Changes in blood flow and S-T segment during coronary arterial occlusion in denervated and nondenervated canine hearts

Myocardial blood flow and S-T segment measurements were made before and during occlusion of the left anterior descending coronary artery in chronically denervated and sham-denervated canine hearts. At similar heart rates, blood pressures and levels of work, left ventricular endocardial and epicardial blood flow values, as measured by radiolabeled microspheres, were significantly lower in denervated hearts than in shamdenervated control hearts. These results suggest that long-term cardiac denervation lowers metabolic demands of the left ventricle as reflected by decreased blood flow to the denervated left ventricle. Under the same conditions, blood flow measured in the right ventricle of denervated and sham-denervated hearts did not show any significant differences. Thus, it is possible that under normal circumstances the neural input to the right ventricle may be less than that to the left ventricle and may play a lesser role in controlling right ventricular tissue metabolic demands. During occlusion of the left anterior descending coronary artery, local epicardial and endocardial S-T segment elevation, measured by epicardial plaque and endocardial plunge electrodes, was less in denervated hearts than in sham-denervated hearts in areas of severely reduced blood flow (30 ml/min per 100 g or less). Also during occlusion the denervated hearts exhibited fewer arrhythmias than did the sham-denervated control hearts. The lower local S-T segment elevation found in the denervated hearts was not due to marked differences in blood flow between the areas sampled in the denervated and sham-denervated hearts. This decreased incidence of arrhythmia combined with less evidence of altered electrical activity suggests that denervation affords protection during coronary occlusion.