New evolution in mitral physiology and surgery: Mitral stentless pericardial valve

The human adult mitral valve, with a mean diastolic area of up to 7.6 cm2, excess leaflet surface area for coaptation in systole, mitral annulus-papillary muscle continuity, and systolic constriction of the posterior left ventricular wall around the mitral annulus functions in concert with other components of the left side of the heart. Mitral valve replacement with an artificial valve that interferes with the normal physiology could account for less than adequate late results. A stentless biologic mitral valve substitute has been designed, constructed, and tested. The size of the valve is selected according to the circumference of the excised valve within certain limits. The valve is manufactured of two square or trapezoidal pieces of selected stabilized human autologous or bovine pericardium. The pericardial pieces are sutured together by their lateral margins, thus creating a frusto-conical valvular body. The upper circumference of the valvular body is sutured at the mitral annulus and the lower margin with the new chordae is attached by suture at each papillary muscle. In vitro testing of six stentless bovine pericardial valves in a Rowan-Ash fatigue tester at 1,200 cycles/min revealed a durability of more than 320 million cycles. Clinical use of described technique initiated in 1989 was performed in 18 patients by one surgeon (30 patients in the same institution). The mean valve size was 29 mm circularized diameter. There was no mortality in this group of patients up to 70 months of follow-up. Valve competence was obtained in every case by adequate sizing of the valve. One reoperation was necessary at 3 months for rupture at the papillary muscle suture, early in the series. One late endocarditis required reoperation at 16 months. Sixteen patients were followed up for a mean of 26 months. Echocardiography revealed normal function of the valves with a mean orifice area of 4.43 ± 1.24 cm2 (standard deviation; n = 11) and a mean valve index of 2.6 cm2/m2. There was one late thromboembolic complication in a patient with atrial fibrillation who stopped anticoagulant treatment. All patients with indications are on limited anticoagulation. A mitral stentless pericardial valve with large orifice and mitral annulus-papillary muscle continuity can function adequately up to a current 70 months after the operation.