Between 1996 and 2003, 222 elective consecutive patients (58.1% males; age, 59 +/- 14 years) underwent simple or complex mitral valve repair. Minimal invasive reconstruction was performed in 150 patients. For correction of annular dilatation, we used double-running 2-0 polytetrafluoroethylene sutures to reinforce the posterior circumference of the annulus. Patients were investigated prospectively by means of transthoracic echocardiography before discharge and 1 and 5 years after the operation. The mean follow up was 32 +/- 21 months (range 1-77 months).
The operative mortality was 3.1%. Hemodynamic performance at 1 and 5 years showed low mean transvalvular gradients (2.1 +/- 0.9 and 2.0 +/- 0.8 mm Hg, respectively) and a calculated mitral valve orifice area of 3.3 +/- 0.9 cm2 and 3.1 +/- 0.6 cm2, respectively, with progressive annular dilatation from 31.2 +/- 3 mm to 33.9 +/- 4 mm at 1 year and 35.7 +/- 4 mm at 5 years (P < .01). Clinical status improved from New York Heart Association class 3.0 +/- 0.4 to 0.6 +/- 0.8 at 1 year and 0.8 +/- 0.8 at 5 years. Freedom form nontrivial residual mitral regurgitation was 82.3%, freedom from reoperation was 95.1% and actuarial survival was 87.2%, all at 77 months.
The midterm results show satisfactory hemodynamic performance and clinical improvement. Valve competence and reoperation rates are comparable with those of other reports. Durability of the mural annulus shortening suture procedure for mitral valve repair is questioned because progressive annular redilatation occurs.
Objective
(s): Tricuspid annular size reduction with annuloplasty rings represents the foundation of surgical repair of functional tricuspid regurgitation (FTR). However, the precise effect of annular size reduction on leaflet motion and geometry remains unknown.
Methods
Ten sheep underwent surgical implantation of a pacemaker with an epicardial lead and were paced 200-240b/min to achieve biventricular dysfunction and FTR. Subsequently, sonomicrometry crystals were implanted on the right ventricle (RV), the tricuspid annulus (TA), and on the belly of anterior (AL), posterior (PL) and septal (SL) tricuspid leaflets. Double layer polypropylene suture was placed around the TA and externalized to a tourniquet. Simultaneous echocardiographic, hemodynamic, and sonomicrometry data were acquired with FTR and during 5 consecutive annular reduction steps (TAR1–5). Annular area, tenting height, and volume, together with each leaflet strain, radial length and angles were calculated from crystal coordinates.
Results
Rapid pacing reduced both LV and RV function and induced FTR (0-3+) in all animals (from 0±0 to 2.4±0.7, p=.002) while TA diameter increased from 2.6±0.3cm to 3.3±0.3cm (p=.001). TAR1–5 resulted in 16±7%, 37±11%, 55±11%, 66±10% and 76±8% TA area reduction, respectively, and successively decreased TR. TAR2-5 induced AL and PL restricted motion and lower diastolic motion velocities. TAR5 perturbed SL range of motion but preserved its angle velocities. TAR3-5 generated compressive strains in all leaflets.
Conclusions
Tricuspid annular area reduction of 55% perturbed AL and PL motion while maintaining normal SL movement. More extreme reduction triggered profound changes in AL and PL motion suggesting that aggressive undersizing impairs leaflet kinematics.
Functional mitral regurgitation (MR;FMR) is the most common type of MR and its development is associated with increased morbidity and mortality. Leaflet tethering with apical shift of the papillary muscle due to adverse left ventricular remodeling and loss of normal leaflet coaptation is the principal mechanism of FMR. Echocardiography plays a central role in the assessment of the FMR. The development of 3D echocardiography has allowed for assessment of the geometric changes of mitral valve morphology and spatial relationship with the left ventricle that accompanies FMR. 2D/3D echocardiographic findings, clinical outcomes of FMR are reviewed and role of surgical intervention is discussed.
Mitral valve suture annuloplasty has been in use for a long time although it is less commonly used in ischemic mitral regurgitation. It does, however, have advantages over other repair techniques and may be suitable in ischemic mitral regurgitation for selected patients. As in other repair techniques, important principles must be followed to ensure long term durability of the repair.
Mitral stenosis is an obstruction of blood flow from the left atrium to the left ventricle. It is generally caused by rheumatic heart disease [1, 2]. Other causes of mitral stenosis are: severe calcification of the valve leaflets, congenital defects of the mitral valve, systemic lupus erythematosus (SLE), tumors, left atrial thrombi, vegetations due to endocarditis, and causes linked to prior device implants.
Objective:
To evaluate late outcomes after posterior mitral valve (MV) annulus double-suture annuloplasty for degenerative (non-ischaemic) MV insufficiency.
Design:
Between 2005 and 2011, 138 patients underwent MV repair using posterior MV double-suture annuloplasty and an additional 105 patients underwent tricuspid valve repair. The study protocol included operative mortality, reoperation rate and reasons, as well as echocardiographic parameters at pre- and postoperative and follow-up periods (2-9 years).
Results:
In-hospital mortality was 2/138 (1.45%). Early post operation, no regurgitation was noted in 74/136 (54.4%) patients, I(o) regurgitation was observed in 55/136 (40.4%), II(o) was observed in 6/136 (4.4%) and III(o) was observed in 1/136 (0.7%); during late follow-up (from 2 to 9 years), no regurgitation was observed in 21.6% patients, I(o) was observed in 58%, II(o) was observed in 17% and III(o) was observed in 3.4%. The mean preoperative anterolateral diameter of the MV annulus was 39.02±4.97 mm and, at late follow-up, it was 27.66±3.94 mm (p=0.000); at these same time points, left ventricular end-diastolic diameter (LVEDD) was 55.74±7.29 mm and 49.17±6.01 mm (p=0.000), respectively, and the left ventricular ejection fraction (LVEF) was 53.08±8.93% and 50.92±6.78%, respectively (p=0.007).
Conclusions:
This study demonstrates suture annuloplasty to be an effective treatment up to 9 years for degenerative mitral valve disease. This technique enables preservation of the posterior mitral valve annulus diameter with stable long-term (up to 9 years) reduction, a competent (no regurgitation/⩽II(o) regurgitation) MV in 96.6% of cases and positive left ventricular (LV) remodelling.
Mitral valve repair surgery has progressed dramatically since its inception over 40 years ago. As techniques have evolved, complicated mitral valve reconstruction has become commonplace, with durable late results. Likewise, the value of concomitant annuloplasty during valve repair has been firmly established as contributing to late valve repair durability. This review discusses the evolution of annuloplasty techniques and the physiologic reasoning behind various approaches.
The distribution of mitral stenosis (MS) in the general population is closely associated with rheumatic fever, since it is its main cause. Recent data of the World Health Organisation (WHO) suggest that acute rheumatic fever and, as a consequence, rheumatic disease, affect about 15.6 million people throughout the world. Females are affected more frequently than males with a ratio ranging between 2:1 and 3:1 [1].
The mitral valve apparatus is a complex structure that incorporates the leaflets, chordae tendinae, papillary muscles, annulus, and left ventricle (LV) in its function. As a result, diseases that affect any of these structures can result in severe mitral regurgitation (MR), which in turn, is associated with reduced survival.1–3 Classification of MR often differentiates between primary or degenerative cause attributable to diseases that affect the leaflets (eg, fibroelastic dysplasia, rheumatic disease, Barlow disease, endocarditis, prolapse) and secondary cause. In the latter category are diseases of the atrium or left ventricle, including ischemic dysfunction and functional disease (eg., dilated cardiomyopathy). Current guidelines recommend surgery in symptomatic patients with severe MR (recommendation class I), in asymptomatic patients with abnormal LV function (class I) as well as in asymptomatic patients with normal LV function when there is a high likelihood of successful repair (class IIa).4,5 Surgery may also be considered for secondary MR in symptomatic patients after optimal medical management (class IIb). It should be noted that the European and American College of Cardiology (ACC)/American Heart Association (AHA) guidelines differ slightly in the definitions of LV dysfunction and the level of evidence assigned to several of these recommendations.4,5
Although there are no randomized trials of surgery versus medical therapy for severe, symptomatic MR, observational studies have demonstrated improved survival with surgery, particularly with repair of primary mitral regurgitation.5,6 Nonetheless, surgery is associated with mortality rates of 1% to 5% and morbidity rates of 10% to 20%, including stroke, reoperation, renal failure, and prolonged ventilation.7 This is particularly true in elderly patients and those with left ventricular dysfunction; mortality in octogenarians may be as high as 17% with morbidity occurring in more than a third of patients.8 Furthermore, surgery in …
Transcatheter mitral interventions are emerging as a novel therapy for patients with severe symptomatic mitral regurgitation who are deemed to be high risk or inoperable. Surgical treatment of mitral regurgitation includes a wide spectrum of therapies, ranging from leaflet and annular repair, to mitral valve replacement. Annuloplasty plays a fundamental role in open heart mitral valve repair, since it is associated with longer durability and higher degree of mitral regurgitation reduction. Direct annuloplasty is the interventional methodology most closely reproducing open heart annular repair. We describe the challenges and opportunities of the most promising technologies currently under development which will become available in clinical practice in the next future.
Functional mitral regurgitation remains one of the most complex and controversial aspect-for both clinicians and surgeons-in the management of mitral valve disease in the context of left ventricular dysfunction. Given the current absence of clear guidelines, as well as of results from randomized trials comparing the outcome of different surgical strategies potentially available for this complex scenario, surgical decision making for these high-risk patients poses a real dilemma in the daily practice. The resulting surgical choices often represent a questionable combination of surgeons' personal feeling, local supplies, patients' life expectancy and risk/benefit ratios, opinions and statements of the experts, and so on. This review provides an overview of the present knowledge about the complex pathophysiology underlying functional mitral regurgitation, the different pathophysiology-guided surgical techniques suggested in the last decades, as well as the current results following these different surgical techniques.
Structural heart disease interventions are the transcatheter techniques used for treating non-coronary heart disease. In recent years, these techniques have generated considerable interest even though they still comprise only a small percentage of the total volume of interventions performed in interventional cardiology departments. The level of interest in these techniques is high probably because their application is characterized by a number of special features: a) the need for multidisciplinary teams; b) the need for specialized education and training; c) the requirement for special skills developed through education and experience, and d) the limited number of referral centers at present. This article describes four specific techniques: a) percutaneous closure of perivalvular leaks; b) percutaneous left atrial appendage obliteration; c) percutaneous treatment of mitral regurgitation, and d) transcatheter implantation of prosthetic aortic valves. We explore the rationale for using the technique, the specific procedures involved and the results obtained.
The mitral valve annulus naturally conforms to a saddle shape in systole. This configuration is believed to put the leaflets into a lower-energy equilibrium with the annulus and subvalvular apparatus. Conventional flat annuloplasty rings restrict posterior leaflet motion, which may result in a "monocusp" valve, affecting valvular stress distribution. It is hypothesized that saddle-shaped annuloplasty rings cause less distortion of the physiologic leaflet geometry than do flat rings.
Twelve pigs were studied in an acute setting with 3-dimensional echocardiography and sonomicrometry before and after implantation of rigid flat (n = 5) and saddle-shaped (n = 7) annuloplasty rings. The rings were true sized to the annulus with equal anterior-posterior and commissure-commissure circumferential dimensions. The saddle-shaped rings had an annular height to commissural width ratio of 15%.
Saddle-shaped rings maintained both leaflets operational (P < .01). Flat rings made the posterior leaflet immobile and the anterior leaflet aligned flat along the annulus in systole, effectively resulting in monoleaflet function. The average distance from the papillary muscle tips to the posterior annulus decreased by 2.4 ± 0.4 mm after flat ring implantation (P < .01).
Saddle-shaped annuloplasty rings provide better leaflet coaptation geometry than do flat rings by not hoisting the papillary muscles toward the posterior annulus through the commissural chordae, allowing greater leaflet mobility. This entails a potentially beneficial impact on valvular stress distribution that could affect durability of the repaired valve.
Over the past 25 years we have witnessed the development of transcatheter techniques for treatment of valvular heart disease. For several years, percutaneous balloon valvuloplasty has been used to treat stenotic valvular disease, including pulmonary stenosis, rheumatic mitral stenosis, tricuspid stenosis, and, sometimes, congenital aortic stenosis. However, major advancements in transcatheter valve repair and replacement have revolutionized progress. Preliminary results of ongoing studies show promise in the percutaneous treatment of mitral regurgitation. This article covers established percutaneous techniques for treatment of mitral stenosis and reviews major recent advancements in the percutaneous treatment of mitral regurgitation.
The Sorin Memo 3D (Sorin Biomedica Cardio S.r.L., Saluggia, Italy) is a new, complete semirigid annuloplasty ring. Clinical use, outcomes, and echocardiographic results are reported as an evaluation of its safety and efficacy in the treatment of mitral valve regurgitation (MVR).
This device was assessed in 63 patients (63.5% men; mean age, 70.2 +/- 10.3 years) who underwent MVR operations between January 2007 and June 2008. Functional classification was normal leaflet motion (type I; 1.6%), leaflet prolapse (type II; 66.7%), and restricted leaflet motion (type III; 31.7%). Valve disease was degenerative (68.25%), ischemic (25.4%), and nonischemic dilated cardiomyopathy (6.35%).
Early mortality (< or = 30 days) was 3.3% (2 patients). Late mortality (11.2 +/- 5.1 months) was 4.9% (3 patients). No deaths were device-related. Thromboembolic stroke occurred in 3.3% and endocarditis in 1.6%. Freedom from reoperation was 98.4%. At 6 months, MVR was grade 0/1 in 93.7% and grade 2+ in 6.4%. Left end-diastolic ventricular diameters decreased significantly from 59.3 +/- 6.9 mm preoperatively to 50.6 +/- 12.2 mm at 6 months, pulmonary arterial pressure decreased from 44.8 +/- 7.1 mm Hg to 38.4 +/- 5.5 mm Hg, and left ventricular ejection fraction increased significantly from 0.469 +/- 0.129 to 0.582 +/- 0.106. New York Heart Association functional class was I in 81% and II in 13.8%.
Early results indicate the Sorin Memo 3D ring safely and effectively minimizes secondary MVR resulting from all causes and preserves mitral annular flexibility and function at follow-up.
We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy.
Catheter-based annuloplasty for secondary mitral regurgitation exploits the proximity of the coronary sinus to the mitral annulus, but is limited by anatomic variants and coronary artery entrapment.
The procedure, "cerclage annuloplasty," is guided by magnetic resonance imaging (MRI) roadmaps fused with live X-ray. A coronary sinus guidewire traverses a short segment of the basal septal myocardium to re-enter the right heart where it is exchanged for a suture. Tension is applied interactively during imaging and secured with a locking device.
We found 2 feasible suture pathways from the great cardiac vein across the interventricular septum to create cerclage. Right ventricular septal re-entry required shorter fluoroscopy times than right atrial re-entry, which entailed a longer intramyocardial traversal but did not cross the tricuspid valve. Graded tension progressively reduced septal-lateral annular diameter, but not end-systolic elastance or regional myocardial function. A simple arch-like device protected entrapped coronary arteries from compression even during supratherapeutic tension. Cerclage reduced mitral regurgitation fraction (from 22.8 +/- 12.7% to 7.2 +/- 4.4%, p = 0.04) by slice tracking velocity-encoded MRI. Flexible cerclage reduced annular size but preserved annular motion. Cerclage also displaced the posterior annulus toward the papillary muscles. Cerclage introduced reciprocal constraint to the left ventricular outflow tract and mitral annulus that enhanced leaflet coaptation. A sample of human coronary venograms and computed tomography angiograms suggested that most have suitable venous anatomy for cerclage.
Transcatheter mitral cerclage annuloplasty acutely reduces mitral regurgitation in porcine ischemic cardiomyopathy. Entrapped coronary arteries can be protected. MRI provided insight into the mechanism of cerclage action.
This investigation sought to determine the feasibility of a novel method of a percutaneous mitral valve repair.
Percutaneous mitral valve repair has emerged as an alternative therapy for patients with functional mitral regurgitation. However, current methods that rely on cannulation of the coronary sinus may not result in direct reduction of the mitral annulus area due to the superior relationship of the sinus to the annulus.
A novel device, consisting of helical stainless steel screws connected by a biocompatible tether, was designed for percutaneous mitral valve repair. This device was implanted by implanting the helical screws directly into the myocardium at the posteromedial mitral annulus of 8 anesthetized pigs from the right internal jugular vein.
Implantation of the device resulted in a 19.7 +/- 0.1% reduction in mitral annular area and an 18.8 +/- 0.1% decrease in the mitral anterior-posterior dimension (both p < 0.05 vs. baseline). This annular reduction persisted at 3-month follow-up. Both the coronary sinus and left circumflex coronary artery remained patent in all animals. There was no evidence of device migration, poor wound healing, or tissue thrombosis at the sites of device implantation.
Percutaneous mitral valve repair targeting the ventricular myocardium from central venous access is feasible. By directly acting on the posteromedial mitral annulus, this methodology targets the mitral annular area most frequently affected by ischemic mitral regurgitation, lessens the risk of coronary artery impingement, promotes coronary sinus patency, and overcomes technical concerns that may arise when the coronary sinus lies significantly superior to the mitral annulus.
Technological advances have recently enabled mitral valve repair to be performed using endovascular techniques and thus open the possibility of nonsurgical treatment of mitral valve disease. While balloon valvotomy has been applied to mitral stenosis for over 20 years, a number of devices aimed at correcting mitral regurgitation are currently in preclinical and clinical development. While some of these, such as edge-to-edge repair, are catheter adaptations of established surgical techniques, others represent true departures from the current surgical paradigms of correcting mitral regurgitation. This review will summarize the current status of percutaneous transcatheter techniques for mitral valve repair. Included are balloon mitral valvotomy, indirect annuloplasty, direct annuloplasty, ventricular shape change, and edge-to-edge repair. These techniques certainly represent a new interdisciplinary paradigm between cardiac surgery and interventional cardiology and may be the next frontier in minimally-invasive cardiac surgery.
Real-time three-dimensional echocardiography (RT3DE) has been used to quantify mitral valve (MV) annular size and leaflet tenting parameters in small numbers of patients with different pathologies. We sought to establish normal values for RT3DE mitral annular, tenting, and papillary muscle parameters over a wide age range and to study their age and body surface area (BSA) dependency.
Transthoracic wide-angled RT3DE images of the MV were acquired in 120 subjects (52 females, 68 males, age: 37+/-20 years) with normal left ventricular (LV) function, no risk factors, and less than or equal to mild mitral regurgitation. Custom software (RealView) was used to trace the MV annulus, leaflets, and the papillary apparatus in mid-systole in 18 sequential cut planes obtained from the 3D data sets. Mitral valve annular area and height as well as tenting parameters (maximum and mean tenting height and mid-systolic tenting volume) were obtained and correlated with age and BSA. Wide inter-subject variability was noted in all parameters. Despite this variability, parameters directly affected by LV size were found to be BSA-dependent: MV annular area showed highest correlation with BSA (r=0.78), followed by inter-papillary distance (r=0.58) and postero-medial (PM) and antero-lateral (AL) papillary muscle annular distance (r=0.57 and r=0.46, respectively). Age did not correlate with either annular or tenting parameters, but showed moderate negative correlation with inter-papillary muscle angle (r= -0.52) and mild negative correlation with inter-papillary distance (r= -0.32), both normalized by BSA.
Real-time three-dimensional echocardiography-derived MV annular, tenting, and papillary muscle parameters vary widely in normal subjects. When used clinically, normal values of parameters that are age- and/or BSA-dependent need to be adjusted accordingly.
The purpose of this study was to compare operative mortality and midterm outcome of patients with ischemic mitral regurgitation (MR) undergoing either coronary artery bypass grafting (CABG) alone or CABG with mitral valve (MV) repair.
From 1996 to 2001, 51 consecutive patients underwent CABG with MV repair for ischemic MR. All patients in this group were matched to similar patients with ischemic MR undergoing CABG alone during the same 6-year period using propensity analysis (considering 24 covariates, including severity of MR and New York Heart Association [NYHA] class).
Propensity score matching yielded 51 closely matched control patients. Preoperative MR severity was 3+ or 4+ in 94% of CABG with MV repair and 96% of CABG-alone patients, and 86% of patients in each group were NYHA class III or IV. Operative mortality was 3.9% +/- 2.8% in both groups. Survival was also similar between CABG with MV repair and CABG alone at 1 year (84% +/- 5% versus 82% +/- 5%) and 3 years (70% +/- 7% versus 71% +/- 7% (p = 0.43). Among survivors, NYHA class improved at follow-up (50 +/- 20 months) from 3.4 +/- 0.7 to 1.7 +/- 1.0 for CABG with MV repair (p < 0.001) and from 3.4 +/- 0.7 to 1.8 +/- 1.0 for CABG alone (p < 0.001).
Operative mortality, midterm survival, and late functional class were similar between two well-matched groups of patients undergoing CABG for ischemic MR, differing only in the addition of MV repair. Whereas MV repair can be added safely to CABG in this group of high-risk patients without increasing mortality, its impact on late survival and functional class may be limited.
Saddle-shaped non-planarity of the mitral annulus has been investigated previously. The study aim was to further clarify the configuration of the mitral annulus in ischemic mitral regurgitation (MR) by using transthoracic real-time three-dimensional (3-D) echocardiography.
Twenty-five patients with previous myocardial infarction and left ventricular dysfunction (ejection fraction < 50%), and 10 healthy control subjects, were examined using real-time 3-D transthoracic echocardiography. The patients were allocated to either a non-MR group or an MR group. By using real-time 3-D echocardiography, the configuration of the mitral annulus was reconstructed in end-systole, and the height of the saddle-shaped mitral annulus calibrated (non-planar index).
In controls, the mitral annulus appeared as non-planar 'saddle shape', with a non-planar index of 5.5 +/- 1.7 mm. The mitral annulus was flattened in both the non-MR and MR groups. The non-planar index was significantly smaller in the MR group than in the non-MR group (1.7 +/- 1.8 mm versus 3.8 +/- 1.2 mm, p < 0.05). The systolic annular area was significantly larger in the MR group than the non-MR group.
The 'saddle shape' of the mitral annulus was deformed in patients with ischemic MR. Mitral annulus deformation may play a role in ischemic MR in conjunction with mitral valve tenting. These results suggest that a non-planar saddle-shaped annuloplasty ring would contribute to successful mitral valve repair durability in patients with ischemic MR.
The case of a 52-year-old woman with subvalvular aortic stenosis and aortic regurgitation is presented. Mitral regurgitation was associated, due to insertion of two abnormal chordae tendineae at the apex of the anterior papillary muscle and at the free border of the subvalvular membranous annulus. This abnormality displaced the anterior papillary muscle, thus applying a traction at the mitral leaflet. The patient was operated on through a valve-sparing approach, in which the discrete subaortic stenosis was removed through aortotomy and the ectopic chordae were excised. Suture mitral annuloplasty completed the procedure. Aortic and mitral insufficiency almost disappeared at follow-up. From the examination of this case and from a review of pertinent literature it emerges that in event of similar complex congenital abnormalities without intrinsic valve disease, a conservative approach should be chosen so that valve replacement can be avoided.
Prosthetic ring annuloplasty is considered the gold standard technique for mitral valve repair, but it has been associated with some drawbacks. Suture annuloplasty is less expensive and may have some physiopathologic advantages. We reviewed the literature to assess clinical results of mitral suture annuloplasty. Thirteen series, each reporting more than 50 patients and published in the last 10 years, were included in the analysis. They comprised 1,648 patients with cumulative follow-up of 5,607 patient-years. Our review suggests that suture annuloplasty is a safe procedure, but a trend toward recurrence of annular dilatation with time was reported. In selected cases, suture annuloplasty is effective, and its mid-term clinical results are encouraging and compare well with those of prosthetic ring repair series. The quality of the results varies according to the particular annuloplasty technique used and to the mitral valve pathology treated. Recent technical modifications have been found to decrease the incidence of repair failure and promise to improve the reproducibility of the procedure. Further investigations are warranted to better assess the long-term results of suture annuloplasty, and to determine whether its theoretical functional advantages translate into a real clinical benefit.
evelopmental efforts to achieve percutaneous catheter-based therapies for cardiac valve repair and replacementhave advanced rapidly over the past several years. A varietyof methods to treat mitral regurgitation (MR) and to replaceaortic and pulmonic valves have already been successfullyemployed in patients. These innovative clinical transcathetervalve therapies were anticipated more than a decade ago bycreative experimentalists who helped develop predicate tech-niques in animal models. For example, in 1992, a catheter-delivered ball-in-cage prosthetic aortic valve was implantedin a canine model by Pavcnik
This editorial refers to Five-year echocardiographic results of combined undersized mitral ring annuloplasty and coronary artery bypass grafting for chronic ischaemic mitral regurgitation by S. Gelsomino et al., on page 231.
The incidence of valvular heart disease is expected to increase over the next several decades as a large proportion of the US demographic advances into the later decades of life. At the same time, the next several years can be anticipated to bring a broad transition of surgical therapy to minimally invasive (minithoracotomy and small port) access and the more gradual introduction of percutaneous approaches for the correction of valvular heart disease. Broad acceptance of these technologies will require careful and sometimes perplexing comparisons of the outcomes of these new technologies with existing standards of care. The validation of percutaneous techniques, in particular, will require the collaboration of cardiologists and cardiac surgeons in centers with excellent surgical and catheter experience and a commitment to trial participation. For the near term, percutaneous techniques will likely remain investigational and will be limited in use to patients considered to be high risk or to inoperable surgical candidates. Although current-generation devices and techniques require significant modification before widespread clinical use can be adopted, it must be expected that less invasive and even percutaneous valve therapies will likely have a major impact on the management of patients with valvular heart disease over the next several years.
Percutaneous catheter-based mitral annuloplasty (PTMA) exploits the anatomic proximity of the coronary sinus (CS) to the mitral valve apparatus. Acute results of PTMA have been favorable, but the durability of the geometric alterations associated with PTMA has not been reported. The study aim was to assess the three-dimensional (3D) geometry of the mitral annulus (MA) in normal sheep at 20 weeks after PTMA implantation.
A PTMA device was implanted percutaneously in the CS of 10 normal sheep without mitral regurgitation. All animals were followed for 20 weeks with real-time 3D echocardiography (RT3DE). The MA area, the diagonal diameters in four directions, and the angle alpha, representing the degree of the saddle shape of MA, were determined.
No significant hemodynamic, pathologic or mechanical complications were observed during implantation or follow up. Both, the MA area (from 4.8 +/- 0.9 cm2 to 3.7 +/- 0.9 cm2) and anterior-posterior (A-P) diameter (from 21.4 +/- 3.0 mm to 17.6 +/- 2.4 mm) were reduced immediately after the procedure (both p <0.05). The angle alpha decreased after the procedure (from 142.0 +/- 11.5 degrees to 128.3 +/- 15.6 degrees; p <0.05). These changes remained stable over the 20-week follow up period.
RT3DE demonstrates that PTMA reduces the MA area and A-P diameter and maintains the physiologic curved or saddle shape of the MA. These changes remained stable for 20 weeks after device implantation.
The effects of ring annuloplasty on mitral leaflet motion are incompletely known. The three-dimensional dynamics of the mitral valve in vivo were examined to determine how two types of annuloplasty rings affect leaflet motion during valve closure.
Miniature radiopaque markers on the mitral leaflets, annulus, and left ventricle were implanted in three groups of sheep. One group served as control (n = 7); other sheep were randomly assigned to receive either a flexible Duran (n = 6) or a semirigid Carpentier-Edwards Physio ring (n = 6). After recovery, three-dimensional marker coordinates were computed from simultaneous (60 Hz) biplane videofluoroscopic marker images.
Both types of rings immobilized the middle scallop of the posterior leaflet without affecting anterior leaflet motion. The excursion of the anterior leaflet edge from maximally open to fully closed was not different between the groups (control, 13+/-2 mm; Duran 13+/-1 mm; Physio ring, 14+/-1 mm; p > 0.05), but posterior leaflet edge excursion was restricted (control, 7.4+/-0.4 mm; 2.3+/-0.3 mm [p < 0.001]; Physio, 2.7+/-0.2 mm [p < 0.001]) by both rings.
Mitral annuloplasty with either ring type markedly reduced the mobility of the central posterior leaflet in normal ovine hearts such that valve closure became essentially a single (anterior) leaflet process with the frozen posterior leaflet serving only as a buttress for closing.
Seven rigid (Carpentier) and six flexible (Duran) annuloplasty rings were implanted in healthy pigs. First, in the intact pig, cinefluoroscopy was used to record movements of the anulus. Results were compared with data from three pigs instrumented with a continuous radiopaque marker on the anulus. Pump function of all hearts with annuloplasty rings and function of the mitral valve were studied 4-6 weeks after the operation, first in the exposed heart and then subsequently in the isolated heart in a perfusion chamber at maximal filling pressure and normal or low arterial pressure. Separation of the blood-perfused coronary circulation from the crystalline solution pumped by the left heart allowed videoendoscopy of the working valve. Flexible rings interfered less with normal movements of the mitral anulus than rigid rings and caused less impairment of filling of the basal part of the ventricle, and the unloaded stroke volume was 16% larger. For normal arterial pressures, the differences were smaller and will be difficult to detect in clinical situations. A stiff anulus was seen to be pushed underneath the aortic valve during systole, which caused a mild subvalvular obstruction. The mean diastolic pressure gradient across rigid annuloplasty rings was slightly larger than across flexible rings of the same or slightly smaller diastolic size. Rigid rings change the pattern of movement of the leaflets; the mural leaflet remains immobile throughout diastole. Although Duran rings interfere less with valvular function and filling of the basal part of the ventricle than do Carpentier rings, the differences are small and probably only of limited clinical importance.
The purpose of this study was to explore whether geometric changes that predispose to left ventricular outflow tract obstruction after mitral ring annuloplasty are coupled to subvalvular apparatus disturbances.
Radiopaque markers were implanted in sheep: 9 in the ventricle, 1 in the high interventricular septum, 1 on each papillary muscle tip, 8 around the mitral anulus, 4 on the anterior mitral leaflet, and 2 on the posterior leaflet. One group served as control (n = 5); the others were randomized to undergo annuloplasty with the Duran ring (n = 6; Medtronic, Inc, Minneapolis, Minn) or Carpentier-Edwards Physio ring (n = 6; Baxter Healthcare Corp, Irvine, Calif). After a 7- to 10-day recovery period, 3-dimensional marker coordinates were measured with biplane videofluoroscopy.
At the beginning of ejection, (1) the anterior leaflet was displaced toward the left ventricular outflow tract; (2) the normal atrially flexed anterior anulus was flattened into the left ventricular outflow tract; (3) the posterior anulus was displaced toward the left ventricular outflow tract; (4) the anterior papillary muscle was displaced septally; and (5) the posterior papillary muscle was dislocated inwardly toward the anterior papillary muscle in the Physio ring group compared with the control group. During ejection, all these structures moved septally, encroaching further on the left ventricular outflow tract. In the Duran ring group, only the posterior anulus was displaced toward the left ventricular outflow tract; the anterior leaflet was not displaced toward the left ventricular outflow tract, and it did not move septally during ejection.
The semirigid Physio ring was associated with perturbations in annular dynamics that caused changes in papillary muscle geometry. We propose an integrated valvular-subvalvular mechanism to explain displacement of the anterior leaflet into the left ventricular outflow tract after mitral ring annuloplasty.
Leaflet curvature is known to reduce mechanical stress. There are 2 major components that contribute to this curvature. Leaflet billowing introduces the most obvious form of leaflet curvature. The saddle shape of the mitral annulus imparts a more subtle form of leaflet curvature. This study explores the relative contributions of leaflet billowing and annular shape on leaflet curvature and stress distribution.
Both numerical simulation and experimental data were used. The simulation consisted of an array of numerically generated mitral annular phantoms encompassing flat to markedly saddle-shaped annular heights. Highest peak leaflet stresses occurred for the flat annulus. As saddle height increased, peak stresses decreased. The minimum peak leaflet stress occurred at an annular height to commissural width ratio of 15% to 25%. The second phase involved data acquisition for the annulus from 3 humans by 3D echocardiography, 3 sheep by sonomicrometry array localization, 2 sheep by 3D echocardiography, and 2 baboons by 3D echocardiography. All 3 species imaged had annuli of a similar shape, with an annular height to commissural width ratio of 10% to 15%.
The saddle shape of the mitral annulus confers a mechanical advantage to the leaflets by adding curvature. This may be valuable when leaflet curvature becomes reduced due to diminished leaflet billowing caused by annular dilatation. The fact that the saddle shape is conserved across mammalian species provides indirect evidence of the advantages it confers. This analysis of mitral annular contour may prove applicable in developing the next generation of mitral annular prostheses.
Mitral regurgitation (MR) and abnormal ventricular wall motion (AVWM) are two cardiac conditions that may increase mitral valve (MV) stresses. Theoretically, increased stress could induce damaging MV tissue alterations. These alterations may impair the preferred option of repair, and mandate replacement. It is hypothesized that MV collagen synthesis is upregulated in response to MR and AVWM. To test this hypothesis in a pilot study, an ischemic sheep model (n = 8) was employed. Four sheep underwent selective coronary artery ligation to infarct a papillary muscle, which resulted in MR. Two other sheep underwent similar coronary ligation to create AVWM. As controls, two sheep underwent sham surgery (no ligation). Sheep were killed 4 or 8 weeks post operatively and their MVs were sectioned. Sections were stained with an antibody (SP1.D8, University of Iowa) to procollagen I (precursor to collagen I). The percent area of procollagen stain present was measured by image analysis (Optimas Corporation) and used as an indicator of collagen synthesis. Procollagen results indicated that MV collagen synthesis was upregulated by a factor of 1.8 in both the MR and AVWM groups versus controls. In addition, results showed greater upregulation in anterior leaflets compared with posterior leaflets in both infarct groups. These results indicate that MV collagen synthesis is upregulated in response to MR and AVWM.
Abstract An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valve repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this geometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight normal subjects. The posterior half of the MVA exhibited translational motion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricular contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterior half exhibited a flexible change in shape during systole, thus maintaining a sufficient left ventricular outflow tract (LVOT). The increase in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 ± 1.0 mm (mean ± SD), indicates the annular flexibility. The preservation of annular flexibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presented in this article.
Background:
We studied the long-term results of a technique of mitral annuloplasty using autologous pericardium.
Methods:
Between June 1989 and December 1994, 113 mitral valvuloplasties were performed for myxomatous degenerative disease. Repair of isolated anterior leaflet prolapse was performed in 26 patients (23%), posterior leaflet prolapse in 38 (33.6%), and prolapse of both leaflets in 49 (43.4%). Posterior pericardial annuloplasty was performed in all patients. In 20 patients, the pericardial graft was marked with metal clips for postoperative cinefluoroscopic assessment of annulus motion.
Results:
The operative mortality rate was 2.7% (3/113). One patient died of myocardial infarction and 2 of low cardiac output syndrome. One patient required replacement of the mitral valve 2 days after operation because of dehiscence of the annular plication. Follow-up (average length, 32.41 +/- 20.09 months; range 1 to 71 months) was 97% complete and revealed good clinical and functional results: 95 patients (84.1%) were in New York Heart Association class I and had no regurgitation or only mild residual regurgitation. Postoperative transmitral flow indices were almost normal (mitral valve area = 3.7 +/- 0.4 cm2; peak flow velocity = 1.06 +/- 0.2 m/s). Only 3 patients had reoperation within 3 years (actuarial 5-year reoperation-free rate, 89.7%) and event-free survival at 5 years was 91%. In patients with metal clips marking autologous pericardium, planimetry of the area derived by fluoroscopic examination showed systolic narrowing of annulus size (8.5% +/- 6.4%; p < 0.01) and a slight systolic fall in the anteroposterior diameter of the annulus contour (5.9% +/- 3.8%; p < 0.01).
Conclusions:
Posterior pericardial annuloplasty seems to be a safe, effective and easily performed technique and a more physiologic correction that preserves mitral annulus motion.
Background:
Ischemic mitral regurgitation or ventricular wall motion abnormalities will alter the stress distribution in the mitral valve. We hypothesize that in response, the regional collagen concentration will be altered and will significantly impact the stress distribution in the mitral valve.
Methods:
Two sheep served as normal (sham) controls. Two other sheep had coronary ligation resulting in abnormal ventricular wall motion. Four sheep underwent ligation to infarct the posteromedial papillary muscle, resulting in ischemic regurgitation. After 4 or 8 weeks, the mitral valves were excised, and the anterior leaflet sections were subjected to an assay for collagen concentration. Next, in a finite element model, to simulate changes in collagen concentration, the tissue stiffness was increased by 20%, and then decreased by 20%. In another model, the thickness of the tissue was increased by 20%, and then combined with decreased tissue stiffness. Physiologic loading pressures were applied, and leaflet stress, chordal stress, and coaptation results were analyzed.
Results:
The average collagen concentration in the normal sheep leaflets was 59.2% (dry weight), 50.6% in the ischemic controls, and 45.8% in the papillary muscle infarct group. Collagen concentration was greatest at the midline and decreased toward the commissures. Increased tissue stiffness resulted in increased leaflet and chordal stresses, as well as reduced coaptation. Decreased stiffness resulted in the opposite. Increased tissue thickness reduced leaflet and chordal stresses, but also reduced coaptation. The combination of increased tissue thickness and decreased stiffness demonstrated the greatest reduction in leaflet and chordal stress, while maintaining normal leaflet coaptation.
Conclusions:
The observed changes may demonstrate an early effort to compensate for increased leaflet stress. Microstructural alterations may demonstrate an early effort to compensate for altered physiologic loading to reduce stress and maintain coaptation. It is crucial in repairing or partially replacing thickened tissue that normal geometry and physiology be restored.
The study objective was to compare coaptation, and leaflet and chordal stresses in normal and dilated mitral valves (18% annular dilatation) versus valves with flexible (Duran) and rigid (Carpentier-Edwards classic) ring annuloplasty, using a computer model. We have developed a 3D finite element model which allows us to evaluate valvular function in terms of coaptation and stresses in both leaflets and individual chordae.
The mitral valve was simulated using ANSYS 4.4A software. Normal model geometry, collagen fiber orientation, tissue thickness and material properties were determined from fresh porcine valves. For annular dilatation, the annular circumference was increased by 18% versus normal. For annuloplasty, a simulated flexible ring was attached to the annulus, and a simulated rigid ring then attached. Valves were evaluated during systolic pressure loading, after which timing of coaptation and leaflet and chordal stresses were determined.
In the normal valve, the anterior leaflet was subject to higher tensile stresses than the posterior leaflet which was under compression. With annular dilatation, all stresses were increased, particularly in the posterior leaflet. The flexible ring returned leaflet and chordal stresses closer to normal than did the rigid ring. Leaflet coaptation began at 5 ms in the normal state, was delayed by dilatation, and returned towards normal with both rings. The flexible ring returned coaptation and stresses closer to normal than did the rigid ring.
Ring annuloplasty reduces the stresses and improves coaptation relative to annular dilatation. The success of mitral annuloplasty is likely due to the re-establishment of posterior leaflet compressive stresses and near-normal coaptation.
During 1975, 67 patients underwent attempted repair of mixed mitral valve disease by use of the new mitral plication suture (MPS) technique. Ninety per cent had successful repair and 10 par cent required valve replacement. The MPS is a double, semicircular, buttressed annuloplasty suture that constricts the enlarged mitral annulus to correct mitral regurgitation (MR), supports mitral subunit repair procedures, and yet maintains the flexibility of the mitral annulus. The hospital mortality rate was 6 per cent. There were no late deaths during 10.4 months of follow-up. Six per cent of the patients who had valve repair required subsequent MVR. Their repair operations are considered late failures. Echocardiography, a useful technique for assessing the status of the patients postoperatively, demonstrated normal mitral valve and left ventricular function in the majority of patients; comparisons with replacement valves are documented. Death and morbidity was less frequent than in patients with MVR, both in the hospital and during follow-up. The aggressive policy of mitral valve repair has reduced the number of MVR's from 95 during 1974 to 52 in 1975. Although follow-up is short, we conclude that the new MPS is a valid surgical adjunct to the complete repair of the mitral valve.
A new, totally flexible ring for atrioventricular annuloplasty is described. The technique for its insertion closely follows the principles of Carpentier's selective annulus reconstruction [4]. Ninety-nine such rings have been inserted (47 in the mitral and 52 in the triscuspid position); 45 valves were simultaneously replaced. There were 6 (4 hospital and 2 late) deaths. The thromboembolic incidence was 4.8%. No instances of dehiscence or late ring deterioration have been detected. Thirty-four patients have been recatheterized, 19 of them with mitral rings. The mitral gradients and angiographic findings show the correct functioning of the implanted ring. It is concluded that use of this flexible ring, which adapts to the continuous changes of the normal mitral annulus, produces a more physiological type of valve operation.
The dynamics between mitral annulus motion and left ventricular function were studied. Thirty subjects (10 normals, 10 with severe cardiac failure and 10 with mitral regurgitation) were examined. Left ventricular long and short-axis dimensions were measured in a two-dimensional apical four-chamber image. A volume was calculated as defined by cardiac cyclic changes of mitral annulus in size and motion. This volume had the approximate geometric configuration of a truncuated cone and was covered by mitral annulus motion at enddiastole and endsystole. Left ventricular ejection fraction was calculated echocardiographically using the prolate ellipsoid/area-length method. The volume defined by mitral annulus motion was 24 ml in normals, 16 ml in patients with cardiac failure and 48 ml in patients with mitral regurgitation while the ejection fraction was 51%, 19% and 53% respectively. Comparison between the volume of the truncuated cone and the ejection fraction in all 30 subjects revealed a statistically significant correlation (p less than 0.01). Thus, the bigger the volume determined by the mitral annulus motion during systole, the larger portion of the left ventricle is "atrialized", and a higher ejection fraction follows. Mitral annulus motion may provide new information about cardiac mechanics in normal and abnormal conditions.
An 80386 PC-based system was designed to track automatically multiple, miniature radiopaque markers implanted in the heart wall. This system eliminated the need for tedious, time-consuming manual digitization of marker coordinates. Use of a MATROX MVP-AT/NP image processing board incorporated advanced image processing and graphics features into the low-cost PC environment. Digital image enhancement and segmentation techniques (such as limiting analysis to predefined windows of interest, spatial band-pass and matched filtering, contrast stretching and clipping, linear adaptive prediction, intensity histogram analysis, adaptive binary thresholding, region growing, expanding region of analysis, and feature extraction) were incorporated into a user-friendly integrated marker processing software environment. Improved speed, accuracy, and reproducibility of the marker digitizing process were realized. These basic techniques have broad applications to other image processing needs in biomedical research.
Cardiac surgery has achieved remarkable progress in the past 10 years. Safer techniques of anesthesia and postoperative care, improved extracorporeal circulation and myocardial protection, and sophisticated surgical techniques are new tools which have been instrumental in reducing hospital mortality and increasing the efficiency of our operations. New surgical tools impose new surgical goals. It's not enough to save patients' lives; we must also take into consideration the quality of life given to the patient and the socioeconomic impact of our surgical actions. There already have been some trends in this direction, such as operating for congenital malformations at an earlier stage and the development of reconstructive operations to replace palliative techniques. Reconstructive valve surgery can very well be considered another example of this nouvelle chirurgie.
During chordal-sparing mitral valve replacement (MVR), some recommend anatomic reattachment of the anterior leaflet chordae to the anterior annulus; others advocate shifting the chordae to the posterior annulus. To compare the results of these techniques with those of conventional MVR (total chordal excision), 21 dogs were studied 5 to 12 days after implantation of tantalum markers to measure left ventricular volume and geometry. One to 3 weeks later, animals underwent conventional MVR (n = 7) or chordal-sparing MVR with either anterior chordal reattachment (n = 7) or posterior transposition (n = 7). Contractility was assessed using physiologic volume intercepts for end-systolic elastance, preload recruitable stroke work, and the relationship of the maximum rate of change of left ventricular pressure to the end-diastolic volume. The physiologic intercept for end-systolic elastance did not change after anterior or posterior MVR, but increased from 60 +/- 14 mL before MVR to 72 +/- 17 mL with conventional MVR (p < 0.002), indicating impaired left ventricular contractility. Similarly, the physiologic intercept for preload recruitable stroke work and the relationship of the maximum rate of change of left ventricular pressure to the end-diastolic volume increased 22% +/- 13% and 28% +/- 13%, respectively, after conventional MVR, but neither changed after anterior or posterior MVR. Although the end-diastolic pressure-volume relationship did not change with either chordal-sparing technique, its slope increased 98% +/- 73% after conventional MVR (p < 0.008). Thus, although chordal preservation maintained better systolic and diastolic function, there was no substantial difference between the results of the anterior and posterior chordal-sparing techniques in this model.
A finite element model was developed to examine deformation and stress patterns in the mitral valve under systolic loading conditions. This is the first three-dimensional finite element model of the mitral valve, incorporating all essential anatomic components, regional tissue thickness, collagen fiber orientation and related anisotropic material properties. A non-linear, transient, dynamic analysis was performed which included time-dependent loading, leaflet and chordal mass inertial effects and chordal element bi-linearity. The model was first analyzed without either annular or papillary muscle contraction and then with either or both. The hypothesis was that the combination of annular and papillary muscle contraction would have a beneficial effect on valve function. In all models, the computed anterior leaflet principal stresses were tensile and of greater magnitude than those in the posterior leaflet. The principal stress directions were observed to correlate well with collagen fiber orientation. Earlier leaflet coaptation was demonstrated with annular contraction, promoting valve closure, while papillary muscle contraction increased the stress on the chordae tendineae and both leaflets, tending to pull the latter apart. The combination of the two combined these effects, and showed the most even stress distribution. The effects of annular and papillary muscle contraction on valve function were shown to be beneficial by this model, and they can be further elucidated by varying the extent and timing of the individual contractions. This model can be used to examine the effects of pathologic changes, surgical manipulations and proposed material replacements. It can thus aid both the surgeon and the biomedical engineer in improving the materials and techniques available for the repair and/or replacement of mitral valve system components.
Although chordal preserving mitral valve replacement is beneficial to cardiac function, the loss of flexibility of the annulus and consequent translational motion of the valve prosthesis during systole may cause potential left ventricular outflow tract (LVOT) obstruction after surgery. The extent of the flexibility of the mitral valve annulus (MVA) necessary for the prosthetic valve to prevent potential LVOT obstruction was determined. The three dimensional images of the MVA at 0, 100, 200, and 300 msec delay from the electrocardiogram R wave were reconstructed from cine-mode magnetic resonance images in eight normal subjects. In the lateral view of the MVA, the dorsal flexion angle (DFA) was defined. This angle implies the extent of the flexion of the anterior half of the MVA in relation to the posterior half. The data (mean +/- SD) for the DFA were 31.7 +/- 5.4 degrees (0 msec), 36.4 +/- 4.5 degrees (100 msec), 39.0 +/- 3.8 degrees (200 msec), and 43.6 +/- 2.6 degrees (300 msec), whereas the systolic increase in DFA was 11.9 +/- 3.2 degrees. The flexibility observed in normal mitral annuli is relevant to prosthetic mitral valves.
Mitral regurgitation (MR) and abnormal ventricular wall motion (AVWM) are two cardiac conditions that may increase mitral valve (MV) stresses. Theoretically, increased stress could induce damaging MV tissue alterations. These alterations may impair the preferred option of repair, and mandate replacement. It is hypothesized that MV collagen synthesis is upregulated in response to MR and AVWM. To test this hypothesis in a pilot study, an ischemic sheep model (n = 8) was employed. Four sheep underwent selective coronary artery ligation to infarct a papillary muscle, which resulted in MR. Two other sheep underwent similar coronary ligation to create AVWM. As controls, two sheep underwent sham surgery (no ligation). Sheep were killed 4 and 8 weeks post operatively and their MVs were sectioned. Sections were stained with an antibody (SP1.D8, University of Iowa) to procollagen I (precursor to collagen I). The percent area of procollagen stain present present was measured by image analysis (Optimas Corporation) and used as an indicator of collagen synthesis. Procollagen results indicated that MV collagen synthesis was upregulated by factor of 1.8 in both the MR and AVWM groups versus controls. In addition, results showed greater upregulation in anterior leaflets compared with posterior leaflets in both infarct groups. These results indicate that MV collagen synthesis is upregulated in response to MR and AVWM.
Mitral annuloplasty is an important element of most mitral repairs, yet the effects of various types of annuloplasty rings on mitral annular dynamics are still debated. Recent studies suggest that flexible rings preserve physiologic mitral annular area change during the cardiac cycle, while rigid rings do not.
To clarify the effects of mitral ring annuloplasty on mitral annular dynamic geometry, we sutured 8 radiopaque markers equidistantly around the mitral anulus in 3 groups of sheep (n = 7 each: no ring, Carpentier-Edwards semi-rigid Physio-Ring [Baxter Healthcare Corp, Edwards Division, Santa Ana, Calif], and Duran flexible ring [Medtronic, Inc, Minneapolis, Minn]). Ring sizes were selected according to anterior leaflet area and inter-trigonal distance (Physio-Ring 28 mm, n = 7; Duran ring 31 mm, n = 5, and 29 mm, n = 2). After 8 +/- 1 days of recovery, the sheep were sedated and studied by means of biplane videofluoroscopy. Mitral annular area was calculated from 3-dimensional marker coordinates without assuming circular or planar geometry.
In the no ring group, mitral annular area varied during the cardiac cycle by 11% +/- 2% (mean +/- SEM; maximum = 7.6 +/- 0.2, minimum = 6.8 +/- 0.2 cm2; P </=.001). Mitral annular area was fixed in the Physio-Ring group (4. 6 +/- 0.1 cm2) and, surprisingly, also static in the Duran ring group (4.8 +/- 0.1 cm2; P =.26 vs Physio-Ring). Furthermore, mitral annular 3-dimensional shape changed in the no-ring group during the cardiac cycle, but not in the Physio-Ring or Duran groups.
Mitral annular area and shape did not change during the cardiac cycle after ring annuloplasty, regardless of ring type. Thus mitral annular area reduction, independent of intrinsic ring flexibility, is the chief mechanism responsible for the salutary effects of mitral ring annuloplasty.
We congratulate Liuzzo et al on the recent publication of their study,1 which suggests that disruption of culprit coronary stenoses by PTCA does not necessarily lead to an increase in the level of systemic inflammatory markers (C-reactive protein [CRP], serum amyloid A protein [SAA], and interleukin-6 [IL-6]) in patients with unstable angina. The authors found that serum levels …
Asymmetrical mitral annular (MA) dilatation and papillary muscle dislocation are implicated in the pathogenesis of functional mitral regurgitation (MR).
To determine the mechanism by which annular and papillary muscle geometric alterations result in MR, we implanted radiopaque markers in the left ventricle, mitral annulus, anterior and posterior mitral leaflets, and papillary muscle tips and bases in 2 groups of sheep. One group served as controls (CTL, n=7); an experimental group (EXP, n=9) underwent topical phenol application to obliterate anterior annular and leaflet muscle (confirmed histologically ex vivo). After 1 week of recovery, markers were imaged with biplane videofluoroscopy, and hemodynamic data were recorded. MA area (computed from 3-dimensional marker coordinates) was 11% to 13% larger in the EXP group than in the CTL group (P<0.05 by ANOVA). This area increase resulted exclusively from intercommissural axis increase except in 1 heart with large (>1 cm) increases in both the intercommissural and septolateral annular axes. The anterior papillary muscle tip in EXP was displaced from CTL by 2.9+/-0.23 mm toward the anterolateral left ventricle and 2.5+/-0.12 mm toward the mitral annulus at end systole; the posterior papillary muscle geometry was unchanged. Transthoracic echocardiography revealed MR only in the heart exhibiting biaxial annular enlargement.
MA dilatation in the intercommissural dimension with anterior papillary muscle tip displacement toward the annulus is insufficient to produce MR in sheep. Functional MR may require MA dilatation in the septolateral axis, as observed with proximal circumflex coronary occlusion.
Incomplete mitral leaflet coaptation during acute left ventricular ischemia is associated with end-diastolic mitral annular dilatation and ischemic mitral regurgitation. Annular rings were implanted in sheep to investigate whether annular reduction alone is sufficient to prevent mitral regurgitation during acute posterolateral left ventricular ischemia.
Radiopaque markers were inserted around the mitral anulus, on papillary muscle tips, and on the central meridian of both mitral leaflets in three groups of sheep: control (n = 5), Physio ring (n = 5) (Baxter Cardiovascular Div, Santa Ana, Calif), and Duran ring (n = 6) (Medtronic Heart Valve Div, Minneapolis, Minn). After 8 +/- 1 days, animals were studied with biplane videofluoroscopy before and during left ventricular ischemia. Annular area was calculated from 3-dimensional marker coordinates and coaptation defined as minimal distance between leaflet edge markers.
Before ischemia, leaflet coaptation occurred just after end-diastole in all groups (control 17 +/- 41, Duran 33 +/- 30, Physio 33 +/- 24 ms, mean +/- SD, P >.2 by analysis of variance). During ischemia, regurgitation was detected in all control animals, and leaflet coaptation was delayed to 88 +/- 8 ms after end-diastole (P =.02 vs preischemia). This was associated with increased end-diastolic annular area (8.0 +/- 0.9 vs 6.7 +/- 0.6 cm(2), P =.004) and septal-lateral annular diameter (2.9 +/- 0.1 vs 2.5 +/- 0.1 cm, P =.02). Mitral regurgitation did not develop in Duran or Physio sheep, time to coaptation was unchanged (Duran 25 +/- 25 ms, Physio 30 +/- 48 ms [both P >.2 vs preischemia]), and annular area remained fixed.
Mitral annular area reduction and fixation with an annuloplasty ring eliminated delayed leaflet coaptation and prevented mitral regurgitation during acute left ventricular ischemia after ring implantation.
The effects of different annuloplasty rings on mitral annulus dynamics and left-ventricular (LV) function after mitral-valve repair (MVR) are still controversial. This study sought to compare biological versus prosthetic rigid rings for annular remodelling in MVR at long term.
Forty-four consecutive patients were retrospectively enrolled. All patients had isolated posterior-leaflet prolapse and underwent identical surgical mitral-valve reconstruction (quadrangular resection of the posterior leaflet associated with annuloplasty). Twenty-three patients underwent mitral annuloplasty with an autologous pericardial ring (group I), whereas 21 patients had MVR with a Carpentier-Edwards rigid ring (group II). No differences existed between the groups in terms of pre-operative patient profile. Post-operative LV systolic indices have been assessed by two-dimensional echocardiography at rest and during supine bicycle exercise. Mitral annular motion has been examined by means of the extent of mitral annulus systolic excursion (MASE), as measured in four longitudinal LV segments (anterior, inferior, septal and lateral). Mean and peak trans-mitral flow velocities (TMFV) have been also evaluated by continuous-wave Doppler.
The mean follow-up did not differ between the groups, those being 41+/-12 months in group I (range17-65 months) and 46+/-15 months in group II (range 23-83 months), respectively. Post-operative echocardiographic study did not show significant mitral regurgitation at rest or at peak exercise in any patient. ANOVA analysis for repeated measures showed a significant interaction in peak TMFV (F((1,42))=5.23; P=0.03), and in left-ventricular ejection fraction (LVEF; F((1,42))=7.61, P=0.01). The analysis of contrasts showed a significant increase in TMFV in both groups (group I from 1.22+/-0.22 to 1.79+/-0.32 m/s, t=-8.8, P<0.0001; and group II from 1.19+/-0.17 to 1.96+/-0.33 m/s, t=-12.8, P<0.0001). Recruitment of LVEF reserve during exercise was observed only in group I (from 59.5+/-6 to 65.8+/-6%, t=-3.95, P<0.005), whereas no substantial change occurred in LV performance in group II. A trend towards better MASE at all the studied longitudinal segments at rest and during exercise was observed in group I. No minor or major calcifications have been observed on pericardial rings.
The autologous pericardium seems to be superior to rigid prosthetic rings for annuloplasty in MVR since it provides more favourable mitral annulus dynamics and preserves LV function during stress conditions. Effective and durable annular remodelling with the autologous pericardium is achieved up to 6 years from surgery, with no echocardiographic sign of degeneration in the long term. Further studies are required to compare biological versus flexible prosthetic rings in MVR.
Mechanistic insights from 3D echocardiography (echo) can guide therapy. In particular, ischemic mitral regurgitation (MR) is difficult to repair, often persisting despite annular reduction. We hypothesized that (1) in a chronic infarct model of progressive MR, regurgitation parallels 3D changes in the geometry of mitral leaflet attachments, causing increased leaflet tethering and restricting closure; therefore, (2) MR can be reduced by restoring tethering geometry toward normal, using a new ventricular remodeling approach based on 3D echo findings.
We studied 10 sheep by 3D echo just after circumflex marginal ligation and 8 weeks later. MR, at first absent, became moderate as the left ventricle (LV) dilated and the papillary muscles shifted posteriorly and mediolaterally, increasing the leaflet tethering distance from papillary muscle tips to the anterior mitral annulus (P<0.0001). To counteract these shifts, the LV was remodeled by plication of the infarct region to reduce myocardial bulging, without muscle excision or cardiopulmonary bypass. Immediately and up to 2 months after plication, MR was reduced to trace-to-mild as tethering distance was decreased (P<0.0001). LV ejection fraction, global LV end-systolic volume, and mitral annular area were relatively unchanged. By multiple regression, the only independent predictor of MR was tethering distance (r(2)=0.81).
Ischemic MR in this model relates strongly to changes in 3D mitral leaflet attachment geometry. These insights from quantitative 3D echo allowed us to design an effective LV remodeling approach to reduce MR by relieving tethering.
Although mitral annuloplasty is an important element of mitral valve repair, the technique employed remains controversial. In this prospective study, we compared two different annuloplasty techniques with regard to hemodynamic performance.
Between October 1995 and December 1998, 109 consecutive patients underwent mitral valve repair for mitral regurgitation. One group of patients (n = 55) received a Carpentier-Edwards (CE) ring for annuloplasty, and a second group (n = 54) underwent the mural annulus shortening suture (MASS) to reinforce the posterior circumference of the annulus. All patients were investigated prospectively by Doppler echocardiography before discharge and annually thereafter. The mean follow up was 22.7+/-11.6 months.
The early mortality rate was 3.7%, with four early deaths in the CE group, and no early death in the MASS group. There was one late death in each group. One patient in each group required reoperation for severe mitral regurgitation after 19 and 30 months, respectively. Postoperative (12 months) Doppler echocardiography showed mean mitral valve gradients to be significantly lower (1.7+/-0.7 versus 2.7+/-1.7 mmHg; p <0.01) and mitral valve areas significantly larger (3.3+/-1.0 versus 2.6+/-0.7 cm2; p <0.01) in MASS patients compared with CE patients. There was no significant difference in mean postoperative mitral regurgitation between the two groups (0.5+/-0.2 versus 0.4+/-0.2).
Both annuloplasty techniques showed excellent results; however, hemodynamic performance of MASS was superior to that of the rigid CE ring, while not increasing postoperative mitral regurgitation. Therefore, MASS may be recommended as an alternative to annuloplasty rings, if future long-term follow up studies confirm the durability of the technique.
Functional mitral regurgitation (FMR) occurs with a structurally normal valve as a complication of systolic left ventricular dysfunction (LVD). Determinants of degree of FMR are poorly defined; thus, mechanistic therapeutic approaches to FMR are hindered.
In a prospective study of 21 control subjects and 128 patients with LVD (defined as ejection fraction <50%, mean 31+/-9%) in sinus rhythm, we quantified simultaneously by echocardiography the effective regurgitant orifice (ERO) of FMR by using 2 methods: mitral deformation (valve and annulus) and left ventricular (LV) global (volumes, stress, function, and sphericity) and local (papillary muscle displacements and regional wall motion index) remodeling. A wide range of ERO (15+/-14 mm(2), 0 to 87 mm(2)) was observed, unrelated to ejection fraction (P:=0.32). The major determinant of ERO was mitral deformation, ie, systolic valvular tenting and annular contraction in univariate (r=0.74 and r=-0.61, respectively; both P:<0.0001) and multivariate (both P:<0. 0001) analyses, independent of global LV remodeling. Systolic valvular tenting was strongly determined by local LV alterations, particularly apical (r=0.75) and posterior (r=0.70) displacement of papillary muscle, with confirmation in multivariate analysis (both P:<0.0001), independent of LV volumes, function, and sphericity.
The presence and degree of FMR complicating LVD are unrelated to the severity of LVD. Local LV remodeling (apical and posterior displacement of papillary muscles) leads to excess valvular tenting independent of global LV remodeling. In turn, excess tenting and loss of systolic annular contraction are associated with larger EROs. These determinants of FMR warrant consideration for specific approaches to the treatment of FMR complicating LVD.
This study aimed to separate proposed mechanisms for segmental ischemic mitral regurgitation (MR), including left ventricular (LV) dysfunction versus geometric distortion by LV dilation, using models of acute and chronic segmental ischemic LV dysfunction evaluated by three-dimensional (3D) echocardiography.
Dysfunction and dilation-both mechanisms with practical therapeutic implications-are difficult to separate in patients.
In seven dogs with acute left circumflex (LCX) coronary ligation, LV expansion was initially restricted and then permitted to occur. In seven sheep with LCX branch ligation, LV expansion was also initially limited but became prominent with remodeling over eight weeks. Three-dimensional echo reconstruction quantified mitral apparatus geometry and MR volume.
In the acute model, despite LV dysfunction with ejection fraction = 23 +/- 8%, MR was initially trace with limited LV dilation, but it became moderate with subsequent prominent dilation. In the chronic model, MR was also initially trace, but it became moderate over eight weeks as the LV dilated and changed shape. In both models, the only independent predictor of MR volume was increased tethering distance from the papillary muscles (PMs) to the anterior annulus, especially medial and posterior shift of the ischemic medial PM, measured by 3D reconstruction (r2 = 0.75 and 0.86, respectively). Mitral regurgitation volume did not correlate with LV ejection fraction or dP/dt.
Segmental ischemic LV contractile dysfunction without dilation, even in the PM territory, fails to produce important MR. The development of MR relates strongly to changes in the 3D geometry of the mitral apparatus, with implications for approaches to restore a more favorable configuration.
Dilated cardiomyopathy is often associated with mitral regurgitation (MR), or so-called functional MR, the mechanism of which continues to be debated. We studied the valvular and ventricular 3D geometric perturbations associated with MR in an ovine model of tachycardia-induced cardiomyopathy (TIC).
Nine sheep underwent myocardial marker implantation in the left ventricle (LV), mitral annulus, and mitral leaflets. After 5 to 8 days, the animals were studied with biplane videofluoroscopy (baseline), and mitral competence was assessed by transesophageal echocardiography. Rapid ventricular pacing (180 to 230 bpm) was subsequently initiated for 15+/-6 days until the development of TIC and MR, whereupon biplane videofluoroscopy and transesophageal echocardiography studies were repeated. LV volume was calculated from the epicardial marker array. Valve closure time was defined as the time after end diastole when the distance between leaflet edge markers reached its minimal plateau. TIC resulted in increased LV end-diastolic volume (P=0.001) and LV end-systolic volume (P=0.0001) and greater LV sphericity (P=0.02). MR increased significantly (grade 0.2+/-0.3 versus 2.2+/-0.9, P=0.0001), as did mitral annulus area (817+/-146 versus 1100+/-161 mm(2), P=0.0001) and mitral annulus septal-lateral diameter (28.2+/-3.5 versus 35.1+/-2.6 mm, P=0.0001). Time of valve closure (70+/-18 versus 87+/-14 ms, P=0.23) and angular displacement of both the anterior (29+/-5 degrees versus 27+/-3 degrees, P=0.3) and posterior (55+/-15 degrees versus 44+/-11 degrees, P=0.13) leaflet edges relative to the mitral annulus after valve closure did not change, but leaflet edge separation after closure increased (5.2+/-0.9 versus 6.8+/-1.2 mm, P=0.019).
MR in TIC resulted from decreased leaflet coaptation secondary to annular dilatation in the septal-lateral direction. These data support the use of annular reduction procedures, such as rigid, complete ring annuloplasty, to address functional MR in patients with dilated cardiomyopathy.
It has previously been shown in sheep that mitral annular physiologic dynamics during the cardiac cycle are abolished by complete ring annuloplasty, but recent clinical studies suggest that flexible partial ring annuloplasty preserves normal mitral annular dynamics.
Eight radiopaque markers were sutured equidistantly around the mitral anulus in 3 groups of sheep: no-ring control animals (n = 16); animals with a flexible Tailor partial ring annuloplasty (n = 6; St Jude Medical, Inc, St Paul, Minn); and animals with a flexible Duran ring annuloplasty (n = 7; Medtronic, Inc, Minneapolis, Minn). After 7 to 10 days' recovery, 3-dimensional marker coordinates were measured by biplane cinefluoroscopy. Mitral annular area and folding (defined as displacement of the mitral anulus from a least-squares plane) and mitral annular septal-lateral and commissure-commissure dimensions were calculated from the 3-dimensional marker coordinates throughout the cardiac cycle every 17 ms.
In the no-ring control group mitral annular area varied from 8.0 +/- 0.2 to 7.2 +/- 0.2 cm(2) (10% +/- 2%), and the septal-lateral and commissure-commissure dimensions varied from 27.7 +/- 0.4 to 25.9 +/- 0.4 mm (7% +/- 1%) and from 38.2 +/- 0.8 to 36.4 +/- 0.8 mm (5% +/- 1%), respectively (mean +/- standard error of the mean, P <.001 for all comparisons). In the Duran ring annuloplasty and Tailor partial ring annuloplasty groups, the anulus was fixed in size throughout the cardiac cycle (area = 4.8 +/- 0.1 and 5.3 +/- 0.3 cm(2), septal-lateral = 21.8 +/- 0.7 and 22.0 +/- 0.8 mm, and commissure-commissure = 27.7 +/- 0.7 and 31.2 +/- 1.7 mm). Mitral annular folding did not differ significantly between the control and Tailor partial ring annuloplasty groups but was dampened in the Duran ring annuloplasty group.
Partial Tailor flexible ring annuloplasty fixed mitral annular area and dimensions throughout the cardiac cycle in sheep; however, it preserved physiologic mitral annular folding dynamics, which might be important in terms of long-term valve function and prevention of left ventricular outflow tract obstruction.
Septal-lateral (S-L) mitral annular diameter reduction is thought to be central to the efficacy of ring annuloplasty in correcting functional mitral regurgitation (MR), but rings perturb mitral annulus (MA) dynamic motion and limit posterior leaflet excursion. The effects of S-L annular cinching ('SLAC'), a novel method for mitral annular reduction, were investigated.
Eight adult sheep had multiple radioopaque markers placed on the left ventricle, leaflet edges, and around the MA. The S-L trans-annular suture was anchored to the mid-septal MA and externalized through the mid-lateral MA and left ventricular wall. Animals were studied immediately postoperatively with biplane videofluoroscopy before and after suture cinching to reduce annular size. MA area (MAA) and S-L dimension were calculated throughout the cardiac cycle from the annular marker coordinates. MAA contraction (AMAA) was expressed as percentage decrease from maximum to minimum MAA. Anterior (AML) and posterior (PML) leaflet angular excursion were calculated as the change in angle between each leaflet edge marker and the S-L annular dimension during the cardiac cycle. MA folding was calculated as the change in distance during systole of the mid-septal annular marker from a plane fitted to the lateral MA markers.
SLAC reduced end-diastolic (ED) S-L diameter (21.6+/-2.8 versus 17.1+/-2.6 mm; p = 0.0005) and ED MAA (618+/-126 versus 525+/-114 mm2; p = 0.0004), but did not perturb normal AMAA (15.8+/-4.1 versus 15.1+/-4.8%; p = 0.4), annular flexion (2.0+/-0.7 versus 1.8+/-0.7 mm; p = 0.3) or AML excursion (55+/-7 versus 53+/-7 degrees; p = 0.1). PML excursion was decreased only slightly (52+/-11 versus 44+/-12 degrees; p = 0.002).
SLAC substantially reduced S-L annular size, but without perturbing normal MA contraction dynamics, MA flexion, or anterior leaflet excursion. This novel surgical method might represent an alternative to mitral annuloplasty for patients with certain types of mitral pathology.
To the Editor:
The article by Doshi et al in the January 1/8, 2002, issue of Circulation ,1 in which the authors suggest that folic acid improves endothelial function by a mechanism largely independent of homocysteine (Hcy), prompted us to report our data on plasma Hcy levels before and after intravenous prostaglandin (PG) E1 α-cyclodextrin in patients with systemic sclerosis. Ten …
Acute posterolateral ischemia in sheep results in ischemic mitral regurgitation (IMR). While complete ring annuloplasty prevents acute IMR, partial annuloplasty rings may offer a more physiologic repair, but are untested in animal models of IMR.
Radiopaque markers were placed on the LV, mitral annulus (MA), and leaflets in 13 sheep. Seven sheep served as controls, and 6 had a St. Jude Tailor partial flexible ring implanted (29 mm in 5, 31 mm in 1). After 8+/-1 day, the animals were studied with biplane videofluoroscopy and echocardiography before and during acute posterolateral LV ischemia (balloon occlusion of circumflex artery). Mitral annular area (MAA), septal-lateral annular diameter (SL), annular perimeters, and leaflet edge separation were calculated from 3-D marker coordinates.
The average degree of mitral regurgitation increased from 0.0+/-0.0 to 2.1+/-0.7 (P=0.0006) in the control group during acute ischemia but remained unchanged in the Tailor group (0.1+/-0.2 for both conditions). The change in MAA throughout the cardiac cycle before ischemia was 17+/-4% in control animals, but only 5+/-2% (P=0.0002) in the Tailor ring group. Unlike the control animals, there was no increase in MAA (5.4+/-0.8 and 5.5+/-0.7 cm(2), respectively; p=NS) nor dilatation of the muscular annulus (6.2+/-0.3 and 6.2+/-0.4, respectively; p=NS) during ischemia with the Tailor ring. Mitral SL dimension increased slightly with ischemia (2.3+/-0.2 versus 2.2+/-0.2 cm, P=0.03). Although posterior leaflet motion was limited, as observed with complete rings, normal annular flexion was maintained with the Tailor ring before and during acute ischemia.
The Tailor partial annuloplasty ring prevented acute IMR probably by limiting SL diameter dilatation during acute ischemia. In this animal model of acute IMR, a partial, flexible posterior annuloplasty ring is as effective as a complete ring.
Will a partial posterior annuloplasty ring prevent acute ischemic mitral regurgitation? Circulation
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Timek TA, Dagum P, Lai DT, et al. Will a partial posterior annuloplasty ring prevent acute ischemic mitral regurgitation? Circulation. 2002; 106(12 Suppl 1):I33–I39.
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Carpentier-Edwards prosthetic ring. J Heart Valve Dis. 2000;9:478 -486.