13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-122

Electrophysiological and pathological correlations in transcatheter ablation of the atrioventricular junction

Domenico Corrado, Renato Ometto, Andrea Corrado, Cristina Basso, Mario Vincenzi, Gaetano Thiene.
Departments of Cardiology and Pathology, University of Padua Medical School, Division of Cardiology, Civil Hospital, Vicenza, Italy

Abstract

The aim of the present study was to correlate electrophysiological mapping of junctional area and topography of trans-catheter ablation lesions in the AV conduction system. Three patients (2 males, one female, aged 65, 67 and 72 years) underwent 4 successful procedures of transcatheter ablation of AV junction (by right atrial approach in 2, and left retroartic in one), followed by pacemaker implantation, because of atrial tachyarrhythmias refractory to medical therapy; all died late from procedure-unrelated causes. Electrophysiologic "coordinates" of transcatheter ablation target sites were correlated to the level and extension of the lesions along the AV conduction axis, as assessed by serial histologic section investigation of the specialized AV conducting tissue. The first patient showed two level histologic interruption of conduction axis: 1) bifurcating AV bundle and bundle branches, and 2) AV node and penetrating AV bundle, with interposed spared common His bundle, which respectively corresponded to a "distal" transcatheter ablation target site (A = 0.3 mV, V = 1,5 mV, A/V = 0.2, H = 0.5 mV, and HV = 40 ms) resulting in 2:1 AV block, and to a "proximal" site (A = 0.8 mV, V = 0.5 mV, A/V = 1.6, H = 0.15 mV) leading to complete AV block. The successful transcatheter ablation target site in the second patient (A = 1 mV, V = 0.75 mV, A/V = 1.3, H = 0.35 mV, HV = 60 ms) provoked a suprahissian complete AV block due to a selective disruption of atrionodal approaches, AV node and proximal His bundle. In the third patient, radiofrequency current delivered on the left side of the AV junction (A = 0.2 mV, V= 1.5 mV, A/V = 0.13, H = 1.2 mV, HV = 55 ms) induced a "distal" complete AV block with severe involvement of bifurcating bundle and left bundle branch, and marked damage of the crista of the interventricular septum. In conclusion, transcatheter ablation of AV junction created "discrete" interruptive lesions of the AV conduction system at different levels that matched electrophysiological target sites.

Key Words

Molecular biology - structural anatomy and pathology 
atrioventricular conduction system, electrophysiological mapping, histologic investigation of transcatheter ablation lesions, OA