Twelve-lead ECG interpretation in a patient with presumed left atrial flutter following AF ablation

The 12-lead ECG provides valuable clues to the mechanism and origin of organized tachycardias occurring in patients after catheter ablation of atrial fibrillation. Many of these patients have cavotricuspid isthmus-dependent flutter, and therefore it is important to be aware of variations from the norm of typical flutter. Left atrial reentrant tachycardias are, however, the most common arrhythmias encountered after catheter ablation of atrial fibrillation. The underlying circuits are typically formed around anatomic obstacles such as the PV ostia or the mitral valve, and facilitated by slow conducting, low voltage isthmuses through gaps through and bordering ablation lesions. They can be recognized by the presence of 12-lead synchronous iso-electric intervals separating flutter waves. Continuous activity ECGs (without 12-lead iso-electric intervals) are typical of larger size reentrant circuits not dependent on markedly slow conducting isthmuses. Delayed bystander activity can also however obscure iso-electric intervals. The integration of informed ECG analysis with a detailed knowledge of the index ablation strategy can provide an optimum platform for successful catheter ablation of these often very symptomatic arrhythmias.     

房性心动过速导管消融进展

Atrial tachycardias (ATs) may be divided into focal and reentrant forms. In recent years, great prngress achieved in catheter ablation of ATs and the success rate of catheter ablatiou has improved dramatically in both focal ATs and reentrant ATs.Focal ATs tend to originate in characteristic locations associated with anatomic structures, such as the erista terminalis,the interatrial septum,the atrioventricular annulus,the coronary sinus,the atrial appendages,the ostial portion of the pulmonary veins. In recent years, successful catheter ablation of focal AT from the nou-coronary aortic sinus, from the mitral annulus-aorta junction, or from the atrial ap-pendages has been reported. Catheter mapping and ablation in the non-coronary aortic sinus should be attempted in patients with narrow P waves on surface ECG and the earliest atrial activation located at the His bundle region. For the cases who had a failed ablation or recur-rence after ablation in the non-coronary aortic sinus,mapping and ablation in the mitral annulus-aorta junction should be considered.Catheter ablation of typical atrial flutter (AFL) has a very high success rate,approximately 100% in some centers. For few difficult cases,several measures can be employed to increase the likelihood of success. Firstly and most importantly,the mechanism of typical AFL other than other ATs should be revaluated and reconfirmed. Other measures include using three-dimensional cardiac electroanatomical mapping system to map the cavotricuspid isthmus (CTI) carefully, using large-curve catheters and/or long guiding sheaths to ensure cath-eter contact across the entire CTI,and employing a large-tip or cooled-tip catheter instead of standard 4 mm-tip ablation catheter.Reentrant ATs usually occur in patients with dilated, severely scarred right or left atria, including previous right or left atriotomy, any form of structural heart disease, or following catheter or surgical ablation of atrial fibrillation. Some reentrant ATs patients present with a large scarred right or left atrium without any other form of structural heart disease, were classified it as "idiopathic arrhythmogen-ic atrial myopathy" by some experts. The earlier experience in mapping and ablation of reentrant ATs came mainly from mapping and ablation of ATs in patients with sugical treatment of congenital heart disease,so the ATs were called "incisional reentrant ATs". In the past decade, the success rate for catheter ablation of reentrant ATs after surgery has improved significantly by combination of electroana-tomical scarred substrate mapping and entrainment mapping. It is noted that the "incisional reentrant ATs" often have multiple reentrant circuits and multiple ATs or coexist with typical AFL, and more than one linear lesions from scar to scar, or scar to anatomical obstacle, or between reentrant isthmuses are needed in most cases.The reentrant ATs after catheter ablation of atrial fibrillation have increased dramatically in recent years, which belong to "iatro-genic reentrant ATs". Different atrial fibrillation ablation approaches have different incidence of reentrant ATs, a few in patients with segmental isolation of the pulmonary vein ostia, more often in patients with circumferential pulmonary vein ablation and most often in pa-tients with stepped ablation of chronic atrial fibrillation (combination of pulmonary vein isolation, linear ablation and ablation of the complex fractionated atrial electrograms). In some cases, mapping and ablation of these reentrant ATs are very difficult.     

Entrainment Techniques for Mapping Atrial and Ventricular Tachycardias

Entrainment Mapping. Many atrial tachycardias, atrial flutter, and postmyocardial infarction ventricular tachycardias are due to reentry through large "macroreentrant" circuits. These circuits can be difficult to define by catheter mapping of the activation sequence. Entrainment techniques allow the relation of a mapping site to the reentrant circuit to be assessed on a site-by-site basis during catheter mapping. Regions of abnormal conduction that are in the reentrant circuit can be distinguished from bystander sites outside the circuit. A mapping site classification to guide catheter ablation is reviewed     

Comparison between three-dimensional electro-anatomical mapping and conventional mapping in the ablation of atrial tachycardias

In atrial tachycardias, catheter ablation using conventional mapping system is associated with high immediate success and low recurrence. Three-dimensional electroanatomical mapping system combined to catheter ablation of atrial tachycardias has reached, in small uncontroled series, success rates of 100%. However, limited data are available about rates of recurrence or complication using this approach. In order to compare both mapping systems, we have conducted a study of 65 consecutive patients (36 women and 29 men) that underwent both electrophysiologic study and catheter ablation for suspected atrial tachycardias. Pre-existing heart disease was noted in 43%, hypertension in 32% and a history of atrial fibrillation of flutter in 52%. Catheter ablation guided by conventional mapping was undertaken in 44 patients and by three-dimensional electroanatomical mapping in 21. Successful ablation was performed in 68% of patients with conventional mapping and in 90% with three-dimensional electroanatomical mapping. No complication and recurrence were observed with the latter approach, while 5 patients had a recurrence and 2 had immediate complication with conventional mapping. Catheter ablation of atrial tachycardias combined with three-dimensional electroanatomical mapping appeared to be effective and safe, however, conventional mapping system still remains a reliable approach that must be considered as the first choice for atrial tachycardias ablation.     

Radiofrequency Current Catheter Ablation for Control of Supraventricular Arrhythmias

Radiofrequency Catheter Ablation in SVT. With the advent of radiofrequency energy, catheter ablation techniques have become an accepted form of treatment for a variety of Supraventricular arrhythmias. The ablation of the atrioventricular (AV) node was performed first and is now widely used in patients with refractory atrial fibrillation or flutter. Ablation has also replaced surgery in patients with preexcitation syndromes, and as the complication rate in experienced centers is low, it has become the first line of treatment in these institutions. The results of catheter ablation in AV nodal reentrant tachycardia are excellent as well, although there is still debate about whether "slow" pathway ablation is superior to "fast" pathway ablation. Radiofrequency current ablation has also contributed to a better understanding of the pathophysiology of AV nodal reentrant tachycardia, as it has provided evidence for atrial participation in the reentrant circuit. Experience with atrial tachycardias and tachycardias due to Mahaim fibers remains limited. The ideal source of energy for specific arrhythmias is still unknown and improvement in catheter technology is needed.     

Mapping and ablation of post-AF atrial tachycardias

Atrial tachycardias are commonly encountered in patients undergoing catheter ablation of persistent atrial fibrillation (AF). Unlike typical atrial flutter that can be readily recognized and ablated, these post-AF tachycardias can arise from a wide variety of locations and involve a multiplicity of mechanisms. Apart from diagnostic challenges, radiofrequency ablation to eliminate the tachycardias may require multiple approaches. In addition, specialized techniques such as epicardial and chemical ablation may be required for definitive treatment. This review describes the various mechanisms and approaches to mapping and ablation of these challenging tachycardias     

Radiofrequency ablation for the treatment of atrial fibrillation--brief report update

Considerable advances have been made in both the understanding of and the curative treatment for atrial arrhythmias over the last decade. Radiofrequency ablation of typical right atrial flutter and focal atrial tachycardia using standard catheters is commonplace and is associated with success rates of over 95%. Recently developed 3-D mapping systems have furthered our understanding of the complex circuits responsible for atypical atrial flutters within the right and left atrium and successful ablation of these previously incurable arrhythmias is now routinely achieved. With the seminal discovery of pulmonary vein triggers and fixed left atrial circuits that are critical for the genesis and perpetuation of atrial fibrillation, ablation techniques have been developed which are associated with cure rates of over 75% for both paroxysmal and persistent forms of atrial fibrillation.     

Treatment of supraventricular tachycardias with transcatheter delivery of radiofrequency current.

Medical therapy for the treatment of supraventricular tachycardias is frequently ineffective and associated with significant side effects, whereas curative surgical approaches have generally been limited by their considerable morbidity and cost. Greater understanding of the mechanisms underlying supraventricular tachycardias has improved our ability to precisely map endocardial areas critical to arrhythmogenesis. Advances in catheter ablation techniques and particularly the use of radiofrequency current to generate thermal energy for ablation have resulted in dramatic success rates for curative catheter ablation. This review examines the physics of radiofrequency current ablation and its application to the treatment of atrial fibrillation, atrial flutter, AV nodal reentrant tachycardia, and arrhythmias associated with the Wolff-Parkinson-White syndrome. The limitations, risks, and cost-effectiveness of this technique relative to medical and surgical approaches are also evaluated.     

Irrigated-tip catheter ablation of intraatrial reentrant tachycardia in patients late after surgery of congenital heart disease

OBJECTIVES: The aim of this study was to evaluate irrigated-tip catheter for ablation of intraatrial reentrant tachycardias late after surgical repair of congenital heart disease. BACKGROUND: In congenital heart disease patients, the right atrium can be markedly enlarged with areas of low blood flow. Radiofrequency (RF) lesion creation may be hampered by insufficient electrode cooling at sites with low blood flow. METHODS: Thirty-six consecutive patients with intraatrial reentrant tachycardia refractory to antiarrhythmic therapy from two centers were included in the study. Entrainment pacing and electroanatomic mapping (CARTO) were used to delineate reentrant circuits and critical isthmus sites. RF ablation was performed using an irrigated-tip catheter (Navistar Thermocool). RESULTS: Fifty-two intraatrial reentrant tachycardia circuits were identified, and 48 were targeted with RF ablation. RF ablation was performed using a mean of 13 +/- 11 irrigated RF applications per tachycardia isthmus with a mean power of 36 +/- 8 W. In a historical control group of congenital heart disease patients managed with conventional catheter ablation, the number of lesions per isthmus was higher (23 +/- 11) and mean power was lower (27 +/- 14 W). Acute success was achieved in 45 intraatrial reentrant tachycardias (94% of targeted tachycardias and 87% of all tachycardias). After a mean follow-up of 17 +/- 7 months, 33 (92%) of 36 patients were free of recurrence. Five patients (14%) developed paroxysmal atrial fibrillation. CONCLUSIONS: The combination of modern techniques including electroanatomic mapping and catheter irrigation allows safe and highly effective ablation of intraatrial reentrant tachycardia in patients with surgically repaired congenital heart disease.     

Persistent Atrial Flutter in Patients Treated for Atrial Fibrillation with Amiodarone and Propafenone:

INTRODUCTION: Antiarrhythmic drugs have been reported to promote the conversion of atrial fibrillation to atrial flutter in patients with paroxysmal atrial fibrillation. However, information about the electrophysiologic mechanism and response to radiofrequency ablation of these drug-induced atrial flutters is limited. Furthermore, the determinants of the development of persistent atrial flutter in patients treated for atrial fibrillation with antiarrhythmic drugs are still unknown. METHODS AND RESULTS: Among the 136 patients treated for atrial fibrillation with amiodarone (n = 96) or propafenone (n = 40), 15 (11%, mean age 65.5 +/- 12.3 years) were identified to have subsequent development of persistent atrial flutter based on surface ECG characteristics during antiarrhythmic drug treatment. The mean interval between the beginning of drug treatment and the onset of atrial flutter was 5.0 +/- 5.5 months. Intracardiac mapping and entrainment studies revealed that 11 patients had counterclockwise typical atrial flutter, and 4 had clockwise typical atrial flutter. All 15 patients underwent successful ablation with creation of complete bidirectional isthmus conduction block. After a mean follow-up of 12.3 +/- 4.2 months, 14 (93%) of 15 patients who underwent successful ablation and continued taking antiarrhythmic drugs have remained in sinus rhythm. Univariate analysis of clinical variables demonstrated that only atrial enlargement was significantly related to the occurrence of persistent atrial flutter. CONCLUSION: In patients with atrial fibrillation, persistent typical atrial flutter might occur during antiarrhythmic drug treatment, and atrial enlargement was a risk factor for the development of such an arrhythmia. Radiofrequency ablation and continuation of pharmacologic therapy offered a safe and effective means of achieving and maintaining sinus rhythm.     

The interrelationship between atrial fibrillation and atrial flutter

For a long time, it has been known that atrial fibrillation and atrial flutter have a close clinical interrelationship. Recent electrophysiological studies, especially mapping studies, have significantly advanced our understanding of this interrelationship. Regarding the relationship of atrial fibrillation with atrial flutter: Atrial fibrillation of variable duration precedes the onset of atrial flutter in almost all instances. During the atrial fibrillation, the functional components needed to complete the atrial flutter reentrant circuit, principally a line of block between the venae cavae, are formed. If this line of block does not form, classical atrial flutter does not develop. If this line of block shortens or disappears, classical atrial flutter disappears. In fact, it is fair to say that the major determinant of whether atrial fibrillation persists or classical atrial flutter develops is whether a line of block forms between the venae cavae. Regarding the relationship of atrial flutter with atrial fibrillation: Studies in experimental models and now in patients have demonstrated that a driver (a rapidly firing focus or a reentrant circuit of very short cycle length) can cause atrial fibrillation by producing fibrillatory conduction to the rest of the atria. When the driver is a stable reentrant circuit of very short cycle length, it is, in effect, a very fast form of atrial flutter. There probably is a spectrum of reentrant circuits of short cycle length, i.e., "atrial flutter," that depend, in part, on where the reentrant circuit is located. When the cycle length of the reentrant circuit is so short that it will only activate small portions of the atria in a 1:1 manner, the rest of the atria will be activated rapidly but irregularly, i.e., via fibrillatory conduction, resulting in atrial fibrillation. In short, there are probably several mechanisms of atrial fibrillation, one of which is due to a very rapid atrial flutter circuit causing fibrillatory conduction. In sum, atrial fibrillation and atrial flutter have an important interrelationship.     

三尖瓣峡部线性消融在心房颤动治疗中的效果

三尖瓣峡部是典型房扑折返环中的缓慢传导区域,对这一解剖结构进行线性消融以达到双向传导阻滞是典型房扑的一线治疗方法。房颤与典型房扑内在关系密切,一方面房颤与典型房扑往往共存于同一患者,另一方面房颤患者在电生理检查中常可见到典型房扑的诱发。因此在房颤射频消融术中常常补充三尖瓣峡部线性消融,以期病人获得更好的远期预后。但最近的研究对这一术式的疗效提出了质疑。本文以两种心律失常的内在联系为切入点,就三尖瓣峡部消融在房颤射频消融术中的疗效进行综述。     

Narrow, slow-conducting isthmus dependent left atrial reentry developing after ablation for atrial fibrillation: ECG characterization and elimination by focal RF ablation

INTRODUCTION: The complete circuit of reentrant left atrial tachycardias (LATs) occurring after ablation for atrial fibrillation (AF) has not been well described. Identifying discrete isthmuses critical to these LATs may simplify their elimination by catheter ablation. METHODS AND RESULTS: Fifteen patients (all male, 56 +/- 8 years) with 15 reentrant LATs following AF ablation underwent activation and entrainment mapping. Eleven patients (11 LATs) had a single localized site with low amplitude (0.16 +/- 0.05 mV), fractionated long duration (131 +/- 23 msec) electrograms coinciding with an isoelectric interval of 106 +/- 24 msec between flutter waves on all 12 ECG leads. Three-dimensional mapping and entrainment revealed this site to be a narrow markedly slowly conducting isthmus adjacent to ablated left (n = 8) or right (n = 3) pulmonary vein (PV) ostia, and critical to nine small diameter (15 +/- 3 mm) and two large diameter (49 +/- 2 mm) circuits. One radiofrequency (RF) application on this isthmus eliminated LAT in all 11 patients. Four patients (four LATs) with large circuits around the mitral annulus and/or PV ostia lacked isoelectric ECG intervals and slow-conducting isthmuses and required multiple RF applications across anatomically wide, rapidly conducting isthmuses. CONCLUSION: Focally ablatable narrow isthmuses of slow conduction are critical for the majority of reentrant LAT occurring after ablation for AF. The role and presence of these isthmuses can be anticipated by observing significant isoelectric intervals between flutter waves on all 12-surface ECG leads. Their distinctive electrophysiological characteristics allow their identification and elimination by simple RF ablation.     

Intravenous flecainide acetate for supraventricular tachycardias

Flecainide acetate, 2 mg/kg body weight, given intravenously at 10 mg/min was administered to 128 (74 male and 54 female) patients whose ages ranged from 11 to 86 years (mean 44). All patients had supraventricular tachycardias (SVT) that developed spontaneously or were induced during electrophysiologic study. There were 26 patients with atrial flutter, 34 with atrial fibrillation, 7 with ectopic atrial tachycardia, 41 with atrioventricular (AV) reentrant tachycardia and 40 with AV nodal reentrant tachycardia. Twenty patients had more than 1 variety of SVT. Flecainide was administered during SVT to 9 patients with atrial flutter, 11 with atrial fibrillation, 7 with atrial tachycardia, 38 with AV reentrant tachycardia and 34 with AV nodal reentrant tachycardia. In the remaining 31 patients with inducible SVT at electrophysiologic study, flecainide was administered during sinus rhythm. Reinitiation of SVT was attempted in these patients after completion of flecainide administration. Flecainide successfully terminated atrial flutter in 2 patients (22%), atrial fibrillation in 9 (82%), atrial tachycardia in 5 (71%), AV reentrant tachycardia in 32 (84%) and AV nodal reentrant tachycardia in 30 (88%). Reinitiation of SVT was possible in 10 of 26 patients with atrial flutter (38%), 5 of 34 with atrial fibrillation (15%), 3 of 7 with atrial tachycardia (43%), 14 of 41 with AV reentrant tachycardia (34%) and 11 of 40 with AV nodal reentrant tachycardia (27%). In patients with AV reentrant tachycardia and AV nodal reentrant tachycardia, reinitiation occurred when retrograde anomalous pathway refractoriness was not significantly prolonged by intravenous flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mechanism and mapping of atrial arrhythmia in the modified Fontan circulation.

The Fontan circulation has been a major success in the management of patients with functionally single-ventricle cardiac lesions, although arrhythmia remains one of the major complications in the long term and historically has been difficult to treat. The electrophysiologic substrate within the right atrium is complex, with areas of scarring and/or anatomic structures acting as central barriers to conduction in reentrant circuits, which may be mechanistically and anatomically different from typical atrial flutter. Developments in three-dimensional mapping have improved our understanding of different arrhythmia mechanisms, which is fundamental to developing a better strategy for arrhythmia ablation using percutaneous techniques.     

Theory and practical approaches in catheter ablation of atrial flutter

Atrial flutter can be understood as atrial tachycardia due to a single intraatrial macroreentrant circuit that is determined by fixed or functional boundaries. In various types of atrial flutter, radiofrequency ablation became an established curative therapy. During the course of an ablation procedure, initially, the reentrant circuit has to be determined, e.g. by activation and entrainment mapping. Subsequently, the boundaries have to be identified. By connecting two appropriate boundaries with a linear lesion, the intraatrial reentrant circuit can be inhibited. Finally, it should be proven that the linear lesion results in a complete line of conduction block. Doing so, the acute and long-term results of atrial flutter ablation are comparable to those of other supraventricular tachycardias.     

非外科手术瘢痕相关性右心房房性心动过速：电解剖标测与消融

目的探讨非外科手术后的瘢痕相关性右心房房性心动过速（房速）的心内电生理和Carto三维电解剖标测特点及消融方法。方法2008年9月至2009年4月我中心诊治的14例无器质性心脏病基础的右心房房速患者,在Carto三维标测系统指导下行心内电生理检查、标测和射频消融。结果14例患者中有4例心内电生理检查和Carto电解剖标测符合右心房大折返性房速且在Carto电解剖电压标测中显示出“自发性瘢痕”,瘢痕分布于右心房游离壁。这4例患者年龄32～48岁,病史（23．40±15．43）个月,曾使用2种以上抗心律失常药物治疗无效。2例患者右心房轻至中度扩大,左心室射血分数均在正常范围,无明显器质性心脏病依据和心外科手术史及导管消融史。3例患者在瘢痕区内标测到缓慢传导的峡部,2例可诱发出三尖瓣峡部依赖性逆时针心房扑动（房扑）。在三尖瓣峡部、上腔静脉与瘢痕之间、下腔静脉与瘢痕之间、瘢痕与三尖瓣环之问,瘢痕与瘢痕之问或瘢痕区内缓慢传导的“峡部”进行线性消融。4例患者均即刻消融成功。随访（4．2±1．8）个月,3例未再发作心动过速,1例偶尔发作非持续性房速,服药控制良好。结论“自发性瘢痕”相关性右心房大折返性房速临床少见,三维电解剖电压标测可提高消融成功率。     

Pharmakotherapie der supraventrikulären Rhythmusstörungen

Supraventricular tachycardias consist of AV-nodal-reentrant-tachycardias, atrioventricular tachycardias with accessory pathways (WPW-syndrome), atrial tachycardias, atrial fibrillation and atrial flutter. Only specific ECG interpretation with an exact arrhythmia classification offers the way to perform modern differential therapy including drug treatment and also interventional therapy modalities. In atrial fibrillation, drug treatment is still first-line therapy: physicians have to make a decision either to follow the rate or rhythm control concept. In case of rhythm control, drug therapy is tailored to the individual patient taking into account the patients symptomatology, left ventricular ejection fraction and nature and degree of an underlying cardiac disease. Drug refractory symptomatic atrial fibrillation patients should be considered for interventional treatment like pulmonary vein ablation. Recurrent typical right atrial flutter, AV-nodal-reentrant-tachycardia and all forms of atrioventricular tachycardias however are indications for catheter ablation; long-term drug treatment will only be performed in rare cases.     

Curative treatment of atrial fibrillation 2000: percutaneous catheter ablation techniques and intraoperative ablation with minimally invasive techniques

Summary Experimental and clinical mapping studies have indicated that the initiation of atrial fibrillation has to be differentiated from the perpetuation. Curative treatment of atrial fibrillation is one of the main challenges of today's electrophysiology, and the trigger as well as the substrate have recently been targeted. The arrhythmogenic foci which have been identified as being critical for the initiation of paroxysmal atrial fibrillation have been found in the vast majority of patients in the area of the proximal pulmonary veins. In a subset of patients with paroxysmal atrial fibrillation, these firing foci may be the only electrophysiologic abnormality. In other patients, different atrial arrhythmia types may be driven by pulmonary vein foci. Haissaguerre et al. have introduced mapping strategies to identify active foci within the pulmonary veins. The success rate of percutaneous pulmonary vein focus ablation strongly depends on the number of active foci. In contrast to elimination of the initiating triggers in patients with paroxysmal atrial fibrillation, modification of the maintaining substrate of atrial fibrillation is the alternative target for ablation in patients with chronic atrial fibrillation or in patients with prolonged episodes of paroxysmal atrial fibrillation. Different linear lesion line concepts within the right and/or left atrium have been followed within the last few years with moderate success rates. The lesion geometries that have been applied percutaneously so far seem to be empirical, and no successful lesion geometry concept for percutaneous application has been validated. A surgical curative treatment concept for patients with chronic atrial fibrillation is the maze procedure introduced by Cox et.al. which, however, is an extensive and time consuming surgical technique. Within the last few years, several attempts have been made to develop alternative surgical treatment strategies that should be safe, effective, and easy to apply. One of the promising new concepts is the intraoperative radiofrequency ablation of atrial fibrillation by elemination of anatomically determined so-called anchor reentrant circuits involving the pulmonary vein orifices and the mitral annulus. In this review, data on percutaneous ablation of pulmonary vein foci, percutaneous placement of linear right and/or left atrial lesion lines and, finally, intraoperative radiofrequency (RF) ablation using minimally invasive techniques are summarized.