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.