Mitral valve replacement with the Biocor stentless mitral valve: early results

Chordal preservation during mitral valve replacement is thought to greatly preserve left ventricular function. Recently a stentless mitral valve (Biocor) became available for clinical use. It is a porcine mitral valve with the entire chordal apparatus, the sewing ring being reinforced by a bovine pericardial ring and the chordae being sutured together onto two pericardial patches. During a six months period, seven patients undergoing mitral valve replacement for mitral insufficiency (four cases), mitral stenosis (two cases) or mixed lesions (one case) received a stentless mitral valve. Their mean age was 66.3 +/- 4.8. The valve was implanted by suturing the pericardial patches onto the papillary muscles and the sewing ring onto the mitral annulus. Echocardiography control immediately after surgery showed good valve function. Three valves failed after a period of seven days, seven and 12 months respectively. The valve lesions were similar and consistent with an excessive tension on the chordae and on the valvular tissue. There were tears along the posterior annulus and at the level of the commissures, often accompanied by chordal rupture. Histology and scanning electron microscopy showed good integration of the prosthesis with the patients own tissues. There were areas of overgrowing tissue without endothelial cells especially in the area of papillary muscle -pericardial patch interaction. The remaining four patients continue to do well after a mean follow up of two years. The apparent excessive tension on the valve tissues leading to the premature failure of the prosthesis could be due to the variability in the distance between mitral annulus and papillary muscles.(ABSTRACT TRUNCATED AT 250 WORDS)