Afterload Mismatch and Preload Reserve

We examined the interrelationship of afterload, preload and left ventricular (LV) performance at two levels of systolic loading in 20 patients with chronic aortic regurgitation to determine if the concept of afterload mismatch and preload reserve can be applied to this clinical entity. We identified two groups of patients at different stages in the natural history of volume overload. Patients in group I had moderate LV enlargement (LV end-diastolic volume < 150 ml/m2), and patients in group 2 had severe LV enlargement (LV end-diastolic volume > 150 ml/m2). Both groups had sufficient eccentric hypertrophy, measured by LV mass, to keep afterload as measured by mean systolic LV wall stress only slightly above normal; LV mean systolic wall stress was similar in each group. Patients in group 2 had a lower LV ejection fraction and velocity of circumferential fiber shortening than those in group 1 at a similar lower level of afterload. At a similar higher level of afterload, which increased end-diastolic volume from 134 4 to 157