Functional evaluation of normothermic intermittent coronary perfusion

The myocardial contractility of papillary muscle from rabbit hearts was used to evaluate various techniques of normothermic intermittent coronary perfusion. A progressive decline of the myocardial contractility was noted as aortic cross-clamping and coronary reperfusion were repeated. After a net anoxic period of 90 minutes, the contractility fell to 58.67, 60.2, and 40 percent of the base line when single aortic cross-clamping time was 5, 10, and 15 minutes, respectively, interrupted by 5 minutes of reperfusion. Repeated application of single cross-clamping of 20 minutes or longer was not tolerated by the rabbit hearts. When the heart was reperfused for 10 minutes, between 15 minute periods of anoxia, the final recovery of contractility was 62 percent. Normothermic intermittent coronary perfusion has a significant adverse effect on the myocardial contractility. If this technique is to be used, single anoxic times should not be longer than 15 minutes and the heart must be reperfused for at least 10 minutes.