Curative Ablation for Atrial Fibrillation:

In contrast to other supraventricular tachycardias, curative treatment of atrial fibrillation, although increasingly available and rapidly evolving, is neither as effective nor the first choice. Until recently, the unavailability of nonsurgical curative treatment may have fueled a debate on the relative importance of restoring sinus rhythm versus controlling the ventricular rate during atrial fibrillation. Recent randomized trials (PIAF, AFFIRM, and RACE) using very limited atrial fibrillation burden assessment show that pharmacologic ventricular rate control is much safer and possibly more effective than pharmacologic restoration of sinus rhythm. A clinical trial comparing a truly curative treatment of atrial fibrillation—such as catheter ablation targeting pulmonary vein isolation—with pharmacologic treatment is required. It should focus on reliable efficacy parameters, use vigilant assessment of safety, and, most importantly, be structured to provide all-important prognostic information on long-term outcome. Atrial fibrillation burden is a theoretically robust efficacy parameter, but accurate quantification over a sufficiently long period of monitoring will require technologically innovative noninvasive rhythm monitoring devices. (J Cardiovasc Electrophysiol, Vol. 14, pp. S48-S51, September 2003, Suppl.)     

Atrial Tachycardias Following Atrial Fibrillation Ablation

One of the most important proarrhythmic complications after left atrial (LA) ablation is regular atrial tachycardia (AT) or flutter. Those tachycardias that occur after atrial fibrillation (AF) ablation can cause even more severe symptoms than those from the original arrhythmia prior to the index ablation procedure since they are often incessant and associated with rapid ventricular response. Depending on the method and extent of LA ablation and on the electrophysiological properties of underlying LA substrate, the reported incidence of late ATs is variable. To establish the exact mechanism of these tachycardias can be difficult and controversial but correlates with the ablation technique and in the vast majority of cases the mechanism is reentry related to gaps in prior ablation lines. When tachycardias occur, conservative therapy usually is not effective, radiofrequency ablation procedure is mostly successful, but can be challenging, and requires a complex approach.     

Catheter Ablation of Atrial Tachycardia Following Atrial Fibrillation Ablation

Atrial tachycardias represent the second front of atrial fibrillation (AF) ablation. They are frequently encountered during the index ablation for patients with persistent AF and are common following ablation of persistent AF, occurring in half of all patients who have had AF successfully terminated. An atrial tachycardia is rightly seen as a failure of AF ablation, as these tachycardias are poorly tolerated by patients. This article describes a simple, practical approach to diagnosis and ablation of these atrial tachycardias.     

Radiofrequency Ablation for Atrial Fibrillation

Opinion statement Catheter ablation has emerged as an excellent treatment option for atrial fibrillation. In appropriate patients, particularly those with paroxysmal atrial fibrillation in the absence of structural heart disease, catheter-based pulmonary vein isolation can eliminate or dramatically reduce the arrhythmia burden. However, with currently available tools, the procedure is complex and labor intensive. Simpler ablation procedures may emerge as newer ablation systems are developed.     

消融法治疗心房颤动的现状及前景

从上世纪80年代Cox率先开展外科迷宫手术治疗心房颤动开始,心房颤动的射频消融从Swartz线性消融模拟迷宫手术,发展到Haissaguerre的方式为代表的局灶性心房颤动点消融、肺静脉口节段性消融以及Pappone的方式为代表的左心房壁环形肺静脉消融。从消融房室交界区阻断房室传导,植入永久性起搏器和房室结改良术,发展到心房壁的线性消融,肺静脉的点状环状消融和环肺静脉左房消融。由于心房颤动的发病机制复杂,左右心房及肺静脉均可成为异位起搏点或折返部位,加之心房和肺静脉的管壁薄,致使标测消融部位,确定消融范围以及消融损伤组织的深浅均不易掌握。现就消融法治疗心房颤动的操作方法以及目前的现状与前景综述如下。     

Ablation of Focally Induced Atrial Fibrillation:

INTRODUCTION: Focally induced atrial fibrillation (AF) often is due to ectopic activity in the pulmonary veins (PV). Although initial approaches were aimed at ablating only the ectopic foci, more extensive ablation approaches have evolved that isolate all PVs empirically and/or create circumferential ablation lines in the left atrium (LA). These techniques last longer and may be associated with more risks. We retrospectively evaluated the outcome and risks of ablation for focally induced AF in a single-center patient population. METHODS AND RESULTS: We report on 47 patients (32 men and 15 women; age 47 +/- 10 years) in whom 52 ablations were performed. In 19 patients (22 sessions), ablation was directed at the site(s) of overt ectopic activity ("selective" group), whereas in 28 patients (30 sessions) without sufficient ectopy to determine the culprit PV a mean of 3.5 PVs were empirically targeted for bidirectional disconnection from the LA ("extensive" group). On a preprocedural Holter recording, the "selective" group had significantly more isolated atrial ectopy (3,276 +/- 2,933 vs 620 +/- 937 beats/24 hours) and runs of atrial tachycardia (330 +/- 202 vs 53 +/- 87 runs/24 hours) than the "extensive" group (P < 0.01 for both). Only 11% had persistent AF before ablation. Acute procedural success was 81% (elimination of all ectopy) and 83%, respectively (bidirectional and fully circumferential isolation of all targeted PVs). Procedure and fluoroscopy times were significantly shorter in the "selective" group. There were no major complications, but 7 minor complications and 2 acute PV stenoses > 50% in the 30 "extensive" procedures were observed. Mean follow-up was 8.4 +/- 8.5 months (median 6.9). Kaplan-Meier analysis, excluding recurrences during only the first month ("delayed cure"), showed AF recurrence in 45% after 6 months and in 55% after 1 year. Outcome was not dependent on ablation approach ("selective" or "extensive") nor was time to first AF (22 +/- 64 days and 30 +/- 69 days). AF recurrence tended to be higher in patients with larger LA (P = 0.08), underlying heart disease or hypertension (P = 0.08), and those "extensive" patients in whom not all 4 PVs were targeted (P = 0.07). CONCLUSION: Trigger-directed ablation for focally induced AF is associated with a relatively high recurrence rate during follow-up. Apart from recurrence of the ectopic trigger, this may point to underlying structural changes in the atrial substrate not addressed by the ablation. Prospective evaluation of the risk-to-benefit profile of any technique (selective, extensive, including linear lines) is required.     

Surgical Ablation of Atrial Fibrillation

The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past.Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary “Afib teams” to obtain optimal long-term sinus rhythm control. This article provides an overview of current surgical strategies for patients with atrial fibrillation and addresses the two main goals in its management.     

Atrial Anatomy and Imaging in Atrial Fibrillation Ablation

Catheter ablation of atrial fibrillation (AF) can be a technically challenging procedure, requiring detailed knowledge of the anatomy of the atria and thoracic veins to achieve successful cure of AF with a low complication rate. In this article, we review the anatomy relevant to AF ablation: the intraatrial septum, the pulmonary veins and left atrial antral region, the left atrial vestibule, the right atrium and related veins, and the esophagus. We focus on normal variations of anatomy and the role of the available imaging modalities in facilitating safe and effective ablation of this common and complex arrhythmia.