Cardiac surgery to repair mitral valve may improve heart function

Acute phase of rheumatic fever:

During the acute phase of rheumatic fever, most patients with valvulitis and mitral regurgitation can be managed medically. In rare occasions, the persistence of an intense inflammatory syndrome associated with severe valvular regurgitation refractory to medical therapy may necessitate a surgical intervention. In 1970’s, our group was the first to perform reconstructive mitral valve surgery in patients with acute rheumatic valvulitis. The surprising fact was that surgical intervention not only corrected valvular regurgitation, but postoperatively there was a significant reduction in the intensity of the inflammatory syndrome. Two other important findings were: 1) we were able to reconstruct effectively the mitral valve during the acute phase of the disease and 2) the surgical intervention was associated with low mortality. Subsequently other groups confirmed our results.

Chronic phase of rheumatic fever:

Mitral stenosis:

During the last few decades the percutaneous mitral valve balloon dilatation has become the first line therapy for many patients with mitral stenosis. This procedure is indicated in symptomatic patients (NYHA II, III and IV) with isolated moderate to severe mitral stenosis (valve area <1.5cm2) and favorable valve morphology. Asymptomatic patients with moderate to severe mitral stenosis and pulmonary hypertension at rest (pulmonary artery systolic pressure >50 mm Hg) may also be considered for percutaneous therapy. The latter technique is, however, contraindicated in several circumstances: the presence of at least moderate mitral regurgitation, the existence of left atrial thrombus on echocardiography, and inadequate valve morphology (e.g. leaflet calcification, extensive subvalvular lesions). Percutaneous mitral balloon dilatation is associated with a finite incidence of recurrent stenosis, particularly in patients undergoing repeat procedures and with iatrogenic mitral regurgitation in patients with high Wilkins valve score.

Surgical intervention is the treatment of choice in symptomatic patients (NYHA class III or IV), with moderate to severe mitral stenosis (valve area <1.5cm2), who are not appropriate for, or who have failed percutaneous balloon dilatation. There is also a subgroup of asymptomatic patients with severe mitral stenosis and severe pulmonary hypertension with unfavorable morphology for percutaneous balloon dilatation. To get more information about Mitral valve surgery , click over to the link http://www.themitralvalve.org/mitralvalve/surgical-indications

In patients with mild asymptomatic mitral stenosis (valve area >1.5 cm2 and mean gradient <5 mm Hg), no further intervention is necessary after the initial workup. These patients are likely to remain stable for years and should be treated medically with a close follow-up.

Mitral regurgitation:

In symptomatic patients with moderate to severe mitral regurgitation, surgical intervention is indicated before ventricular dilatation or dysfunction occurs. Similarly, it is preferable to proceed with surgery while the patient is in NYHA I and II and before atrial fibrillation takes place.

In asymptomatic patients with severe mitral regurgitation, the timing of surgery depends greatly on the likelihood of valve reconstruction. The extent of valvular lesions and surgeon’s experience are the two most important variables predicting the feasibility of valve reconstruction. In this context, only asymptomatic patients who can be guaranteed a reconstructive procedure should be considered for surgery.

Mitral Valve – Fundamentals

Mitral valve:

The exposure of the mitral valve, the entire mitral valve apparatus is carefully examined. A detailed surgical valve analysis is performed to determine the functional type and the segmental localization. Valvular analysis will enable the surgeon to establish a comprehensive inventory of the lesions and the operative road map.

The presence of endocardial thickening or jet lesions is assessed. Jet lesions indicate a leaflet prolapse opposite to the side of the jet or a restricted leaflet motion on the side of the jet. The mitral valve annulus is examined to detect any annular dilatation and to assess its severity. The presence and the extent of annular calcification is carefully noted.

Mitral valve leaflets are examined using two nerve hooks to proceed to a functional analysis of all valvular segments. Leaflets motion is assessed using Carpentier’s reference point technique. The free edge of P1 commonly serves as the reference point, as this segment is rarely affected by abnormal leaflet motion. This finding is particularly verifiable in patients with degenerative mitral valve disease. In this scenario, we first confirm the normal leaflet motion of P1 by pulling its free edge upward with a nerve hook. The free edge of P1 segment should not be prolapsing (it should not override the plane of the mitral annulus) nor be restricted. Using a second hook, other valve segments are examined in a systematic manner and compared to P1 to verify if they present with any abnormal leaflet motion. In the setting of type II dysfunction, the free edge of the prolapsing segment would be higher in the left atrium compared to the free edge of P1. In type III dysfunction, the mobility of the affected segment would be significantly reduced compared to P1. It is important to emphasize that type III dysfunction often affects all three segments of the posterior leaflet. Therefore, during intraoperative valve analysis the surgeon should compare the mobility of the posterior leaflet to that of the anterior leaflet. Echocardiographic valve analysis is of critical importance in patients with type III dysfunction.

Aortic Valve Replacement:

A significant number of clinical studies have investigated the long-term outcomes of mechanical valves and bioprostheses. Prosthetic heart valves are associated with several complications including structural valve deterioration, nonstructural dysfunction, valve thrombosis,embolism, bleeding event, endocarditis, and reoperation.The American College of Cardiology / American Heart Association Guidelines for Reporting Morbidity and Mortality After Cardiac Valve Interventions provide a precise definition of these complications.These guidelines represent a useful framework for investigating these events after heart valve surgery.Below we report the long-term results of mechanical and bioprosthetic aortic valve replacement. We have included clinical studies published during the last decade with a minimum follow-up of five years. If you click on each variable you will visualize the corresponding table. Each table can be reorganized according to the parameters included in the first row allowing the reader to analyze the data in a more personalized manner. References are provided and are linked to Pubmed.

He discussed several cases of double mitral and aortic valve diseases. He described the seat and characteristics of each murmur and emphasized the difficulty of diagnosis in this setting. This is a brief quotation from his comments on auscultation in double valve disease:

“…for the mitral valves may be so altered as that no murmur whatever shall be produced during the passage of blood through them; and again the murmur from the aortic opening may be so loud, and also propagated downwards into the ventricle, as to obscure the mitral murmur, even should it exist.”

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Mitral Valve Regurgitation – Ischemic Valvular Disease

Peri-operative management:

Standard techniques of monitoring (arterial line, central venous access, Foley catheter…) are used in patients undergoing a combined mitral valve reconstruction and coronary bypass grafting. A Swan-Ganz catheter should be inserted in every patient. Initially a transesophageal echocardiogram should be performed. It is a key element to determine the functional type of mitral regurgitation and to assess left ventricular size and function. At the completion of cardiopulmonary bypass, it allows the surgeons to assess the quality of valve reconstruction, to detect residual air in left side cavities, and to monitor ventricular filling. An epiaortic scan of the ascending aorta is recommended to rule out the presence of atherosclerotic lesion prior to arterial cannulation.

Surgical approaches, cardio pulmonary bypass, and myocardial protection:

Median sternotomy is the surgical approach of choice in patients undergoing combined mitral valve reconstruction and myocardial revascularization. In reoperative setting ( e.g. mitral valve surgery after previous coronary artery bypass grafting), a right thoracotomy approach is a viable alternative. Femoral vessels exposure is recommended if severe mediastinal adhesions are suspected (recent reoperation, multiple previous sternotomies, mediastinitis, and mediastinal radiation) and in patients with patent left internal mammary graft. Mitral valve surgery is classically performed with cannulation of both vena cava and the aorta, intermittent antegrade or a combined antegrade and retrograde cardioplegic arrest with cold blood high potassium cardioplegia for myocardial protection. Further myocardial protection can be obtained by moderate systemic hypothermia between 28-30C and local hypothermia with topical ice.

Exposure of the mitral valve and valve analysis:

Following completion of coronary bypass grafting, the perfect exposition of the Mitral Valve Regurgitation is essential before undertaking any type of mitral valve surgery. The most commonly used approach is the interatrial approach through the Sondergaard’s groove.

The valvular apparatus is inspected and then examined with a nerve hook in order to assess tissue pliability and to identify the functional type of mitral regurgitation. The anterior paracommissural scallop of the posterior leaflet (P1) constitutes the reference point. Applying traction to the free edge of other valvular segments and comparing them to P1 determines the extent of leaflet prolapse in patients with papillary muscle rupture. This technique is, however, not very reliable to assess the severity of leaflet tethering in the arrested heart. The presence and severity of annular dilatation/deformation is also evaluated. In postero-lateral myocardial infarction, this dilatation is asymmetrical, involving mostly the p2, p3 and posterior commissural area. In antero-septal infarction, the annulus is symmetrically dilated.

Mitral valve reconstructive Surgery:

Type I mitral regurgitation

Type I mitral regurgitation is best treated with a remodeling annuloplasty. The ring is downsized by one size.

Type II mitral regurgitation

Mitral valve replacement with the preservation of the subvalvular apparatus is the surgical treatment of choice in patients with complete rupture of a papillary muscle.
Papillary muscle reimplantation can be attempted in selected patients, provided that necrosis of the supporting myocardial wall is limited and in the absence of akinetic or dyskinetic wall. The non-prolapsed area of the valve serves as a reference point to determine the site and level of implantation of the papillary muscle remnant. At this site a 5mm deep trench is created in the muscular wall. The papillary muscle remnant is trimmed in order to preserve only the fibrous cuff. The papillary muscle remnant is buried in the trench using interrupted 4/0 polypropylene sutures. The trench is then closed around the papillary muscle remnant using a figure of eight suture. The procedure should be completed with a remodeling annuloplasty.

Elongated papillary muscle can be treated by its plication or resection of its extra length followed by reconstitution of the continuity of the remaining segments. The procedure is completed with a slightly downsized ring annuloplasty to reduce the tension on the reconstructed valve. If the papillary muscle is too thin and the anatomic conditions are not favorable, Mitral Valve Regurgitation should be preferred.

Type IIIb mitral regurgitation

Remodeling annuloplasty using a downsized ring is the technique of choice in type IIIb dysfunction. The goals of valve reconstruction are: preserving leaflet mobility, restoring a large surface of coaptation by reducing the septo-lateral dimension, and stabilizing the annulus to ensure long-term stability.

From Carpentier A, Adams DH, Filsoufi F. Carpentier’s Reconstructive Valve Surgery. Saunders (Elsevier), 2010.The prosthetic ring should be downsized by one size or two sizes depending on the severity of leaflet tethering. The use of double-row annuloplasty suture technique is recommended to reduce the risk of ring dehiscence.

From Carpentier A, Adams DH, Filsoufi F. Carpentier’s Reconstructive Valve Surgery. Saunders (Elsevier), 2010 Additional procedure such as the resection of a large aneurysm or dyskinetic plaque may be necessary to enhance the results of valve reconstruction.

During the last decade, adjunct techniques including the closure of the indentation between p2-p3 segments, resection of secondary chordae, patch extension of the posterior leaflet and papillary muscle sling have been described to minimize the risk of residual or recurrent mitral regurgitation. Clinical experience with these procedures remains limited and there are no long-term data available.

Finally, it is important to stress that in selected patients particularly those with severe bileaflet tethering and enlarged left ventricle with an end diastolic diameter greater than 65 mm, mitral valve replacement with a bioprosthesis may be the surgical procedure of choice.