Retrograde Fast Pathway Ablation in Atrioventricular Nodal Reentrant Tachycardia

Abstract

Nowadays, slow pathway ablation is the first-line therapy for atrioventricular nodal reentrant tachycardia (AVNRT). However, it may cause inadvertent AV block especially inpatients with a prolonged PR interval on the baseline ECG. Retrograde fast pathway ablation may be attempted in such AVNRT patients as an alternative approach to maintain the original AV conduction over the slow pathway.

When we consider which pathway should be ablated in patients with a prolonged PR interval, the antegrade slow or retrograde fast, the most important thing is to electrophysiologically evaluate in detail whether dual AV nodal physiology is present or not. If dual AV nodal physiology is absent, or the baseline PR interval exceeds 300 ms, retrograde fast pathway ablation should be performed. In such a situation, cryoablation may be much safer than RF ablation, especially for retrograde fast pathway ablation, because the tip of the ablation catheter adheres to the ablative tissue firmly during freezing, which provides good catheter stability and can avoid any inadvertent catheter dislodgement. Further, the lesion damage created by cryoablation progresses more slowly than that by RF ablation.