Preliminary Clinical and Hemodynamic Results after Mitral Valve Replacement Using St. Jude Medical Prostheses in Comparison with the Björk-Shiley Valve

Summary

The clinical improvement and the hemodynamic performance at rest and during bicycle exercise in 12 patients one year after St. Jude Medical mitral valve (SJMM) replacement were compared to the results of 40 patients after Björk-Shiley mitral valve (BSM) Implantation. In both groups subjective and functional improvement was significant. In the SJMM-group no thromboembolic event had occurred, while 5 patients suffered from embolism during the first postoperative year after BSM (12.5%). Hemolysis was significantly lower in BSM but remained subclinical in SJMM. This may be explained by a premature backward movement of the posterior leaflet of the SJMM-prosthesis in late diastole resulting in a change of flow pattern. Low resistance to blood flow in the SJMM-prosthesis could be verified by a smaller diastolic transvalvular gradient (SJMM: 2.8 ± 1.1; BSM: 5.3 ± 2.6 mmHg). In valves with equal tissue annulus diameters (29 mm) the calculated effective valve orifices were significantly different (SJMM: 2.83 ± 1.3 cm²; BSM: 1.85 ± 0.53 cm²). In both groups the mean pulmonary artery pressure was significantly reduced at the time of re-investigation but increased under exercise. Durability may become a problem because of the 2 moving parts of SJMM but until now we have observed no malfunction. St. Jude Medical mitral valve seems to be a good alternative in heart valve replacement with prostheses of small sizes, both for the mitral and tricuspid valve.

Key words

Mitral valve replacement - St. Jude Medical valve - Björk-Shiley valve - Hemodynamics - Hemolysis