Hypertrophic and functional response to experimental chronic aortic regurgitation

Aortic regurgitation was induced by retrograde perforation of an aortic valve cusp under hemodynamic guidance in 12 New Zealand White rabbits. Regurgitant fraction was documented by electromagnetic flow probe and six sham-operated animals served as controls. Two-dimensional, M-mode and Doppler echocardiography was performed pre-operatively and serially postoperatively for 3 to 6 months. Animals with aortic regurgitation developed progressive left ventricular dilatation and eccentric hypertrophy. Left ventricular internal dimension at end-diastole and left ventricular mass were increased from baseline values by 41 and 94% (P<0.001), respectively; fractional shortening was stable while end-systolic stress increased 50% (P<0.01). Thus, acutely induced aortic regurgitation in rabbits results in a chronic model which may be appropriate for simulation of the hypertrophic response to aortic regurgitation in humans.