Route Graph-A New Method for Analysisof Atrial Fibrillation by Epicardial Mapping

For further clarifying the mechanisms of atrial fibrillation(AF) through epicardiac mapping, we developed a "route graph" method for the analysis of epicardial mapping signal during AF. Three procedures were used to construct the route graph: detecting character points and constructing isochronal maps, calculating direction vectors and finally generating activation route graph. This method was applied to five dogs during induced atrial fibrillation, Preliminary experiments show the potential of this method to study electrophysiological activity of AF.

Epicardial adipose tissue around the superior vena cava: A single center study of factors related to atrial fibrillation

The superior vena cava(SVC)is the main component of non-pulmonary vein(PV)ectopy in patients with atrial fibrillation(AF).Researchers have found that epicardial adipose tissue(EAT)volume is related to the AF substrate,which can be defined by the low voltage area(LVA).This study aimed to investigate the relationship between SVC-EAT and SVC-AF.Twenty-six patients with SVC-AF triggers were identified as the SVC-AF group.Other three groups were defined and included as the LVA-AF group(LVA>5%),non-LVA-AF group(LVA<5%),and physical examination(PE)group.EAT around left atrium(LA-EAT)and SVC-EAT volumes were obtained using a cardiac risk assessment module.According to the SVC/LA-EAT ratio,there are significant differences between the SVC-AF group and the three control groups(the SVC-AF group 0.092±0.041 vs.the LVA-AF group 0.054±0.026,the non-LVA-AF group 0.052±0.022,and the PE group 0.052±0.019,all P<0.001).Receiver operating characteristic curve analysis suggests the optimal cut-off point of SVC/LA-EAT ratio is 6.8%for detecting SVC-AF patients,with 81.1%sensitivity,73.1%specificity,and an area under the curve of 0.83(95%confidence interval,0.75-0.91).Those with SVC-AF have a higher SVC/LA-EAT ratio and empirical SVC isolation could be considered if the SVC/LA-EAT ratio was over 6.8%.

Role of Epicardial Adipose Tissue in Triggering and Maintaining Atrial Fibrillation

Atrial fibrillation is the most common arrhythmia leading to cardiogenic stroke.Without membranous sructure between epicardial adipose tissue and atrial myocardium,epicardial adipose tissue directly covers the surface of the atrial myocardium.The formation of an epicardial adipose tissue inflammatory microenvironment,fibrosis,infiltration by epicardial adipose tissue,autonomic dysfunction and oxidative stress are important mechanisms that trigger and maintain atrial fibrillation.Those mechanisms are reviewed herein.

Rotor identification by body surface mapping and endocardial mapping：impact on atrial fibrillation ablation

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!

Role of three-dimensional imaging integration in atrial fibrillation ablation

Atrial fibrillation is the most common arrhythmia and in symptomatic patients with a drug-refractory form,catheter ablation aimed at electrically disconnecting the pulmonary veins(PVs) has proved more effective than use of antiarrhythmic drugs in maintaining sinus rhythm during follow-up.On the other hand,this ablation procedure is complex,requires specific training and adequate clinical experience.A main challenge is represented by the need for accurate sequential positioning of the ablation catheter around each veno-atrial junction to deliver point-by-point radiofrequency energy applications in order to achieve complete and persistent electrical disconnection of the PVs.Imaging integration is a new technology that enables guidance during this procedure by showing a three-dimensional,pre-acquired computed tomography or magnetic resonance image and the relative real-time position of the ablation catheter on the screen of the electroanatomic system.Reports in the literature suggest that imaging integration provides accurate visual information with improvement in the procedure parameters and/or clinical outcomes of the procedure.

Reduction of radiation exposure in catheter ablation of atrial fibrillation: Lesson learned

Over the last decades, the concern for the radiation injury hazard to the patients and the professional staff has increased in the medical community. Since there is no magnitude of radiation exposure that is known to be completely safe, the use of ionizing radiation during medical diagnostic or interventional procedures should be as low as reasonably achievable(ALARA principle). Nevertheless, in cardiovascular medicine, radiation exposure for coronary percutaneous interventions or catheter ablation of cardiac arrhythmias may be high: for ablation of a complex arrhythmia, such as atrial fibrillation, the mean dose can be > 15 m Sv and in some cases > 50 m Sv. In interventional electrophysiology, although fluoroscopy has been widely used since the beginning to navigate catheters in the heart and the vessels and to monitor their position, the procedure is not based on fluoroscopic imaging. Therefore, nonfluoroscopic three-dimensional systems can be used to navigate electrophysiology catheters in the heart with no or minimal use of fluoroscopy. Although zerofluoroscopy procedures are feasible in limited series, there may be difficulties in using no fluoroscopy on a routine basis. Currently, a significant reduction in radiation exposure towards near zero-fluoroscopy procedures seems a simpler task to achieve, especially in ablation of complex arrhythmias, such as atrial fibrillation. The data reported in the literature suggest the following three considerations. First, the use of the non-fluoroscopic systems is associated with a consistent reduction in radiation exposure in multiple centers: the more sophisticated and reliable this technology is, the higher the reduction in radiation exposure. Second, the use of these systems does not automatically lead to reduction of radiation exposure, but an optimized workflow should be developed and adopted for a safe non-fluoroscopic navigation of catheters. Third, at any level of expertise, there is a specific learning curve for the operators in the non-fluoroscopic manipulation of catheters; however, the learning curve is shorter for more experienced operators compared to less experienced operators.

Coronary sinus reentrant tachycardia after atrial fibrillation ablation: From bad to worse

Herein we present a case of atrial tachycardia as a sequel of AF ablations. A 42-year-old man was admitted to our department because of a very symptomatic tachycardia. The patient, because of paroxysmal AF and typical atrial flutter, had been already submitted (three times) to ablation procedures in both left (pulmonary vein insulation) and right atria (cavo-tricuspidal isthmus). During the electrophysiological study, a huge and very fast atrial tachycardia was induced: 230 ms cycle length, 1/1 atrio-ventricular conduction with the ventricular rate of 260 bpm, complete left bundle branch block, and clinically recognized by the patient. Four minutes later, a 2/1 AV conduction without branch block permitted mapping and ablation. A high-density mapping around isthmus and coronary sinus (CS) was performed. The analysis of the chronological activation clearly showed a circuit propagation around the CS ostium with a very slow conduction in the anterior zone enlightened by the tight color progression, and counterclockwise activation of the right atrium lateral wall. In anterior zone of CS ostium diastolic fragmented electrograms were detected. After preventing his position localization, radiofrequency delivering (35 W) was effective to interrupt the arrhythmia in 3 seconds. Energy delivering was continued to anchor the lesion to the inferior vena cava. Confirmation of successful ablation was determined by unsuccessful attempts at reinduction of the arrhythmia, in basal state and during infusion of isoproterenol.

Linear ablation of left atrium for the treatment of atrial fibrillation guided by double Lasso catheters and three dimensional electroanatomical mapping

Background Linear ablation of left atrium （LA） guided by three dimensional （3-D） electroanatomical mapping （Carto） has been used in many centres worldwide for the treatment of atrial fibrillation （AF） instead of pure anatomical approaches. There were little data about linear ablation of LA guided by Carto and double Lasso catheters in China. We report the results of linear ablation of LA guided by both Carto and double Lasso catheters. Methods After the anatomical model of LA and all pulmonary veins （PVs） had been established, circumferential ablations of the left pulmonary vein antrum and the right pulmonary vein antrum were performed with 2 circumferential mapping catheters （Lasso） placed within the ipsilateral superior and inferior PVs. The endpoint of ablation was abolishment or dissociation of the pulmonary vein potentials （PVPs）. Oral amiodarone or propafenone was taken for at least 3 months by patients with persistent AF, permanent AF or those whose PVPs had not been isolated completely. The recurrence of atrial tachyarrhythmias was observed 3 months after the procedure. Results There were 106 patients （mean age, 51.4±9.9 years）. Seventy-eight patients had paroxysmal AF, 12 persistent AF and 16 permanent AF. Onset of atrial fibrillation occurred in 52 patients during ablation procedure. Thirty-two patients restored to sinus rhythm eventually after the procedure. Abolishment or dissociation of PVPs was accomplished during the procedure in 94 patients （88.7%）. The duration of procedure and exposure to X-ray were （213±45） minutes and （32.5± 12.8） minutes, respectively. Among the 87 patients followed up for over 3 months, 62 were free of atrial tachyarrhythmias （including 8 patients who were still taking oral amiodarone）. The success rate was 71.3% in the first procedure. Two patients had pericardial effusion treated by pericardial puncture and effusion drainage. No pulmonary vein stenosis, atrioesophageal fistula, stroke or procedural death occurred. Conclusions Combination of double Lasso catheters with 3-D electroanatomical mapping to guide the linear ablation of left atrium procedure can confirm the isolation of PVPs.

Review of Ex Vivo Cardiac Electrical Mapping and Intelligent Labeling of Atrial Fibrillation Substrates

With the development of computer hardware and the growth of clinical database,tremendous progress has been made in the application of deep learning to electrocardiographic data,which provides new ideas for the ex vivo cardiac electrical mapping of atrial fibrillation(AF)substrates.The AF mechanism and current status of AF substrate research are first summarized.Then,the advantages and limitations of cardiac electrophysiological mapping techniques are analyzed.Finally,the application of deep learning to electrocardiogram(ECG)data is reviewed,the problems with the ex vivo intelligent labeling of an AF substrate and the possible solutions are discussed,an outlook on future development is provided.

Three-dimensional Dominant Frequency Mapping Using Autoregressive Spectral Analysis of Atrial Electrograms of Patients in Persistent Atrial Fibrillation

Areas with high frequency activity within the atrium are thought to be 'drivers' of the rhythm in patients with atrial fibrillation (AF) and ablation of these areas seems to be an effective therapy in e-liminating DF gradient and restoring sinus rhythm. Clinical groups have applied the traditional FFT-based approach to generate the three-dimensional dominant frequency (3D DF) maps during electro-physiology (EP) procedures but literature is restricted on using alternative spectral estimation tech-niques that can have a better frequency resolution that FFT-based spectral estimation.

Catheter ablation using pulsed-field energy:Do we finally have the magic wand to defeat atrial fibrillation?

Clinical outcomes of catheter ablation remain suboptimal in patients with atrial fibrillation(AF),particularly in those with persistent AF,despite decades of research,clinical trials,and technological advancements.Recently,pulsed-field ablation(PFA),a promising non-thermal technology,has been introduced to improve procedural outcomes.Its unique feature of myocardial selectivity offers safety advantages by avoiding potential harm to vulnerable adjacent structures during AF ablation.However,despite the global enthusiasm within the electro-physiology community,recent data indicate that PFA is still far from being a“magic wand”for addressing such a complex and challenging arrhythmia as AF.More progress is needed in mapping processes rather than in ablation technology.This editorial reviews relevant available data and explores future research directions for PFA.

A randomized prospective comparison of CartoMerge and CartoXP to guide circumferential pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation

Background CartoXP and CartoMerge have been used to treat atrial fibrillation （AF） for several years. Our randomized prospective study compared clinical outcomes of these two versions of three dimensional electroanatomic mapping system in guiding catheter ablation for paroxysmal atrial fibrillation （PAF）. Methods Eighty-one patients with symptomatic, drug refractory PAF were randomly assigned to CartoMerge group （n=-42, mean age （54.5 ＋ 13.1） years, history of AF = 3.2 years） or CartoXP group （n=39, mean age （59.8 ± 15.6） years, history of AF = 2.9 years）. All patients underwent 64-slice computed tomography （MSCT） 1 to 3 days prior to ablation procedure. Using CartoMergeTM Image Integration Module, 3D anatomical images of the left atrium （LA） and pulmonary veins （PVS） derived from MSCT of CartoMerge group were established and merged with the electroanatomical map. The integrated images were used to guide the procedure of circumferential pulmonary vein isolation （CPVl）. In the other group, CPVl was guided just by CartoXP. The endpoint of CPVl in both groups was abolition or dissociation of pulmonary vein potentials （PVPs）. Results Mapping points to establish the electroanatomical model of the LA/PVs were 48.7＋13.4 in CartoMerge group and 62.5±15.7 in CartoXP group （P〈0.001）. Mean distance between mapping points and the MSCT surfaces in CartoMerge group was （1.59±0.33） mm. Accomplishment of abolition or dissociation of PVPs was achieved 95.2% in CartoMerge group and 92.3% in CartoXP group. Durations of procedure and exposure to X-ray were （156±25） minutes, （179±21） minutes （P〈0.001） and （19.6±7.5） minutes, （28.5±12.8） minutes （P 〈0.001）, respectively. After a follow-up with duration of （11.9＋3.1） months vs （12.4±3.6） months post the first ablation procedure, patients free of AF were 33 （78.6%） in CartoMerge group and 29 （74.4%） in CartoXP group （P〉0.50）. No patient suffered pulmonary vein stenosis, atenoesophageal fistula, stroke or death. Conclusion Compared to CartoXP, CartoMerge shortened the catheter ablation procedure and exposure to X-ray, without affecting the clinical outcomes of circumferential pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation in experienced centres.

Initial experience with circumferential pulmonary vein isolation guided~ by Overlay Ref and CartoMerge in the treatment of paroxysmal atrial fibrillation

Background CartoMerge has been widely used in guiding circumferential pulmonary vein isolation （CPVI） for the treatment of paroxysmal atrial fibrillation （PAF）. However, the procedure of landmarks selection varies among operators according to their experience. Techniques have to be established to standardize this procedure. We propose that Overlay Ref could facilitate this procedure. This paper aimed to report our initial experience with CPVI guided by Overlay Ref and CartoMerge for the treatment of PAF. Methods Fifty-nine patients with PAF were enrolled in this study. Using Overlay Ref technique, a reference image （inverted） was faded into the live fluoroscopic image. Landmarks of CartoMerge were selected from anatomic points of the top of superior pulmonary veins （PVs） and the bottom of inferior PVs guided by Overlay Ref image. Overlay Ref images were also used to guide the ablation procedure combining with CartoMerge. Results All patients were successfully mapped by CartoMerge guided by Overlay Ref. The distance between the mapping points and the CT surfaces was （1.42±0.67） mm for the patients as a whole. This led to a successful rate of 96% for isolation of pulmonary veins. Duration of ablation procedure was （92±17） minutes. And the total duration of procedure was （139±32） minutes. CartoMerge could also be performed just with 3 paries to 4 paries selected landmarks guided by Overlay Ref without a full anatomic model constructed by Carto. Then, the total duration of procedure could be shortened to （115±38） minutes. Conclusions Overlay Ref technique can facilitate the catheter ablation of PAF and can help to standardize the procedure of landmarks selection.

Left atrial voltage remodeling after pulmonary venous isolation with multipolar radiofrequency ablation

Purpose: Pulmonary vein isolation (PVI) is the accepted primary endpoint for catheter ablation of atrial fibrillation (AF). The aim of this study was to evaluate the level of PVI by PVAC, a multipolar circular catheter utilizing bipolar/unipolar radiofrequency (RF) energy. Methods: Twenty patients with paroxysmal AF underwent PVAC ablation. PVI was validated by voltage reduction and pacing tests. Before and after RF ablation, left atrium (LA) and PV electroanatomic mapping (EAM) were performed by EnSite NavX system. Voltage abatement was considered for potentials 24mm: 9/20 (45%) vs 11/57 (19%),

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.

Pulmonary vein antrum isolation of pre-excited atrial fibrillation

Background Pulmonary vein antrum isolation （PVAI） of pre-excited atrial fibrillation （AF） is controversial. This study aimed to observe the therapeutic effects of PVAI on pre-excited AF. Methods Twenty-nine patients with pre-excited AF were prospectively divided into a PVAI group （group I, 19 cases） and a control group （group II, 10 cases）. To each case in group I, PVAI was performed, and then electroanatomical mapping of accessory pathways （AP） and ablation were constructed on a three-dimensional （3D） map of the valve annulus. Only AP ablation was performed in each case of group II. Results Of the 29 cases, three were found to have dual APs, two had intermittent APs, and the remaining 24 had single APs. All APs were successfully ablated after the procedure. There were no significant statistical differences in the AP procedure duration （（77.4±21.3） minutes vs. （85.3±13.1） minutes）, the AP ablation time （（204±34） seconds vs. （223±62） seconds） and the AP X-ray exposure time （（18.6±4.4） minutes vs. （19.1±4.5） minutes） respectively between groups I and II. As compared with the control group （5 of 10 cases, 50%）, the PVAI group had a significantly lower AF recurrence rate （2 of 19 cases, 11%; P 〈0.05） during follow-up of （20.5±10.0） months. All seven patients who recurred were successfully abolished by a second ablation. Conclusions In patients with pre-excited AF, PVAI is an effective therapeutic approach with a low AF recurrence rate. 3D electroanatomical maps of AP contributed to the high success rate of ablation without significantly prolonging of operational duration and X-ray exposure time.

改良心脏磁共振T1 mapping序列在持续心房颤动患者中的应用研究

目的分析改良采集模式T1 mapping成像序列在心房颤动成像中的应用价值。方法收集2018年1—12月首都医科大学附属北京安贞医院经临床确诊为持续性房颤同时接受心脏磁共振检查的患者50例为研究对象。扫描序列包括常规T1 mapping序列、改良T1 mapping序列、电影序列、延迟增强序列。比较患者采用常规与改良模式下T1 mapping序列所得图像的质量和测量结果的差异。房颤患者中5例接受了电复律治疗,在治疗前后各进行1次心脏磁共振检查,比较同一患者在房颤心律和窦性心律下采用改良模式扫描T1 mapping结果的准确性。结果50例持续性房颤患者,常规模式下T1 mapping增强前103幅图像的492个心肌节段和增强后123幅图像的515个节段存在伪影,明显多于改良模式下T1 mapping增强前42幅图像的168个节段和增强后59幅图像的190个节段(χ^2=189.871,P<0.01)。改良模式下扫描的左心室增强前T1值、增强后T1值和细胞外基质容积(ECV)均高于常规扫描模式(t=-4.145、-2.431、-4.049,均P<0.05)。5例接受电复律治疗的房颤患者T1 mapping结果比较显示,电复律后常规模式的T1 mapping结果与电复律前改良模式结果无明显差异(P>0.05),而电复律前常规模式T1 mapping结果各项指标明显低于电复律后常规模式的T1 mapping结果(P均<0.05)。结论对于房颤患者,改良模式可明显改善T1 mapping图像质量且结果可靠,能有效避免由于常规模式扫描导致的T1值低估情况。

Initial experience with circumferential pulmonary vein ablation guided by fusion of magnetic resonance imaging with three-dimensional electroanatomic mapping

Catheter ablation for the treatment of atrial fibrillation （AF） has been a focal target ofelectrophysiological study in recent years. Up to date, circumferential pulmonary vein ablation （CPVA） guided by three-dimensional （3-D） electreanatomic mapping （Carto, USA） has been one of the most favourable procedures for the treatment of AF. However, it is still difficult to acquire the detailed information on number, location, and branching pattern of all pulmonary veins （PVs） when the 3-D electroanatomic mapping system is used alone.

Epicardial isolation of pulmonary veins with ethanol in open chest dogs

Background Radiofrequency （RF） ablation has become a widely accepted treatment for atrial fibrillation （AF）. This study aimed to identify the efficacy and safety of pulmonary vein （PV） ablation with ethanol and to explore an alternative energy source for catheter ablation of AF. Methods Twelve open-chest mongrel dogs were randomized into ethanol ablation group and control group. Both the injections and electrophysiological mapping procedures were performed epicardialy. In ethanol ablation group （n=-6）, injections were performed to circumferentially ablate the root of each PV （0.2 ml each site, 3 mm apart） with 95% ethanol using an 1 ml injector. In control group （n=6）, saline was injected other than ethanol.