New approaches to ablation of left-sided and posteroseptal accessory pathways

Abstract

The accessory pathways located in the posteroseptal region constitute a significant proportion of all pathways seen in patients with Wolff-Parkinson-White syndrome. Catheter ablative approaches using direct current shocks and radiofrequency [RF] energy have been applied to these locations. Anatomic complexities in the posteroseptal region make anatomically guided ablation difficult in this particular location. Techniques of ablation have been largely guided by atrial and ventricular electrogram recordings and the location of other important electrical structures such as the normal atrioventricular conduction system. In early reports, the posteroseptal region of the tricuspid annulus or the margin of the coronary sinus ostium was usually targeted for ablation [1]. The left-sided endocardial approach was used for left posteroseptal pathways. Right posteroseptal pathway locations were seen in 35% while 33% were present inside the terminal coronary sinus and the ostium and 23% were located in the left paraseptal region [2]. The endocardial method thus had to approach, in early two-thirds of patients, locations outside the right atrium to achieve successful ablation. Thus, it is not surprising that the highest complication rates with respect to atrioventricular block and highest failure rates are observed in the posteroseptal region. Left ventricular catheterization and ablation has been necessary in a significant proportion of patients with attendant risk of significant systemic complications.