Induction of partial alterations in atrioventricular conduction in dogs by percutaneous emission of high-frequency currents

Ten anesthetized dogs were studied in an attempt to provoke partial alterations in atrioventricular (AV) conduction by high-frequency current (HFC) transcatheter ablation. A discharge power (10 to 15 W) was used for less than 5 seconds after reaching complete AV block (CAVB). The catheter was placed within an area having an A/V ratio = 1 with His bundle deflection. If following discharge, no appreciable lengthening an AH, AV nodal block cycle length (Wenckebach point, WP), and/or functional nodal refractory period (FRPAVN) was observed, the procedure was repeated. Four dogs (group I) were killed immediately, and the other six (group II) after 2 to 4 weeks. The AH interval, WP, and FRPAVN were found to prolong significantly following HFC, without variations in HV interval. In group II, two dogs progressed to CAVB, whereas the other four maintained 1:1 AV conduction with AH, WP, and FRPAVN greater than before the power discharge. In conclusion, HFC is an efficient technique to induce partial alterations in AV conduction, since the discharge can be adjusted and the ablation can be localized to specific regions.