Heart failure due to chronic experimental aortic regurgitation

Previously reported experimental models of aortic regurgitation generally have manifested normal systolic performance and have not developed heart failure [Magid et al. Am. J. Physiol. 263 (Heart Circ. Physiol. 32): H226-H233, 1992]. To determine whether more severe chronic experimental aortic regurgitation would generate systolic malperformance, heart failure, and emulate the human disease process, 11 New Zealand White rabbits underwent surgical induction of aortic regurgitation and 5 control animals underwent sham operation. Doppler echocardiography was performed serially for up to 3 yr, and pathological studies were performed at necropsy. Left ventricular internal dimension at end diastole increased 80% (P < 0.00002) and left ventricular weight increased 250% (P < 0.0002) in aortic regurgitant rabbits (regurgitant fraction 52 +/- 13%) compared with baseline values. Six of 11 aortic regurgitant animals died with pathological evidence of congestive heart failure at 1.5 +/- 0.8 yr postoperatively; 2 of these developed severe systolic malperformance, manifest as fractional shortenings of 15 and 19% at 1.6 and 1.7 yr, respectively. Five of 11 aortic regurgitant animals survived until killed at 2.9 +/- 0.1 yr. Thus moderate-to-severe chronic aortic regurgitation in rabbits frequently results in heart failure and systolic dysfunction and may usefully model chronic aortic regurgitation and heart failure in humans.