Second degree type II and complete atrioventricular block due to hyperkalemia.

An 83-year-old woman was hospitalized with complete atrioventricular block and a pulse of 20/min. Three days earlier an electrocardiogram had revealed right bundle branch block with classic type II second degree atrioventricular block. Admission potassium was 7.8 meq/L; within 24 hours the potassium was lowered to 4.9 meq/L and the atrioventricular block disappeared. The patient was followed for nineteen months and remained normokalemic without recurrence of atrioventricular block, although the right bundle branch block persisted. She was then readmitted with bradycardia due to complete atrioventricular block despite normokalemia. We conclude that hyperkalemia can produce the classic picture of progressive bilateral bundle branch disease leading to high degree atrioventricular block, although this seems to occur in patients with extensive intrinsic disease of the conduction system.