Left Ventricular Function and Compliance in Swine during Halothane Anesthesia

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Abstract
Halothane (0.05-1.7 vol% end-tidal) in N2O, 60%: O2, 40% was administered to nonmedicated closed-chest pigs. Ventricular function was analyzed from cardiac output (thermodilution) and left ventricular (LV) pressure indices. Ventricular volumes and compliance were estimated from single and biplane LV angiography. In separate experiments the effects of N2O, time and the angiographic dye injections were minimal. Halothane caused dose-dependent decreases in aortic blood pressure, cardiac output, peak 1st derivative of left ventricular pressure (LV dP/dt), the in vivo maximum velocity of fiber shortening (Vmax) and ejection fraction; non-dose-dependent decreases in heart rate and circumferential fiber shortening rate. A pronounced dose-related negative inotropic effect of halothane in the pig heart was seen but there was no definite effect on ventricular pressure-volume relationships (compliance). If there was any such effect of halothane it was obscured by the cardiac depression produced.