New safe approach to target symptomatic Hisian ectopy/tachycardia.

AIMS: Although cryoenergy safety profile is appropriate for the ablation of arrhythmogenic foci near the conduction system, mapping using the cryoablation catheter is of limited precision. Combining the safety of cryoenergy and the high precision of a 3D mapping system therefore appears the most appropriate set-up for ablation in the vicinity of the His bundle. METHODS AND RESULTS: A 29-year-old woman with a 3-year history of increasing shortness of breath and palpitations refractory to medical treatment was sent to the electrophysiology (EP) laboratory for catheter ablation. Surface electrocardiogram showed sinus rhythm and frequent ectopic beats with narrow QRS complexes similar to those of the sinus beats. The left ventricular ejection fraction was impaired (38%) with no other aetiology found, apart from frequent ectopies. Detailed intracardiac mapping, using a 3D electroanatomical system, revealed that the ectopy originated from the distal His bundle, which was indicated by both antegrade and reversed His bundle activation sequence during ectopy compared to that during sinus rhythm. Due to the proximity of the conduction system, cryoenergy rather than radiofrequency was chosen to target this Hisian ectopy. A special set-up was made in order to allow the cryoablation catheter to be visualized into the 3D mapping system. Cryoenergy delivered to the site of earliest Hisian ectopy activation completely abolished it. CONCLUSION: Such a combined approach may help to improve the therapeutic strategy for ablation procedures with a high risk of injury to the conduction system. It could notably be extended to the ablation of para-Hisian ectopy or accessory pathways.

RVOT premature ventricular contractions induce significant anatomical displacement during 3D mapping: A cause of mid-term ablation failure?

BACKGROUND: Catheter ablation is a first-line treatment for symptomatic right ventricular outflow tract (RVOT) premature ventricular complexes (PVCs). There is evidence of displacement of the ablation target site during PVCs relative to the location in sinus rhythm (SR). AIM: To analyse the extent of displacement induced by RVOT PVCs and its effect on the ablation sites and the mid-term efficacy of ablation. METHODS: In this multicentre French study, we retrospectively included 18 consecutive adults referred for ablation of RVOT PVCs using a three-dimensional (3D) mapping system. PVC activation maps were performed conventionally (initial map), then each PVC activation point was manually reannotated considering the 3D location on a previous SR beat (corrected map). The ablation-site locations on the initial or the corrected area, including the 10 best activation points, were analysed. Mid-term efficacy was evaluated. RESULTS: The direction of map shift during PVCs relative to the map in SR occurred along a vertical axis in 16 of 18 patients. The mean activation-point displacement for each of the 18 mapped chambers was 5.6±2.2mm. Mid-term recurrence of RVOT PVCs occurred in 5 (28%) patients. In all patients with recurrences, no significant ablation lesion was located on the corrected (true) site of origin. CONCLUSIONS: RVOT PVCs induce a vertical anatomical shift that can mislead physicians about the true location of the arrhythmia's site of origin. Our study highlights the association between mid-term PVC recurrence and the absence of spatial overlap between ablation points and the corrected site of origin.