Serum enzymes after cardiac surgery using cardiopulmonary bypass

Abstract

Electrocardiographic and enzyme studies were made on an unselected series of 172 patients admitted to the intensive-care unit after cardiac surgery using cardiopulmonary bypass. Fifty-eight patients had aortic valve, 22 patients multiple valve, 40 patients mitral valve, 27 patients congenital, and 25 patients ischemic disease. There were five hospital deaths. The following observations were made preoperatively and on the first, second, and third postoperative days: 13-lead electrocardiograms, serum glutamic oxaloacetic transaminase, lactic dehydrogenase, creatine phosphokinase, and alkaline phosphatase. At least one further electrocardiogram was recorded later in the hospital stay. In 88 of the patients, isoenzymes of LDH were measured. Details of surgical technique and the postoperative course were recorded in each patient. SGOT and LDH values were elevated in all groups but were highest in patients with aortic- and multiple-valve disease. LDH isoenzyme patterns were typical of myocardial damage in only a small number of patients with high total enzymes. There was no relationship between high enzyme levels and age, hemolysis during bypass, or postoperative complications, but a correlation between enzyme levels and cardiopulmonary bypass time was shown in patients in the aortic and congenital groups and between enzyme levels and aortic cross-clamping time in patients in the aortic and mitral groups. Twenty-seven out of 34 patients with a peak postoperative SGOT level equal to or greater than 200 units per milliliter showed electrocardiographic evidence of myocardial damage but only nine out of 138 patients with SGOT levels less than 200 units per milliliter showed such evidence. All but one patient in the aortic and multiple groups showing myocardial damage had an SGOT level equal to or greater than 200 units per milliliter, but SGOT levels in patients in the mitral, congenital, and ischemic groups showing myocardial damage were usually around 100 units per milliliter. Myocardial damage was more common in the aortic, multiple, and ischemic groups. In patients in the aortic group prolonged ventricular fibrillation during operation was associated with high postoperative enzyme levels but this was largely explained by faulty coronary perfusion in some patients. It is concluded that postoperative elevation of serum enzymes is, in part, an inevitable consequence of cardiopulmonary bypass but exceptionally high levels usually indicate myocardial damage. Routine recording of electrocardiograms, serum SGOT, and serum LDH levels on the first two postoperative days is recommended for all patients.