The Modified Anterior Line: An Alternative Linear Lesion in Perimitral Flutter

Modified Anterior Line for Perimitral Flutter. Introduction: Ablation of left atrial flutter (LAF) is often limited by the need for technically demanding linear lesions. We evaluated the safety and efficacy of a new modified anterior line (MAL), connecting the anterior/anterolateral mitral annulus with the left superior pulmonary vein for ablation of perimitral flutter. Methods and Results: MAL was performed in 65 patients (15 females, age 63.6 ± 9.8 years) with perimitral flutter using 3D mapping systems (70.8% Carto, 29.2% NavX). Perimitral flutter was either the presenting arrhythmia (73.8%) or an intermediate organized rhythm during atrial fibrillation ablation. Follow‐up included repetitive 7‐day Holter with 93.8% of patients off antiarrhythmics. MAL was acutely effective in 63/65 patients (96.9%). Termination to sinus rhythm occurred in 36 of 65 patients (55.4%), and in 27 of 65 patients (41.5%) there was a change to another LAF type. Bidirectional block across the MAL was achieved in 56 of 65 patients (86.1%). After 6 months of follow‐up, 20 of 41 patients (48.8%) had a LAF recurrence, with 6 patients undergoing a reablation. In all redo patients the MAL was still complete and LAF mechanism was different to the initially targeted. No major complication occurred during the ablation procedures or in the postablation period. Conclusion: The MAL is a safe and effective linear lesion for the treatment of perimitral LAF. Its value compared to more established linear lesions as the mitral isthmus line has to be evaluated in larger studies. (J Cardiovasc Electrophysiol, Vol. 21, pp. 665‐670, June 2010)     

Macroreentrant Atrial Tachycardia in Patients without Previous Atrial Surgery or Catheter Ablation: Clinical and Electrophysiological Characteristics of Scar‐Related Left Atrial Anterior Wall Reentry

Scar‐Related Left Atrial Anterior Wall Reentry. Introduction: Macroreentrant atrial tachycardia (MRAT) has been described most frequently in patients with prior cardiac surgery. Left atrial tachycardia and flutter are common in patients who undergo atrial fibrillation ablation; however, few reports describe left atrial MRAT involving the regions of spontaneous scarring. Here, we describe left atrial MRAT in patients without prior cardiac surgery or catheter ablation (CA) and discuss the clinical and electrophysiological characteristics of tachycardia and outcome of CA. Methods and Results: An electrophysiological study and CA were performed in 6 patients (3 men; age 76 ± 6 years) with MRAT originating from the left atrial anterior wall (LAAW). No patient had a history of cardiac surgery or CA in the left atrium. Spontaneous scars (areas with bipolar voltage ≤ 0.05 mV) were observed in all patients. The activation map showed a figure‐eight circuit with loops around the mitral annulus (4 counterclockwise and 2 clockwise) and a low‐voltage area with LAAW scarring. The mean tachycardia cycle length was 303 ± 49 milliseconds. The conduction velocity was significantly slower in the isthmus between the scar in the LAAW and the mitral annulus than in the lateral mitral annulus (0.17 ± 0.05 m/s vs 0.94 ± 0.35 m/s; P = 0.003). Successful ablation of the isthmus caused interruption of the tachycardia and rendered it noninducible in all patients. Conclusion: Spontaneous LAAW scarring is an unusual cause of MRAT, showing activation patterns with a figure‐eight configuration. Radiofrequency CA is a feasible and effective treatment in such cases. (J Cardiovasc Electrophysiol, Vol. 24, pp. 404‐412, April 2013)     

Bundle Branch Reentry Ventricular Tachycardia:

Bundle Branch Reentry VT. We describe a patient with bundle branch reentry ventricular tachycardia with 1:1 VA conduction in whom resetting was performed while obtaining simultaneous recordings from the right ventricular apex (V) and His-bundle electrogram. Both the tachycardia return cycle and the V-His interval demonstrated an increasing reset response, while the His-V interval demonstrated a flat reset response. These reset responses are consistent with a partially excitable gap localizing to the V-His portion of the bundle branch reentry circuit.     

DDD-Pacing-Induced Cardiomyopathy Following AV Node Ablation for Persistent Atrial Tachycardia

Ventricular rate control by catheter ablation of the AV node and pacing in patients with persistent atrial tachycardia has been reported to improve left ventricular function. However, this approach requires careful selection of the pacing mode. We report a patient who underwent AV node ablation for persistent multiple atrial tachycardias, and who then had a non-mode-switching pacemaker implanted. Because of an inappropriately programmed relatively high upper rate limit, the patient developed left ventricular dysfunction after 6 years. This resolved after programming the pacemaker to VVI at 70 bpm.     

Catheter Ablation of Atrial Tachycardia Following Atrial Fibrillation Ablation

Atrial tachycardias represent the second front of atrial fibrillation (AF) ablation. They are frequently encountered during the index ablation for patients with persistent AF and are common following ablation of persistent AF, occurring in half of all patients who have had AF successfully terminated. An atrial tachycardia is rightly seen as a failure of AF ablation, as these tachycardias are poorly tolerated by patients. This article describes a simple, practical approach to diagnosis and ablation of these atrial tachycardias.     

Bundle Branch Reentry Tachycardia and Possible Sustained Interfascicular Reentry Tachycardia with a Shared Unusual Induction Pattern

Bundle Branch Reentry and Interfascicular Reentry. A case of bundle branch reentry tachycardia with an unusual induction pattern is presented. Unlike typical cases of this arrhythmia in which tachycardia is usually inducible with routine programmed ventricular stimulation and/or short-long sequences, tachycardia in this case was inducible only with atrial stimulation. It also arose spontaneously during atrial flutter and during isoproterenol administration. After ablation of the right bundle, possible interfascicular reentry tachycardia with a similar induction pattern was observed. This tachycardia was successfully ablated in the region of the posterior fascicle of the left bundle branch.     

An Anterior Ablation Line Is Preferred for Perimitral Flutter After Heart Transplant

Perimitral atrial flutter in cardiac allograft recipients is uncommon. In general, mitral isthmus ablation can be quite challenging in all patients with perimitral flutter, including the subset of patients who present following left atrial ablation for atrial fibrillation. We report 2 cases where an anterior ablation line was easily performed to eliminate perimitral flutter and produce bidirectional block. (J Cardiovasc Electrophysiol, Vol. 21, pp. 574‐576, May 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.     

Cure of Interfascicular Reentrant Ventricular Tachycardia by Ablation of the Anterior Fascicle of the Left Bundle Branch

Ablation of Interfascicular Reentrant Tachycardia. Introduction: Fascicular reentrant ventricular tachycardia (VT) using the anterior fascicle of the left bundle anterogradely is rare and may produce identical QRS morphology during sinus rhythm and VT. Catheter ablation of this type of VT has not been described in detail.
Methods and Results: In a postinfarct patient with dilated left ventricle and recurrent VT (showing a QRS configuration of right bundle branch, left posterior fascicular block), endocardial recordings from the His-Purkinje system showed that VT was due to interfascicular reentry. Induction of VT occurred after progressive retrograde conduction delay on increasing the prematurity of the extrastimulus. Anterograde conduction occurred exclusively over the left anterior fascicle, which caused identical QRS morphology during sinus rhythm and VT. During VT, the left posterior fascicle was used retrogradely. The usual target for bundle branch reentry ablation, the right bundle, did not participate in the reentrant circuit. While performing left ventricular endocardial mapping, VT was interrupted when positioning the catheter on the left anterior fascicle, and "reversed" nonsustained bundle branch reentry occurred with anterograde conduction over the posterior fascicle and retrograde conduction over the anterior fascicle. Ablation of conduction in the anterior fascicle led to cure of the VT.
Conclusion: Interfascicular reentrant VT with right bundle branch block, right-axis QRS configuration can be cured by catheter ablation of anterior fascicle conduction.     

Tachycardia transition during ablation of persistent atrial fibrillation

Tachycardia Transition . Background: The “sequential ablation” strategy for persistent AF is aimed at progressive organization of AF until the rhythm converts to sinus rhythm or atrial tachycardia (AT). During ablation of an AT, apparently seamless transitions from one organized AT to another occur. The purpose of our study was to quantify the occurrence and the mechanism of this transition. Methods and Results: Twenty‐nine of 90 patients undergoing ablation for persistent AF had multiple AT during the procedure and constitute the study group. Thirty‐nine direct transitions from one AT to another during ablation were observed classified in four types: type I (79.4%), i.e., a direct transition of a faster to a slower tachycardia without significant intervening pause; type II (7.69%)—transition after intervening ectopy or longer pause; type III (10.26%)—A slower AT accelerated; type IV (2.56%)—alteration of activation sequence but with no change on CL. Conclusions: Transition to a second AT occurs frequently in the midst of ablation of AT in persistent AF patients. This transition occurs most commonly abruptly within the range of a single cycle length of the original AT. This is best explained by a continuation of AT that was “present” simultaneously with the pretransition tachycardia, being “entrained” (for a reentrant tachycardia) or “overdriven” for an automatic focal tachycardia. The presence of multiple tachycardia mechanisms active simultaneously would be consistent with the eclectic pathophysiology of persistent AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 506‐512 May 2011)     

Catheter Ablation of the Left Bundle Branch for the Treatment of Sustained Bundle Branch Reentrant Ventricular Tachycardia

Sustained Bundle Branch Reentrant VT. Radiofrequency catheter ablation of the left bundle branch (LBB) was attempted in a patient with sustained bundle branch reentry. During sinus rhythm, the QRS had a complete LBB block pattern, and the LBB was activated retrogradely (transseptal). Ablation of the LBB eliminated inducibility of the tachycardia, while the QRS complex and the duration of the HV interval (70 msec) remained unchanged. Successful ablation of the LBB eliminated bundle branch reentry and yet maintained the anterograde conduction properties of the His-Purkinje system, obviating implantation of a permanent pacemaker.     

A Deductive Mapping Strategy for Atrial Tachycardia Following Atrial Fibrillation Ablation: Importance of Localized Reentry

Background: Atrial tachycardia (AT) occurring following catheter ablation of persistent atrial fibrillation (AF) may be challenging to map and ablate because their mechanism and location is unpredictable and may be multiple in an individual patient.
Methods and Results: A prospective cohort of 128 consecutive patients presenting 246 AT in the context of prior AF ablation was investigated. Using activation and entrainment mapping and applying the consensus definition of AT, we evaluated a deductive diagnostic approach based on up to three steps: (1) cycle length regularity, (2) search for macroreentry (i.e., involving >2 separate atrial segments), and (3) if macroreentry excluded, search for focal origin giving a centrifugal activation of the atria. A total of 238/246 (97%) sustained AT (mean cycle length [CL] 284 ± 87 ms) were successfully mapped (single AT, 51 pts; multiple AT, 77 pts) with a diagnostic time of 10 ± 8 min per tachycardia. AT were macroreentrant in 109 (46%) and focal in 129 (54%). Of the latter, only 34 focal AT originated from a discrete point site fulfilling the consensus criteria, while a distinct mechanism, localized reentry (AT that was neither macro reentry nor focal), was identified in 95. Localized reentry was defined by (1) electrograms covering ≥75% of the cycle length of AT within an area covering a single or 2 contiguous segments, (2) postpacing interval (PPI) < 30 ms at the site, (3) an identifiable zone of slow conduction, and (4) centrifugal activation of the atrium from the area.
Conclusions: This prospective study demonstrates the feasibility of rapid and accurate identification of all types of postablation AT in a large cohort of patients and describes the dominant role of localized reentry as a novel mechanism of AT.     

Atrioventricular Nodal Reentrant Tachycardia with Paroxysmal Atrial Fibrillation: Clinical and Electrophysiological Features and Predictors of Atrial Fibrillation Recurrence Following Elimination of Atrioventricular Nodal Reentrant Tachycardia

Introduction: Clinical and electrophysiological characteristics of patients with atrioventricular nodal reentrant tachycardia (AVNRT) and paroxysmal atrial fibrillation (AF) have not been studied in a large patient cohort. We aimed to define the clinical features and cardiac electrophysiological characteristics of these patients, and to examine the incidence and identify predictors of AF recurrences after elimination of AVNRT. Methods and Results: Thirty-six patients with AVNRT and documented paroxysmal AF (Group 1) and 497 patients with AVNRT alone undergoing ablation in the same period (Group 2) were studied. There were no significant differences between groups regarding clinical features, except age, which was higher in Group 1 (p < 0.001). Presence of atrial vulnerability (induction of AF lasting > 30 seconds) and multiple AH jumps (≥50 ms) before ablation were significantly more prevalent in Group 1 (p < 0.001, p = 0.010 respectively). During follow-up of 34 ± 11 months, AF recurred in 10 patients (28%) in Group 1, while 2 patients in Group 2 (0.4%) developed paroxysmal AF (p < 0.001). Univariate predictors of AF were: left atrial diameter > 40 mm (p = 0.001), presence of mitral or aortic calcification (p = 0.003), atrial vulnerability after ablation (p = 0.015) and valvular disease (p = 0.042). However, independent predictors of AF recurrences were left atrial diameter > 40 mm (p = 0.002) and the presence of atrial vulnerability after ablation (p = 0.034). Conclusion: In patients with both AVNRT and paroxysmal AF, the recurrence rate of AF after elimination of AVNRT is 28%. Left atrial diameter greater than 40 mm and atrial vulnerability after elimination of AVNRT are independent predictors of AF recurrences in the long term.     

Outcome of Ablation for Sustained Focal Atrial Tachycardia in Patients With and Without a History of Atrial Fibrillation

Objectives: The aim of this study was to determine the long-term results of ablation for sustained focal atrial tachycardia in patients with and without a history of atrial fibrillation.Methods: A history of atrial fibrillation was documented in 25 of 111 patients (23%) with focal atrial tachycardias. We studied the results of focal ablation during a follow-up of 27 ± 22 months.Results: Enlargement of left atrium (Odds ratio 2.99) and septal origin of the atrial focus (Odds ratio 5.68) were independent predictors of coexisting atrial fibrillation. Patients with a septal origin of the focal atrial tachycardia were older (62 vs. 54 years) and had a higher rate of structural heart disease than patients with a non-septal site of origin (51 vs. 29%). A higher rate of atrial fibrillation was found in patients with anteroseptal (56%), midseptal (50%) and posteroseptal (36%) atrial tachycardias than in patients with focal atrial tachycardias arising from the crista terminalis (9%), the tricuspid (12%) and mitral annulus (0%), the ostia of thoracic veins (17%) and other right atrial (27%) and left atrial free wall sites (10%). During the follow-up, atrial fibrillation was documented in 3% of patients without preexisting atrial fibrillation. In patients with focal atrial tachycardia and a history of atrial fibrillation, at least one episode of atrial fibrillation was documented during follow-up in 64% of patients, but 60% of patients reported marked symptomatic improvement.Conclusion: An increased rate of coexisting atrial fibrillation was found in patients with a septal origin of focal atrial tachycardia. Ablation of the focal atrial tachycardia may eliminate both arrhythmias, but patients with a history of atrial fibrillation may still be prone to recurrences of atrial fibrillation after focal ablation.     

心房颤动导管消融术后快速性房性心律失常的机制和治疗

随着心房颤动导管消融治疗的日益广泛开展,导管消融术后快速性房性心律失常（即继发性房性心律失常,包括房性心动过速和心房扑动）逐渐成为临床心律失常治疗的关注热点,其机制在不同患者中不尽相同,甚至同一患者亦可涉及多种机制,因此这种心律失常的处理可能较心房颤动本身更为棘手。现就心房颤动导管消融术后发生快速性房性心律失常的可能机制及其防治策略作一综述。     

Induced Atrial Tachycardia After Circumferential Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation: Electrophysiological Characteristics and Impact of Catheter Ablation on the Follow-Up Results

Introduction: Atrial tachycardia (AT), including focal and reentrant AT, can occur after circumferential pulmonary vein isolation (CPVI). The aim of this study was to investigate the electrophysiological characteristics of induced AT and its clinical outcome.
Methods and Results: In our series of 160 patients with paroxysmal atrial fibrillation (AF), 45 ATs were induced by high-current burst pacing after CPVI in 26 patients. All induced ATs were mapped using a three-dimensional ( 3D) mapping system. Noninducibility was the endpoint of the ablation of the AT. Gap-related AT was considered if the AT was related to the CPVI lesions. A 16-slice multidetector computed tomography scan was performed in all patients to correlate the anatomical structure with electroanatomical mapping. Thirty-five (78%) reentrant ATs and 10 (22%) focal ATs were identified. Of those, 34 were gap-related ATs (24 reentrant and 10 focal ATs). Reentrant AT had more gaps in the left atrial appendage ridge than did focal AT (39.6% vs 0%, P = 0.02). Focal AT had a higher incidence of gap in the PV carina compared with reentrant AT (80% vs 10%, P < 0.001). Reentrant ATs were mostly terminated during the ablation creating the mitral and roof lines with crossing of the gaps. During a mean follow-up of 21 ± 8 months, only one patient (0.6%) with induced mitral reentry had a recurrent AT.
Conclusion: The location of the AT gap may be related with the complex anatomy of the LA. The induced ATs after CPVI can be eliminated by catheter ablation.