Effects of Preferred Prosthetic Valve Diameter on Long-term Left Ventricular Function in Mitral Valve Replacement

Normally, shortening of the minor (transverse) axis accounts for 85-90% of the left ventricular stroke volume. In this study, left ventricular functions of 27 mitral valve replacement cases treated with Medtronic-Hall prosthetic mitral valve 29 or 31 mm in diameter were evaluated in the late postoperative period (16-34th month) by two-dimensional, M-mode echocardiographic techniques. Echocardiographic and clinical findings of 12 patients treated with 29 mm and 17 patients treated with 31 mm prosthetic valves were compared in preoperative and late postoperative period. There was no difference between two groups preoperatively. In the late postoperative period, ejection fraction (EF) was significantly higher and endsystolic volume index (ESVI) was significantly lower in patients treated with 29 mm prosthetic valves (EF: 68±7% and 60.5±7%, ESVI: 29.9±12.7 and 42.3±14.1 in patients treated with 29 mm and 31 mm prosthetic valve, respectively, p<0.05). Differences between enddiastolic volume index and stroke volume index were not found significant statistically. In conclusion, large diameter mitral valve may lead to deterioration in left ventricular systolic function in the late postoperative period, probably by limiting the shortening of the minor axis during systole.