Activation Pattern in the Left Atrium during Sinus Rhythm in the Intact Human Heart with Contact Mapping System

Abstract

Background: Previous studies have reported that lines of conduction block are present in the left atrium (LA) during sinus rhythm (JCE 2004; 15:1111–1117, Circulation 2003; 107:733–739). However, these reports were based on the non-contact mapping system (Ensite 3000 multielectrode array). We evaluated LA activation pattern during sinus rhythm using high-density contact mapping system. Methods: In six patients with paroxysmal (n=2) and persistent (n=4) atrial fibrillation (AF), bipolar electrograms were recorded from LA using duo-decapolar lasso catheter (Spiral, St. Jude Medical, MN, USA) during sinus rhythm. Three-dimentional isochronal mapping was constructed by Navx system (St. Jude Medical) from 448±110 points recording sites. Results: Early LA endocardial breakthrough was located at anterosuperior LA wall, consistent with the position of Bachmann’s bundle and activation wavefront proceeded toward the inferolateral LA without obvious conduction block. Conclusion: LA activation pattern is homogeneous during sinus rhythm evaluated by contact bipolar mapping system.