Digitoxin intoxication in a 79-year-old patient.: A description of a case and review of the literature

This report concerns a 79-year-old patient with a pacemaker who presented with exertional shortness of breath, fatigue and peripheral pulse rates of about 35/min which had been present for about 3 weeks. An electrocardiogram at rest revealed paced QRS complexes at a rate of 38/min (1579 ms) followed by monomorphic ventricular extrasystoles at 480 ms. On exercise, the peripheral pulse rose to only 42 beats/min with spontaneous ventricular bigeminy. Serum digitoxin concentration was 32.9 μg/l (therapeutic range, 13–25). Two days later, at a digitoxin concentration of 29 μg/l, there was paced rhythm together with ventricular bigeminy only on effort, but not so at rest. On day 6 after admission, at a digitoxin concentration of 24.5 μg/l, isolated ventricular extrasystoles and fusion beats were present exclusively on termination of exercise. Thus, there is a clear correlation between serum digitoxin concentrations and the occurrence of ventricular ectopy. The latter was apparently precipitated by adrenergic drive during exertion.