Nonsurgical ablation of accessory pathways: Physical, anatomical, and clinical considerations

Catheter ablation of accessory pathways in the Wolff-Parkinson-White and related syndromes has been explored as an alternative to surgery. Anatomical differences between left freewall, posterior septal, and right freewall sites, are sufficient to affect both the potential and the results of catheter ablation. Left free wall accessory pathways are approached through the coronary sinus. The fragility of this structure limits the energies that can be delivered without danger of rupture. There is the possibility of damage to nearby coronary arteries. These considerations have limited the success of ablation of left freewall accessory pathways, as well as the percentage of patients who are suitable candidates. With right freewall pathways, major concerns center around methods localizing the level of the tricuspid annulus, and the possibility of damage to the ubiquitous right coronary artery. Thus far, accessory pathways located in the posterior septum at the ostium of the coronary sinus appear to be most amenable to successful ablation. Other types of accessory pathways, such as those found in the permanent form of junctional reciprocating tachycardia, and some fascicular tachycardias may also be suitable for ablation. In the literature reviewed, a total of 77 cases were reported with 50 successes, 9 partial successes, and 18 failures. Complications, including exsanguinating rupture requiring immediate surgical attention, also were reported and underscore the potential risks of the procedures.