Evidence for specialized atrioventricular conduction in hyperkalemia.

A patient who had chronic coarse atrial fibrillation developed severe hyperkalemia accompanied by total loss of fibrillatory waves while an irregularly irregular ventricular rhythm persisted. Correction of hyperkalemia resulted in prompt return of coarse atrial fibrillation. This sequence of events renders strong support to direct atrioventricular conduction through the specialized internodal tracts.