Hemodynamic dose-responses to halothane and isoflurane are different in swine with and without critical coronary artery stenosis

This study examined global hemodynamic responses to increasing concentrations of halothane and isoflurane in pigs with an acute critical coronary stenosis (CCS) on the left anterior descending coronary artery (LAD). The CCS was caused by graded infiltration of an hydraulic occluder to the point where no hyperemic response was observed following a 10 sec. total LAD-occlusion. A minute, piezoelectric epicardial Doppler probe applied without dissection was used to monitor the stenosis. Previously reported minimum alveolar concentrations (MAC) were used as endtidal concentrations ([Et]). The [Et] was increased stepwise until each animal died. Recordings obtained in this study were compared to recording obtained during similar stepwise increments of these anesthetics in pig preparations without CCS. Isoflurane had a significantly less depressant effect on global hemodynamics compared to halothane and caused death at higher MAC than halothane in either case. A critical LAD-stenosis caused no major changes in the general dose-response pattern of isoflurane but further aggravated the depression of cardiac output and stroke volume induced by increasing concentrations of halothane.