Cardioplegia versus intermittent ischaemic arrest in coronary bypass surgery.

No definitive method of myocardial preservation has been established and conclusions based on experimental data may not be applicable to patients with coronary artery disease. Fifty patients undergoing coronary bypass grafting were randomly assigned to one of two groups for myocardial preservation. In group A cold cardioplegia with external cardiac cooling was used and in group B ischaemic arrest with mild systemic cooling to 32 degrees C. Myocardial preservation was assessed by analysis of enzymes specific to the heart, left ventricular biopsy, and electrocardiography. Equal protection of the myocardium was provided in both groups but the mean cross-clamp time in group A was significantly longer than in group B. This implies that cardioplegia confers greater protection than intermittent ischaemic arrest.