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Background Perimitral flutter (PMF) is a macro-reentrant tachycardia, and mitral isthmus (MI) linear ablation is considered to be the preferable mode of treatment. Additionally, PMF can sometimes develop via epicardial connections, including coronary sinus and vein of Marshall. However, there are no reports of three-dimensional (3D) atrial tachycardia (AT) via the intramural tissue. Case summary A 78-year-old man underwent catheter ablation for paroxysmal atrial fibrillation and AT, including pulmonary vein isolation, left atrial posterior wall isolation, superior vena cava isolation, and MI linear ablation in a total of four procedures. However, AT reoccurred, and he underwent a 5th procedure for AT. Although the MI block line was complete in both the endocardial and epicardial voltage maps, AT indicated PMF. The total activation time did not cover all phases of tachycardia cycle length due to the conduction pathway through the intramural muscle/bundles that could not be mapped with the addition of epicardial mapping. The tachycardia was terminated by ablation at the mitral valve annulus in the 2 o'clock position, where the bundles might have been attached. Discussion Both endocardial and epicardial activation maps indicated 3D-PMF, whose circuit included the intramural muscle and bundles in a tachycardia circuit. It is necessary to recognize AT, which is involved via intramural tissues. [ABSTRACT FROM AUTHOR]

Catheter ablation for persistent atrial fibrillation (PeAF) is particularly challenging, as the clinical outcomes are modest. Pulmonary vein isolation (PVI) plus linear ablation is one of the main strategies for PeAF ablation. Completely durable transmural lesions are difficult to achieve by catheter ablation during mitral isthmus ablation. The ligament of Marshall contains the vein of Marshall (VOM), myocardial tracts and innervation, and serves as arrhythmogenic foci that make it an attractive target in catheter ablation of atrial fibrillation. Additionally, it co-localizes with the mitral isthmus, and may serve as a part of the perimitral isthmus reentrant circuit. Ethanol infusion into the VOM results in rapid ablation of the neighboring myocardium and its innervation. Its incorporation into PVI significantly increases the success rate of mitral isthmus block and the clinical outcome of PeAF ablation.

Background: Left atrial flutter following atrial fibrillation (AF) ablation is increasingly common and difficult to treat. We evaluated the safety and efficacy of ablation of the anteroseptal line connecting the right superior pulmonary vein (RSPV) to the anteroseptal mitral annulus (MA) for the treatment of perimitral flutter (PMF). Methods: We systematically studied patients who were previously treated with AF ablation and who presented to the electrophysiology laboratory with atrial tachyarrhythmias between January 2000 and July 2010. The diagnosis of PMF was confirmed by activation mapping and/or entrainment. After re-isolation of any recovered pulmonary vein, a linear radiofrequency (RF) ablation was performed on the line that connected the RSPV to the anteroseptal MA. In this analysis, we included only patients who were treated with an anteroseptal line for their PMF. Results: Ablation was performed at the anteroseptal line in 27 PMF patients (63±13 years; 9 women) who had undergone prior ablation for paroxysmal (n=3) or persistent (n=24) AF, using electroanatomic activation mapping (70% CARTO, 30% NavX). The anteroseptal ablation line was effective in 22/27 (81.5%) patients in the acute-care setting. Termination of AF to sinus rhythm occurred in 15/22 (68.2%) patients, and 7/22 (31.8%) patients׳ AF converted to another right or left atrial flutter. At the 6-month follow-up, 20% of patients demonstrated recurrent left atrial tachyarrhythmia. Only one patient required repeat ablation, and the remaining patients׳ condition was controlled with antiarrhythmic medications. No major procedural complications or heart block occurred. Conclusion: Ablation at the left atrial anteroseptal line is safe and efficacious for the treatment of PMF. Unlike ablation at the traditional mitral isthmus line, ablation at the left atrial anteroseptal line does not require ablation in the coronary sinus.

The ligament of Marshall is an embryological remnant of the left superior vena cava that contains neural tissues shown to be an arrhythmogenic source of atrial fibrillation (AF). Vein of Marshall (VOM) ethanol ablation is an ablation technique that can potentially treat AF by targeting the ligament of Marshall. We report a case of a patient who developed a pro-arrhythmic effect related to VOM ethanol ablation, which manifested as a perimitral flutter., Competing Interests: The authors report no conflicts of interest for the published content. No funding information was provided., (Copyright: © 2023 Innovations in Cardiac Rhythm Management.)

Competing Interests: There is no conflict of interest declared by all the authors.

Aims: The success of mitral isthmus (MI) ablation has been related to CT scan defined MI anatomy. We sought to correlate electroanatomical MI characteristics with MI ablation success in patients with perimitral flutter (PMF). Methods and Results: In 53 consecutive patients (46 males, 61 ± 10 years) with PMF, MI was ablated with endocardial ± coronary sinus (CS) linear radiofrequency (RF) ablation lesion. Acute (termination of PMF during ablation) and long-term procedural success were studied. Mitral isthmus characteristics (thickness--minimal endocardial to CS distance, length, maximal MI bipolar voltage), as well as MI ablation line length and width, RF duration, and delivered energy were analysed. In 43 of the 53 patients (81%), acute success was observed. This was more frequently achieved in patients with thinner MI (2.4 ± 3.1 vs. 7 ± 3.2 mm; P = 0.0009). Mitral isthmus thickness predicted ablation failure with a ROC area of 0.84. The best threshold to predict MI ablation failure was 8.3 mm with a sensitivity of 67% and a specificity of 97%. Left atrial size was of greater importance in failed cases (2D echo surface: 24.1 ± 2.5 vs. 32.5 ± 6.9 cm2, P = 0.005; electroanatomic volume: 124 ± 32 vs. 165 ± 23 mL, P = 0.02). None of the other electroanatomical characteristics were associated with outcome. After a mean follow-up of 28 ± 15 months, 21 patients (39%) had atrial fibrillation (AF) or atypical flutter (PMF recurrence in four). Conclusion: Smaller MI thickness is associated with acute success in PMF ablation. Mitral isthmus electroanatomical characteristics might be used for decision-making on strategy during persistent AF ablation and for selecting the best location for interrupting PMF. [ABSTRACT FROM AUTHOR]

Background Left atrial flutter following atrial fibrillation (AF) ablation is increasingly common and difficult to treat. We evaluated the safety and efficacy of ablation of the anteroseptal line connecting the right superior pulmonary vein (RSPV) to the anteroseptal mitral annulus (MA) for the treatment of perimitral flutter (PMF). Methods We systematically studied patients who were previously treated with AF ablation and who presented to the electrophysiology laboratory with atrial tachyarrhythmias between January 2000 and July 2010. The diagnosis of PMF was confirmed by activation mapping and/or entrainment. After re-isolation of any recovered pulmonary vein, a linear radiofrequency (RF) ablation was performed on the line that connected the RSPV to the anteroseptal MA. In this analysis, we included only patients who were treated with an anteroseptal line for their PMF. Results Ablation was performed at the anteroseptal line in 27 PMF patients (63±13 years; 9 women) who had undergone prior ablation for paroxysmal ( n =3) or persistent ( n =24) AF, using electroanatomic activation mapping (70% CARTO, 30% NavX). The anteroseptal ablation line was effective in 22/27 (81.5%) patients in the acute-care setting. Termination of AF to sinus rhythm occurred in 15/22 (68.2%) patients, and 7/22 (31.8%) patients׳ AF converted to another right or left atrial flutter. At the 6-month follow-up, 20% of patients demonstrated recurrent left atrial tachyarrhythmia. Only one patient required repeat ablation, and the remaining patients׳ condition was controlled with antiarrhythmic medications. No major procedural complications or heart block occurred. Conclusion Ablation at the left atrial anteroseptal line is safe and efficacious for the treatment of PMF. Unlike ablation at the traditional mitral isthmus line, ablation at the left atrial anteroseptal line does not require ablation in the coronary sinus. [ABSTRACT FROM AUTHOR]

Background: Mitral isthmus is often targeted as a part of stepwise approach during radiofrequency ablation for persistent atrial ablation. Acute success rate in achieving the mitral isthmus block is only modest, late reconduction rate is relatively high and, consequently, incomplete lesion may be proarrhythmic. We describe the first-in-man experience with successful MI ablation by bipolar RF energy delivery.Case Presentation: A 64-year-old caucasian man after two previous ablation procedures for drug resistant atrial fibrillation in recent four years, which included pulmonary vein isolation and linear left atrial lesions, was referred for the treatment of recurrent perimitral flutter. Despite the third attempt to create bidirectional block at the mitral isthmus region, we were not even able to stop the arrhythmia by aggressive unipolar radiofrequency ablation both from the left atrium and coronary sinus, because of deeply embedded slow conducting channel probably around the vein of Marshall. Arrhythmia was finally terminated and the block was achieved by bipolar radiofrequency ablation between two irrigated-tip catheters positioned at the left atrial endocardium and contralaterally inside the coronary sinus.Conclusion: Bipolar radiofrequency energy delivery can be an option for ablation of perimitral flutter resistant to standard unipolar radiofrequency ablation. This may improve clinical outcome of patients undergoing non-pharmacological treatment for persistent atrial fibrillation. The safety and efficacy of this technique has to be confirmed in future studies. [ABSTRACT FROM AUTHOR]

Aims The modified anterior line (MAL) is an alternative to the mitral isthmus (MI) line for the treatment of perimitral atrial flutter (PMFL). We sought to investigate acute and long-term efficacy of this line if routinely used for PMFL. Methods and results The cohort included 77 consecutive patients who underwent catheter ablation of PMFL. The anterior line was deployed between the anterolateral mitral annulus and the ostium of the left superior pulmonary vein. Perimitral atrial flutter was either the presenting arrhythmia after persistent atrial fibrillation (AF) ablation (Group 1, n = 42, 54.5%), occurring during AF ablation (Group 2, n = 25, 35%) or presenting as primary arrhythmia (Group 3, n = 8, 10%). Acute success was defined as PMFL termination during MAL deployment with demonstration of bidirectional line block. Acute success was achieved in 68 of 77 patients (88%) without difference between the three groups. In five patients an additional MI line was necessary to terminate PMFL and in four patients both lines failed to achieve termination. During follow-up (16 ± 7 months), 38 of 77 (49%) patients underwent a repeat procedure for a recurrent arrhythmia. During reablation, 13 of 38 (34%) patients were identified to have a PMFL recurrence. Persistent MAL block was demonstrated in 22 of 38 (58%) patients during the repeat ablation. Conclusion The MAL is effective for acute and long-term treatment of PMFL. Maintenance of bidirectional MAL block was shown in 58% of patients during a repeat ablation. [ABSTRACT FROM PUBLISHER]

Objectives: This study hypothesized that P-wave morphology and timing under left atrial appendage (LAA) pacing change characteristically immediately upon anterior mitral line (AML) block., Background: Perimitral flutter commonly occurs following ablation of atrial fibrillation and can be cured by an AML. However, confirmation of bidirectional block can be challenging, especially in severely fibrotic atria., Methods: The study analyzed 129 consecutive patients (66 ± 8 years, 64% men) who developed perimitral flutter after atrial fibrillation ablation. We designed electrocardiography criteria in a retrospective cohort (n = 76) and analyzed them in a validation cohort (n = 53)., Results: Bidirectional AML block was achieved in 110 (85%) patients. For ablation performed during LAA pacing without flutter (n = 52), we found a characteristic immediate V 1 jump (increase in LAA stimulus to P-wave peak interval in lead V 1 ) as a real-time marker of AML block (V 1 jump ≥30 ms: sensitivity 95%, specificity 100%, positive predictive value 100%, negative predictive value 88%). As V 1 jump is not applicable when block coincides with termination of flutter, absolute V 1 delay was used as a criterion applicable in all cases (n = 129) with a delay of 203 ms indicating successful block (sensitivity 92%, specificity 84%, positive predictive value 90%, negative predictive value 87%). Furthermore, an initial negative P-wave portion in the inferior leads was observed, which was attenuated in case of additional cavotricuspid isthmus ablation. Computational P-wave simulations provide mechanistic confirmation of these findings for diverse ablation scenarios (pulmonary vein isolation ± AML ± roof line ± cavotricuspid isthmus ablation)., Conclusions: V 1 jump and V 1 delay are novel real-time electrocardiography criteria allowing fast and straightforward assessment of AML block during ablation for perimitral flutter., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)