e0338 Ablation of left-variated dual atrioventricular nodal pathway in coronary sinus

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common paroxysmal supraventricular tachycardia. It is well accepted that the mechanism of AVNRT is reentry associated with dual or multiple atrioventricular nodal (AVN) pathway. Typical AVNRT pathways including fast and slow pathways are confined in right atrium. Radiofrequency catheter ablation slow pathway, occasionally fast pathway, has become the definitive treatment of choice for most symptomatic patients. Besides typical AVNRT, there exists some atypical AVNRT with various manifestations. Several groups have reported successful ablation of leftward dual AVN pathway in the left side of the heart. We present one case of left-variated AVN as well as dual AVN pathway. Routine ablation methods failed to eliminate the tachycardial. Detailed electrical physiological study showed that His Bundle potential was minimal recorded in the right atrium septum but was prominent when recorded in the left septum using a catheter via transaortic approach. Left variated dual AVN pathway was considered. Since routine methods were unsuccessful, an ablating was forward deep into coronary sinus when a target with A/V≈1/4 and without His bundle electrogram was mapped. A small energy attempt showed effective and the tachycardia was successfully eliminated by ablation of slow pathway deep in the coronary sinus.