Kamala Tamirisa

Computed Tomographic Analysis of the Anatomy of the Left Atrium and the Esophagus. Implications for Left Atrial Catheter Ablation

Background—During left atrial (LA) catheter ablation, an atrioesophageal fistula can develop as a result of thermal injury of the esophagus during ablation along the posterior LA. No in vivo studies have examined the relationship of the esophagus to the LA. The purpose of this study was to describe the topographic anatomy of the esophagus and the posterior LA by use of CT. Methods and Results—A helical CT scan of the chest with 3D reconstruction was performed in 50 patients (mean age, 54±11 years) with atrial fibrillation before an ablation procedure. Consecutive axial and sagittal sections of the CT scan were examined to determine the relationship, size, and thickness of the tissue layers between the LA and the esophagus. The mean length and width of the esophagus in contact with the posterior LA were 58±14 and 13±6 mm, respectively. The esophagus had a variable course along the posterior LA. The esophagus was close (10±6 mm from the ostia) and parallel to the left-sided pulmonary veins (PVs) in 56% of patients and had an oblique course from the left superior PV to the right inferior PV in 36% of patients. The mean thicknesses of the posterior LA and anterior esophageal walls were 2.2±0.9 and 3.6±1.7 mm, respectively. In 98% of patients, there was a fat layer between the esophagus and the posterior LA. However, this layer was often discontinuous. Conclusions—The esophagus and posterior LA wall are in close contact over a large area that may often lie within the atrial fibrillation ablation zone, and there is marked variation in the anatomic relationship of the esophagus and the posterior LA. Both the esophageal and atrial walls are quite thin. However, a layer of adipose tissue may serve to insulate the esophagus from thermal injury, explaining why atrioesophageal fistulas are rare.

Noninducibility of Atrial Fibrillation as an End Point of Left Atrial Circumferential Ablation for Paroxysmal Atrial Fibrillation A Randomized Study

Background—An anatomic approach of left atrial radiofrequency circumferential ablation (LACA) to encircle the pulmonary veins is often effective in eliminating paroxysmal atrial fibrillation (AF). However, no electrophysiological end points other than voltage abatement and/or conduction slowing or block across ablation lines have been used. It has been unclear whether noninducibility of AF is a clinically useful end point. Methods and Results—In 100 patients with paroxysmal AF (mean age, 55±10 years), LACA to encircle the left- and right-sided pulmonary veins was performed during AF, with additional ablation lines in the posterior left atrium and mitral isthmus, with an 8-mm-tip catheter. After completion of this lesion set, sinus rhythm was present, and AF lasting >60 seconds was not inducible in 40 patients (40%; group 1). The 60 patients in whom AF was still present or who still had inducible AF were randomly assigned to no further ablation (group 2; 30 patients) or to additional ablation lines along the left atrial septum, roof, and/or anterior wall where there were fractionated electrograms (group 3; 30 patients). In group 3, AF was rendered noninducible in 27 of 30 patients (90%). At a 6-month follow-up, 67% of patients in group 2 were free of AF without drug therapy compared with 86% of patients in group 3. (P=0.05, log-rank test). Left atrial flutter occurred in 17% and 27% of patients in each group, respectively (P=0.3). Conclusions—After LACA in patients with paroxysmal AF, AF usually can be rendered noninducible by additional ablation at sites of fractionated electrograms. Noninducibility of AF attained by additional electrogram-guided left atrial ablation may be associated with a better midterm clinical outcome than when AF is still inducible after LACA alone.

Prevalence of Asymptomatic Recurrences of Atrial Fibrillation After Successful Radiofrequency Catheter Ablation

Introduction: The long‐term efficacy of radiofrequency catheter ablation of atrial fibrillation (AF) has been based on patient‐reported symptoms suggestive of AF. However, asymptomatic recurrences of AF may remain undetected. The aim of this study was to determine the prevalence of asymptomatic recurrences of AF after an apparently successful catheter ablation procedure for AF.

Ventricular tachycardia associated with transmyocardial migration of an epicardial pacing wire

A 66-year-old man who had undergone a three-vessel coronary artery bypass grafting (CABG) procedure 3 years previously presented with ventricular tachycardia (VT) and cardiac arrest. Echocardiography demonstrated a wire coursing through the right ventricle into the pulmonary artery. The wire was removed with a snare and confirmed to be an epicardial temporary pacing wire placed during the CABG operation. We suspect that the epicardial pacing wire eroded through the right atrium and migrated into the right ventricle, contributing to the VT. Complications due to temporary epicardial pacing wires placed during CABG are discussed.

Detection of Inadvertent Catheter Movement into a Pulmonary Vein During Radiofrequency Catheter Ablation by Real-Time Impedance Monitoring

Introduction: During radiofrequency ablation to encircle or isolate the pulmonary veins (PVs), applications of radiofrequency energy within a PV may result in stenosis. The aim of this study was to determine whether monitoring of real‐time impedance facilitates detection of inadvertent catheter movement into a PV.

Effects of eliminating complex electrograms by radiofrequency catheter ablation on spectral characteristics of atrial fibrillation

SESSION 32: CATHETER ABLATION V: New Techniques and Approaches Friday, May 6, 2005 10:45 a.m.–12:15 p.m.

1052-221 Accurate identification of pulmonary vein ostia with real-time impedance measurements

Ca rd ia c Ar rh yt hm ia s PAF episodes were divided into group A (“sudden onset”) and group B (“PAC activity before onset”). The mean PAF episode durations of both groups were then compared. Sudden PAF onset was defined as missing PAC activity in the last 10 beats before PAF initiation. Results: Group A comprised 145 (54.9 %) PAF episodes. A significantly longer mean PAF episode duration was found in group A as compared to group B (6.06 ± 42.36 vs. 1.85 ± 6.72 hours, p < 0.01). Conclusion: 1. In our study group more than half of the PAF episodes were initiated without any PAC activity in the last 10 beats before onset. 2. Arrhythmia episodes with sudden PAF onset were associated with a prolonged PAF episode duration as compared to PAF episodes with prevalent pre-onset PAC activity. 3. The combination of missing PAC activity and long PAF episode duration may reflect a higher atrial “substrate factor” facilitating PAF induction and maintenance. The efficacy of preventive pacing algorithms might therefore be limited in patients with predominantly sudden onset of PAF.