A canine model of chronic ischemic cardiomyopathy: characterization of regional flow-function relations

The controversy regarding the mechanism(s) of left ventricular (LV) dysfunc tion in chronic coronary artery disease is, in part, related to the lack of an appropriate animal model for this condition. We have developed such a m odel by placing Ameroid constrictors on proximal portions of coronary arter ies in dogs who were euthanized (mean of 6 wk) after the development of sev ere global LV dysfunction noted on two-dimensional echocardiography. The LV end-systolic size nearly doubled (P < 0.001) over the observation period, and the percent change in LV size from end diastole to end systole decrease d by >50% (P < 0.001). Regional dysfunction was noted in 23 of 24 myocardia l beds analyzed within regions showing no gross evidence of infarction. In 10 of these beds, severe dysfunction was noted without a decrease in radiol abeled microsphere-derived myocardial blood flow (MBF). In 13 myocardial be ds, decrease in function was associated with a decrease in MBF (P < 0.001), with close coupling noted between percent wall thickening and MBF. In the beds that exhibited an ultimate decrease in MBF, the decrease in function p receded the decrease in MBF. In conclusion, we describe chronic LV dysfunct ion in a canine model of multivessel stenosis that closely mimics chronic i schemic LV dysfunction in humans. Whereas regional function is severely red uced in this model, MBF is varied in different segments and at different ti mes during the observation period. These results provide new insights regar ding flow-function relations in chronic ischemic LV dysfunction.