Myocardial protection during aortic valve replacement. Selective infusion of cold cardioplegic solution into the left...

A simple method for hypothermic cardioplegia during aortic valve surgery is described. Cold cardioplegic solution (Ringer's acetate with 16 mEq potassium added) was selectively infused into the left coronary artery after the aorta had been opened. This resulted in an even cooling of the left ventricle with a relatively small amount of cardioplegic solution. Local cooling with "soft ice" was then initiated and the heart isolated from its warmer surroundings with the aid of a specially designed pad of compressed plastic foam. Thus, the left ventricular temperature could be kept below 20 degrees C for more than one hour. One hundred and three (103) patients were operated on with this method during a one-year-period. Only one patient died (1%). There were few early and/or late complications. Postoperative heart function was excellent in 23 patients subjected to a special study. Peak aortic pressure during the first 16 postoperative hours was 130 (+/- 22) mmHg, mean left atrial pressure 12 (+/- 2) mmHg, mean right atrial pressure 10 (+/- 2) mmHg and all patients were in sinus rhythm. There was a brief and limited release of myocardial enzymes postoperatively, indicating slight intra-operative myocardial damage. Apart from the cardioplegic technique, there are certain factors of importance for the efficacy of myocardial protection during aortic valve replacement. Among them may be mentioned avoidance of ventricular fibrillation, gentle reperfusion after release of the aortic cross-clamping, avoidance of left ventricular distension and administration of calcium intravenously before termination of bypass.