A case of concealed WPW syndrome with three different reciprocal tachycardias due to triple AV nodal pathways.

Triple atrioventricular nodal pathways (TAVNP) occur occasionally, but it is rare for them to produce more than two different tachycardias. Here we report a case of concealed WPW syndrome with three different tachycardias. During electrophysiologic studies, three different reciprocal tachycardias were induced. Tachycardia #1 was characterized by a cycle length of 230 msec and an A'-H interval of 70 msec. For tachycardia #2, these parameters were 300 msec and 140 msec, while they were 370 msec and 200 msec for tachycardia #3. During all three tachycardias, the earliest atrial activity was observed in the left atrium. Ventriculoatrial conduction occurred following ventricular stimulation, and the earliest atrial activity was observed in the left atrium, indicating the existence of left-sided accessory pathway. Persistence of tachycardia for 15-30 min caused marked pulmonary congestion. The heart rate was very high (260 beats/min) during tachycardia #1, and the pulmonary arterial pressure rose to 40/30 mmHg, with the pulmonary arterial diastolic pressure remaining at about 30 mmHg throughout the tachycardia. It seems that the pulmonary venous pressure rises abnormally during paroxysmal supraventricular tachycardia with a very high heart rate and that pulmonary congestion can easily occur during a short period of tachycardia.