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Background: Characteristics of multiple-loop atrial tachycardia (AT) circuits have never precisely examined., Methods: In 193 consecutive post-atrial fibrillation ablation patients with AT, 44 multiple-loop ATs including 42 dual-loop AT and 2 triple-loop AT in 41 (21.2%) were diagnosed with the high-resolution mapping system and analyzed off-line., Results: In dual-loop ATs, 3 types were identified: type M, a combination of 2 anatomic macroreentrant ATs (AMATs) in 19 (43.2%); type MN, with 1 AMAT and 1 non-AMAT in 12 (27.3%); and type N with 2 non-AMATs in 11 (25.0%). The remaining 2 triple-loop ATs (4.5%) were a combination of perimitral-, roof-dependent-, and non-AMAT. At least 1 AMAT was included in 33 (75.0%), and 1 non-AMAT in 25 (56.8%). Of the ATs with at least 1 non-AMAT circuit, a pulmonary vein formed part of the circuit in 16/25 (64.0%). The length of the common isthmus was 3.6±1.4 cm in type M, 1.6±0.7 cm in type MN, and 1.1±0.7 cm in type N ( P <0.0001). The area of the common isthmus was 12.92±7.68, 2.46±1.53, and 0.90±0.81 cm 2 , in Type M, MN, and N ( P <0.0001). The narrowest width of the common isthmus was 1.8±0.7 cm, 1.1±0.3 cm, and 0.7±0.3 cm in type M, MN, and N ( P <0.0001), respectively. The electrograms in the common isthmus showed longer duration and lower voltage in type N, type MN, and type M (duration: 106±25 ms, 87±27 ms, and 69±27 ms; P =0.006; and voltage: 0.06±0.02 mV, 0.22±0.21 mV, and 0.57±0.50 mV; P <0.0001), respectively., Conclusions: Multiple-loop ATs are complex, frequently including anatomic circuits. They have specific characteristics determined by the combination of AMAT and non-AMAT., (© 2018 American Heart Association, Inc.)

Objectives: This study prospectively evaluated the role of a novel 3-dimensional, noninvasive, beat-by-beat mapping system, Electrocardiographic Mapping (ECM), in facilitating the diagnosis of atrial tachycardias (AT)., Background: Conventional 12-lead electrocardiogram, a widely used noninvasive tool in clinical arrhythmia practice, has diagnostic limitations., Methods: Various AT (de novo and post-atrial fibrillation ablation) were mapped using ECM followed by standard-of-care electrophysiological mapping and ablation in 52 patients. The ECM consisted of recording body surface electrograms from a 252-electrode-vest placed on the torso combined with computed tomography-scan-based biatrial anatomy (CardioInsight Inc., Cleveland, Ohio). We evaluated the feasibility of this system in defining the mechanism of AT-macro-re-entrant (perimitral, cavotricuspid isthmus-dependent, and roof-dependent circuits) versus centrifugal (focal-source) activation-and the location of arrhythmia in centrifugal AT. The accuracy of the noninvasive diagnosis and detection of ablation targets was evaluated vis-à-vis subsequent invasive mapping and successful ablation., Results: Comparison between ECM and electrophysiological diagnosis could be accomplished in 48 patients (48 AT) but was not possible in 4 patients where the AT mechanism changed to another AT (n = 1), atrial fibrillation (n = 1), or sinus rhythm (n = 2) during the electrophysiological procedure. ECM correctly diagnosed AT mechanisms in 44 of 48 (92%) AT: macro-re-entry in 23 of 27; and focal-onset with centrifugal activation in 21 of 21. The region of interest for focal AT perfectly matched in 21 of 21 (100%) AT. The 2:1 ventricular conduction and low-amplitude P waves challenged the diagnosis of 4 of 27 macro-re-entrant (perimitral) AT that can be overcome by injecting atrioventricular node blockers and signal averaging, respectively., Conclusions: This prospective multicenter series shows a high success rate of ECM in accurately diagnosing the mechanism of AT and the location of focal arrhythmia. Intraprocedural use of the system and its application to atrial fibrillation mapping is under way., (Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Introduction: Persistent atrial fibrillation (AF) ablation may lead to partial disconnection of the coronary sinus (CS). As a result, disparate activation sequences of the local CS versus contiguous left atrium (LA) may be observed during atrial tachycardia (AT). We aimed to evaluate the prevalence of this phenomenon and its impact on activation mapping., Methods: AT occurring after persistent AF ablation were investigated in 74 consecutive patients. Partial CS disconnection during AT was suspected when double potentials with disparate activation sequences were observed on the CS catheter. Endocardial mapping facing CS bipoles was performed to differentiate LA far-field from local CS potentials., Results: A total of 149 ATs were observed. Disparate LA-CS activations were apparent in 20 ATs after magnifying the recording scale (13%). The most common pattern (90%) was distal to proximal endocardial LA activation against proximal to distal CS activation, the latter involving the whole CS or its distal part. Perimitral macroreentry was more common when disparate LA-CS activations were observed (67% vs 29%; P = 0.002). Partial CS disconnection also resulted in "pseudo" mitral isthmus (MI) block during LA appendage pacing in 20% of patients as local CS activation was proximal to distal despite distal to proximal activation of the contiguous LA., Conclusion: Careful analysis of CS recordings during AT following persistent AF ablation often reveals disparate patterns of activation. Recognizing when endocardial LA activation occurs in the opposite direction to the more obvious local CS signals is critical to avoid misleading interpretations during mapping of AT and evaluation of MI block., (© 2012 Wiley Periodicals, Inc.)

Background: Achievement of complete conduction block across left mitral isthmus (MI) is a challenging endpoint of linear lesion, and recognizing the precise moment of block is important during ongoing ablation. The objective of this study is to evaluate the changes in P wave morphology and local MI potential at the moment of block during ongoing radiofrequency (RF) application., Methods and Results: We evaluated 69 patients (procedures) in whom successful MI linear conduction block was achieved during coronary sinus (CS) pacing. P wave morphology and/or local MI potential could be evaluated in 64 (93%) and 69 (100%) procedures, respectively. The achievement of MI block was associated with substantial instantaneous changes in 57/69 (82.6%) procedures. P wave morphology changed in 44 (64%) procedures with the change restricted to lateral leads in 39 (57%). Abrupt prolongation of local conduction delay from 106 ± 24 ms to 167 ± 39 ms (P < 0.0001) was observed on proximal bipole of ablation catheter in 34/69 (49.3%) procedures during ongoing RF application. In addition, prolongation of conduction delay was associated with significant change in the electrogram amplitude and polarity in 11 and 19 procedures, respectively. The substantial change in P wave morphology was not observed in any patients without achievement of complete block., Conclusions: The achievement of conduction block across MI line is associated with recognizable changes in the local MI electrograms and the P wave morphology especially in the lateral leads. These instantaneous critical changes may assist catheter ablation and indicate the requirement for prolonged RF application, if necessary., (© 2011 Wiley Periodicals, Inc.)