The direct cardiac effect of propofol on intact isolated rabbit heart

Background: The objective of the current study was to determine the direct effect of propofol on intact isolated rabbit heart using the modified Langendorff model. Methods: Eighteen rabbits were decerebrated under light ether anesthesia. Their hearts were then excised and prepared pursuant to the modified Langendorff model. Left ventricular pressure, left ventricular contractility (dp/dt) and heart rate were recorded in the absence of propofol and in the presence of propofol of four different concentrations (1, 5, 25, 50 mg/L). In one group of hearts (N = 11) the heart rate was not paced. In another group of hearts (N = 7), the hearts were paced (during the control period and in propofol of each concentration) at a rate slightly higher than control rate and then allowed to revert to original state; pressure and contractility were measured and taken at both paced and unpaced rates. Results: In the unpaced group of hearts, a significant dose-dependent, negative effect on both left ventricular pressure and contractility was found at the two higher propofol concentrations (25 and 50 mg/L). A significant heart rate decrease was also revealed at these two concentrations. In the paced group, the left ventricular pressure and dp/dt also decreased significantly at higher propofol concentrations, and they did not return toward control values even though the heart was paced at the baseline unpaced rate. Conclusions: Propofol depressed left ventricular pressure and contractility and heart rate in a dose-dependent manner at higher concentrations. These negative cardiac effects were independent of changes in heart rate.