Pathophysiology and Natural History Valvular Heart Disease

Left ventricular cineangiography and micromanometry were performed simultaneously in 27 patients with chronic severe mitral regurgitation (MR group) and in 23 normal subjects (NL group). Stress (c) and volume (V) were computed frame by frame. Measurements were repeated after pharmacologic load manipulation in subsets of MR (n = 10) and NL (n = 11) groups. An inverse relationship (r = -.90) between EFc (ejection fraction determined from a common preload) and 1es (afterload) was observed for the NL group. For the MR group, 10 of 14 with EFs less than 0.60 and four of 13 with EFs greater than 0.60 had muscle dysfunction, falling below the 95% prediction band of the normal EFC-Ges relationship. Maximum myocardial stiffness (maxEN) determined from the end-systolic stress-strain relationship of Mirsky, (ces = maxENwY 1og0(Ves/V0), was 1398 + 716 in the MR (n = 10) vs 1165 + 394 in the NL group (n = 11, NS). EF was 0.62 + 0.13 in the MR and 0.65 + 0.08 in the NL group. Mitral valve surgery was performed on 19 of the patients with MR. All survived and all but one were symptomatically improved; that patient required reoperation in the early postoperative period because of transverse midventricular disruption. Thus, contractile function as assessed by stress-strain and EFc-afterload relationships is frequently normal in individuals with MR when EF is normal. When EF is depressed, contractile function as assessed by EFc-afterload relationships is frequently depressed, but this does not preclude a satisfactory surgical result. Circulation 77, No. 3, 515-525, 1988. EJECTION FRACTION is often depressed after chronic mitral regurgitation (MR) is corrected with a prosthetic valve. This occurs even when preoperative ejection fraction is normal.1 Since reduced afterload tends to augment ejection performance in acute MRII1,2 3it seems logical that correction of chronic MR might cause the ejection fraction to be depressed by afterloading the ventricle, thereby "unmasking" preoperative contractile dysfunction. This hypothesis, which has long been accepted as an explanation for the disappointing surgical results in patients with chronic MR,4-9 has not been confirmed with studies of preoperative contractile function, since no load-independlent methods have been available for clinical use. Accordingly, the purpose of the present study was to assess preoperative contractile state in patients with chronic, severe MR by use of recently developed methFrom the Veterans Administration and University of Kentucky Medical Centers, Lexington, KY. Supported in part by a grant from the American Heart Association, Kentucky Affiliate. Address for correspondence: Thomas Wisenbaugh, M.D., MN 670 Cardiovascular Division, University of Kentucky Medical Center, 800 Rose St., Lexington, KY 40536. Received July 15, 1987; revision accepted Nov. 20, 1987. Vol. 77, No. 3, March 1988 ods that are relatively independent of load. The possible prognostic significance of these measures of contractile state were then examined in patients undergoing mitral valve surgery.