Radiofrequency Ablation of Atrial Flutter

RF Ablation of Atrial Flutter. Activation mapping in common atrial flutter has shown circular (reentrant) activation of the right atrium around anatomic structures and areas of functional block. The direction of rotation is counterclockwise (in a frontal view), and in the low right atrium the myocardium between the inferior vena cava (IVC) and the tricuspid valve (TV) is critical to close the activation circle. The circuit can be interrupted by radiofrequency ablation of the myocardium between the TV and the IVC, and, in some cases, by ablation between the coronary sinus and TV. Flutter interruption does not mean complete isthmus ablation, as it may remain inducible, requiring further ablation. Despite attaining noninducibility, flutter may recur, and new procedures may be needed for complete ablation. Atrial fibrillation occurs in up to 30% of the cases during follow-up but is generally well controlled with antiarrhythmic drugs that were ineffective in treating flutter before ablation. Some noncommon atrial flutters show circular right atrial activation in a reversed (clockwise) direction, with the same critical areas in the low right atrium, and in these isthmus ablation is effective. Other noncommon flutters have different substrates in the right or left atrium, and mapping has to define specific critical isthmuses as ablation targets in each case. Left atrial flutter circuits remain inaccessible to ablation.     

Higher Rate of Recurrent Atrial Flutter and Atrial Fibrillation Following Atrial Flutter Ablation After Cardiac Surgery

Atrial Flutter After Cardiac Surgery . Introduction: Atrial flutter (AFL) is common after cardiac surgery. However, the types of post‐cardiac surgery AFL, its response to catheter‐based radiofrequency ablation, and its relationship to atrial fibrillation (AF) are unknown. Methods and Results: We retrospectively studied all patients who underwent mapping and ablation for AFL after cardiac surgery from January 1990 to July 2004. One hundred randomly selected patients without prior cardiac surgery (PCS) who underwent mapping and ablation of AFL served as the control population. A total of 236 patients formed the study population (mean age 62 + 13 years, 22% female) and 100 patients formed the control population (mean age 60 + 13 years, 25% female). The majority of patients without PCS had cavo‐tricuspid isthmus (CTI)‐dependent AFL when compared to patients with PCS (93% vs 72%, respectively, P < 0.0001). In contrast, scar‐related AFL was more common in patients with PCS as compared to patients without PCS (22% vs 3%, P < 0.0001). Predictors of scar related AFL in multivariable regression analysis included PCS and left‐sided AFL. Acute success rates and complications were similar between the groups. When compared to patients with AFL ablation without PCS, those that had AFL after PCS had higher rates of recurrence of both AFL (1% vs 12%, P < 0.0001; mean time to recurrence 1.85 years) and AF (16% vs 28%, P = 0.02; mean time to recurrence 2.67 years). Conclusion: Despite ablation of AFL, patients with PCS have a higher rate of AFL and AF when compared to patients without PCS who underwent ablation of atrial flutter during long‐term follow‐up. (J Cardiovasc Electrophysiol, Vol. pp. 760‐765, July 2010)     

Early versus Late Atrial Fibrillation after Atrial Flutter Ablation

Introduction: Radiofrequency catheter ablation of atrial flutter (AFl) has high initial success with a 10–15% recurrence. Atrial fibrillation (AFib) after radiofrequency catheter ablation of AFl can occur but may be transient (lasting no more than four weeks). Methods: Of one hundred seventeen consecutive patients studied, one hundred and four consecutive patients with sustained, symptomatic AFl, as the predominant rhythm disturbance (some of whom had transient pre-ablation AFib), referred for radiofrequency catheter ablation, had clinical follow-up. All had evidence for successful AFl ablation. Patients were followed prospectively. Results: Over a mean follow-up of 28 months, 28 patients developed AFib after ablation of AFl [12 early AFib (<2 months) and 16 late AFib (>2 months)]. Seven of 12 (58%) patients in the early onset group reverted to normal sinus rhythm; none required long-term antiarrhythmic therapy. Only one (8%) developed permanent AFib. No patient in the late onset group remained in sinus rhythm without an antiarrhythmic drug. Three (19%) developed permanent AFib despite therapy among those with late onset AFib. Two (17%) patients with early onset AFib reverted to normal sinus rhythm with treatment versus 5 (31%) in the late onset group. Finally, only 2 patients (17%) with paroxysmal/persistent episodes of Afib from the early onset group stayed in normal sinus rhythm despite therapy, while 8 patients ( ± %) with paroxysmal/persistent AFib episodes from the late onset group required therapy to maintain normal sinus rhythm. Conclusion: Early onset AFib after ablation of AFl is likely to be transient and self-limited. Late onset AFib after ablation of AFl can persist and require chronic therapy.     

典型心房扑动的经导管射频消融治疗

回顾分析 35例典型心房扑动 (简称房扑 )患者电生理检查和射频消融治疗的临床结果。心内激动标测显示沿三尖瓣环 (TA)逆钟向折返性房扑 2 7例 ,顺钟向折返 2例 ,同时存在二种折返 6例。 8例行TA峡部拖带起搏者均呈隐匿性拖带 ,起搏后间期与房扑周长差值为 1± 4(- 3～ 5 )ms。采用TA峡部双线性消融、后峡部或 /和间隔峡部消融的方法治疗所有患者均成功。 15例以房扑不能再诱发为手术终点 ,随访 10例 ,3例复发 ,复发率 30 % ;2 0例达到TA峡部双向阻滞 ,随访 19例 ,1例复发 ,复发率 5 % ,两组比较P <0 .0 5。随访的 2 9例中 ,7例发生心房颤动 (简称房颤 ) ,发生率 2 4%。与无房颤发作者相比 ,合并器质性心脏病、心房扩大和有房颤病史者的比例明显增加 (6 / 7比 9/ 2 2 ,6 / 7比 4/ 2 2和 7/ 7比 2 / 2 2 ,均P <0 .0 5 )。结果表明 ,心内激动标测结合拖带起搏技术可确定典型房扑的诊断 ,后峡部或间隔峡部消融是治疗房扑的有效方法 ,以TA峡部双向阻滞为手术终点较房扑不能被再诱发为终点可明显降低复发率。房扑消融术后发生房颤与合并器质性心脏病、心房扩大和术前存在房颤有关     

右房射频消融术治疗心房扑动

对５例阵发性心房扑动（简称房扑）患者行右房射频消融术。３例单型房扑消融成功，２例复合型房扑／房颤失败。３例成功者随访６个月无复发。房扑与右房内大折返运动有密切关系。射频消融结果与右房结构、房扑的类型及折返运动有关。右房射频消融的远期效果仍有待研究     

Electrophysiologic Study and Radiofrequency Catheter Ablation of Isthmus-Independent Atrial Flutter

INTRODUCTION: We report the electrophysiologic study and radiofrequency catheter ablation of isthmus-independent atrial flutter in 2 patients. The isthmus-independent atrial flutter in these 2 patients had similar ECG and electrophysiologic findings. Both were reproducibly induced by rapid atrial pacing. The atrial activation sequence and entrainment study proved that these atrial flutters were not isthmus-dependent. A high-right atrial site was identified as the critical site of the slow conduction zone of the tachycardia in both. This site showed double potentials and mid-diastolic potentials. Radiofrequency catheter ablation at this site successfully eliminated the isthmus-independent atrial flutter in both patients.     

Radiofrequency Ablation of Atrial Flutter Using Large-Tip Electrode Catheters

The use of large-tip ablation catheters in both animal and clinical studies has been documented in work conducted over the last 10 years. These studies have demonstrated the safety and efficacy of the use of 8- and 10-mm tip ablation catheters in the treatment of type I isthmus-dependent atrial flutter. Shorter procedure times are reported with the larger-tip ablation catheters compared to standard 4- or 5-mm tip ablation catheters, with comparable or greater efficacy, no significant increase in complications, and an improved quality of life. Larger-tip ablation electrodes do require the use of higher-power radiofrequency generators up to 100 W. The benefits of large-tip ablation catheters are thus well documented for the treatment of type I isthmus-dependent atrial flutter.     

Electroanatomic Magnetic Mapping during Ablation of Isthmus-dependent Atrial Flutter

Introduction: Although recent studies have demonstrated that the endpoint of isthmus conduction block is superior to that of termination and subsequent inability to induce atrial flutter (AFl), the optimal method for determining isthmus conduction block has not been determined. Electroanatomic magnetic mapping during coronary sinus (CS) pacing may provide a reliable endpoint for AFl ablation. Methods and Results: Catheter mapping and ablation was performed in 42 patients with isthmus-dependent AFl. The patients were divided into two groups, based on procedural endpoint: Group I (28 patients) – isthmus conduction block was determined based on multipolar catheter recordings and electroanatomic mapping, and Group II (14 patients) – isthmus conduction block was determined by electroanatomic mapping during CS pacing alone. In Group I, ablation procedures were acutely successful in 25 of 28 patients (89±%). A 100±% concordance between the data presented by multipolar catheter recordings and electroanatomic mapping was noted in determining the presence or absence of isthmus conduction block. In Group II, ablation procedures were acutely successful in 13 of 14 patients, 13 (93±%). After a mean of 16.3±3.7 months follow up, there was 1 atrial flutter recurrence in the 38 patients (2.6±%) with demonstrated isthmus block at the end of the procedure. Conclusions: Electroanatomic magnetic mapping during CS pacing is comparable to the multipolar catheter mapping technique for assessing isthmus conduction block as an endpoint for AFl ablation procedures.     

Predictors of Success in Radiofrequency Catheter Ablation of Atrial Flutter

Radiofrequency catheter ablation of typical atrial flutter at the isthmus between the tricuspid annulus and the inferior vena cava is established. However in selected patients, the creation of a continuous linear lesion at the targeted isthmus requires a lengthened procedure or is not feasible at all and atrial flutter recurrences are common.In a retrospective analysis, we found that an intraoperatively determined distance between the tricuspid annulus and the inferior vena cava of <.2.5 cm is an independent predictor of a lengthened or failed ablation procedure. Additional equipment, e.g., long introducer sheaths, adapted ablation catheter design, or irrigated tip ablation, as well as alternative ablation approaches, e.g., linear lesions between the tricuspid annulus and Eustachian ridge, have been invented in order to increase the acute success rate or decrease fluoroscopy and procedure time.In a prospective study on the effects of various conduction properties at the isthmus between tricuspid annulus and inferior vena cava following radiofrequency ablation of atrial flutter, we showed previously that others than a complete bidirectional conduction block predicts a high recurrence rate of atrial flutter. For determination of transisthmal conduction properties following ablation, established mapping approaches are documentation of double potentials at the ablation line and right atrial activation sequence following posteroseptal and low lateral right atrial pacing. Novel threedimensional mapping systems, i.e., Carto® and EnSite®, may further enhance the accuracy of conventional mapping techniques.     

Radiofrequency Catheter Ablation of Common Atrial Flutter in 200 Patients

RF Ablation of Common Atrial Flutter. Introduction: The purpose of this study was to evaluate the efficacy and safety of radiofrequency (RF) catheter ablation of common atrial flutter and to determine the optimum target sites in a large series of patients. Three different approaches were used to target the ablation site. The first used a combined anatomic and electrophysiologic approach, whereas the second and the third approaches relied primarily on anatomic guidelines to target the critical area in the atrial flutter reentrant circuit located in the low right atrium. Background: Recent studies report the efficacy of RF current application in the low right atrial region to interrupt and prevent recurrences of common atrial flutter using either anatomic or electrophysiologic targets. However, larger groups of patients are required to confirm the efficacy of this technique and to specify the target sites. Methods and Results: Two hundred consecutive patients with drug-resistant common atrial flutter were studied. In the first 50 patients, target sites were localized using both anatomic landmarks and electrophysiologic parameters. The anatomic landmarks were area 1 between the tricuspid valve and inferior vena cava orifice; area 2 between the tricuspid valve and coronary sinus ostium; and area 3 between the inferior vena cava and coronary sinus. The electrophysiologic criterion was to ablate when there was an atrial electrogram occurring during the plateau phase (preceding F wave). The first targeted area was that giving the more stable catheter position. In the following 30 patients, we assessed the effect of RF energy application in a single line to area 1 in the first 10 patients, area 2 in the next 10, and area 3 in the last 10 patients. In the last 120 patients, RF energy was applied only in area 1 using repeated applications. RF energy of 12 to 30 W, or that achieving a temperature of 70°C, was applied for 60 to 90 seconds at each site. The endpoint of the ablation procedure was interruption and noninducibility of common atrial flutter in the first 110 patients and additional isthmal block in 48 of the last 90 patients. Overall, atrial flutter was interrupted and rendered noninducihie after a single session in 191 (95%) patients and could not be interrupted in 9 (4.5%) patients. The mean number of RF applications was 12 ± 8. After a mean follow-up of 24 ± 9 months, recurrences occurred in 31 (15.5%) patients, 26 of whom underwent a successful second or third session without further recurrences of atrial flutter. Atrial fibrillation not documented before the ablation was detected in 11 patients. On a retrospective analysis of the final successful site in the first group of 50 patients, the location was in area 1 in 39% of patients: area 2 in 36% of patients, and area 3 in 25% of patients. Atrial electrograms recorded at these sites showed a single spike pattern in 46% of patients, and double spike pattern (28%) or fractioned electrogram in 26% patients. When lines of RF lesions were placed at several sites, they produced a success rate of 70%, 40%, and 10% at areas 1, 2, and 3 respectively. In the last series of 120 patients, the procedure was