Coexistence of Functional Kent and Mahaim-type

An unusual patient with Ebstein's anomaly of the tricuspid valve and the Wolff-Parkinson-White syndrome is presented. Ventricular pre-excitation related to conduction over both a right posterior Kent bundle and Mahaim fibers coursing from the atrioventricular node to the right ventricle. Two types of supraventricular tachycardia were demonstrable. These were due to re-entry involving antegrade conduction over either the normal or Mahaim paths, and retrograde conduction via the Kent bundle. Surgical division of the Kent bundle has abolished the clinically debilitating arrhythmias.