Characteristic electrocardiographic features of manifest left anterior paraseptal accessory atrioventricular connection

Abstract

Manifest left anterior paraseptal accessory atrioventricular (AV) connections are extremely rare, and their associated electrocardiographic preexcitation pattern has not been well defined. In this report we give an account of the unique surface electrocardiographic (ECG) features exhibited by a patient with a documented left anterior paraseptal accessory AV pathway. Additionally, we show that this unique ECG pattern can be reproduced in patients lacking this pathway by ventricular pacing at this left anterior paraseptal location. A 28-year-old woman with a 10-year history of paroxysmal supraventricular tachycardia was referred for intracardiac electrophysiology study. A 12-lead ECG obtained during atrial-paced rhythm (Fig. 1, A) showed a frontal plane axis of +110 degrees and ventricular preexcitation with a P wave to A wave interval of 60 msec. The h waves were positive in leads II, III, and aVF and negative in lead V1. QRS complexes were isoelectric in lead V1, negative in leads V2 to V4, and positive in leads V5 to V6. With standard percutaneous techniques, intracardiac multipolar electrode catheters were placed in the high right atrium, right ventricular apex, His bundle region, and coronary sinus. To precisely localize the ventricular insertion of the accessory AV connection, a deflectable quadripolar catheter (2 mm interelectrode distance) was positioned along the ventricular side of the mitral annulus with the retrograde transaortic approach. During sinus rhythm with ventricular preexcitation evident, mapping of the mitra] annulus revealed earliest ventricular activation with the tip of the mapping catheter located at a left anterior paraseptal location (Fig. 2, A). During orthodromic AV reciprocating tachycardia, the earliest retrograde atria] activation was recorded at the same site (Fig. 2, B). Simultaneous activation