Simultaneous left ventricular micromanometry and biplane cineangiography were performed in nine control subjects (group 1), 14 patients with chronic mitral regurgitation and an ejection fraction of 57% or greater (group 2), and 13 patients with mitral regurgitation and an ejection fraction of less than 57% (group 3). End-diastolic volume index was increased in both groups with mitral regurgitation (p < .001) compared with the control group. Left ventricular end-diastolic wall thickness did not differ among the three groups, but the left ventricular muscle mass index was greater in both groups with mitral regurgitation than in controls (p < .001). End-diastolic pressure was elevated in both groups 2 and 3 compared with group 1 (p < .05), but peak systolic, mean systolic, and incisural pressure were not different among the three groups. End-diastolic stress was larger in groups 2 and 3 than in group 1 (p < .05). Muscle fiber stretch was greater in group 2 than in the control group (p < .05) but was not different between the controls and group 3. End-systolic stress, determined as the circumferential stress at aortic valve closure, at the maximal pressure/volume ratio, or using a nonsimultaneous method, was larger in group 3 than in groups 1 and 2. Mean systolic stress was evaluated from aortic valve opening to aortic valve closure in all patients; mean stress from end-diastole to aortic valve closure and from end-diastole to minimum volume was assessed in mitral regurgitation alone. For all three intervals, mean stress determinations were larger in group 3 than the mean stress from aortic valve opening to closure in the controls (p < .05), whereas only the mean stress determined from aortic valve opening to closure was greater in group 2 than in the control group (p < .01). For each of the intervals, the calculated mean stress was larger in group 3 than in group 2 (p < .05). Evaluation of the end-systolic stress- and mean ejection stress-ejection fraction relationships revealed an overlap of control with group 2 data, group 3 values were downwardly displaced. The absence of an upward shift of group 2 values in the setting of an augmented preload suggests that these patients maintained only a normal level of ventricular performance with the use of preload reserve and were operating at a somewhat reduced contractile state. The downward displacement of group 3 data points in the presence of only moderately higher levels of afterload than in groups 1 and 2 implies impaired myocardial contractility. Recognition of chronic mitral regurgitation as a stress overload state may provide insight into the mechanism of myocardial injury that occurs in both volume and pressure overload.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)