Atrial Tachyarrhythmia: What is the Ideal Site for Successful Ablation?

Abstract

An 82-year-old woman was admitted to the hospital with congestive heart failure and tachycardia. She had a past medical history of prior myocardial infarction, hypertension, and diabetes. A 12-lead ECG demonstrated atrial tachyarrhythmia with 2:1 block, and P wave morphology that was positive in the inferior leads and biphasic in the lead V1 ( Fig. 1). After medical therapy for rate control and appropriate investigations including a transesophageal echocardiogram, she was brought to the electrophysiology (EP) laboratory for EP study and ablation. A duodecapolar Halo catheter was placed along the tricuspid annulus to form a clock face when viewed in the left anterior oblique projection such that the distal Figure 1. A 12 lead ECG of the presenting arrhythmia.(Duo 1-2), mid (Duo 9-19), and the proximal poles (Duo 19-20) recorded lower lateral, upper lateral, and the upper septal atrial activation, respectively. A decapolar catheter and a quadripolar catheter were placed in the coronary sinus (CS 9-10, proximal and CS 1-2, distal) and in the His bundle locations (p = proximal, m = mid, and d = distal), respectively. During the study, the arrhythmia was demonstrated to be atrial arrhythmia at a cycle length of 320 ms and with a clockwise activation sequence around the tricuspid annulus. An 8-mm-tipped ablation catheter was then placed at the cavotricuspid isthmus, and pacing at 300 ms was performed at this site to entrain the tachycardia. Based on the response of this maneuver (Fig. 2), should ablation be performed at this site? Figure 2A shows the initial four beats of atrial arrhythmia that are consistent with atrial flutter, and subsequent beats are paced beats with pacing stimuli delivered from the distal ablation electrode placed at the right atrial cavotricuspid isthmus. Figure 2B shows termination of the arrhythmia with resumption of sinus rhythm. As seen in Figure 3, the atrial flutter has a clockwise activation sequence along the tricuspid annulus and the septum, and the coronary sinus activates in Discussion