EFFECTS OF DENOPAMINE WITH OR WITHOUT DILTIAZEM ON THE ISCHEMIC HEART OF ANESTHETIZED DOGS

Effects of denopamine with or without diltiazem on the ischemic heart were investigated in anesthetized open-chest dogs. Partial occlusion of the left circumflex coronary artery (LCX) produced significant decreases in LCX flow and regional myocardial segment shortening rate (%SS) in the LCX-perfused area, and a significant increase in left ventricular enddiastolic pressure (LVEDP). Heart rate (HR) and mean aortic pressure (mAoP) were not altered, but aortic flow (AoF), positive first derivative of left ventricular pressure ((+)LVdP/dt), stroke volume (SV). stroke work index (SWI) and double product showed a tendency to decrease. Total peripheral vascular resistance (TPR) tended to increase. During coronary stenosis, saline infusion (vehicle group) did not change any parameter, but diltiazem infusion (diltiazem group) decreased HR, mAoP, TPR and double product and increased SV and SWI. Under these conditions, denopamine infusion produced increases in HR, mAoP. AoF, (+)LVdP/dt and double product and decreases in LVEDP and TPR in both groups. %SS in the left anterior descending coronary artery-perfused area was increased, but %SS in the LCX-perfused area was slightly decreased in both groups. SV and SWI were decreased by denopamine infusion in the vehicle group, while they were increased in the diltiazem group. Differences in changes in SV and SWI between the groups were statistically significant. Results suggest that combined treatment of denopamine and diltiazem may exert an advantage in alleviation of heart failure due to coronary stenosis.