Atypical ventricular tachycardia as a manifestation of disopyramide toxicity.

An unusual ventricular tachyarrhythmia developed in a 57 year old woman with recurrent ventricular tachycardia and toxic disopyramide plasma concentrations. The rhythm was similar to the patient's previous ventricular tachycardia, but the rate was slower and the QRS complex was markedly widened, mimicking the electrocardiographic changes associated with electrolyte abnormalities. Disopyramide, which has electrophysiologic properties similar to those of quinidine, probably caused the arrhythmia and should be added to the list of drugs associated with atypical ventricular tachycardia.