Echocardiographic changes after myocardial infarction in a model of left ventricular diastolic dysfunction.

To determine the early and late effects of myocardial infarction on left ventricular (LV) diastolic function in the rabbit postinfarction model, male New Zealand White rabbits were randomly assigned to ligation of the circumflex artery or sham operation. Serial echocardiographic and Doppler studies were performed on both groups of animals at baseline and 1 h and 3 wk after surgery (n = 10 for each group) after verification of the reproducibility and repeatability of the measurements. At 1 h postinfarction, decreases in early mitral inflow velocity (E wave) and mitral inflow velocity with atrial contraction (A wave) and increases in the mean pulmonary venous systolic-to-diastolic ratio and A wave reversal velocities were observed, without changes in LV geometry. By 3 wk postinfarction, increases in the mitral E-to-A ratio (1.1 +/- 0.3 vs. 2.9 +/- 0.9, P < 0.001) and left atrial area (131 +/- 23 vs. 510 +/- 72 mm2, P < 0.001) and decreases in the pulmonary venous systolic-to-diastolic ratio (0.56 +/- 0.20 vs. 0.79 +/- 0.14, P = 0.008) were consistent with severe diastolic abnormalities (restricted physiology). The findings of this study demonstrate that coronary artery ligation in the rabbit provides a reproducible echocardiographic and Doppler model of LV diastolic dysfunction that is consistent with abnormalities found in humans with previous myocardial infarction, symptoms of heart failure, and preserved LV systolic function.