Paroxysmal Supraventricular Tachycardia and Bundle Branch Block

Atrioventricular (AV) accessory connections are accepted as the underlying substrate of Wolff-Parkinson-White (WPW) syndrome. Such anomalous connections between atrium and ventricle are now known to be a common, but seldom recognized, cause of paroxysmal supraventricular tachycardia (PSVT). The following interesting case illustrates some of the principles involved in PSVT utilizing AV connections. REPORT OF A CASE A 55-year-old man presented with a 25-year history of recurrent palpitations. Episodes had been increasing both in frequency and duration and had become associated with light-headedness. A narrow complex tachycardia had been documented on various occasions and diagnosed as of supraventricular origin. On other occasions, a wide complex tachycardia had led to concern that this might be of ventricular origin. His arrhythmia was unresponsive to verapamil hydrochloride and digoxin, and he was referred for electrophysiologic evaluation. An ambulatory electrocardiographic recording showed the initiation of a wide complex tachycardia that rapidly converted to a narrow