A comparison of the effects of fentanyl and propofol on left ventricular contractility during myocardial stunning

Background The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could protect the heart and improve recovery of ventricular contractile function in open-chested dogs. Methods Twenty adult beagles were acutely instrumented, under halothane anaesthesia, to measure ECG; aortic, left ventricular pressures; cardiac output; coronary flow; and segmental lengths in the regions perfused by the left anterior and left circumflex coronary arteries. After surgery and a stabilisation period halothane anaesthesia was terminated and fentanyl (100 microg x kg[-1] bolus followed by 2 microg x kg[-1] x min[-1] infusion; n=10) or propofol (5 mg x kg[-1] bolus followed by 0.3 mg x kg[-1] x min[-1] infusion; n=10) anaesthesia commenced. After a stabilisation period the LAD coronary artery was occluded for 10 min and then reperfused for 3 h. Measurements were taken throughout the protocol. Results We found no significant difference in recovery of contractile function between propofol and fentanyl as assessed by normalised preload recruitable work area (50+/-10 vs 47+/-16%), normalised systolic shortening (36+/-12 vs 48+/-14%) and peak left ventricular dP/dt (1665+/-276 vs 1846+/-151 mmHg x s[-1]) at the end of reperfusion. Conclusion We conclude that at the concentration used in this study propofol shows no improvement in contractility during "stunning" when compared to fentanyl.