Since the chronically cyanotic myocardium appears to be more susceptible to
reperfusion injury after cardiac operations than the noncyanotic myocardium, we studied the association between the preoperative arterial
oxygen tension and the myocardial
superoxide dismutase,
catalase, and
glutathione peroxidase activities. Fourteen patients with
tetralogy of Fallot scheduled for elective operations had baseline arterial blood gas measurements done before operation. During the operation right ventricular biopsy specimens were taken for
enzyme analysis immediately before cold blood cardioplegic arrest and 20 minutes after crossclamp removal. The tissue
antioxidant enzyme activities of the patients with
tetralogy of Fallot were compared with the myocardial results in 15 adults with
stable angina pectoris having elective aorta-
coronary artery bypass graft operations. Myocardial tissues removed from two patients with
hypertrophic obstructive cardiomyopathy who had corrective operations were analyzed for
antioxidant activities. There were no changes in myocardial
antioxidant enzyme activities during the operation in the patients with
tetralogy of Fallot and
coronary artery bypass graft. The myocardial
superoxide dismutase,
catalase, and
glutathione peroxidase activities correlated (0.82, 0.68, and 0.89, respectively) significantly (p values were less than 0.01, 0.05, and 0.01, respectively) with the preoperative arterial
oxygen tensions in the patients with
tetralogy of Fallot. The myocardial
glutathione peroxidase activities were at least four times higher in the myocardium of patients with
coronary artery bypass graft and
hypertrophic obstructive cardiomyopathy than in that of those with
tetralogy of Fallot. This study provides putative evidence that the myocardium of patients with
tetralogy of Fallot is a risk of
oxygen-derived
free radical injury during and immediately after corrective cardiovascular operations.