Left ventricular function before and following double valve replacement by Björk-Shiley prostheses.

Abstract

Postoperative survival and cardiac function were studied in 45 patients who underwent combined mitral and aortic valve replacement by Bjork-Shiley prostheses between 1971 and 1977. The average follow-up was three years. Pre-operative left ventricular ejection fraction ranged from 28 to 78% (mean 57%). The hospital mortality rate for the entire series was 18%, the five year survival rate 58%. Hospital mortality decreased from 22% in 1971/72 to 8% in 1976/77. Sixteen patients were restudied 12 to 60 months after operation. In these patients functional class improved significantly, pulmonary arteriolar resistance decreased (255 to 122 dynes s cm-5, P < 0.05), left ventricular end-diastolic volume (159 to 103 ml/m2, P < 0-01), muscle mass (198 to 134ml/m2, P < 0.05) and ejection fraction improved (50 to 61%, P < 0.05). Postoperatively, mean pulmonary artery pressure increased with exercise (23 to 41 mm Hg, P < 0.001), and pulmonary artery pressure during exercise was linearly related to pulmonary arteriolar resistance at rest (r=0.72, P < 0.05). Patients with successful repair of mitral and aortic valve without a paravalvular leak achieved normal pulmonary arteriolar resistance, left ventricular end-diastolic volume, muscle mass and ejection fraction, but cardiac index remained slightly reduced as compared to a control group (2.8 v. 3.3l/min m2, P < 0.05). This study shows (1) early and late mortality rates remained high after double valve replacement by Bjork-Shiley prostheses, but hospital mortality decreased in the time period analysed, and (2) late survivors revealed normalization of left ventricular dilation, hypertrophy and ejection fraction when the prosthesis functioned well.