[The effects of sevoflurane on the coronary circulation in the instrumented dog with or without coronary stenosis].

The effects of sevoflurane on the coronary circulation were investigated in the instrumented dogs with or without coronary stenosis. A-V block was produced by injection of formalin into A-V node to control heart rate at 120 beats.min-1 by pacing and mean systemic blood pressure was held constant at 65 mmHg with the pressurized blood reservoir. Left anterior descending coronary artery was cannulated with stainless steel tube supplied from the femoral artery. Total coronary flow was measured with an electromagnetic flow probe and the regional myocardial blood flow was calculated using color microsphere technique. Coronary resistance was reduced with the increasing end-tidal concentrations of sevoflurane up to 1.2 MAC. An adjustable screw clamp was used to reduce the coronary flow down to 50% of control value. Inner/outer ratio of regional myocardial blood flow decreased with stenosis, but was unaffected with 1.2 MAC of sevoflurane. We concluded that 1.2 MAC of sevoflurane was not strong enough to dilate the coronary artery to produce the transmural steal phenomenon in the dog with coronary stenosis. Further investigations are needed to clarify how hemodynamic factors influence the transmural steal phenomenon in myocardium.