Examining the causes of ablation failure in the Wolff-Parkinson-White syndrome

Abstract

the His-bundle at a midseptal or anteroseptal location, increasing the risk of inadvertent complete atrioventricular block. The use of a long sheath may facilitate catheter stability if the accessory pathway is located along the right midseptal or anteroseptal region. In these cases, we favour advancement of the ablation catheter from the right jugular vein, since this site of access is in direct alignment with the location of the accessory pathway. Stable wall contact is accomplished by counterclockwise torque of the catheter. In addition, we found that an anteroseptal pathway may be successfully ablated from the non-coronary cusp. 7 Some operators prefer to use cryothermia. Our laboratory routinely uses RF current when ablating para-Hisian pathways. A His potential is practically always recorded at the earliest site of accessory pathway activation. However, the His bundle is protected by fibrous tissue, whereas the accessory pathway is superficially located, making damage to the His bundle very unlikely with the judicious use of RF energy. An epicardial accessory pathway location may not be amenable to a routine endocardial approach. If a posteroseptal accessory pathway is suspected, coronary sinus angiography will facilitate proper anatomic delineation and catheter ablation. In 21% of patients with a suspected posteroseptal or left posterior accessory pathway, coronary sinus angiography demonstrated a diverticulum originating from the middle cardiac vein, coronary sinus, or both. 8 Ablation is performed by advancing the ablation catheter into the coronary sinus, targeting the neck of the diverticulum. In rare cases, an epicardial accessory pathway may mimic electrocardiographic criteria of a manifest right anteroseptal accessory pathway. Clues to the correct diagnosis during endocardial