Serum, Atrial, and Urinary Digoxin Levels During Cardiopulmonary Bypass in Children

Serum, urine, and tissue samples were collected from 42 children undergoing open-heart surgery and analyzed for digoxin by radioimmunoassay. Of these, 24 had been digitalized prophylactically (RECENT) and 18 had been receiving maintenance therapy (MAINT) for one month or longer. Twenty-five percent of the RECENT patients exhibited arrhythmias during the postoperative period as compared to none in the MAINT group. Serum digoxin levels were equivalent in the two groups throughout the study. Although no change in tissue digoxin concentrations occurred during bypass, right atrial appendage concentrations were significantly higher in the RECENT group (109 vs 62 ng/g; P < 0.001). This high atrial digoxin concentration presumably resulted from the large doses used for initial digitalization, and concomitant with postoperative hypokalemia and myocardial metabolic changes secondary to perfusion, may have been responsible for the high incidence of arrhythmias in the RECENT group. Both digoxin and creatinine excretion were depressed following bypass. The amount of biotransformation of digoxin was 2-59.