MRI of the left atrium: predicting clinical outcomes in patients with atrial fibrillation

Atrial fibrillation is a significant public health burden, with clinically, epidemiologically and economically significant repercussions. In the last decade, catheter ablation has provided an improvement in morbidity and quality of life, significantly reducing long-term healthcare costs and avoiding recurrences compared with drug therapy. Despite recent progress in techniques, current catheter ablation success rates fall short of expectations. Late gadolinium-enhancement cardiovascular MRI is a well-established tool to image the myocardium and, most specifically, the left atrium. Unique imaging protocols allow for left atrial structural remodeling and fibrosis assessment, which has been demonstrated to correlate with clinical outcomes after catheter ablation, assessment of the individual's risks of thromboembolic events, and effective imaging of patients with left atrial appendage thrombus. Late gadolinium-enhancement MRI aids in the individualized treatment of atrial fibrillation, stratifying recurrence risk and guiding specific ablation strategies. Real-time MRI offers significant safety and effectiveness profiles that would optimize the invasive treatment of atrial fibrillation.     

Cardiac MRI in the treatment of arrhythmias

Catheter-based ablation techniques are extensively used for the treatment of atrial and ventricular arrhythmias. Preprocedural cardiac MRI is valuable for the management of these patients due to its ability to provide high-resolution anatomic mapping and tissue characterization in the absence of ionizing radiation. Delayed enhancement imaging can be used to localize the arrhythmia substrate within the chamber of interest prior to the procedure. There is growing evidence that delayed enhancement cardiac MRI may be useful in patients with atrial fibrillation in terms of treatment decisions and assessment of ablation efficacy.     

Anatomy-Guided Linear Atrial Lesions for Radiofrequency Catheter Ablation of Atrial Fibrillation

The surgical atrial maze procedure has provided proof that atrial fibrillation can be cured by performing atrial incisions based on anatomical and electrophysiological principles. Preliminary reports of attempts at radio frequency catheter ablation of atrial fibrillation utilizing an anatomy-based "linear incision" method have shown the feasibility of the method. However, postprocedural atrial fibrillation recurrence has been common and in addition new, uniform tachycardias have developed in some patients. Both of these outcomes may be in part due to incomplete or inconsistent lesion deployment. This article details the use of the CARTO system for deploying anatomy guided linear atrial lesions for the purpose of curing atrial fibrillation. The procedure is comprised of three phases, which are discussed in detail: (1) baseline map: (2) lesion deployment and; (3) lesion assessment. Using a single standard ablation electrode, lesions can be deployed safely, and complete lesions can be confirmed. Paradigms for right and left atrial incisions are proposed.     

CARTO系统指导下行心房颤动导管消融术病人的护理

[目的]探讨CARTO系统指导下行心房颤动经导管射频消融治疗术病人的护理。[方法]对52例心房颤动病人行射频消融治疗,经穿刺房间隔,常规置管,在CARTO指导下构建左房电解剖图,所有病人均完成环肺静脉消融,部分病人加行左房顶部线,二尖瓣峡部线和(或)三尖瓣峡部线消融,同时加强护理。[结果]52例心房颤动病人成功接受经导管射频消融治疗术;术后并发心包渗出1例,迷走神经反射5例,局部出血与血肿2例;18例病人术后因心房颤动发作出现明显的紧张、焦虑、抑郁、失望等心理问题。[结论]加强CARTO系统指导下行心房颤动经导管射频消融治疗术的护理是手术成功的保证。     

Predictive value of early atrial tachyarrhythmias recurrence after circumferential anatomical pulmonary vein ablation

OBJECTIVE: Radiofrequency (RF) ablation at the ostia of the pulmonary veins (PVs) to cure atrial fibrillation (AF) is often followed by early AF recurrence. The aims of this study were to determine the rate of early atrial tachyarrhythmia as recurrence after circumferential anatomical PV ablation; to evaluate whether the early recurrence of atrial tachyarrhythmias correlates with the long-term outcome of ablation; and to identify the predictors of early atrial tachyarrhythmias relapse. METHODS: We studied 143 consecutive patients who underwent circumferential anatomical PV ablation. We defined early atrial tachyarrhythmias relapse as the recurrence of atrial tachyarrhythmias during the first 3 months after RF ablation. RESULTS: After a mean follow-up of 18.7 +/- 7.2 months, 102/143 patients (71%) were deemed responders to ablation. Atrial tachyarrhythmias relapsed during the first 3 months of follow-up in 65/143 (46%) patients. Patients without early atrial tachyarrhythmias relapse had a higher probability of long-term clinical success than patients with early atrial tachyarrhythmias relapse (95% vs 43%, P < 0.0001). However, patients who relapsed within the first month had 45.5% probability of long-term clinical success. On multivariate analysis, the presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV were significantly and independently correlated with early atrial tachyarrhythmias relapse. CONCLUSION: A delayed cure may be expected in almost 50% of patients in whom atrial tachyarrhythmias relapses within the first month after circumferential anatomical PV ablation. The presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV predict early atrial tachyarrhythmias recurrence.     

Complex fractionated atrial electrogram or linear ablation in patients with persistent atrial fibrillation--a prospective randomized study

Background: Catheter ablation of complex fractionated atrial electrograms (CFAE) for persistent atrial fibrillation (AF) is a promising treatment strategy. We tested the hypothesis that CFAE ablation is superior to linear ablation in patients with persistent or long‐standing persistent AF. Methods: In this study, 116 patients with persistent AF were randomly assigned to undergo circumferential PVI plus additional lines (linear ablation group; 59 patients) or CFAE ablation plus ostial pulmonary vein isolation (PVI) (spot ablation group; 57 patients). Primary endpoint was freedom from atrial tachyarrhythmia after a single ablation procedure (clinical and repeat 7‐day Holter), 12 months after ablation without antiarrhythmic medication. Results: The primary endpoint was reached in 22 of 59 (37%) patients of the linear ablation group and in 22 of 57 (39%) patients of the spot ablation group (P = 0.9). Freedom from atrial tachyarrhythmias, including reablations, was achieved in 54% of patients (linear ablation group) versus 56% of patients (spot ablation group; P = 0.8). The incidence of recurrent persistent AF was higher after linear ablation than after spot ablation (21/37 vs 11/35 patients; P = 0.03); atrial tachycardia (AT) was seen more often after spot ablation (10/35 vs 4/37 patients; P = 0.03). Conclusion: In patients with persistent AF, CFAE ablation plus PVI reaches the same results as circumferential PVI plus lines, in terms of freedom from symptomatic atrial tachyarrhythmias within the first year after a single ablation procedure. Arrhythmia recurrences in patients after spot ablation were caused more often by AT, whereas recurrent persistent AF was more prevalent after the linear ablation approach. (PACE 2011; 34:939–948)     

Ablation strategies for atrial fibrillation

Atrial fibrillation remains the most common arrhythmia in the USA and is associated with an increased risk for stroke, congestive heart failure and overall mortality. There has been a tremendous advance in the field of catheter ablation of atrial fibrillation that has resulted in better outcomes for patients. The approach for ablation of atrial fibrillation can be different depending on patients’ presentation of paroxysmal or persistent atrial fibrillation. Pulmonary vein isolation remains the cornerstone of any ablation strategy for atrial fibrillation; however, further ablation, end points of the procedure, clinical end points for successful ablation and appropriate follow-up remain controversial. We aim to discuss these different approaches and the major controversies in catheter ablation of atrial fibrillation.     

低能量心内膜除颤在持续性房颤射频消融术中的风险因素与护理对策Risk Factors and Nursing measures for Low-energy Endocardial Defibrillation in patients with PAF 刘慧凤,董永蓉,施维捷

【】 目的 探讨低能量心内膜除颤技术在持续性房颤射频消融术中的风险因素及护理对策。方法 2010年3月至2012年12月,在新华医院心脏介入诊治部行房颤射频消融术患者648例,回顾性分析在术中行心内膜除颤的102例患者的临床资料。结果102例术中行心内膜除颤的患者中：98例均一次复律即成功转为窦性心律,放电能量为2~30J(焦耳);4例患者经多次放电复律成功,放电能量为5~20J;1例患者出现急性心包填塞,2例患者出现迷走神经亢进。讨论 低能量心内膜除颤技术,为持续性房颤行射频消融术中终止房颤最为理想的方法,术前、术中、术后认真评估风险因素并采取有效的措施,能确保手术的成功和患者的安全。     

收缩期左房应变及应变率与阵发性房颤射频消融治疗效果的研究

【目的】用基于斑点追踪技术的应变及应变率来评价房颤患者左房机械功能,并探讨其与射频消融治疗效果的关系。【方法】对拟行射频消融治疗的42例阵发性房颤患者术前测量收缩期左房应变及应变率,追踪观察患者射频消融术治疗效果。分析收缩期左房应变及应变率与射频消融治疗效果的关系。【结果】42患者均顺利完成射频消融治疗,在3个月追踪期内13例患者出现房颤复发（33．3％）,余29例维持窦性心率。复发组年龄、性别比、左房内径、左房客积、左室射血分数与无复发组比较均无显著性差异（P〉0.05）;复发组左房收缩期总体应变及应变率均低于无复发组,其差异有统计学意义（P〈0.05）。【结论】收缩期左房应变及应变率与房颤患者射频消融术成功率有明显关系。     

Contemporary Challenges of Catheter Ablation for Atrial Fibrillation

Purpose

Catheter ablation of atrial fibrillation (AF) is now one of the most frequently performed ablation procedures, but there are currently 2 important challenges: achieving permanent/durable rather than transient pulmonary vein isolation (PVI) and improving the results of ablation for the wider patient population with persistent AF.

Methods

Recent technical advances in the technique of ablation and the results of clinical trials aimed at achieving more permanent and durable PVI are reviewed. We also summarize recent advances in identifying atrial fibrosis and in understanding the pathophysiology of AF relevant to selecting patients for ablation of persistent AF.

Findings

The use of contact force–sensing technology, adenosine testing after ablation, and pace capture–guided ablation all have the potential for achieving more durable ablation. Selection of patients suitable for ablation of persistent AF may be improved by assessing the extent of atrial fibrosis with delayed enhancement imaging with cardiac magnetic resonance or by assessing the pattern of atrial electrical activity with the use of complex atrial electrograms. Advances in treatment are likely to result from the recognition of localized rotors and focal sources as primary sustaining mechanisms for all types of human AF and in the use of noninvasive mapping for their identification. Linear ablation to supplement PVI may improve the results of AF ablation.

Implications

Rapidly unfolding advances in the techniques of AF ablation and the understanding of mechanisms of AF hold promise for improving the durability of PVI and for extending the technique to carefully selected patients with persistent AF.     

Novel Form of Atrial Tachycardia Originating at the Atrioventricular Annulus

We report two patients with reentrant atrial tachycardia that originated at the AV annulus. Atrial tachycardia originated in the posterior portion of mitral annulus in one patient (case 1) and the posterolateral portion of tricuspid annulus in one patient (case 2). Tachycardia was successfully eliminated by RF catheter ablation in both patients, with the catheter placed underneath the mitral valve in case 1 and on the tricuspid annulus in case 2. Spiky potentials were recorded in the diastolic phase of the atrium during tachycardia at the sites of successful ablation. Spiky potentials were also recorded after atrial electrogram during sinus rhythm, and showed decremental properties during atrial pacing. An accelerated atrial rhythm was observed during RF application, and tachycardia could not be induced after ablation in either patient. Tachycardia in these patients seemed to be due to reentrant tachycardia originating in the accessory AV node (Mahaim fiber) without ventricular connection.     

经导管消融治疗心房颤动伴心动过缓

目的探讨经导管消融治疗心房颤动合并心动过缓的方法和患者的安全性。方法对24例心房颤动伴心动过缓患者行经导管消融治疗心房颤动,消融策略包括环肺静脉电隔离、左心房线性消融及复杂心房碎裂电位(CFAE)消融。观察消融前及术后1个月动态心电图,并记录24h平均心率、最高窦性心率,以超声心动图评价术后6个月左心房直径变化。结果心房颤动消融术后患者平均心率、最高窦性心率均高于术前(P<0.001);术后6个月左心房舒张末期直径减小(P<0.001)。经(19.8±9.9)个月门诊随访,15例(15/24,62.50%)无心房颤动复发,无缓慢型心律失常相关症状;6例患者仍有房性期前收缩或房性心动过速发作,1例患者因心动过缓植入起搏器治疗,余2例心房颤动发作较术前频度减少。结论心房颤动转复时的窦性停搏和心动过缓以及部分快-慢综合征患者的窦房结功能不良可能是源于快速心房率对窦房结功能的抑制。对这部分患者行经导管消融治疗可安全、有效地改善窦房结功能不良,逆转重构。     

Mechanism of spontaneous transition from typical atrial flutter to atrial fibrillation: role of ectopic atrial fibrillation foci

Paroxysmal AF has been known to be initiated by ectopic beats, especially in the pulmonary veins (PVs), and radiofrequency catheter ablation could cure it. We considered that the spontaneous transition from typical atrial flutter to AF also could be initiated by ectopic beats. Twenty patients (18 men, mean age 66 +/- 14 years) with episodes of spontaneous transition from typical atrial flutter to AF were included in this study. They underwent detailed mapping of both atria. All the patients had spontaneous AF initiated by ectopic beats, and all of them had typical atrial flutter and spontaneous transition from typical atrial flutter (12 patients with counterclockwise atrial flutter and 8 patients with clockwise atrial flutter) to AF. The transition was initiated by ectopic beats from the PVs (17 foci, 85%), crista terminalis (2 foci, 10%), and superior vena cava (1 focus, 5%). After successful ablation of AF foci, typical atrial flutter was induced again, but no spontaneous transition was found after at least 10 minutes of observation. We concluded that paroxysmal AF and spontaneous transition from typical atrial flutter to AF were initiated by ectopic beats, and successful catheter ablation of the ectopic foci can eliminate paroxysmal AF and spontaneous transition from typical atrial flutter to AF.     

Radiofrequency Ablation Therapy in Three Patients with Paroxysmal Atrial Tachycardia

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectiveiy. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo-atrial conduction during ventricular pacing. Tiie earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His-bundle recording site, at the anterior-superior border of Koch's triangle slightly posterior to the His-bundle recording site, and at the mid-lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was deiivered to the site of the earliest atrial activation during tachycardia through a 4-mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. FoIIow-up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat eiectrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.     

Long-term outcome of right and left atrial radiofrequency ablation in patients with persistent atrial fibrillation

OBJECTIVES: To investigate the clinical outcome of right and left atrial radiofrequency ablation after the first 12 months in patients with drug-refractory persistent atrial fibrillation (AF), and to identify predictors of long-term success. METHODS: We analyzed the clinical outcome of 74 consecutive patients with a follow-up >12 months who underwent right and left atrial ablation for persistent AF. Patients who did not present symptomatic or asymptomatic atrial tachyarrhythmias (AT) lasting >30 seconds after the first 3 months of follow-up were defined responders to pulmonary veins ablation. RESULTS: After a mean follow-up of 20.2 +/- 6.3 months (12-36), 52/74 (70%) patients were deemed responders. AT relapsed within the first 12 months in 19/74 (26%) patients (17 AF and 2 left atrial flutter). Among those patients who did not relapse within the first 12 months, only 3 patients (5%) presented AF after the first year of follow-up. At the multivariate analysis presence of early AT relapse and history of AF >7 years inversely correlated with a successful long-term clinical outcome. CONCLUSION: Right and left atrial ablation, alone or in association with antiarrhythmic drugs, prevented AT relapses in 70% of patients with drug-refractory persistent AF also after the first 12 months. Presence of AT relapse within the first 3 months and history of AF >7 years identified patients with a lower probability of successful long-term clinical outcome.     

Efficacy of radiofrequency catheter ablation in treatment of elderly patients with supraventricular tachyarrhythmias and ventricular tachycardia

Radiofrequency catheter ablation was performed in 100 men and 81 women, mean age 78 +/- 5 years, referred for ablation of atrial flutter, supraventricular tachycardia, and ventricular tachycardia, and for ablation of the atrioventricular junction with permanent pacemaker implantation in patients with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy. A hematoma in 1 of 182 ablation procedures (<1%) was the only complication. Radiofrequency catheter ablation was successful in treating 63 of 70 patients (90%) with atrial flutter, in treating 60 of 66 patients (91%) with supraventricular tachycardia, in treating 2 of 2 patients (100%) with ventricular tachycardia, and in ablating the atrioventricular junction in 43 of 44 patients (98%) with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy.     

Myocardial Injury Induced by Radiofrequency and Low Energy Ablation: A Quantitative Study of CK Isoforms,CK-MB,and Troponin-T Concentrations

We conducted a prospective, controlled study to investigate the use of CK-MB concentration and newer methods such as troponin-T concentration and CK isoforms, in the assessment of myocardial damage caused by radiofrequency current or low energy DC catheter ablation. The study population consisted of 3 consecutive patients who underwent low energy catheter ablation, 28 consecutive patients subjected to radiofrequency ablation, and 4 patients wbo were subjected to radiofrequency energy ablation but also bad external DC shocks for cardioversion of atrial fibrillation that occurred during the procedure. The control group comprised eight subjects undergoing electrophysiological study. Prior to ablation and at 30 minutes, 1,2,6, and 12 hours following the procedure, serial blood samples were taken for measurement of troponin-T and CK-MB concentrations, and calculation of the MM3/MM1 and MB2/MB1 ratios. Troponin-T concentration was raised above normal in all patients subjected to low energy ablation and in all but two patients subjected to radiofrequency ablation. Only 42% of all patients subjected to ablation had at least one raised CK-MB concentration postablation. The MB2/MB1 ratio was raised in all but two patients following radiofrequency or low energy ablation but it was also abnormal in the preablation samples in nine patients. The MM3/MM1 ratio failed to detect myocardial damage in 71 % of all patients. There was a statistically significant difference between the control and patient groups regarding all four indices of myocardial damage. Low energy ablation caused a significantly higher degree of myocardial damage compared with radiofrequency (RF); this effect could not be attributed to different numbers of total energy discharges. Our results indicate that catheter ablation, regardless of the mode of energy used, inflicts detectable injury upon the myocardium. This injury can be quantitated by using newer analytical techniques, such as serial, postablation measurements of troponin-T concentration.     

Strategies to Minimize the Risk of Esophageal Injury durings Catheter Ablation for Atrial Fibrillation

Esophageal injury is a rare but serious complication of catheter ablation for atrial fibrillation using radiofrequency energy. Recent studies have begun to identify variables that may determine heat transfer to and thermal injury of the esophagus. There is significant variability in the relationship between the esophagus and left atrium among individuals. New imaging techniques can facilitate assessment of esophagus position relative to intended ablation targets. Strategies to minimize the risk of esophageal injury include avoidance of ablation near the esophagus, titration of RF energy delivery at the posterior left atrial endocardium, and the use of alternative ablation methods.     

心房颤动患者环肺静脉左房线性消融术后的护理

目的 探讨心房颤动(房颤)患者环肺静脉左房线性消融术后的观察和护理要点.方法 对3l例房颤患者采用CARTO电解削标测系统及双Lasso表测电极技术,分别进行环左、右侧肺静脉线性消融;消融终点为肺静脉电位消失,左房-肺静脉双向传导阻滞,并对观察护理要点进行总结.结果 患者初次消融术后平均随访(245±65)d,21例无复发,8例复发房性心律失常包括5例典型房扑、2例其他房性心动过速、1例阵发性房颤、2例左上肺静脉电位未完全隔离者仍持续房颤.除1例持续性房颤外,9例接受了再次消融术,8例射频消融成功并随访(192±92)d无复发.2次射频消融术后总成功率为92.8%.结论 护理人员应根据患者在行环肺静脉左房线性消融术术前、术中、术后,对出现的症状进行有效的护理措施,以解除患者的痛苦.     

Quality of life and occurrence of atrial fibrillation in long-term follow-up of common type atrial flutter ablation:

Objectives The ablation of common type atrial flutter is mainly performed by two approved techniques, whose efficacy and outcome in terms of quality of life have not been evaluated so far in a long-term follow-up study over years. A high proportion of patients suffer from coexistent atrial fibrillation, which may worsen the ablation result. The question arises whether one technique is more effective than the other when immediate ablation results, the occurrence of atrial fibrillation and the quality of life are compared. Considering these facts, it is reasonable to think about new ablation strategies for common type atrial flutter in the era of new concepts in catheter ablation of atrial fibrillation. Methods In a retrospective study we evaluated a detailed questionnaire in 132 patients who underwent ablation of common type between 1999 and 2004. Radiofrequency ablation was performed irrespective of coexistent atrial fibrillation either with an irrigated tip or the 8 mm tip electrode. Acute and long-term ablation outcome, and the associated quality of life, pre-, under- and post-ablation was compared in the two different ablation groups. Recurrent tachycardia were re-evaluated by 12 lead ECG analysis and assessed for both ablation groups. Results 88 (67%) of the 132 patients contacted answered the questionnaire polling the perceived benefits of the procedure. Of the other 44 patients (33%); 4 (3%) had died, 7 (5.3%) had moved, 33 patients (25%) could not be included due to missing or incoherent answers. Independent of the ablation technique there was a high acute and long-term ablation success rate at about 95%. After a mean of 3 years of follow-up this benefit persists in spite of a high proportion of recurrent tachycardia, mainly atrial fibrillation (55/88 patients, 59.1%). Despite the occurrence of secondary tachycardia, there was a high significant long-term symptomatic benefit in the state of healthy and daily practice work, evaluated with a p-value of < 0.0005. The frequency of episodes and the symptom "tachycardia" were significantly reduced after effective ablation of common type atrial flutter, p-values of 0.003 and 0.002, respectively. Therefore the need for hospitalization was significant reduced (p = 0.001). Comparison of both approaches revealed that there was no significant difference related to the incidence and occurrence of atrial fibrillation. Conclusions The two mainly accepted and applied techniques for the ablation of common type atrial flutter show an excellent outcome under the aspect of ablation efficacy and quality of life in longterm follow-up. Three years after the ablation procedure the majority of patients consider the intervention beneficial. Despite the relatively high appearance of atrial fibrillation in the long-term follow-up this effect is still traceable.