AF Ablation ITarget of ablation of peri-mitral flutter: mitral valve isthmus or triggers?Comparison of sensitivity of transthoracic, transoesophageal, and intracardiac echocardiography for guiding transeptal puncturePulmonary antrum radial-linear ablation: a new therapy for atrial fibrillationPulmonary vein isolation with a multi-electrode ablation catheter using duly-cycled bipolar and unipolar radiofrequency energyAutonomic mechanism for complex fractionated atrial electrograms: evidence by pathology

# Target of ablation of peri-mitral flutter: mitral valve isthmus or triggers? {#article-title-2} Introduction Patients with previous ablation for atrial fibrillation (AF) may experience the recurrence of peri-mitral flutter (PMFL). These arrhythmias are usually triggered from sources that may also induce atrial fibrillation. We sought to determine whether ablation of triggers or completing mitral valve isthmus (MVI) block prevents more arrhythmia recurrences. Methods A total of 65 patients with recurrent PMFL after initial ablation of long-standing persistent AF were included in the study. Thirty-two were randomized to MVI ablation only (Group 1) and 33 were randomized to cardioversion and repeat pulmonary vein (PV) isolation plus ablation of others non-PV triggers (Group 2). Results MVI bidirectional block was achieved in all but one patient from Group 1. In Group 2, reconnection of 17 PVs was detected in 14 patients (42%, 1.21 veins per patient). With isoproterenol challenge, 44 non-PV trigger sites were identified in 28 patients (85%, 1.57 sites per patient). With a follow-up of 18 months, 27 patients (84%) from Group 1 had recurrent atrial arrhythmias and 15 remained on AAD, while 28 patients from Group 2 (85%, P < 0.0001 vs. Group 1) were free of arrhythmia off AAD. Cox regression model revealed that the ablation strategy used in Group 2 was associated with a significant lower risk of recurrence of atrial tachyarrhythmia (hazard ratio = 0.10, 95% CI = 0.04–0.28, P < 0.001). The Kaplan–Meier curves demonstrated significant better arrhythmia-free survival in Group 2 compared with Group 1 (log rank P < 0.0001). Conclusions In patients presenting with PMFL after ablation for long-standing persistent AF, MVI block had limited impact on arrhythmia recurrence. On the other hand, elimination of all PV and non-PV triggers achieved higher freedom from atrial arrhythmias at follow-up. # Comparison of sensitivity of transthoracic, transoesophageal, and intracardiac echocardiography for guiding transeptal puncture {#article-title-3} Objective Compare the sensitivity of transthoracic (TTE), transoesophageal (TEE), and intracardiac (ICE) echocardiography for guiding interatrial septum (IAS) puncture. Methods The study consisted of 208 patients (48 females, mean age 56.4 ± 11.3 years) who underwent RFA of LA because of atrial fibrillation. Transeptal puncture was performed after IAS visualization using TTE in 32 (15.4%), TEE in 26 (12.5%), ICE in 150 (72.1%) patients. Adequate contact of transeptal needle with IAS was defined as a tension of septum using echocardiographic techniques. Verification of tenting and following transeptal puncture with LA catheterization was defined as a true positive result. Lack of visualization of tenting with successful transeptal puncture under fluoroscopy was defined as a false-negative result. Results Clear visualization of the IAS using TTE technique was demonstrated in 2 (6%) cases, and the sensitivity amounted for 6.7%. Obvious verification of IAS by TEE was revealed in 20 (77%) patients, and sensitivity of this technique was 86.9%. ICE control of septum puncture was performed in 127 patients. ICE allowed visualizing septum and tenting in 125 patients and the tension of septum was unable to be determined in two cases despite of the efforts of specialists. ICE sensitivity for IAS verification was 98.4%. Conclusion ICE is the most sensitive ultrasound technique for verification of optimal location of the transeptal needle in the region of IAS comparing with TTE and TEE. # Pulmonary antrum radial-linear ablation: a new therapy for atrial fibrillation {#article-title-4} The abnormality of substrates in pulmonary vein antrum (PVA) plays a critical role in maintaining atrial fibrillation (AF). PVA radial-linear ablation (PVARA) was performed for an organized modification of substrates in paroxysmal AF. This study consisted of two phases: preclinical phase using 22 canine models with acutely induced AF, and clinical phase in patients with paroxysmal AF ( n = 15) in paired control with PV isolation. Radial-linear lesions were created from PV orifice to left atrium-PV junction in both dogs and patients. Successful creation of chronic radial-linear lesions was confirmed pathologically in dogs. The AF inducibility and duration decreased by 89 and 90%, respectively, after ablation in dogs. All the patients showed inducible AF prior to the procedure. No AF was inducible immediately after PVARA in 14 patients. The procedural time was significantly shorter in patients with PVARA than PV isolation. Within 1 week after ablation, there were six patients with early recurrent AF and seven with atrial tachycardia (AT) in PVARA group, and three patients with AF and six with AT in control. During follow-up of 6–12 months, 11 patients were free of AF and AT with four patients taking propafenone or amiodarone in the PVARA group, and nine patients free of AF and AT with seven patients taking propafenone or amiodarone in control. No complication related to the ablation developed in the two groups. This pilot study demonstrated that PVARA was a simple and safe strategy for paroxysmal AF ablation, and might provide a better long-term outcome than PV isolation. # Pulmonary vein isolation with a multi-electrode ablation catheter using duly-cycled bipolar and unipolar radiofrequency energy {#article-title-5} Background Traditional catheter ablation of atrial fibrillation (AF) requires long procedure times and high level of operator skill. A multielectrode catheter (PVAC, ablation frontier) combining circular mapping and duly-cycled bipolar and unipolar radiofrequency energy delivery has been developed to map and isolate the pulmonary veins. Aim The aim of this study to evaluate the efficacy of PVAC for pulmonary vein isolation in paroxysmal AF ablation. Methods Fifty consecutive patients with paroxysmal AF who had failed at least one anti-arrhythmic drug and eligible for catheter ablation were included in the study. All four pulmonary veins were isolated and confirmed the absence of pulmonary vein potentials with PVAC. At six months, 48 h Holter monitoring was performed to determine freedom of AF. Results All patients had structurally normal hearts with a mean duration of AF of 4.28 + 4.39 years. The mean procedure time was 109.74 + 28.35 min. Mean fluoroscopy time was 36.52 + 12.29 min. Mean number of RF applications were 27.79 + 13.80 min. The mean follow-up duration was 9.39 + 4.90 months. After AF ablation with PVAC, 36 patients completed 6-month follow-up and 25 patients (69.4%) were in sinus rhythm without drugs. No procedure-related complication was observed. Conclusions Pulmonary vein isolation using the PVAC has a success rate of ∼70% with the first ablation. # Autonomic mechanism for complex fractionated atrial electrograms: evidence by pathology {#article-title-6} Background The mechanism(s) underlying complex fractionated atrial electrograms (CFAEs) has not been well elucidated. The present study addressed to observe the histological characteristics at the area with CFAEs in canine atria to investigate the mechanism of CFAEs. Methods Ten adult mongrel dogs were involved in the present study. AF was induced through rapid atrial pacing with vagosympathetic nerve stimulation. CFAEs was recorded by Lasso catheter. Irrigated ablation was performed at sites with CFAEs. After finishing procedures above, all dogs were sacrificed and the whole hearts were taken out and fixed in 4¢Hformalin for more than 48 hours for histological examination. The specimens were divided into CFAEs group and non-CFAEs group. Serial sections were taken and stained with hematoxylin and eosin(HE) and general neural marker protein gene product 9.50(PGP9.50), respectively. Compare the characteristics of myocardial and autonomic nerve distribution between the CFAEs and non-CFAEs groups. Results Sections stained by HE: The myocardium in non-CFAEs group was well-arranged, usually in parallel with little interstitial and epicardial adipose tissue. However, the myocardium in CFAEs group distributed in disorganization with more interstitial tissue and epicardial adipose tissue. Nerve fibers and ganglionated plexi (autonomic nerves) in CFAEs group were more abundant than non-CFAEs group (7±5.4 vs. 1.9±2.7; P<0.001). Autonomic nerves were abundant in epicardium. Conclusion Disorganized myocardial distribution and abundant autonomic nerves may account for CFAEs formation, which may play an important role in the initiation and maintenance of AF.