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Endothelin-1 (ET-1) is the strongest vasoconstrictor peptide isolated so far, which has a known arrhythmogenic property, as well. Intracoronary ET-1 infusion may cause ventricular premature beats (VES), ventricular tachycardia (VT) and ventricular fibrillation (VF). The aim of our study was to compare the thermographic and electrophysiologic changes during left anterior describing coronary artery (LAD) occlusion and ic. ET-1 administration. The measurements were performed on 16 sodium-pentobarbital anesthetized, open- chest dogs. The dogs were divided into 2 groups. In group A LAD occlusion was carried out for 30 minutes, followed by a 60 min reperfusion period. In group B ET-1 was administered into LAD at 60 pmol/min dose. Arterial blood pressure, coronary blood flow (CBF), heart rate (HR) and standard ECG were monitored. IR thermography was applied to follow epimyocardial heat emission changes. To determine the electrophysiological changes an endocardial monophasic action potential (MAP) electrode was inserted into the right ventricle and an MAP electrode was placed onto the left ventricle and an MAP electrode was placed onto the left ventricular epicardium. In group A CBF returned to baseline 20 minutes after releasing the occlusion. Ic. ET-1 infusion significantly reduced CBF in group B. Epimyocardial temperature decreased in both groups. In group A ventricular extrasystoles were noticed. In group B ventricular techycardias occurred with satisfactory CBF in 4 cases. In 5 dogs VF was observed. MAP duration 90 (MAPD90) decreased significantly in group A whereas significant increase was observed in group B. The left ventricular epicardial upstroke velocities correlated excellently with the epimyocardial temperature changes. Our result suggests that the decrease of epimyocardial heat emission and upstroke velocity correlates well in both groups, indicating ischemia, whereas the lack of the other ischemic MAP signs and the change of MAPD90 in the opposite direction suggests a different arrhythmia pathomechanisms in the ET group. Cardiothermography proved to be a useful tool in monitoring epimyocardial temperature changes during coronary artery occlusion and ET-1 induced vasoconstriction.
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