| Research Abstract |
Twenty-five mongrel dogs were divided into three groups : fentanyl group (n=8), sevoflurane group (n=9), and sevoflurane-IP group (n=8). Anesthesia was maintained with continuous infusion of fentanyl (0.3 μg/kg/min) in fentanyl group, and with 1 MAC sevoflurane in sevoflurane and sevoflurane-IP groups. The volume conductance catheter and the pressure-transducer-tipped catheter were placed in the left ventricle. Integrated backscatter (IBS) images of left ventricular short-axis view at the mid-papillary muscle level were obtained from the heart surface using a 12-MHz ultrasonic transducer. Regions of interest were designated in the midseptum, supplied by the left descending coronary artery (LAD), and the inferior wall supplied by the right coronary artery. The magnitudes of cyclic variation of IBS and % systolic wall thickening (%WT) in each region were determined. The ratio of stroke work to pressure volume area (SW/PVA) was used to evaluate the left ventricular work efficiency. Both f
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entanyl and sevoflurane groups underwent 20 min of LAD occlusion, followed by 120 min of reperfusion. The sevoflurane-IP group was pretreated with two 5-min LAD occlusions interspersed with 15-min periods of reperfusion. Hemodynamic and echocardiographic variables were recorded simultaneously before LAD occlusion (baseline), 20 min after occlusion (immediately before reperfusion), 20, 60, and 120 min after reperfusion.
In all groups, %WT in the LAD area decreased significantly following LAD occlusion, however, %WT 20 min after occlusion in the IP group was significantly higher than those in fentanyl and sevoflurane groups (13±8%, -2±13%, -7±13%, respectively). In fentanyl and sevoflurane groups, IBS cyclic variations in the LAD area and SW/PVA significantly decreased immediately before and, 20, 60, and 120 min after reperfusion. In sevoflurane-IP group, IBS cyclic variations did not decrease significantly at the same time intervals, and SW/PVA was maintained.
Ischemic preconditioning under sevoflurane anesthesia preserved regional systolic function, myocardial tissue ultrastructural integrity, and left ventriculo-arterial coupling, but did not sevoflurane alone. Less
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