Preliminary results in mitral valve replacement with St. Jude medical prosthesis: comparison with the Björk-Shiley valve.

The clinical improvement and the hemodynamic performance at rest and during bicycle exercise in 22 patients 1 year after implantation of a St. Jude Medical mitral valve (SJMM) were compared with the results of 40 patients after implantation of a Björk-Shiley mitral valve (BSM). In both subjective and functional improvement were significant. In the SJMM group no thromboembolic event occurred, while five patients in the BSM group suffered from embolism during the first year postoperative year (12.5%). Hemolysis was significantly lower in the BSM group but remained subclinical in the SJMM group. This may be explained by a premature backward movement of the posterior leaflet of the SJMM prosthesis in the late diastole, which resulted in a change of flow pattern. Low resistance to blood flow in the SJMM prosthesis could be verified by a small diastolic transvalvular gradient. In valves with equal tissue annulus diameters (29 mm), the calculated effective valve orifices were significantly different (3.07 +/- 1.36 cm2 in SJMM, 1.85 +/- 0.53 cm2 in BSM). In both groups, the mean pulmonary artery pressure was significantly reduced at the time of reinvestigation but increased during exercise. Durability may become a problem because of the two moving parts of SJMM, but we have observed no malfunction. The SJMM appears to be a good alternative in mitral valve replacement.