Unusual electrocardiographic finding--bifascicular block due to hyperkalemia.

A unique case in which the patient had bifascicular block consisting of right bundle branch block and left posterior hemiblock as a result of marked hyperkalemia is presented. To our knowledge, this is the first reported case in which such unusual electrocardiographic abnormalities due to hyperkalemia were demonstrated. The electrocardiographic abnormalities produced by hyperkalemia in this case disappeared promptly by hemodialysis, as the serum potassium level returned to normal. It has been stressed that hyperkalemia should be considered as an important etiologic factor in the differential diagnosis of bundle branch block, hemiblocks and bifascicular block, particularly when these intraventricular blocks are produced suddenly.