[Evaluation of the contractile state of the left ventricle before and after aortic valve replacement from end-systolic stress-volume relations in patients with chronic aortic regurgitation].

Before and one month after aortic valve replacement, the contractile state of the left ventricles in 10 patients with chronic aortic regurgitation were studied. The slope and intercept of the end-systolic stress-volume relationship (ESSVR) determined by M-mode echocardiography during intravenous infusion of Nitroprusside were used as an index of myocardial contractility. We found that the end-systolic wall stress-volume relationship from more than four points of pressure and dimension data have shown the linear relation for each subject with linear coefficients ranging from 0.848-0.997. There was no significant change in the slope of ESSVR between the pre- and early postoperative studies (1.66 +/- 0.37 to 1.92 +/- 1.02; p greater than 0.05), however, the intercept decreased significantly (44.7 +/- 32.4 to 29.4 +/- 28.0; p less than 0.01), which meant the leftward shift of the line of ESSVR and may imply the improvement of myocardial contractility. On the contrary, the fractional shortening decreased significantly (25.6 +/- 8.5 to 18.9 +/- 8.8%; p less than 0.01), reflecting marked reduction in preload or left ventricular end-diastolic volume (7.52 +/- 1.07 to 6.04 +/- 1.38; p less than 0.01). The change in the slope of the liner of ESSVR demonstrated that myocardial contractility might not be depressed at this time but rather improving.