Electrophysiologic effects of volatile anesthetics,sevoflurane and halothane,in a canine myocardial infarction model

The effects of sevoflurane and halothane on the effective refractory period (ERP) and ventricular activation were examined in a canine myocardial infarction model. Sevoflurane (1 MAC) reduced the heart rate and prolonged ERP in both normal and infarcted zones. A prolongation of ERP with sevoflurane was observed also during atrial pacing at a fixed rate, but the effect was less than during sinus rhythm. Sevoflurane either further delayed or blocked the delayed activation entirely in the infarcted zones with only slight effects on the activation of the normal zones. Halothane (1 MAC) prolonged ERP during sinus rhythm and atrial pacing, but to a lesser extent during the latter. Halothane also depressed ventricular activation in the infarcted zone during atrial pacing. In conclusion, sevoflurane as well as halothane selectively depresed the delayed activation and the prolongation of ERP in myocardial infarction, which may inhibit ventricular arrhythmias in myocardial infarction.