[Comparison of cold blood cardioplegia and cold crystalloid cardioplegia with or without magnesium]

Blood cardioplegia has recently been advocated as a superior method of myocardial protection, but its temperature is important, and it has not been compared to a magnesium containing crystalloid cardioplegia. This study was undertaken to compare the protective effect of cold blood cardioplegia (BCP) and cold crystalloid cardioplegia with or without magnesium (MgKCP and KCP). Fourty-five patients were undertaken prosthetic cardiac valve replacement with left ventricular volume overload from valvular regurgitation. They were divided into three groups for the difference of the cardioplegic solution. Intraoperatively, myocardial temperature and the tissue PCO2 was monitored, and the content of calcium and magnesium of right atrium was measured before and after aortic cross clamping. Postoperatively, left ventricular stroke work index and serum CPK-MB isozyme activity were measured at 3, 6, 24 and 48 hours after weaning from cardiopulmonary bypass. The increase of the tissue PCO2 during aortic cross clamping and its recovery at ten minutes after reperfusion were significantly suppressed in BCP. The retension of the tissue calcium after reperfusion and calcium to magnesium ratio were significantly low in MgKCP. The recovery of cardiac pump function and decrease of CPK-MB were superior in MgKCP.