Electrophysiologic effects of selective right versus left atrial linear lesions in a canine model of chronic atrial fibrillation

INTRODUCTION: Long linear lesions have been shown to eliminate atrial fibrillation in animal models, but little is known about the electrophysiologic response in one atrium to lesions in the contralateral atrium. METHODS AND RESULTS: Twelve dogs with chronic atrial fibrillation were randomized to either right atrial ablation (n = 4), left atrial ablation first (n = 4), or a sham procedure (n = 4). Simultaneous biatrial endocardial mapping was performed before and after three linear lesions were applied at specific points in either atrium, using an expandable ablation catheter. Atrial fibrillation was reinducible after single atrial ablation in each dog and no longer inducible after biatrial ablation in five dogs. At baseline, the mean atrial fibrillation cycle length was longer on the trabeculated (117+/-15 msec) compared with the smooth right (101+/-16 msec) or left atrium (88+/-10 msec; P < 0.01). Single right and left atrial ablation caused a significant cycle length increase in the ablated atrium. Left atrial ablation increased the cycle length on both the trabeculated (121+/-18 msec vs 137+/-11 msec; P < 0.05) and smooth right atrium (108+/-12 msec vs 124+/-9 msec; P < 0.05). Right atrial ablation, however, had no significant effect on left atrial fibrillation cycle length (82+/-8 msec vs 86+/-7 msec). CONCLUSION: Left atrial linear lesions affect right atrial endocardial activation, whereas right atrial lesions do not affect left atrial activation in a canine model of atrial fibrillation. These findings suggest that the left atrium is the driver during chronic atrial fibrillation in this animal model and may explain the limited success of right atrial ablation alone in human atrial fibrillation.     

Creating continuous linear lesions in the atria: a comparison of the multipolar ablation technique versus the conventional drag-and-burn

INTRODUCTION: Catheter-based treatment of atrial fibrillation (AF) requires the isolation of the triggering foci as well as modification of the atria with substrate that sustains AF. The creation of linear lesions in the left atrium with standard radiofrequency ablative methods requires long procedural times with unpredictable results. METHODS: The simultaneous delivery of phase-shifted radiofrequency energy from a multipolar catheter was compared to the conventional drag-and-burn technique for creating linear lesions in 10 dogs. Four atrial sites were targeted under intracardiac ultrasound and fluoroscopic guidance in each of 10 dogs. The conventional drag-and-burn technique or the multipolar phase-shifted ablation catheter was randomly applied for 60 seconds and compared. RESULTS: Creating linear lesions using the simultaneous multipolar phase-shifted ablation catheter was on average 11.0 minutes faster (33.6 minutes vs 44.6 minutes, P < 0.01) than the drag-and-burn method. The fraction of the lesion length achieved using phase-shifted ablation compared to that intended was 23% greater (76% vs 53%, P < 0.01), and has less discontinuities (0.1 compared to 0.8 discontinuities/line, P < 0.003). There was no significant difference in either the lesion transmurality, or fluoroscopy times. CONCLUSION: The simultaneous delivery of phase-shifted, radiofrequency energy using a multipolar catheter is more effective and efficient in producing linear lesions than the traditional drag-and-burn technique. Using the multipolar ablative method to create linear lesions may be a useful technique in the treatment of patients with substrate-mediated atrial fibrillation.     

消融犬右肺静脉脂肪垫对心房及右上肺静脉电生理特性及房颤诱发的影响

目的探讨消融右肺静脉脂肪垫对心房及右上肺静脉电生理特性及房颤诱发的影响。方法犬18只分别在颈部迷走神经未刺激和刺激的情况下,观察射频消融肺静脉脂肪垫前后心房不同部位及右上肺静脉有效不应期、房颤诱发率及房颤诱发窗口的变化。结果在刺激迷走神经的情况下,与消融前相比,消融后高位右心房有效不应期延长（P<0.05）,其余部位有效不应期无显著差异,消融后高位右心房房颤诱发率降低（P<0.01）,房颤诱发窗口变窄（P<0.05）,左心房（P<0.01）及右上肺静脉（P<0.01）房颤诱发率升高,诱发窗口增宽。同时,心房有效不应期离散度增加（P<0.01）。结论消融右肺静脉脂肪垫使高位右心房房颤诱发率降低及房颤诱发窗口变窄,却使左房、右上肺静脉房颤诱发率升高及房颤诱发窗口增宽。     

Atypical left atrial flutter after intraoperative radiofrequency ablation of chronic atrial fibrillation: successful ablation using three-dimensional electroanatomic mapping

Curative treatment of chronic atrial fibrillation (AF) remains a challenging task for electrophysiologists. Eliminating the initiating triggers by focal radiofrequency ablation in a subset of patients with paroxysmal AF and modifying the maintaining substrate by performing linear lesions within the left atrium in patients with prolonged episodes of AF are among the alternative approaches for management of these patients. Recently, a new intraoperative treatment procedure aimed at eliminating left atrial anatomic "anchor" reentrant circuits by induction of contiguous lesions using radiofrequency energy under direct vision was introduced. However, atypical left atrial flutter may occur during follow-up after intraoperative ablation of AF. These arrhythmias most likely are due to discontinuities in linear lesions; therefore, they can be successfully mapped and ablated in a subsequent percutaneous catheter ablation procedure. We report and discuss the case of a patient who underwent successful intraoperative ablation of chronic AF, but who developed atypical left atrial flutter postoperatively. Three-dimensional nonfluoroscopic electroanatomic mapping revealed a gap in the linear lesion line connecting the left upper and right upper pulmonary vein orifices. Ablation at the exit site of the breakthrough was successful.     

Pulmonary vein paced activation sequence mapping: comparison with activation sequences during onset of focal atrial fibrillation

INTRODUCTION: Atrial fibrillation (AF) may originate from a single focus, with the vast majority observed within the pulmonary veins. To facilitate mapping, we hypothesized that there would be a characteristic right atrial endocardial activation sequence pattern associated with pacing and spontaneous focal activity from each of the four pulmonary veins. METHODS AND RESULTS: In 10 patients with focal AF, a standardized set of catheters was positioned in the right atrium. These included a 20-pole catheter along the crista terminalis, a decapolar catheter in the coronary sinus (CS), and a His-bundle electrode. Pacing (700 and 300 msec) was performed with a mapping catheter from each of the four pulmonary veins. Activation sequence maps were created by measurement of activation times to each of the recording bipoles with the proximal CS bipole as the arbitrary reference point. Similar maps were constructed for the activation sequence of the pulmonary vein ectopic that initiated AF. There was a characteristic right atrial activation map created by pacing each pulmonary vein that corresponded closely with the map from the same pulmonary vein during initiation of focal AF. The pulmonary vein of origin could be distinguished on the basis of this characteristic pattern and some stereotypic observations. CS activation occurred proximal to distal for right pulmonary veins and distal to proximal for left pulmonary veins. Significant differences in activation timing between the CS and crista terminalis differentiated upper from lower pulmonary veins. CONCLUSION: There is a characteristic right atrial activation map for activity arising from each of the four pulmonary veins that corresponded closely with the map from the same pulmonary vein during initiation of focal AF. These findings may facilitate mapping and ablation of focal AF.     

Right Atrial Mapping and Linear Ablation for Paroxysmal Atrial Fibrillation

Objective: Catheter ablation techniques to cure atrial fibrillation (AF) are under investigation. This study evaluates a mapping-based, individualized approach to right atrial (RA) linear ablation in patients with paroxysmal AF. Methods: In this prospective observational study, 29 patients with recurrent symptomatic AF refractory to medical therapy, underwent linear ablation between May 1998 and December 1999. Inclusion criteria were symptomatic paroxysmal AF, failure of at least 2 antiarrhythmic medications, and informed consent. Radiofrequency ablation was performed in the RA using a 3.3 French multielectrode catheter, ablating through sequential electrodes to establish linear lesions. Lesions were delivered during sustained AF, guided by an empiric mapping scheme, targeting arrhythmogenic areas noted during electrophysiologic testing in sinus rhythm and areas of most disorganization during AF. Reinduction of AF was attempted at the end of successful ablation. Results: The mean age was 58 years. There were 15 male and 14 female patients. Sustained AF was inducible in all patients at electrophysiology study. Acute success was achieved in 24 patients (83%). Long term success (maintaining sinus rhythm off antiarrhythmic medications) was seen in 23 (79%) over a mean follow-up of 19.7 months. Ablation lines varied from patient to patient. There were no complications. Conclusions: Individualized linear ablation in the RA using a multielectrode catheter system can produce effective suppression of paroxysmal AF. Ablation during AF, and testing to reinduce AF at the end of the procedure, make this study unique.     

峡部依赖性心房扑动对心房颤动发作的影响

目的观察导管射频消融治疗峡部依赖性心房扑动(房扑)对心房颤动(房颤)发作的影响,进一步探讨房扑和房颤的关系。方法86例房扑患者,其体表心电图均提示典型房扑,男性54例、女性32例,年龄50.0±15.6(11～74)岁,病程5.6±6.4(0.1～30)年。将所有患者分成A、B两组,A组为房扑合并房颤患者,共25例;B组为不合并房颤患者,共61例;其中A组同时合并房室结折返性心动过速(AVNRT)3例,房室折返性心动过速(AVRT)4例,阵发性房性心动过速(PAT)10例;B组合并房室结折返性心动过速5例,房室折返性心动过速7例。对峡部依赖性房扑者,线性消融下腔静脉—三尖瓣环峡部致双向传导阻滞;房室折返性心动过速者行旁道消融术;房室结折返性心动过速者行慢径改良术,阵发性房速术中持续或可诱发,予以射频消融。平均随访27.1±14.1(6～63)月。结果A组25例患者中,术后68%(17/25)患者不再发作房颤;其余8例仍有房颤发作,其中1例为术前同时合并房室折返性心动过速,5例为合并阵发性房速。61例术前不合并房颤者,术后随访中有16.4%(10/61)新发房颤。86例患者中,6例因病态窦房结综合征行起搏器植入术,随访未诉心悸、胸闷,心电图为窦性心律与起搏心律交替出现。结论房扑可能与房颤具有共同的发生基质,也可以是房颤的触发因素,成功消融房扑后可以阻止房颤的发生。但房颤发生机制多样,消融峡部依赖性房扑,仍会发生房颤,术前合并房颤或房速者是最强的预测因子。     

冷冻球囊消融与射频消融对阵发性心房颤动患者心房重构的影响

目的:比较冷冻球囊消融(CBA)与射频消融(RFA)对阵发性心房颤动(房颤)患者心房重构的影响.方法:本研究选取在2014年5月-2017年5月于郑州大学第一附属医院因阵发性房颤行CBA或RFA治疗的患者.所有患者均于术前、术后半年、1年、2年和3年时行12导联心电图或24 h动态心电图和超声心动图检查.左心房电重构通...     

The effect of left atrial remodeling after cryoballoon ablation and radiofrequency ablation for paroxysmal atrial fibrillation

BackgroundCryoballoon ablation (CBA) and radiofrequency ablation (RFA) are the most common procedures used to treat refractory atrial fibrillation (AF) and are performed through pulmonary vein isolation (PVI). Studies have shown that CBA can approximately match the therapeutic effects of RFA against AF. However, few studies have investigated the difference between CBA and RFA of the effects on left atrial remodeling for paroxysmal AF.ObjectiveAtrial remodeling is considered pivotal to the occurrence and development of AF, therefore we sought to assess the influence of atrial remodeling in patients with paroxysmal AF after CBA and RFA in this study.MethodsIn this nonrandomized retrospective observational study, we enrolled 328 consecutive patients who underwent CBA or RFA for refractory paroxysmal AF in May 2014 to May 2017 in our hospital. After propensity score matching, 96 patients were included in the CBA group, and 96 were included in the RFA group. Patients were asked to undergo a 12‐lead electrocardiogram, a 24‐h Holter monitor, and an echocardiogram and to provide their clinical history and symptoms at 6 months and 1, 2, and 3 years postprocedurally. Electrical remodeling of the left atrium was assessed by P wave dispersion (Pdis); structural remodeling was assessed by the left atrium diameter (LAD) and left atrial volume index (LAVI) during scheduled visits.ResultsAs of January 2020, compared with baseline, at 1 year, 2 years, and 3 years after ablation, the average changes in Pdis (∆Pdis), LAD (∆LAD), and LAVI (∆LAVI) were significant in both the CBA and RFA groups. Six months after ablation, ∆Pdis, ∆LAD, and ∆LAVI were greater in the CBA group than in the RFA group. There was no significant difference between the two groups in AF/flutter recurrence, but the AF/flutter‐free survival time of CBA group may be longer than RFA group after 2 years after ablation. A higher ∆Pdis, ∆LAD, or ∆LAVI at 1 year after ablation may increase AF/flutter‐free survival.ConclusionsAlthough CBA and RFA are both effective in left atrial electrical and structural reverse‐remodeling in paroxysmal AF, CBA may outperform RFA for both purposes 6 months after ablation. However, during long‐term follow‐up, there was no significant intergroup difference.     

Pulmonary edema after extensive radiofrequency ablation for atrial fibrillation

Background: More extensive ablation strategies for the treatment of atrial fibrillation (AF) have increased success rates but are associated with new and sometimes serious complications. We describe a new complication after extensive radiofrequency (RF) ablation in the left atrium (LA) for persistent AF.
Methods and Results: Electroanatomic guided circumferential ablation around both ipsilateral pulmonary veins (PV) was performed with the endpoint of complete conduction block. When necessary, supplementary RF applications were added, including ablation of complex fractionated potentials and/or isolation of other thoracic veins and/or linear left atrial lesions. RF energy was delivered via an irrigated tip catheter with a maximum power of 30–35 W. Four out of 120 patients undergoing extensive RF ablation for persistent AF (including two patients with additional LA substrate modification) developed dyspnea, bilateral pulmonary edema, and signs of a systemic inflammatory response syndrome (SIRS) (rise in body temperature, leukocyte count, and C-reactive protein (CRP levels) 18–48 hours after the procedure. There were no signs of PV stenosis, focal lung injury, left ventricular dysfunction, circulatory failure, or infection. All patients had complete recovery with supportive therapy within 3–4 days after the onset of symptoms.
Conclusions: Extensive LA radiofrequency ablation bears the risk of a severe pulmonary edema. Although the precise mechanism is elusive, clinical features point toward a systemic inflammatory response.     

Saline-irrigated radiofrequency ablation electrode with external cooling

INTRODUCTION: Open flush, irrigated ablation electrodes may improve the safety of radiofrequency catheter ablation by preventing protein aggregation and coagulum formation. This is particularly important in left-sided procedures like catheter ablation of atrial fibrillation. Electrode cooling and the inherent loss of temperature feedback, however, grossly reduce the ability to monitor tissue heating. Intimate contact may not be recognized and the delivery of nominal RF power levels may then lead to excessive tissue heating, steam explosions, and even tamponade. METHODS AND RESULTS: Standard, open flush, irrigated catheters (Sprinklr, Medtronic Inc, Minneapolis, MN) were modified by thermally insulating the irrigation channels inside the ablation electrode. Using the thigh muscle preparation, multiple lesions were created with standard and modified catheters using 60 s, 20-50 Watt applications and a constant saline flush rate of 20 cc/min. A total of 57 lesions were created on five thigh muscles of three dogs. Lesion dimensions were not significantly different between both types of catheter, but the maximum electrode temperature rise during ablation was significantly higher with the modified catheter. Insulation of the irrigation channels improved the correlation coefficient between maximum electrode temperature rise and lesion volume from 0.38 (ns) to 0.62 (P < 0.001). CONCLUSION: Thermal insulation of the irrigation channels facilitates temperature feedback during radiofrequency ablation and controllability of lesion formation.     

经体表和心内膜标测的转子识别及其对房颤消融的影响

为及时反映海外心脏病学领域的最新进展,努力缩短国内外心电学研究的差距,自本期起,本刊推出“海外论坛”栏目。本栏目主要刊发国内外心脏病学研究领域前沿成果的专题述评、综述和重要学术会议快报等,形式不拘。欢迎海内外学者惠赐大作！开栏之初,我们有幸得到了两位国际知名心脏病学专家---欧洲心律协会（HRS ）主席Karl-Heinz Kuck 教授与德国伊丽莎白医院Contilia心脏和血管中心的Dietmar Schmitz教授的大力支持,为读者介绍有关转子标测及房颤消融和心脏再同步化治疗的最新研究进展,其中Schmitz教授的述评中囊括了今年8月31日在欧洲心脏病学会年会（ESC2014）上发布的最新数据。现将英文原文及译稿奉上,以飨读者。     

射频消融治疗老年房扑房颤患者疗效及安全性的评价

目的展望射频消融治疗老年房扑房颤患者的前景，评价其安全性及疗效。方法回顾3年来在北京大学第一医院进行射频消融的年龄在60～82岁的房扑房颤患者的病例。结果46名患者中1例因不能耐受未能继续消融治疗；20例房扑患者全部消融成功，成功率100％，随访1～30个月无复发；25例房颤患者消融肺静脉78条，以肺静脉电位消失为标准，成功率96％，随访1～30个月，5例复发，成功率80．0％。5例复发患者药物控制心室率；1例出现急性心脏压塞，治疗后好转。将该组并发症的发生率与同期在北京大学第一医院因阵发性室上性心动过速行射频消融的年龄16～60岁组并发症的发生率进行比较，差异无显著性。结论射频消融因其安全性、有效性，对老年患者可明显减少药物副作用，提高生活质量，可成为无禁忌房扑房颤患者的一线治疗方案。     

房颤射频消融术术后AF早期复发的预测因素

房颤(AF)是临床上最常见的一种心律失常。AF射频消融术作为一种非药物治疗AF的手段正被广泛利用,但术后AF的复发率较高。早期有研究显示,高龄、超重和肥胖、病程、左房内径、左房疤痕和纤维化等为预测AF消融术术后AF复发的相关因素。最新研究显示,阻塞性睡眠呼吸暂停综合征、伴有慢性肾脏疾病、4q25等位基因多态性等对AF早期复发的预测具有一定的意义。     

The Disparities in the Electrogram Voltage Measurement During Atrial Fibrillation and Sinus Rhythm

Unipolar Electrogram Voltage in Patients with Atrial Fibrillation . Introduction: The peak electrogram voltage is a typical metric applied at each site for voltage mapping. However, the peak amplitude depends on the direction and complexity of the wavefront propagation. The root‐mean‐square (RMS) measure of the amplitude is a temporal integral that represents the steady‐state value. The objective of this study was to investigate the disparities between the electrogram voltage during SR and AF by using 2 recording modalities: the conventional peak voltage and an RMS measurement. Methods and Results: This study enrolled 20 patients (age = 59 ± 13) with paroxysmal AF undergoing catheter ablation guided by Ensite array. The unipolar electrogram voltage during SR and AF (7 seconds in duration) was obtained from the same sites, and labeled by the 3‐dimensional (3D) geometry. Overall 1,200 electrograms were analyzed from equally distributed mapping sites in the left atrium. A point‐by‐point comparison of the unipolar peak negative voltage (PNV) showed less agreement (Bland and Altman test: 10.4% outside 2 standard deviations, and intraclass correlation coefficient [ICC]= 0.64). The RMS voltage demonstrated agreement between SR and AF for all sites (BA test: 5.9% of the sites, and the ICC = 0.81). The probability of predicting a low‐voltage during AF using the voltage during SR was significantly lower when using the PNV measurement compared to that when using the RMS voltage (15% vs 61%, P < 0.05). Conclusion: The peak electrogram unipolar voltage during AF did not represent the voltage during SR. The RMS amplitude may be an alternative metric for voltage mapping to characterize the myocardial substrate. (J Cardiovasc Electrophysiol, Vol. 21, pp. 393–398, April 2010)     

双极射频消融心房颤动同时手术治疗器质性心脏病的临床效果

目的：探讨双极射频消融钳治疗心房颤动同期行开胸手术治疗器质性心脏病的手术方法和临床结果,提高对此类疾病的治疗水平。方法：回顾分析2009年8月～2012年5月对58例器质性心脏病并发心房颤动用双极射频消融钳治疗房颤的临床资料。结果：本组患者手术均顺利完成。射频时间16～38（24±4） min,主动脉阻断时间64～200（126±36） min,体外循环时间91～238（150±37） min;手术结束及出院时窦性心率分别为46（79%）,45（78%）例,随访3个月,6个月和12个月,窦性心率分别为41（71%）,40（69%）和42（72%）例。全组病例无手术死亡和射频相关并发症。所有患者均无需安装永久起搏器。双心房消融与单独左房消融比较无显著差异。结论：此方法可行,效果满意,但要注意把握适应证。     

Acute effects of left atrial radiofrequency ablation on atrial fibrillation

INTRODUCTION: Acutely, when left atrial ablation is performed during atrial fibrillation (AF), the AF may persist and require cardioversion, or it may convert to sinus rhythm or to atrial tachycardia/flutter. The prevalence of these acute outcomes has not been described. METHODS AND RESULTS: Left atrial ablation, usually including encirclement of the pulmonary veins, was performed during AF in 144 patients with drug-refractory AF. Conversion to sinus rhythm occurred in 19 patients (13%), to left atrial tachycardia in 6 (4%), and to atrial flutter in 6 (4%). In the 6 patients with a focal atrial tachycardia, the mean cycle length was 294 +/- 45 ms. The tachycardia arose in the left atrial roof in 3 patients, the left atrial appendage in 2, and the anterior left atrium in 1. In 3 of 6 patients, the focal atrial tachycardia originated in an area that displayed a relatively short cycle length during AF. In 6 patients, AF converted to macroreentrant atrial flutter with a mean cycle length of 253 +/- 47 ms, involving the mitral isthmus in 5 patients and the septum in 1 patient. All atrial tachycardias and flutters were successfully ablated with 1 to 15 applications of radiofrequency energy. CONCLUSION: When left atrial ablation is performed during AF, the AF may convert to atrial tachycardia or flutter in approximately 10% of patients. Focal atrial tachycardias that occur during ablation of AF may be attributable to driving mechanisms that persist after AF has been eliminated, whereas atrial flutter results from incomplete ablation lines.