Atrial Tachycardia Confined Within the Left Atrial Appendage

AT Confined Within the LAA. Left atrial tachycardias are often seen following catheter ablation of persistent atrial fibrillation (AF). We report here an unusual case where AF was converted to sinus rhythm following catheter ablation, but ongoing atrial tachycardia confined within the left atrial appendage (LAA) was observed. Although the LAA tachycardia was dissociated from the atrium in sinus rhythm, bidirectional conduction between the left atrium and the LAA was, however, demonstrated after tachycardia termination. (J Cardiovasc Electrophysiol, Vol. 21, pp. 933‐935, August 2010)     

Organized Left Atrial Tachyarrhythmia During Stepwise Linear Ablation for Atrial Fibrillation

Introduction: This study attempted to delineate the mechanism of organized left atrial tachyarrhythmia (AT) during stepwise linear ablation for atrial fibrillation (AF) using noncontact mapping.
Methods and Results: Eighty patients in whom organized ATs developed or induced during stepwise linear ablation for AF were enrolled. Left atrial (LA) activation during ATs was mapped using noncontact mapping. Radiofrequency (RF) energy was delivered to the earliest activation site or narrowest part of the reentrant circuit of ATs. A total of 146 ATs were mapped. Four ATs were characterized as a focal mechanism (cycle length (CL): 225 ± 49 ms). A macroreentrant mechanism was confirmed in the remaining 142 ATs. LA activation time accounted for 100% of CL (205 ± 37 ms). All 142 ATs used the conduction gaps in the basic figure-7 lesion line. There were three types of circuits classified based on the gap location. Type I (n = 68) used gaps at the ridge between left atrial appendage (LAA) and left superior pulmonary vein (LSPV). Type II (n = 50) used gaps on the LA roof. Type III (n = 24) passed through gaps in the mitral isthmus. Ablation at these gaps eliminated 130 ATs. During the follow-up period of 16.2 ± 6.7 months, 82.5% of the 80 patients were in sinus rhythm.
Conclusion: The majority of left ATs developed during stepwise linear ablation for AF are macroreentrant through conduction gaps in the figure-7 lesion line, especially at the LAA–LSPV ridge. Noncontact activation mapping can identify these gaps accurately and quickly to target effective catheter ablation.     

Left Atrial Appendage Wall‐Motion Velocity Associates with Recurrence of Nonparoxysmal Atrial Fibrillation after Catheter Ablation

Catheter ablation (CA) for nonparoxysmal atrial fibrillation (AF) is controversial due to its high recurrence rate. The aim of this study was to assess retrospectively the diagnostic value of preprocedural left atrial appendage (LAA) wall‐motion velocity in predicting recurrence of AF within 1 year after CA. We hypothesized that tissue Doppler‐derived measurement of LAA wall‐motion velocity associate with recurrence of AF within 1 year after CA. We retrospectively reviewed 47 consecutive patients with nonparoxysmal AF (defined as AF lasting for 1 week or longer) who underwent both transthoracic and transesophageal echocardiography before their first treatment by CA in a single center. Forty‐one patients aged 58 ± 10 years were included, and variables predicting the recurrence of AF within 1 year after CA were evaluated. Seventeen patients (41%) developed recurrence of AF within 1 year after CA. Univariate analyses showed that preprocedural LAA upward wall‐motion velocity at the apex assessed by transesophageal echocardiography was significantly lower in patients with recurrence of AF than those without recurrence (OR = 1.45, 95% CI: 1.13–2.01, P = 0.009). Multivariate logistic analyses including other potential predictors (duration of AF, left ventricular ejection fraction, E‐wave deceleration time, and left atrial wall‐motion velocity) identified LAA upward wall‐motion velocity at the apex as an independent predictor of outcome. These data suggest in patients with nonparoxysmal AF, preprocedural LAA upward wall‐motion velocity at the apex, as determined by tissue Doppler imaging during transesophageal echocardiography, may be a useful indicator for predicting recurrence of AF within 1 year after CA.     

Prevalence and Clinical Characteristics Associated With Left Atrial Appendage Thrombus in Fully Anticoagulated Patients Undergoing Catheter‐Directed Atrial Fibrillation Ablation

LAA Thrombus Among Anticoagulated AF Patients. Introduction: Catheter‐directed atrial fibrillation (AF) ablation is contraindicated among patients with left atrial appendage (LAA) thrombus. The prevalence of LAA thrombus among fully anticoagulated patients undergoing AF ablation is unknown. Methods and Results: We retrospectively evaluated the prevalence of LAA thrombus among 192 consecutive patients undergoing AF ablation between July 2006 and January 2009. Seven of 192 patients (3.6%) had evidence of thrombus on transesophageal echocardiogram (TEE) despite being fully anticoagulated on warfarin (international normalized ratio [INR] 2–3) for 4 consecutive weeks prior to echocardiogram. Univariate analysis demonstrated that structural heart disease, large left atrial dimension, and number of AF ablations were associated with thrombus. Three patients with thrombus had paroxysmal AF with normal LV function. Conclusion: Despite full anticoagulation, 3.6% of patients undergoing AF ablation had LAA thrombus. We recommend that all patients, regardless of LV function or left atrial size, should undergo preprocedural TEE to exclude the presence of LAA thrombus. (J Cardiovasc Electrophysiol, Vol. 21, pp. 849‐852, August 2010)     

左心耳在预测心房颤动发生脑卒中的作用

成为公共健康沉重负担的心房颤动和相关的血栓栓塞性脑卒中事件仍在以惊人的速度增长。心房颤动导致脑卒中的风险增加了5倍．．因此,预防脑卒中的心房颤动管理仍然是最关键的一方面。现在公认的重点预防措施就是规范抗凝,包括已使用很广泛的华法林和现在出现的新抗凝药如利伐沙班等。而且抗凝药的使用已有据可查。由于左心耳在心房鲡动血栓的发生中起关键作用,所以有目的性地去除或结扎左心耳来预防发生脑卒中就成了一种可替代的治疗方法,尤其是适用于那些不适合口服抗凝药的患者,,现就左心耳预测心房颤动发生脑卒中进行介绍。     

CT定量评价左心耳解剖结构与心房颤动射频消融术后复发的相关性研究

目的:采用256层螺旋CT定量评价左心耳解剖结构与心房颤动(房颤)射频消融术后复发的关系。方法:研究纳入83例首次进行射频消融术的房颤患者,平均年龄(60.36±10.11)岁,男性49例(59.04%)。所有患者术前均行256层螺旋CT检查,测量左心房体积、左心耳体积、左心耳开口周长、短径、长径、深径并收集患者临床资料。83例房颤患者行射频消融术后中位随访时间19(4~24)个月,27例(32.53%)患者复发。根据有无复发分为复发组(n=27例)和未复发组(n=56例)。结果:对83例患者的临床资料进行分析,复发组持续性房颤患者及心力衰竭(心衰)患者较未复发组比例更高,CHA2DS2-VASc评分更高(P均<0.05);对左心耳解剖结构分析,左心房体积、左心耳体积、左心耳开口周长、短径、长径、深径,复发组均大于未复发组(P均<0.05);多因素Cox比例风险回归分析显示较大的左心耳体积是房颤复发的独立预测因子(HR=1.160,95%CI:1.095~1.229,P<0.001);左心耳体积>9.25 ml对射频消融术后复发具有一定预测价值,敏感度85.2%、特异度67.9%、AUC 0.82,房颤复发率较高(P<0.00l)。结论:房颤会造成心脏结构重构,左心耳各解剖径线明显增大可能是房颤射频消融术后复发的原因,并且发现左心耳体积增大是房颤射频消融术后复发的独立预测因子。     

Left Atrial Appendage Dimensions Predict the Risk of Stroke/TIA in Patients With Atrial Fibrillation

Risk of Stroke/TIA in Patients With Atrial Fibrillation. Introduction: Most strokes in patients with atrial fibrillation (AF) arise from thrombus formation in left atrial appendage (LAA). Our aim was to identify LAA features associated with a higher stroke risk in patients with AF using magnetic resonance imaging and angiography (MRI/MRA). Methods: The study included 144 patients with nonvalvular AF who were not receiving warfarin and who underwent MRI/MRA prior to catheter ablation for AF. LAA volume, LAA depth, short and long axes of LAA neck, and numbers of lobes were measured. Results: Of the 144 patients, 18 had a prior stroke or transient ischemic attack (TIA) (13 and 5, respectively). Compared with patients who had no history of stroke/TIA, these patients were older, had higher prevalence of hypertension and hyperlipidemia and had higher LAA volume (22.9 ± 9.6 cm³ vs. 14.5 ± 7.1 cm³, P < 0.001). Their LAA depth (3.76 ± 0.9 cm vs. 3.21 ± 0.8 cm, P = 0.006) and the long and short axes of the LAA neck (3.12 ± 0.7 cm vs. 2.08 ± 0.7 cm, P < 0.001; 2.06 ± 0.5 cm vs. 1.37 ± 0.4 cm, P < 0.001, respectively) were larger. Using stepwise logistic regression model, the only statistically significant multivariable predictors of events were age (OR = 1.21 per year, 95% CI 1.06‐1.38, P = 0.004), aspirin use (OR = 0.039, 95% CI 0.005‐0.28, P = 0.001), and LAA neck dimensions (short axis × long axis) (OR = 3.59 per cm², 95% CI 1.93‐6.69, P < 0.001). Conclusion: LAA dimensions predict strokes/TIAs in patients with AF. LAA assessment by MRI/MRA can potentially be used as an adjunctive tool for risk stratification for embolic events in AF patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 10‐15, January 2011)     

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.     

Percutaneous Left Atrial Appendage Ligation for Stroke Prevention in Atrial Fibrillation

Prevention of thromboembolic complications in atrial fibrillation remains a tremendous clinical challenge. Knowledge that the left atrial appendage (LAA) is the most common anatomical origin of cardioembolic strokes1 has been the main motivation to develop clinical and procedural strategies to exclude the LAA from the circulation, either surgically or percutaneously. This review discusses the rationale behind these strategies, their relative merits, and future prospects for LAA exclusion strategies.     

CartoXP Guided Catheter Ablation for Paroxysmal Atrial Fibrillation Without Three-dimensional Modeling of Left Atrium and Pulmonary Veins

Objectives This study was to investigate the differences between modeling and non-modeling left atrium （LA） in CartoXP system guided catheter ablation for paroxysmal atrial fibrillation （PAF）. Methods From Jan to Dec in 2008 total 31 cases with PAF were enrolled. All were treated by the same electrophysiologist with CartoXP guidance. Catheter ablation was accomplished without left atrium and pulmonary veins modeling in 17 patients （non-modeling group） and with left atrium modeling in 14 patients （modeling group）. The detailed ablation method was based on circumferential pulmonary veins isolation （CPVI）. And linear ablation of tricuspid valvular isthmus was performed individually. The ablation endpoint was a complete isolation of pulmonary vein potential from left atrium and no further induced continuous fast atrial arrhythmia including atrial fibrillation （AF）, atrial flutter （AFL） and atrial tachycardia （AT）. Each step for the procedures and the follow-up outcomes were compared correspondingly. Results The total procedure time was 107.23 ± 28.92 min in modeling group vs 93.47 ±26.09 min in non-modeling group （ P 〉 0.05 ）. The X-ray exposure time was significantly longer in modeling group （21.09 ±6. 49 rain） than in non-modeling group （14. 16 ± 5.35 min）. The CPVI times of right pulmonary veins and left pulmonary veins were 28. 14 ± 9. 26 min was 27.29 ± 18.53 min in modeling group respectively, vs 18.00 ±4. 51 min and 23.94 ± 7. 10 min in non-modeling group respectively, （P 〈 0. 05 ）. There is no significant difference between modeling group （85.7%） and non-modeling group （82.4%） over follow-up period of 2 to 13 months. Confusions CartoXP system guided catheter ablation of PAF without modeling of left atrium and pulmonary veins took less time in X-ray exposure and ablation steps, comparing with left atrium modeling procedure.