Ventricular performance in rats with myocardial infarction and failure.

Ventricular performance was assessed in rats three weeks following coronary artery ligation and the subsequent production of a wide range of infarct sizes. The entire spectrum of ventricular dysfunction was observed, from minimal impairment to overt congestive heart failure. Rats with small infarcts ejected normal baseline and volume-stressed forward outputs from a modestly dilated ventricular chamber. Rats with moderate infarcts exhibited normal baseline hemodynamics but had a reduced reserve flow capacity when challenged with a volume load despite considerable ventricular dilatation. Rats with large infarcts demonstrated frank congestive heart failure with elevations in both left and right ventricular filling pressures and consequent right ventricular hypertrophy; marked reductions in both baseline and volume-stressed forward outputs; and ventricular volumes that were twice those of rats without infarcts. Thus, a progressive impairment in ventricular performance and an increase in chamber volume occurred in relation to infarct size in rats with healed myocardial infarction.