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.     

Successful Catheter Ablation of Atrial Fibrillation

Catheter Ablation of AF. Introduction: Catheter ablation of a case of incessant atrial fibrillation was attempted using linear right atrial lesions created by sequential applications of radiofrequency energy.
Methods and Results: A 46-year-old patient had incessant episodes of atrial fibrillation. He had previously undergone successful radiofrequency catheter ablation of a common atrial flutter. Antiarrhythmic drugs including amiodarone and various drug combinations were ineffective. A 7-French specially designed 14-polar catheter with interelectrode distance of 3 mm was used to create linear lesions in the right atrium. Each electrode was 4 mm in length and able to transmit radiofrequency energy. Three linear lesions, two longitudinal and one transverse that connected the two longitudinal lesions, were created using 30 radiofrequency applications of 10 to 40 W. The final application interrupted an atrial fibrillation that had been persistent for 55 minutes. No sustained atrial fibrillation was inducible despite repeated pacing maneuvers. There was no complication. In short-term follow-up of 3 months, the patient has been free of arrhythmias without antiarrhythmic medication.
Conclusion: Successful catheter ablation of human atrial fibrillation is feasible using linear atrial lesions created by radiofrequency energy delivery. Further studies are mandatory to ascertain the efficacy and safety of this procedure, as well as to assess different catheter techniques.     

Update on Catheter Ablation for Atrial Fibrillation

Atrial fibrillation (AF) is a common arrhythmia that can be treated with antiarrhythmic drugs and electrical cardioversion. New therapies such as the automatic implantable atrial defibrillator, multisite atrial pacing, and catheter ablation are being studied extensively. Ablation for AF is in its infancy. There are different mechanisms of AF, and, therefore, there can be no single approach to therapy. One question is whether radiofrequency electricity (RF) is the best source of energy for catheter ablation for AF. RF results have been disappointing for the treatment of ventricular tachycardia, presumably because of the small size of the lesions that are produced. Other sources of energy such as microwave energy, which produces larger and deeper lesions, may be necessary in the future. RF might be modified to produce a larger lesion, perhaps by cooling the ablating electrode so that neighboring myocardium does not become charred and a higher dose of electricity can be delivered with greater penetration into deeper layers of myocardium. These efforts at producing larger lesions must be tempered by close attention to maintaining a high level of safety. AF usually is not immediately life threatening, thus a risky therapy will not be acceptable. The procedure should not expose the patient to excessive procedural time or an excessive radiation dose. From laboratory and clinical evidence, it is clear that a catheter ablation cure for some forms of AF will become available in the future, as long as our understanding of the mechanisms of AF continues to increase and ablative techniques continue to evolve.     

经导管射频消融治疗局灶性心房颤动

报道19例局灶性心房颤动（简称房颤）射频消融治疗的结果,其中药物治疗无效且发作频繁（＞1次／日）的阵发性房颤17例、慢性房颤2例。17例患者尚同时合并有频发房性早搏（简称房早）（动态心电图显示＞700个／日）。同步记录高位有房、冠状静脉窦及左、右上肺静脉电图。根据房早或房颤开始发作时的心房激动顺序确定异位兴奋灶部位,以局部双极电图较体表心电图P'波起点最提前处为消融靶点。成功标准为消融后6Omin内房早／房颤消失及随访期内可以无须药物而维持窦性心律。结果：92．6％（25／27）的异位兴奋灶位于肺静脉,其中尤以双上肺静脉居多（21／25）。随访2．4±3．7个月后有13例患者（68．4％）达上述成功标准,其房早数目由术前的3720±2741个／日降至216±139个／日,除1例发生心房穿孔外无其他严重并发症。结论：射频消融治疗局灶性房颤效果较好,可以作为药物治疗无效的阵发性房颤患者的治疗选择。     

Catheter Ablation for Long-Standing Persistent Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and represents a major burden to health care systems. Atrial fibrillation is associated with a 4- to 5-fold increased risk of thromboembolic stroke. The pulmonary veins have been identified as major sources of atrial triggers for AF. This is particularly true in patients with paroxysmal AF but not always the case for those with long-standing persistent AF (LSPAF), in which other locations for ectopic beats have been well recognized. Structures with foci triggering AF include the coronary sinus, the left atrial appendage (LAA), the superior vena cava, the crista terminalis, and the ligament of Marshall. More than 30 studies reporting results on radiofrequency ablation of LSPAF have been published to date. Most of these are observational studies with very different methodologies using different strategies. As a result, there has been remarkable variation in short- and long-term success, which suggests that the optimal ablation technique for LSPAF is still to be elucidated. In this review we discuss the different approaches to LSPAF catheter ablation, starting with pulmonary vein isolation (PVI) through ablation lines in different left atrial locations, the role of complex fractionated atrial electrograms, focal impulses and rotor modulation, autonomic modulation (ganglionated plexi), alcohol ablation, and the future of epicardial mapping and ablation for this arrhythmia. A stepwise ablation approach requires several key ablation techniques, such as meticulous PVI, linear ablation at the roof and mitral isthmus, electrogram-targeted ablation with particular attention to triggers in the coronary sinus and LAA, and discretionary right atrial ablation (superior vena cava, intercaval, or cavotricuspid isthmus lines).     

心房颤动导管消融的少见并发症

随着心房颤动导管消融适应证的不断拓宽,导管消融手术日益广泛的开展,一些相对少见的并发症也逐渐见诸报道。现对这些相对少见、甚至罕见的并发症作一综述。     

New Technologies for Catheter Ablation of Atrial Fibrillation

The past decade of ablation for atrial fibrillation (AF) has seen the adaptation of catheters designed for “focal” tachycardias or single pathways to perform wide encirclement of the pulmonary veins (PV). During the next decade, technologies designed specifically for PV isolation will emerge. Each system has its unique attributes. The cryoballoon system offers rapid PV isolation and the promise of enhanced safety, whereas the success rate is likely to be similar to catheter-based approaches. Although preclinical studies do suggest a very low likelihood of left atria-esophageal fistula using this technology, concerns of phrenic nerve damage and a small incidence of PV stenosis need to be addressed. It is likely that use of the larger 28-mm balloon will mitigate these concerns. The cryoballoon is also the first balloon technology to be approved by the US Food and Drug Administration for clinical use, and this may gain the technology an early foothold in the AF ablation market. The laser balloon ablation system is a more time-consuming and technically demanding procedure, and the risk of thrombus formation if ablation is performed in stagnant blood is a concern. However, early studies suggest a high rate of persistent PV isolation, which hopefully will translate into high single-procedure efficacy. The Ablation Frontiers system is the only system currently being developed for more persistent forms of AF. This system offers a rapid approach to PV isolation and left atrial defragmentation. The early results do not demonstrate a success rate better than that described for catheter ablation; however, the results are difficult to compare to standard catheter ablation in this recalcitrant patient group without a prospective randomized study.     

Approaches to Catheter Ablation of Nonparoxysmal Atrial Fibrillation

Purpose of review

We describe the technical aspects and outcomes of several different ablation strategies for nonparoxysmal (persistent and long-standing persistent) atrial fibrillation (AF) and discuss our ablation strategy for these patients.

Recent findings

Catheter ablation is an effective treatment strategy for patients with AF. Outcomes of ablation in patients with nonparoxysmal forms of AF tend to be worse than in patients with paroxysmal AF. Several recent studies have examined the long-term ablation success rates of different ablation approaches in patients with nonparoxysmal AF. While observational studies have suggested benefit of several different ablation strategies for persistent AF, large randomized controlled studies have shown similar success rates with pulmonary vein isolation (PVI) alone as compared versus PVI plus additional ablation.

Summary

The optimal ablation strategy to achieve long-term freedom from recurrent arrhythmias in patients with nonparoxysmal AF remains controversial. Achieving durable PVI should be the cornerstone of AF ablation. Additional large-scale randomized controlled studies are necessary to determine whether additional ablation might result in improved long-term ablation success rates in these patients.

     

影像学检查在心房颤动射频导管消融术的应用进展

射频导管消融术已成为临床心房颤动的一线治疗方案,充分的术前和术后评估对提高手术的成功率及减少并发症有重要价值.近年来,随着各类新的影像学方法的出现及原有影像学技术的不断发展,心房颤动消融的围手术期评估体系呈现多元化态势.熟悉及准确地运用影像学检查,在指导患者选择、术前准备及预后判断中起着不可替代的作用.