High-resolution parahisian mapping and ablation using microelectrode embedded ablation catheters

Abstract

BACKGROUND Accurate mapping of the compact atrioventricular (AV) node is critical during ablation of a range of arrhythmias.& nbsp;OBJECTIVE The purpose of this multicenter prospective study was to test the hypothesis that microelectrode (ME)-embedded catheters more accurately define the near -field compact AV node compared to conventional catheters.& nbsp;METHODS For the mapping phase, detailed AV junction maps were created in 47 patients using an ME-embedded catheter. His electrograms (EGMs) detected by conventional electrodes (Hisc) and by ME (His(mu)) were annotated. For the ablation phase, AV nodal ablation (Qmode 50 W) was performed in 10 patients after pacemaker implantation, with initial His(c)-only ablation in group 1 (n = 6) and initial His(mu), ablation in group 2 (n = 4). For the clinical phase, a prospective registry of parahisian tachycardia using QDOT was obtained.& nbsp;RESULTS In the mapping phase, 7.0 +/- 5.4 His(c) and 8.0 +/- 5.6 His(mu), points were acquired per map (n = 47). His, cloud was smaller and & nbsp;& nbsp;more proximally located than Hisccloud: (99.4674.7 mm(2 & nbsp;)vs 197.66110.6 mm(2); P=.0008). HismEGMs had larger amplitudesthan His(c)EGMs (0.4060.38 mV vs 0.1660.1 mV;P=.0002). Inthe ablation phase, for group 1: Hisc-only ablation never resulted in AV & nbsp; block, whereas Hismablation resulted in AV block after limitedablation in all patients (after 13.369.2 s); and for group 2: Hismablation always resulted in AV block after 1 application (after14.3610.3 s). In the clinical phase, a Hism-avoidance strategycould avoid AV block in a prospective registry of 11 patients.& nbsp;CONCLUSION ME more accurately defines the region of thecompact node, and ablation in this region is associated with ahigh risk for AV block. ME-based mapping has the potential tosignificantly enhance ablation safety and efficacy