Assessment Of Mitral Valve Replacement(Report Of 36 Cases) With Preservation Of Subvalvular Apparatus

Sub-valvular apparatus preservation after mitral valve replacement is not a new conception, yet to date there has been no quantification of its clinical effectiveness as a procedure and no consensus as to which surgical preservation technique should be adopted to achieve the best immediate and midterm clinical outcomes. In 1961, the first reported mitral valve replacement (MVR) procedure with implantation of the Starr-Edwards prosthetic valve was published, and involved the complete excision of mitral leaflets, chordae tendineae and the tips of the papillary muscles. The early days of MVR were complicated by an increased incidence of low cardiac output (LCO) syndrome and associated mortality, but since then several strategies have been implemented to decrease the prevalence of LCO syndrome including:revising the indications for MVR, improving myocardial protection strategies, wider application of mitral valve repair techniques, the use of selection criteria for the type of inserted mitral prosthesis, and sub-valvular apparatus preservation (SAP) whenever repair is not possible. The sub-valvular apparatus consists of the left ventricular free wall, two papillary muscles, and the chordae tendineae. The two papillary muscles (anterolateral and posteromedial) give off the chordae tendineae, which insert onto the ventricular surfaces of the anterior and posterior mitral leaflets. Patients with chronic mitral regurgitation have progressively worsening left ventricular function, demonstrated by increasingly impaired left ventricular contractility and increasing left ventricular filling pressures. A number of comparative clinical studies have been published comparing MVR-P to MVR-NP. And the conclusion is: Preserving valve tissue rather than resecting because tissue maintenance reduces the risk of ventricular rupture. Preserving symmetry of the mitral annulus will allow better contact between the valve prosthesis and mitral annulus and consequent avoidance of paravalvular leak. Preserving natural chordae tension allowing more physiological systolic and diastolic function of the left ventricle.Objective:To sum up the operative skills and special details of the technique evaluate the effect on left ventricular systolic and pump functions and discuss the potential complications in 36 patients who underwent mitral valve replacement (MVR) with total preservation of Subvalvular apparatusMethods:From Jan.2007 to Dec 2009,36 patients (20 males and 16 females, aged 64-82 years) underwent mitral valve replacement whit preservation of Subvalvular apparatus. The mitral valve diseases were all severe chronic mitral valve insufficiency (MI).All cases were operated on under hypothermia and cardiopulmonary bypass. Myocardial protection consisted of intermittent antegrade cold hyperkalemic cardioplegia. Only St. Jude (St.Jude Medical, Inc) Epic bioprosthesis (27-29mm) were inserted.the entire subvalvular apparatus was preserved in an anatomic fashion, Briefly, the anterior leaflet was detached 2 mm from the annulus and a central elliptically shaped portion excised. The anterior mitral leaflet was partially excised The remained anterior mitral leaflet with whole chordae tendineae and the entire posterior mitral leaflet with its chordae tendineae were resuspended at anterior and posterior mitral annulus respectively. The end diastolic and systolic left ventricular volume indexes(LVEDVI.LVESVI), left ventricular ejection fraction(LVEF),the peak of emptying rate of the left ventricle(LVPER) and the blood flow velocity in left ventricular outflow tract(LVOT) were measured by echocardiography 10 days after operation.Results:No mortality or severe complications related to this new technique happened. Both LVEDVI and LVEDVI decreased significantly (P<0.01,respectively),and both LVEF and LVPER increased significantly (P<0.05,respectively).No signs suggested accelerations in LVOT blood flow velocity and systolic anteriormotion(SAM)of the remaining anterior leaflet.Conclusion:This new technique is not difficult to master up and it is easy to reproducibility The motive obstacle of prostheses is not observed during operation and after operation by echocardiographic examination, but the LVOT obstruction may be a potential complication.