Mahaim pathway potential revealed by high-resolution three-dimensional mapping

Abstract

Mapping and ablation of atriofascicular fibers can be highly challenging due to the complex and dynamic anatomy of the tricuspid valve annulus. This case highlights the utility of a multi-electrode catheter three-dimensional mapping approach to localize the Mahaim pathway along the tricuspid annulus in order to guide catheter ablation.

Keywords: 3D mapping; Atriofascicular pathway; Catheter ablation; Mahaim fiber; Multi-electrode catheter.

Fig. 1

Clinical tachycardia. Wide complex tachycardia at a rate of 170 bpm with left axis deviation, late transition left bundle branch block, and QRS duration of 138 ms indicating an origin at the right ventricular free wall insertion of the moderator band where the right bundle arborizes

Fig. 2

Baseline 12-lead electrocardiogram

Fig. 3

Antidromic echo. The atrial premature beat is conducted antegrade over the accessory pathway followed by retrograde His activation and an antidromic echo beat with retrograde block in the AV node. Note long stim‑V interval, left axis deviation and left bundle branch block pattern in V1 after S2. HRA high right atrium, CS coronary sinus, RVa right ventricular apex

Fig. 4

Mahaim potential. Mahaim “M” pathway potential recorded on the inner bipoles (7.8 and 11.12) of the Pentaray® catheter (Biosense Webster, Irvine, CA, USA) facing the lateral TA. Ablation tags indicate sites with Mahaim automaticity during radiofrequency ablation

Fig. 5

Mahaim automaticity. Mahaim automaticity induced by radiofrequency ablation (30–40 Watts, 30–60 sec., contact force > 10 g) at the lateral TA using an open-tip irrigation contact force catheter (ThermoCool SmartTouch®, Biosense Webster) and an Agilis® sheath (St. Jude Medical/Abbott)