Definition of conducting channels within myocardial scars

Definition of conducting channels within myocardial scars

Myocardial scars following infarction can have channels of conduction within them. These channels if connected to normal myocardium, can be the source of ventricular arrhythmias. Infarcted areas are defined as regions with an electrogram signal voltage of 1.5 millivolts or less. If the signals are only 0.5 millivolts or less, it is considered as a dense scar. Conducting channels within these scars should have higher signal amplitude and be bounded by two scar areas or one scar area and the mitral annulus. They should also be connected to normal myocardium at minimum of two sites.

Conduction channels are targets for ventricular tachycardia ablation [1]. These channels can be identified with contrast enhanced cardiac magnetic resonance imaging as border zone corridors. Three dimensional structure of these channels can be visualized by 3D reconstruction of CE-CMR images. Juan et al studied 21 patients with healed myocardial infarction and ventricular tachycardia. The patients underwent CE-CMR prior to CARTO-guided ablation of ventricular tachycardia. Border zone channels on CE-CMR identified 74% of the critical isthmus of clinical ventricular tachycardias and half of all the conducting channels found in electroanatomic maps.

Reference

1. Juan Fernández-Armenta, Antonio Berruezo, David Andreu, Oscar Camara, Etelvino Silva, Luis Serra, Valeria Barbarito, Luigi Carotenutto, Reinder Evertz, José T Ortiz-Pérez, Teresa María De Caralt, Rosario Jesús Perea, Marta Sitges, Lluis Mont, Alejandro Frangi, Josep Brugada. Three-dimensional Architecture of Scar and Conducting Channels Based on High Resolution ce-CMR: Insights for Ventricular Tachycardia Ablation. Circ Arrhythm Electrophysiol. 2013 Jun;6(3):528-37.