Diastolic Compliance Is Reduced in Obese Rabbits

Abstract

—Obesity often leads to symptoms of cardiopulmonary congestion associated with normal systolic but abnormal diastolic function. This study analyzed alterations in passive diastolic compliance in obesity using the rabbit model. New Zealand White rabbits were fed a normal (n=8) or 10% added fat diet (n=8). After 12 weeks, rabbits fed the high fat diet developed obesity (5.34±0.11 versus 3.68±0.04 kg, P ≤0.05) and left ventricular hypertrophy (1.37±0.07 versus 0.98±0.03 g dry weight, P ≤0.05). Compliance was assessed with the isolated heart preparation by analyzing the passive end-diastolic left ventricular pressure-volume relationship. The pressure-volume relation was fit to an exponential function by regression analysis; results showed that the modulus of stiffness was greater in obese than in lean rabbits (1.21±0.16 versus 0.83±0.05, P ≤0.05), indicating that diastolic compliance was reduced. Computer simulation analyses suggested that an isolated reduction in diastolic compliance may contribute to elevated cardiac filling pressures and exercise intolerance. These data suggest that diastolic compliance is reduced early in the development of obesity and may be an important component in the reduction of cardiac reserve in obesity.