Myocardial preservation during aortic valve surgery. Assessment of five techniques by cellular chemical and biophysical methods.

Five different types of myocardial protection were employed in this series of 168 patients undergoing aortic valve replacement. Two methods of assessing myocardial preservation were used: cellular biological estimations and quantitative polarization measurements. Both parameters showed that either of two methods, continuous perfusion at 32 degrees C. with a beating heart or cardioplegic hypothermic arrest, protected the myocardum best. Intermittent perfusion at 30 degrees C. with a fibrillating heart was the worst means of preservation. Our investigations (both clinical and experimental) have also shown that changes in birefringence, indicative of deteriorating myocardial function, are often detectable before parallel cytochemical changes are apparent.