RESUMO
For studying the effect of regional myocardial blood flow changes on the epicardial ECG of right and left ventricular walls under acute right ventricular pressure overload, we mapped the epicardial using 64-channel shock electrodes, and estimated the myocardial blood flow with radioactive microspheres. In 9 anesthetized open-chest dogs, the main pulmonary artery was gradedly constricted to the level of mild (peak RV pressure: PRVP, 50-70 mmHg), moderate (PRVP, 70-80 mmHg) and severe stenosis (PRVP, over 80 mmHg). Labeled microspheres were injected into the left atrium before and after the PA constriction, and the epicardial ECGs were recorded continuously. After the completion of the experiment, 9 areas of each right and left ventricular wall were excised. The myocardium was divided into three layers and the flow data were compared to the changes of ECG parameters. In the cases where there was severe PA stenosis, the right ventricular myocardial blood flow decreased to a significantly greater degree (63% reduction from the control), especially in the subepicardial layer, than the flow in the left ventricle (37% reduction from the control). ST potential, STT and QRST Area Map increased in the right ventricle but decreased in the left ventricle. Activation Recovery Time of the right ventricle decreased due to the severe ischemia of the right ventricle. The value of QRS Area Map of the left ventricle decreased significantly in parallel with the decrease in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)
