Abstract
BackgroundThis study describes the electrophysiologic characteristics of the para-hisian accessory pathway (AP), the outcome of different ablation approaches, and ablation safety at different sites.MethodA total of 120 patients diagnosed as para-hisian AP were included in this study. The electrophysiologic characteristics and outcomes at different ablation sites were analyzed.ResultsIn total, 107 APs and 13 APs were diagnosed as right anteroseptal (RAS) and right midseptal (RMS), respectively. The significant ECG difference between RAS and RMS was lead III, which mainly manifested as positive and negative delta waves, respectively. Catheter trauma to AP was recorded in 21 of 120 (17.5%) patients. The recurrence rate of direct ablation at the “bumped” sites was higher than the conventional ablation method (37.5 vs. 14.1 %, p = 0.036). For RAS APs, there was no significant difference in the success rate between the inferior vena cava (IVC) and superior vena cava (SVC) approaches (76.6 vs. 73.3%, p = 0.63). The RAS was separated into three regions: (1) Site 1: superior part above the real “His” recorded site with far-field “His” potential; (2) Site 2 (true para-hisian): the site with near-field “His” potential; and (3) Site 3: inferior part below the biggest real “His” with far-field “His” potential. Mid-septal was defined as an area that is bounded anteriorly by His recording location and posteriorly by the roof of coronary sinus (CS) ostium. The incidence of atrioventricular (AV) conduction injury at different sites was as follows: 3 of 6 (50%) at Site 2, 4 of 13 (30.8%) at RMS, 7 of 34 (20.6%) at Site 3, and 3 of 46 (6.5%) at Site 1. Even if ablation was performed at the atrial side of the para-hisian region, the right bundle branch block (RBBB) was caused in 6 patients (5%).ConclusionAblation via IVC or SVC was comparative for para-hisian APs, but not for the noncoronary cusp (NCC) approach. The AV conduction injury risk ranks as follows: Site 2 > RMS > Site 3 > Site 1. RBBB could be caused while ablating at the atrial side, which could further demonstrate the His bundle longitudinal dissociation theory.
Highlights
Para-hisian atrioventricular (AV) accessory pathways (APs) have been described previously, such as the ECG [1, 2] and electrophysiology characteristics [3] and different ablation strategies [4]
Excluded 21 patients from anteroseptum without X-ray or Carto data who could not find out the specific ablation site, 47 APs were eliminated from site 1, 5 APs were eliminated from site 2, and the left 34 APs were from site 3
The precordial transition was various: V2 transition was recorded in 20 patients (40%), V2– V3 transition in 13 patients (26%), and >V3 transition in 17 patients (34%)
Summary
Para-hisian atrioventricular (AV) accessory pathways (APs) have been described previously, such as the ECG [1, 2] and electrophysiology characteristics [3] and different ablation strategies [4]. Catheter ablation of the para-hisian AP remains highly challenging [5] because it was “bumped” while mapping and highly risky while ablation. There was no systematic description of the AV conduction injury risk at different ablation sites and few descriptions of different ablation approaches. We report a case series of para-hisian APs that successfully ablated by the inferior vena cava (IVC) approach, superior vena cava (SVC) approach, NCC approach, and comparison between different ablation strategies. This study describes the electrophysiologic characteristics of the para-hisian accessory pathway (AP), the outcome of different ablation approaches, and ablation safety at different sites
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