Simultaneous Block of the Normal AV Pathway and Abnormal AV Bypass Tract by Digitalis Intoxication in a Patient with Type A WPW Syndrome

A 65-year-old male entered the Yamaguchi Red Cross Hospital with a tentative diagnosis of ventricular tachycardia. However, continuous ECG registration disclosed a presence of "f" waves, indicating that the basic rhythm was atrial fibrillation with a rapid ventricular response. Immediately, a rapid digitalization was instituted with lanatoside C. After digitalization, ECG showed a) atrial fibrillation with anomalous QRS complexes in the form of type A WPW syndrome, b) atrial fibrillation with intermittent complete AV block with normally configurated AV nodal QRS complexes, c) atrial fibrillation with normal and anomalous QRS complexes and idioventricular beats following the normally configurated nodal QRS complexes, d) sinus rhythm with apparently normal and anomalous QRS complexes and supraventricular premature beats of anomalous configuration and e) sinus rhythm with anomalous QRS complexes in the form of type A WPW syndrome. The duration of the anomalous QRS complex in sinus rhythm was shorter than that in atrial fibrillation.