Sinus node dysfunction caused by methyldopa and digoxin.

Symptomatic sinus bradycardia developed in two patients while they were taking methyldopa and digoxin. In one patient, bradycardia did not occur with either digoxin or methyldopa alone. The other patient, who had never taken methyldopa alone, did not demonstrate bradycardia with digoxin alone. In each patient, normal sinus node function was demonstrated after methyldopa and digoxin therapy was discontinued. Both patients continued to receive digoxin without recurrence of bradycardia.