QUANTITATIVE DYNAMICS OF LEFT-VENTRICULAR EMPTYING AND FILLING AS A FUNCTION OF HEART SIZE AND STROKE VOLUME IN PURE AORTIC REGURGITATION AND IN NORMAL SUBJECTS

Quantitative understanding of the dynamics of left ventricular (LV) emptying and filling as the left ventricle dilates but maintains ejection fraction is limited. Cine computed tomography was used to quantify peak LV emptying and filling characteristics in 30 patients with normal ejection fraction but variable end-diastolic and stroke volumes. Group I consisted of 15 normal male patients and group II of 1 5 male patients with chronic, well-compensated, isolated aortic regurgitation. For each patient global LV volumes, absolute peak emptying and peak early diastolic filling rates and the timing of these maximal slopes were quantified. Mean arterial pressure and heart rate were within the normal range and ejection fraction and ages similar between groups I and II. Between group analyses showed significantly increased end-diastolic and stroke volumes in group II compared with group I but nearly identical end-systolic volumes. Likewise, absolute peak emptying and filling rates were significantly greater in group II than in group I patients. The ratio of peak emptying rate to peak filling rate remained constant between groups. Timing of peak emptying and filling were similar in both groups. Absolute LV peak emptying and filling rates were found vary linearly with end-diastolic and stroke volumes in all subjects examined. However, referencing peak emptying or peak filling rates to end-diastolic or total stroke volumes eliminated intergroup differences. Thus, in the presence of preserved ejection fraction and normal arterial pressure, the dynamic rates of LV emptying and early diastolic filling increase in direct proportion to absolute end-diastolic and stroke volumes, but the ratio of peak emptying to peak filling rate remains constant.