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 cm(2), excess leaflet surface area for coaptation in systole, mitral a nnulus-papillary muscle continuity, and systolic constriction of the p osterior left ventricular wall around the mitral annulus functions in concert with other components of the left side of the heart. Mitral va lve replacement with an artificial valve that interferes with the norm al physiology could account for less than adequate late results. A ste ntless biologic mitral valve substitute has been designed, constructed , and tested. The size of the valve is selected according to the circu mference of the excised valve within certain limits. The valve is manu factured of two square or trapezoidal pieces of selected stabilized hu man autologous or bovine pericardium. The pericardial pieces are sutur ed together by their lateral margins, thus creating a frusto-conical v alvular body. The upper circumference of the valvular body is sutured at the mitral annulus and the lower margin with the new chordae is att ached by suture at each papillary muscle. In vitro testing of six sten tless bovine pericardial valves in a Rowan-Ash fatigue tester at 1,200 cycles/min revealed a durability of more than 320 million cycles. Cli nical use of described technique initiated in 1989 was performed in 18 patients by one surgeon (30 patients in the same institution). The me an valve size was 29 mm circularized diameter. There was no mortality in this group of patients up to 70 months of follow-up. Valve competen ce was obtained in every case by adequate sizing of the valve. One reo peration was necessary at 3 months for rupture at the papillary muscle suture, early in the series. One late endocarditis required reoperati on at 16 months. Sixteen patients were followed up for a mean of 26 mo nths. Echocardiography revealed normal function of the valves with a m ean orifice area of 4.43 +/- 1.24 cm(2) (standard deviation; n = 11) a nd a mean valve index of 2.6 cm(2)/m(2). There was one late thromboemb olic complication in a patient with atrial fibrillation who stopped an ticoagulant treatment. All patients with indications are on limited an ticoagulation. A mitral stentless pericardial valve with large orifice and mitral annulus-papillary muscle continuity can function adequatel y up to a current 70 months after the operation.