Abnormal cardiovascular regulation in the mitral valve prolapse syndrome

Studies of patients with mitral valve prolapse syndrome have suggested autonomic nervous system dysfunction, but a precise definition of mechanisms is lacking. We measured supine and standing heart rate, blood pressure, cardiac output, oxygen consumption, plasma catecholamines, and blood volume in 23 symptomatic women with both echocardiographic and phonographic signs of MVP and in 17 normal control subjects. An analysis of the results revealed 2 distinct subgroups of patients: those with normal heart rates but increased vasoconstriction (Group I, n = 10) and those with orthostatic tachycardia (Group II, n = 13). Group II patients had heart rates at rest supine of 97 ± 3 compared with 79 ± 2 in Group I patients and 78 ± 8 in control subjects. Estimated total blood volumes were lowest in Group I patients, intermediate in Group II patients, and highest in control subjects (p<0.05). Other measurements at rest supine were similar in patients and controls. After standing for 5 minutes, patients had a higher mean plasma epinephrine value, diastolic blood pressure (81 ± 2 versus 74 ± 3 mm Hg, p < 0.05), and peripheral resistance (1,878 ± 114 versus 1,414 ± 92, dynes s cm^?5, p < 0.01), wider arteriovenous oxygen difference (6.7 ± 0.4 versus 5.3 ± 0.5 vol%), and lower stroke volume index (26 ± 2 versus 33 ± 2 ml/m², p < 0.01) than did the control subjects. Cardiac output was normal in Group II patients but reduced in Group I patients, who demonstrated marked vasoconstriction. No patient had evidence of a “hyperkinetic” circulatory state. A cycle of decreased forward stroke volume, vasoconstriction, and blood volume contraction appears to be present in at least some symptomatic patients with MVP.     

Functional evaluation of the autonomic regulation in mitral valve prolapse

We examined fifty patients aged from 15 to 35 years, mean 23 +/- 5, with mitral valve prolapse (MVP) documented by two-dimensional echocardiography in the apical 4-chamber view as well as in the parasternal-long axis. The patients have been submitted to 4 tests: Valsalva maneuver, standing and exercise test and 24 hours ambulatory ECG monitoring. Fourty-five healthy subjects of similar age and sex served as controls. During the standing test the patients with MVP showed a significantly faster heart rate than the control subjects both in resting and in the standing position; during the exercise test they exhibited higher prevalence of ST segment and T wave abnormalities disappearing at the peak of the exercise. These observations support the hypothesis of a hyperadrenergic state. The greater bradycardia showed during the Valsalva maneuver, the lower heart rate and the higher incidence of bradyarrhythmias and A-V blocks during the sleeping period suggest an increased vagal tone. Our results suggest therefore that in subjects with MVP a dysfunction of both, sympathetic and parasympathetic nervous system is present.     

Floppy mitral valve, mitral valve prolapse, and mitral valvular regurgitation

Opinion statement  

Floppy mitral valve/mitral valve prolapse and genetics

Mitral valve prolapse (MVP) is a defect in the mitral valve where a redundancy of valve tissue is associated with a variety of clinical expressions, ranging from an isolated mild bulging of the mitral valve to a severe prolapse of the mitral valve with extensive mitral regurgitation. As the natural history and complications of MVP are not always benign, it seems essential to strive for the proper management of these patients. The identification of functionally related genes could provide helpful clues and increase the present understanding of the pathogenesis of MVP, with the ultimate goal of developing targeted therapies. The genetics of MVP can be divided into two parts: (i) Genetics in floppy mitral valve/MVP; and (ii) genetics in heritable connective tissue disorders (Marfan syndrome, polycystic kidney, etc.) associated with floppy mitral valve. Herein, the known genetic aspects of MVP are described, according to the above-mentioned scheme.     

The long-term outcome of mitral valve repair for mitral valve prolapse

The rationale of early surgery for severe chronic mitral regurgitation (MR) due to mitral valve prolapse (MVP) has been developed over the past decade on the basis of the understanding of the natural history of this disease and the predictors of outcomes after surgical correction of MR. The important decrease in operative mortality associated with the advancements in myocardial preservation, and more importantly the improved reparability of the myxomatous mitral valve, were an additional incentive to develop the concept of early surgery. Previous studies showed that mitral valve repair offers a survival advantage at short- and 10-year follow-up, and therefore suggested that it should be the treatment of choice for severe MR due to MVP. Moreover, very recent data provided new insight on the very long-term follow up, ie, beyond the usual first 10 years in which the initial survival benefit of repair may be negated by a late deterioration.     

Long-term echocardiography results of mitral valve repair for mitral valve prolapse

BACKGROUND AND AIM OF THE STUDY: The study aim was to assess the long-term durability of mitral valve (MV) repair for MV prolapse using echo-Doppler evaluation. METHODS: Between July 1991 and December 2006, MV repair was performed in 603 patients with nonischemic, severe mitral regurgitation (MR). A subset of 517 patients (mean age 56.3 +/- 12.0 years) with MR caused by leaflet prolapse resulting from degeneration of the MV was subsequently investigated. The main techniques used for MV repair included chordal replacement with ePTFE sutures for 274 of 278 patients with anterior leaflet (AL) prolapse, and leaflet resection for 239 patients with posterior leaflet (PL) prolapse. A prosthetic ring or band was used for annuloplasty in 340 patients, and a band of autologous pericardium in 161; no ring or band was used in the remaining 16 cases. Postoperative serial transthoracic echocardiography was performed for all hospital survivors before discharge, and on at least one occasion after discharge in 507 patients. Echocardiographic follow up was available for up to 15 years (mean 4.4 +/- 3.6 years). Residual MR flow detected by color Doppler echocardiography was classified according to the maximum regurgitant jet area (MRA). RESULTS: The 30-day mortality was 0.57% (three deaths). There were 21 late deaths and 22 reoperations (five of which were re-repair for hemolysis). Kaplan-Meier survival and freedom from reoperation at 14 years were 79.0 +/- 6.0% and 74.5 +/- 9.6%, respectively. Estimates of freedom from severe MR (MRA > or = 7.0 cm2) at five, 10 and 14 years were 94.2 +/- 1.5%, 82.8 +/- 3.6% and 77.5 +/- 5.5%, respectively. Freedom from severe MR at 14 years for 239 patients with isolated PL prolapse was 98.4 +/- 1.6%. CONCLUSION: Echocardiographic follow up of MV repair for MV prolapse demonstrates good long-term results. In particular, the results of MV repair for isolated PL prolapse were excellent.     

Troublesome factors in mitral valve repair for mitral valve regurgitation

Limitations in the long-term results of medical treatment for mitral regurgitation are well recognized, but the advances in its surgical repair have produced good results. Therefore, early surgical intervention has been the focus of treatment in Europe and America. Increased surgical intervention depends on the development of technical skills in mitral reconstruction. This study investigated presurgical factors making surgical reconstruction difficult in 103 patients who underwent mitral operations performed from April 1994 to September 1997 in our hospital. Records were reviewed retrospectively for etiology, type of operation, and the immediate result of operation. The etiology of mitral regurgitation was prolapse in 65 patients (63%), restriction in 14, normal in 11, infectious endocarditis in 10, and others in 3. The type of prolapse involved the anterior leaflet in 22 patients (34%), posterior in 28 (43%), and both leaflets in 15 (23%). Valve repair was attempted in 74 patients, of which 16 were switched to valve replacement during operation. These included anterior leaflet prolapse in 9 patients, posterior leaflet in 1, both leaflets in 3, restriction in 2 and infectious endocarditis in 1. The success rate for reconstruction of anterior leaflet prolapse was not high. The cause of mitral regurgitation was mostly prolapse of the mitral valve, in our country as well as in Europe and America. Prolapsed posterior leaflet is much more common in Europe and America, and there is a high success rate reported for its valve reconstruction. In contrast, this study cannot recommend earlier surgical intervention because of difficult repair for anterior leaflet prolapse.     

二尖瓣前叶脱垂手术修复的疗效分析

目的 探讨治疗二尖瓣前叶脱垂的外科修复方法及治疗效果.方法 1998年11月至2007年10月对210例二尖瓣前叶脱垂患者行二尖瓣修复术,并在术前、术中、术后利用超声心动图对心脏结构及功能进行评价.结果 采用缘对缘技术修复二尖瓣前叶脱垂134例(63.8%).出院时心脏功能(纽约心脏病协会分级)Ⅰ级168例,Ⅱ级40例.随访1～150(25.7±29.0)个月,围术期死亡2例(0.95%).超声心动图检查显示,术前左心房舒张末径为(47.5±12.7)mm,术后1年减小为(37.7±9.2)mm(P＜0.05);术前左心室舒张末径为(67.7±10.3)mm,术后1年减小为(51.7±7.9)mm(P＜0.05);术前左心室射血分数为(52.2±6.4)%,术后1年提高为(62.2±3.2)%(P＜0.05);术前二尖瓣反流面积为(10.4±4.1)cm~2,术后1年减少为(4.1±1.7)cm~2(P＜0.01).结论 二尖瓣修复术治疗二尖瓣前叶脱垂可获得良好的手术效果.缘对缘技术修复二尖瓣前叶脱垂安全、有效.     

Results of valve reconstruction for mitral regurgitation secondary to mitral valve prolapse

Mitral valve prolapse (MVP), often the result of myxomatous degeneration of the mitral valve, is the most commonly known pathologic entity leading to pure mitral regurgitation (MR). Reconstruction of the mitral valve rather than replacement is particularly applicable to this pathologic defect, but is not often used in the U.S. Experience with reconstruction of the mitral valve for MR secondary to MVP during the period January 1970 to January 1984 was reviewed. A total of 479 patients with mitral valve disease underwent operation during this period, 82 (17%) of whom had MR secondary to MVP. Thirty-one patients (6%) had valve reconstruction by a technique of leaflet plication and posteromedial anuloplasty. Eleven of these patients had associated cardiac disease requiring correction: 2 requiring aortic valve replacement and 9 requiring coronary artery bypass grafting procedures. One hospital death (3%) and 6 late deaths (19%) occurred, of which only 3 were related to cardiac factors. Major complications included recurrent MR in 5 patients and cerebral embolus in 1 patient. The adjusted 5-year survival rate was 89 +/- 6 (mean +/- standard error of the mean), and the overall survival rate of patients free of cardiac-related complications was 73 +/- 9%. Thus, reconstruction of the mitral valve is a highly effective surgical approach to the management of symptomatic patients with MR secondary to MVP, and its use is favored over replacement in the management of these patients.     

Percutaneous mitral valve repair for mitral regurgitation

Mitral regurgitation (MR) associated with, ischemic, and degenerative (prolapse) disease, contributes to left ventricular (LV) dysfunction due to remodeling, and LV dilation, resulting in worsening of MR. Mitral valve (MV) surgical repair has provided improvement in survival, LV function and symptoms, especially when performed early. Surgical repair is complex, due to diverse etiologies and has significant complications. The Society for Thoracic Surgery database shows that operative mortality for a 1st repair is 2% and for re-do repair is 4 times that. Cardiopulmonary bypass and cardiac arrest are required. The attendant morbidity prolongs hospitalization and recovery. Alfieri simplified mitral repair using an edge-to-edge technique which subsequently has been shown to be effective for multiple etiologies of MR. The MV leaflers are typically brought together by a central suture producing a double orifice MV without stenosis. Umana reported that MR decreased from grade 3.6 +/- 0.5 to 0.8 +/- 0.4 (P < 0.0001) and LV ejection fraction increased from 33 +/- 13% to 45 +/- 11% (P = 0.0156). In 121 patients, Maisano reported freedom from re-operation of 95 +/- 4.8% with up to 6 year follow-up. Oz developed a MV "grasper" that is directly placed via a left ventriculotomy and coapts both leaflets which are then fastened by a graduated spiral screw. An in-vitro model using explanted human valves showed significant reduction in MR and in canine studies, animals followed by serial echo had persistent MV coaptation. At 12 weeks the device was endothelialized. These promising results have paved the way for a percutaneous or minimally invasive-off pump mitral repair. Evalve has developed catheter-based technology, which, by apposing the edges of a regurgitant MV, results in edge-to-edge repair. Release of the device is done after echo and fluoroscopic evaluation under normal loading conditions. If the desired effect is not produced the device can be repositioned or retrieved. Animal studies show excellent healing, with incorporation of the device into the leaflets at 6-10 weeks with persistent coaptation. Another percutaneous approach has been to utilize the proximity of the coronary sinus (CS) to the mitral annulus (MA). Placement of a self-compressing device in the CS along the region of the posterior MA has, in canine models, reduced MR and addresses the issues of MA dilation and its contribution to MR. Ongoing studies are underway for both techniques.