Factors influencing left ventricular systolic function in nonhypertensive morbidly obese patients, and effect of weight loss induced by gastroplasty.

Heart rate and blood pressure were measured, and echocardiography was performed in 39 patients whose actual body weight was greater than twice their ideal body weight to identify factors influencing left ventricular (LV) systolic function in morbidly obese patients and assess the effect of weight loss on LV systolic function. Patients were studied before and after weight loss induced by gastroplasty. The study cohort was 133 +/- 8% overweight before weight loss and 39 +/- 7% overweight at the nadir of weight loss. Before weight loss, LV fractional shortening varied inversely with LV internal dimension in diastole (an indirect index of preload), LV end-systolic wall stress and systolic blood pressure (indexes of afterload). The weight loss-induced change in LV fractional shortening varied directly with the pre-weight loss LV internal dimension in diastole, LV end-systolic wall stress and systolic blood pressure, and inversely with the pre-weight loss LV fractional shortening. The weight loss-induced change in LV fractional shortening varied inversely with the weight loss-induced changes in LV end-systolic stress and systolic blood pressure. In patients with reduced LV fractional shortening (n = 14), weight loss produced a significant increase in LV fractional shortening that was accompanied by a significant decrease in LV internal dimension in diastole, LV end-systolic stress and systolic blood pressure. The results suggest that LV loading conditions have an important role in determining LV systolic function in morbidly obese patients. Improvement in LV systolic function in these patients is closely related to weight loss-induced alterations in LV loading conditions.