Ligament and vein of Marshall: A therapeutic opportunity in atrial fibrillation

The autonomic nerves around the vein of Marshall: a postmortem study with clinical implications

This study aims to analyze the vein of Marshall (VOM) in human autopsy hearts and its correlation with clinical data to elucidate the morphological substrates of atrial fibrillation (AF) and other cardiac diseases. Twenty-three adult autopsy hearts were studied, assessing autonomic nerves by immunohistochemistry with tyrosine hydroxylase (sympathetic nerves), choline acetyltransferase (parasympathetic nerves), growth-associated protein 43 (neural growth), and S100 (general neural marker) antibodies. Interstitial fibrosis was assessed by Masson trichrome staining. Measurements were conducted via morphometric software. The results were correlated with clinical data. Sympathetic innervation was abundant in all VOM-adjacent regions. Subjects with a history of AF, cardiovascular cause of death, and histologically verified myocardial infarction had increased sympathetic innervation and neural growth around the VOM at the mitral isthmus. Interstitial fibrosis increased with age and heart weight was associated with AF and cardiovascular cause of death. This study increases our understanding of the cardiac autonomic innervation in the VOM area in various diseases, offering implications for the development of new therapeutic approaches targeting the autonomic nervous system.

Vein of Marshall chemical ablation decreases atrial fibrillation drivers detected by CARTOFINDER

INTRODUCTION

This study sought to elucidate the impact of vein of Marshall (VOM) chemical ablation on atrial fibrillation (AF) drivers by investigating the changes in CARTOFINDER mappings before and after VOM chemical ablation in patients with persistent AF.

METHODS

This study included 23 consecutive patients undergoing catheter ablation for long-persistent AF (>18 months). VOM chemical ablation was performed following pulmonary vein isolation. CARTOFINDER and AF cycle length (AFCL) maps were created in the left atrium (LA) before and after VOM chemical ablation. The LA was divided into 8 segments, and the number of focal activation points with 6 or more repetitions was counted in each segment.

RESULTS

The number of focal activation points was largest in the LA appendage (LAA). After VOM chemical ablation, the number of focal activation points in the LA decreased significantly (37 [interquartile range, IQR: 19-55] vs. 15 [IQR: 7-21], p < .001), and median AFCL was significantly prolonged (159 [147-168] vs. 164 [150-173] ms, p < .001). In the assessment of each segment, significant decreases in focal activation points were observed in the inferior, lateral, and anterior segments and LAA. Among the focal activation points disappearing after chemical ablation, the number in the non-ethanol-affected area was significantly larger than that in the affected area (13 [8-25] vs. 4 [1-10], p < .001).

CONCLUSIONS

VOM chemical ablation decreases AF drivers detected by CARTOFINDER. Mechanisms other than direct myocardial damage are considered to contribute the attenuation of AF drivers.

Vein of Marshall Ethanol Infusion for AF Ablation; A Review

The outcomes of persistent atrial fibrillation (AF) ablation are modest with various adjunctive strategies beyond pulmonary vein isolation (PVI) yielding largely disappointing results in randomised controlled trials. Linear ablation is a commonly employed adjunct strategy but is limited by difficulty in achieving durable bidirectional block, particularly at the mitral isthmus. Epicardial connections play a role in AF initiation and perpetuation. The ligament of Marshall has been implicated as a source of AF triggers and is known to harbour sympathetic and parasympathetic nerve fibres that contribute to AF perpetuation. Ethanol infusion into the Vein of Marshall, a remnant of the superior vena cava and key component of the ligament of Marshall, may eliminate these AF triggers and can facilitate the ease of obtaining durable mitral isthmus block. While early trials have demonstrated the potential of Vein of Marshall 'ethanolisation' to reduce arrhythmia recurrence after persistent AF ablation, further randomised trials are needed to fully determine the potential long-term outcome benefits afforded by this technique.

Efficiency and Durability of EIVOM on Acute Reconnection After Mitral Isthmus Bidirectional Block

BACKGROUND

Reconnection after mitral isthmus (MI) block with radiofrequency ablation is common.

OBJECTIVES

The aim of this study was to investigate the effects of ethanol infusion in the vein of Marshall (EIVOM) on acute reconnection after MI bidirectional block.

METHODS

Patients with persistent atrial fibrillation who were scheduled to receive radiofrequency ablation for the first time were randomly assigned to the radiofrequency catheter ablation (RFCA) group (n = 44) or the EIVOM group (n = 45). The RFCA group's strategy was bilateral pulmonary vein ablation and linear ablation; in the EIVOM group, EIVOM was performed first. The primary endpoint was acute reconnection 30 minutes after MI bidirectional block.

RESULTS

A total of 89 patients (average age 62.9 years; 57.3% male) were enrolled. The average duration for persistent atrial fibrillation was 2.3 years. Before observation, all patients in the EIVOM group achieved MI bidirectional block (45 of 45 [100%]), compared with 84.1% (37 of 44) in the RFCA group. After the observation, 3 cases of MI reconnection occurred in the EIVOM group and 13 cases in the RFCA group (6.7% vs 35.1%; P < 0.05). After additional ablation, the final MI block rates in the EIVOM and RFCA groups were 97.8% (44 of 45) and 72.7% (32 of 44), respectively. During a 1-year follow-up, 8 of 45 patients who underwent EIVOM had recurrent atrial fibrillation, compared with 14 of 44 in the RFCA group (17.8% vs 31.8%; P < 0.01).

CONCLUSIONS

EIVOM can reduce acute reconnection after MI bidirectional block and significantly increase first-pass MI block.

Use of intracardiac echocardiography in vein of Marshall ethanol infusion for ablation of persistent atrial fibrillation

BACKGROUND

Few methods have been reported to demonstrate real-time effects during vein of Marshall (VOM) ethanol infusion in persistent atrial fibrillation (PeAF).

OBJECTIVE

This study was to evaluate the impact of left atrial (LA) monitoring using intracardiac echocardiography (ICE) during VOM ethanol infusion.

METHODS

Seventy-four consecutive patients with PeAF who underwent VOM ethanol infusion followed by radiofrequency (RF) ablation were included. Patients with findings on ICE consistent with echogenic streaming in the LA and with increased myocardial local echogenicity along the VOM area were placed into one group (group A) and those without into the other group (group B). Outcomes between the 2 groups were compared.

RESULTS

Forty-six patients (62%) were placed into group A. A new ethanol-induced low-voltage area in group A was larger than that in group B (8.5 cm2 [5.5-10.2 cm2] and 4.0 cm2 (2.4-6.3 cm2]; P < .001). The RF ablation time required to achieve MI block was reduced in group A patients (263.0 seconds [196.0-351.0 seconds] vs 417.0 seconds [315.0-709.5 seconds] in group B patients; P < .001). MI block was achieved in 46 patients (100%) via an endocardial approach in group A and 27 patients (96.4%) in group B (extra coronary sinus ablation in 4 patients). One patient developed clinically significant pericardial effusions and required pericardiocentesis in group B.

CONCLUSION

Presence of increased myocardial local echogenicity at the ridge and consistent echogenic streaming in the LA detected by ICE-based imaging during VOM ethanol infusion suggests increased ablated tissue in that region and lower RF ablation time during ablation for PeAF.

Efficacy and safety of the vein of Marshall ethanol infusion with radiofrequency catheter ablation for the treatment of persistent atrial fibrillation in elderly patients

Background

Increasing age is a significant risk factor for atrial fibrillation (AF) recurrence after catheter ablation (CA). We accomplished this study to evaluate the efficacy and safety of the vein of Marshall (VOM) ethanol infusion (VOM-EI) with CA in elderly patients with persistent AF (PsAF).

Methods

This retrospective observational study included 360 consecutive adult patients with PsAF, of which 141 were in the Elder group (age ≥65 years) and 219 were in the Younger group (age <65 years), who underwent the VOM-EI and radiofrequency CA (RFCA) between May 2020 and April 2022. The efficacy endpoint was no recurrence of AF within one year after CA.

Results

The VOM-EI was successfully performed in 90.8% of patients from the Elder and 88.6% from the Younger group. All patients achieved PVI; 97.9% of patients from the Elder and 98.6% from the Younger group reached LA roof block, and 93.6% of patients from the Elder and 95.9% from the Younger group achieved MI block. There was no significant difference in 1-year survival without recurrence of AF between the two groups (83.0% and 84.5%, respectively). The incidence of complications within 30 days after the procedure from the two groups was low and did not differ significantly.

Conclusion

The VOM-EI combined with RFCA proved to be an effective and safe strategy for treating PsAF in elderly and younger patients.

Pro-arrhythmic Effect of the Vein of Marshall Ethanol Ablation: A Case Report of Perimitral Flutter After Vein of Marshall Ethanol Ablation

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.

Selection of patients for hybrid ablation procedure

Catheter ablation for treatment of symptomatic non-paroxysmal atrial fibrillation remains challenging. Clinical failure and need for continued medical therapy or repeat ablation is common, especially in more advanced forms of atrial fibrillation. Hybrid ablation has emerged as a more effective and safe therapy than endocardial-only ablation particularly for longstanding persistent atrial fibrillation as demonstrated by the randomized controlled CONVERGE trial. Hybrid ablation requires collaboration of electrophysiologists and cardiac surgeons to develop specific workflows. This review describes the Hybrid Convergent approach in the context of available ablation options and offers guidance for workflow development and patient selection.

Neuromodulation therapy for atrial fibrillation

Atrial fibrillation has a multifactorial pathophysiology influenced by cardiac autonomic innervation. Both sympathetic and parasympathetic influences are profibrillatory. Innovative therapies targeting the neurocardiac axis include catheter ablation or pharmacologic suppression of ganglionated plexi, renal sympathetic denervation, low-level vagal stimulation, and stellate ganglion blockade. To date, these therapies have variable efficacy. As our understanding of atrial fibrillation and the cardiac nervous system expands, our approach to therapeutic neuromodulation will continue evolving for the benefit of those with AF.

Optimization of intra-operative electrophysiological localization of the ligament of Marshall

Background

The ligament of Marshall (LOM) may play a role in the pathophysiology of several tachyarrhythmias and accurate electrophysiological localization of this structure is crucial for effective ablation therapy. This study therefore quantifies electrophysiological properties of the LOM, and identifies which electrogram (EGM) recording (uni- or bipolar) and processing technologies [local activation time (LAT) and/or voltage mapping] are most suitable for accurate localization of the LOM.

Methods

The LOM was electrophysiologically identified in 19 patients (mean age 66 ± 14 years; 12 male) undergoing elective cardiac surgery using intra-operative high-density epicardial mapping, to quantify and visualize EGM features during sinus rhythm.

Results

Only a third of LOM potentials that were visualized using unipolar EGMs, were still visible in bipolar activation maps. Unipolar LOM potentials had lower voltages (P50: LOM: 1.51 (0.42–4.29) mV vs. left atrium (LA): 8.34 (1.50–17.91) mV, p < 0.001), less steep slopes (P50: LOM: –0.48 (–1.96 to –0.17) V/s vs. LA: –1.24 (–2.59 to –0.21) V/s, p < 0.001), and prolonged activation duration (LOM: 20 (7.5–30.5) ms vs. LA: 16.5 (6–28) ms, p = 0.008) compared to LA potentials. Likewise, bipolar LOM voltages were also smaller (P50: LOM: 1.54 (0.48–3.28) mV vs. LA: 3.12 (0.50–7.19) mV, p < 0.001).

Conclusion

The LOM was most accurately localized in activation and voltage maps by using unipolar EGMs with annotation of primary deflections in case of single potentials and secondary deflections in case of double or fractionated potentials.

Ethanol Infusion of Vein of Marshall for the Treatment of Persistent Atrial Fibrillation: The Basics and Clinical Practice

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.

Anatomical variations in Coronary Venous Drainage: Challenges and Solutions in Delivering Cardiac Resynchronisation Therapy

AIMS

To investigate the abnormalities of the coronary venous system in candidates for cardiac resynchronization therapy (CRT) and describe methods for circumventing the resulting difficulties.

METHODS

From 4 implanting institutes, data of all CRT implants between October 2008-October 2020 were screened for abnormal cardiac venous anatomy, defined as an anatomical variation not conforming to the accepted 'normal' anatomy. Patient demographics, procedural detail and subsequent left ventricle (LV) lead pacing indices were collected.

RESULTS

From a total of 3548 CRT implants, 15 (0.42%) patients (80% male) of 72.2±10.6 years in age with a LV ejection fraction of 34±10.3% were identified to have had an abnormal cardiac venous anatomy over the study period. There were 13 cases of persistent left side superior vena cava (pLSVC), 5 of which had coronary sinus ostium atresia (CSOA) including 2 with an 'unroofed' coronary sinus (CS); 1 patient had a unique anomalous origin of the CS and 1 patient had an isolated CSOA. In total 14 patients (60% repeat attempt) had successful percutaneous implant under general anaesthesia (46.7%) via the cephalic vein (59.1%), using the femoral approach (53.3%) for levophase venography and/or pull-through, including 1 case of endocardial LV implant. Pacing follow-up over 37.64±37.6 months demonstrated LV lead threshold between 0.62-2.9 volts (pulsewidth 0.4-1.5 milliseconds) in all cases; 5 patients died within 2.92±1.6 years of successful implant.

CONCLUSION

CRT devices can be implanted percutaneously even in the presence of substantial abnormalities of coronary venous anatomy. Alternative routes of venous access may be required. This article is protected by copyright. All rights reserved.

Innovations in atrial fibrillation ablation

BACKGROUND

Catheter-based ablation to perform pulmonary vein isolation (PVI) has established itself as a mainstay in the rhythm control strategy of atrial fibrillation. This review article aims to provide an overview of recent advances in atrial fibrillation ablation technology.

METHODS

We reviewed the available literature and clinical trials of innovations in atrial fibrillation ablation technologies including ablation catheter designs, alternative energy sources, esophageal protection methods, electroanatomical mapping, and novel ablation targets.

RESULTS

Innovative radiofrequency (RF) catheter designs maximize energy delivery while avoiding overheating associated with conventional catheters. Single-shot balloon catheters in the form of cryoballoons, radiofrequency, and laser balloons have proven effective at producing pulmonary vein isolation and improving procedural efficiency and reproducibility. Pulsed field ablation (PFA) is a highly anticipated novel nonthermal energy source under development, which demonstrates selective ablation of the myocardium, producing durable lesions while also minimizing collateral damage. Innovative devices for esophageal protection including esophageal deviation and cooling devices have been developed to reduce esophageal complications. Improved electroanatomical mapping systems are being developed to help identify additional non-pulmonary triggers, which may benefit from ablation, especially with persistent atrial fibrillation. Lastly, the vein of Marshall alcohol ablation has been recently studied as an adjunct therapy for improving outcomes with catheter ablation for persistent atrial fibrillation.

CONCLUSIONS

Numerous advances have been made in the field of atrial fibrillation ablation in the past decade. While further long-term data is still needed for these novel technologies, they show potential to improve procedural efficacy and safety.

Unique Left Pulmonary Vein Isolation in Straight Common Trunk Based on Longitudinal Conduction of Left Lateral Ridge

BACKGROUND

A left common pulmonary vein (LCPV) is the most common anatomical variation in the pulmonary vein (PV) and often influences strategies of PV isolation for atrial fibrillation (AF). Our objective was to elucidate the electrical properties of the specific shape of LCPV and to apply it to an ablation procedure.

METHODS AND RESULTS

We investigated consecutive 12 out of 204 paroxysmal AF patients who had the shape of a straight common trunk in LCPV defined by the formation of a single conduit with parallel cranial and caudal walls after the coalescence of superior and inferior pulmonary veins on the distal side. The distance between the top of the bifurcation of LPVs and the level coinciding with the middle of the anterior wall of LCPV (left lateral ridge: LLR) was more than 10 mm in all the patients. The activation pattern of the LLR showed longitudinal conduction without outside connections. All the LCPV except one were successfully isolated without ablating the LLR (C-shape ablation). Only one patient had AF recurrence during the follow-up period.

CONCLUSION

The LLR in LCPV with a straight common trunk has longitudinal conduction without outside connections, which permits the isolation of LCPV without ablating LLR. This article is protected by copyright. All rights reserved.

Neuromodulatory Approaches for Atrial Fibrillation Ablation

In this review, the authors describe evolving alternative strategies for the management of AF, focusing on non-invasive and percutaneous autonomic modulation. This modulation can be achieved – among other approaches – via tragus stimulation, renal denervation, cardiac afferent denervation, alcohol injection in the vein of Marshall, baroreceptor activation therapy and endocardial ganglionated plexi ablation. Although promising, these therapies are currently under investigation but could play a role in the treatment of AF in combination with conventional pulmonary vein isolation in the near future.

[Safety and Medium- and Long-Term Efficacy of Treating Atrial Fibrillation with Surgical Radiofrequency Ablation during Concomitant Mitral Valve Surgery]

OBJECTIVE

To investigate the safety and medium- and long-term efficacy of surgical radiofrequency ablation to treat atrial fibrillation during concomitant mitral valve surgery.

METHODS

From January 2014 to December 2018, 280 patients with mitral valve disease and the comorbidity of preoperative atrial fibrillation were recruited for the study. Among them, 130 patients received only mitral valve surgery (non-ablation group), and 150 patients were underwent surgical radiofrequency ablation for the atrial fibrillation during concomitant mitral valve surgery (ablation group). Among the 150 patients of the ablation group, 80 had biatrial ablation, and 70 had left atrial ablation. Under general anesthesia, median sternotomy was done on all patients and cardiopulmonary bypass was established through the ascending aorta and superior and inferior venae cavae. After aortic occlusion, patients in the ablation group underwent the ablation procedure with the Atricure® bipolar ablation device, using the Cox Maze Ⅲ procedure as a reference. In addition, the left atrial appendage was removed and electrocautery of the ligament of Marshall and Waterston's groove were performed in all Cox Maze cases. Following ablation, mitral valve replacement or repair was performed. All patients were given 200 mg oral amiodarone on the first day after surgery, for three times/d×7 d, which was followed by twice/d×7 d, and then oral amiodarone 200 mg/d was maintained till the end of 3 months after surgery (ablation group) or 12 months after surgery (non-ablation group). Patients were followed up at the intervals of 3 months, 6 months, 12 months, 2 years, 3 years, and 5 years after discharge. The follow-up service included standard 12-lead chest electrocardiogram (ECG) and 24-h dynamic ECG. The primary end point of the study was the time point of postoperative atrial fibrillation and the secondary endpoints were major cardiovascular events, death, and readmission due to heart failure.

RESULTS

The surgeries were successfully performed in all subjects of the study. A total of 30 patients were lost to follow-up within 5 years after operation (10.7% losses to follow-up), including 11 patients in the ablation group and 19 patients in the non-ablation group. The proportion of patients who did not have atrial fibrillation in the ablation group and the non-ablation group at 6 months, 12 months, 2 years, 3 years and 5 years after surgery was 83.3% and 27.7%, 72.7% and 20.8%, 66.0% and 15.4% 61.3% and 13.1%, and 43.3% and 10.8%, respectively, with the data from the two groups showing statistically significant difference ( P<0.001). The proportion of patients who did not have atrial fibrillation in the biatrial ablation and the left atrial ablation group at 6 months, 12 months, 2 years, 3 years and 5 years after surgery was 87.3% and 87.5%, 92.4% and 82.8%, 90.5% and 85.7%, 94.8% and 88.1%, and 75.5% and 69.4%%, respectively, with the data from the two groups showing no statistically significant difference ( P>0.05). However, the cumulative incidence of atrial fibrillation in the two groups showed statistically significant difference ( P<0.001). There were no deaths within 30 days after operation in either group. There was no significant difference in cerebrovascular accident, readmission for heart failure, pulmonary infection and mediastinal infection between the two groups within one year after operation ( P>0.05). However, the proportion of patients who had permanent pacemaker installed due to Ⅲ-degree atrioventricular block in the ablation group was higher than that in the non-ablation group ( P<0.05). The proportion of patients who required re-drainage due to delayed pericardial effusion in the ablation group was higher than that in the non-ablation group ( P<0.05).

CONCLUSION

In the group of patients who had modified Cox Maze procedure with bipolar ablation device to treat atrial fibrillation during concomitant mitral valve surgery, the maintenance rate of sinus rhythm after cardioversion was significantly higher than that in the non-ablation group. The surgery showed better safety and significantly better medium- and long-term outcomes. Left atrial ablation and biatrial ablation were both considered safe and effective surgical treatment for atrial fibrillation. Compared with the left atrial ablation group, the biatrial ablation group achieved better effects in restoring and maintaining sinus rhythm without an increase the incidence of perioperative complications.

Asymmetry and Heterogeneity: Part and Parcel in Cardiac Autonomic Innervation and Function

The cardiac autonomic nervous system (cANS) regulates cardiac adaptation to different demands. The heart is an asymmetrical organ, and in the selection of adequate treatment of cardiac diseases it may be relevant to take into account that the cANS also has sidedness as well as regional differences in anatomical, functional, and molecular characteristics. The left and right ventricles respond differently to adrenergic stimulation. Isoforms of nitric oxide synthase, which plays an important role in parasympathetic function, are also distributed asymmetrically across the heart. Treatment of cardiac disease heavily relies on affecting left-sided heart targets which are thought to apply to the right ventricle as well. Functional studies of the right ventricle have often been neglected. In addition, many principles have only been investigated in animals and not in humans. Anatomical and functional heterogeneity of the cANS in human tissue or subjects is highly valuable for understanding left- and right-sided cardiac pathology and for identifying novel treatment targets and modalities. Within this perspective, we aim to provide an overview and synthesis of anatomical and functional heterogeneity of the cANS in tissue or subjects, focusing on the human heart.

Stepwise endo-/epicardial catheter ablation for atrial fibrillation: The Mediterranea approach

Background

Outcomes of catheter ablation (CA) among patients with nonparoxysmal atrial fibrillation (AF) are largely disappointing.

Objective

We sought to evaluate the feasibility, effectiveness, and safety of a single‐stage stepwise endo‐/epicardial approach in patients with persistent/longstanding‐persistent AF.

Methods

We enrolled 25 consecutive patients with symptomatic persistent (n = 4) or longstanding‐persistent (n = 21) AF and at least one prior endocardial procedure, who underwent CA using an endo‐/epicardial approach. Our anatomical stepwise protocol included multiple endocardial as well as epicardial (Bachmann's bundle [BB] and ligament of Marshall ablations) components, and entailed ablation of atrial tachycardias emerging during the procedure. The primary outcome was freedom from any AF/atrial tachycardia episode after a 3‐month blanking period. The secondary outcome was patients' symptom status during follow‐up.

Results

The stepwise endo‐/epicardial approach allowed sinus rhythm restoration in 72% of patients, either directly (n = 6, 24%) or after AF organization into atrial tachycardia (n = 12, 48%). BB's ablation was commonly implicated in arrhythmia termination. After a median follow‐up of 266 days (interquartile range, 96 days), survival free from AF/atrial tachycardia was 88%. Antiarrhythmic drugs could be discontinued in 22 patients (88%). As compared to baseline, more patients were asymptomatic at 9‐month follow‐up (0% vs. 56%, p = .02). Five patients (20%) developed mild medical complications, whereas one subject (4%) had severe kidney injury requiring dialysis.

Conclusion

A single‐stage endo‐/epicardial CA resulted in favorable rhythm and symptom outcomes in a cohort of patients with symptomatic persistent/longstanding‐persistent AF and one or more prior endocardial procedures. Epicardial ablation of BB was commonly implicated in procedural success.

Vein of Marshall ethanol infusion in the treatment of atrial fibrillation: From concept to clinical practice

The vein of Marshall (VOM) contains innervation, myocardial connections, and arrhythmogenic foci that make it an attractive target in catheter ablation of atrial fibrillation (AF). Additionally, it co-localizes with the mitral isthmus, which is critical to sustain perimitral flutter, and is a true atrial vein that communicates with underlying myocardium. Retrograde balloon cannulation of the VOM from the coronary sinus is feasible and allows for ethanol delivery, which results in rapid ablation of neighboring myocardium and its innervation. Here we review the body of work performed over a span of 13 years, from the inception of the technique, to its preclinical validation, to demonstration of its ablative and denervation effects, and finally to completion of a randomized clinical trial demonstrating favorable outcomes, improving rhythm control in catheter ablation of persistent AF.

Coronary Venous Mapping and Catheter Ablation for Ventricular Arrhythmias

Catheter ablation is an effective treatment method for ventricular arrhythmias (VAs). These arrhythmias can often be mapped and targeted with ablation from the left and right ventricular endocardium. However, in some situations the VA site of origin or substrate may be intramural or epicardial in nature. In these cases, the coronary venous system (CVS) provides an effective vantage point for mapping and ablation. This review highlights situations in which CVS mapping may be helpful and discusses techniques for CVS mapping and ablation.

Atrial Fibrillation Ablation Using Vein of Marshall Ethanol Infusion

Catheter ablation has become a cornerstone treatment for atrial fibrillation (AF). Pulmonary vein isolation is the accepted approach for paroxysmal AF ablation, but it is less effective for persistent AF. The vein of Marshall (VOM) is located in the epicardial left atrium and can be a source of AF triggers as well as a tract for autonomic nerves. It directly communicates with the underlying myocardium, including the left atrial ridge and the posterior mitral isthmus. This review discusses the latest evidence regarding the mechanisms, procedural aspects, and outcomes of VOM ethanol infusion when used as an adjunct to pulmonary vein isolation in patients with persistent AF.

Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation (Marshall-PLAN): Prospective, single-center study

BACKGROUND

Beyond pulmonary vein isolation (PVI), the optimal ablation strategy for persistent atrial fibrillation (AF) remains poorly defined.

OBJECTIVE

The purpose of this study was to examine a novel comprehensive ablation strategy (Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation [Marshall-PLAN]) strictly based on anatomical considerations.

METHODS

Left atrial (LA) sites were sequentially targeted as follows: (1) coronary sinus and vein of Marshall (CS-VOM) musculature; (2) PVI; and (3) anatomical isthmuses (mitral, roof, and cavotricuspid isthmus [CTI]). The primary endpoint was 12-month freedom from AF/atrial tachycardia (AT).

RESULTS

Seventy-five consecutive patients were included (age 61 ± 9 years; 10 women; AF duration 9 ± 11 months; mean LA volume 197 ± 43 mL). VOM ethanol infusion was completed in 69 patients (92%). The full Marshall-PLAN lesion set (VOM, PVI, mitral, roof, and CTI with block) was successfully completed in 68 patients (91%). At 12 months, 54 of 75 patients (72%) were free from AF/AT after a single procedure (no antiarrhythmic drugs) in the overall cohort. In the subset of patients with a complete Marshall-PLAN lesion set (n = 68), the single procedure success rate was 79%. After 1 or 2 procedures, 67 of 75 patients (89%) remained free from AF/AT (no antiarrhythmic drugs). After 1 or 2 procedures, VOM ethanol infusion was complete in 72 of 75 patients (96%).

CONCLUSION

A novel ablation strategy that systematically targets anatomical atrial structures (VOM ethanol infusion, PVI, and prespecified linear lesions) is feasible, safe, and associated with a high rate of freedom from arrhythmia recurrence at 12 months in patients with persistent AF.

Identification and Endocardial Ablation of the Ligament of Marshall for Pulmonary Vein Isolation

OBJECTIVES

The aims of this study were to establish criteria for identifying ligament of Marshall (LOM) connections that are responsible for pulmonary vein isolation (PVI) failure, assess their incidence, and determine if they can be targeted by focal endocardial ablation at the anterior carina of the left superior pulmonary vein (LSPV).

BACKGROUND

Wide antral ablation of the left pulmonary veins (PVs) may not achieve PVI, sometimes requiring empirical ablation of the PV carina. The mechanism could be due to epicardial conduction along the LOM, which courses adjacent to the anterior carina.

METHODS

In patients undergoing radiofrequency ablation for atrial fibrillation, if wide ablation of the left PV did not achieve isolation, bidirectional mapping was performed. A presumptive LOM connection was diagnosed if the earliest entrance was mapped to the anterior LSPV, while the earliest exit was mapped inferior to the left inferior PV. Focal ablation at the LSPV anterior carina was performed, even if not at the site of earliest entrance activation. The primary endpoint was successful PVI immediately after ablation.

RESULTS

The study included 455 consecutive patients who underwent 570 procedures, of which 364 were first-time ablations. Presumptive LOM connections were identified in 48 procedures (8.4%) and in 41 patients (11.2%) undergoing first-time ablation and were successfully ablated at the anterior carina of the LSPV in 47 of 48 procedures (98%).

CONCLUSIONS

LOM connections may be a common cause of PVI failure and can be easily identified and reliably ablated with focal endocardial ablation at the anterior LSPV carina.

A case report of ethanol infusion in the vein of Marshall using the right jugular vein approach

Background

Ethanol infusion has recently been described as a curative strategy for certain peri-mitral flutters by blocking electrical conduction across the mitral isthmus along with the Marshall bundle. The present case showed that a right jugular vein approach, less described, may be a good choice when performing an ethanol infusion in the vein of Marshall (VOM).

Case summary

A 45-year-old man was admitted to our unit for dyspnoea associated with an atypical atrial flutter with a cycle length of 320 ms. The left atrial activation map showed a peri-mitral counter-clockwise circuit. The atrial flutter cycle length went up to 345 ms once an endocardial and epicardial point-by point-ablation of the mitral line was completed. At this stage, a new activation map showed that the mitral line was still permeable with an epicardial conduction bridge through the VOM. We decided to use an ethanol infusion for the ablation of the VOM. The coronary sinus could not be thoroughly catheterized due to a winding and angular shape so we decided to try a right jugular vein approach. A total of 9 mL of ethanol was injected into the VOM. A final venogram showed the diffusion of ethanol around the VOM. Sinus rhythm was restored during the last ethanol infusion. A new voltage map confirmed the completion of the mitral line, and we confirmed the bidirectional block.

Discussion

The present case showed that a right jugular vein approach may be a good choice when catheterizing and performing an ethanol infusion in the VOM.

Ganglionated Plexi Ablation for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and is associated with significant morbidity and mortality. The autonomic nervous system (ANS) plays an important role in the initiation and development of AF, causing alterations in atrial structure and electrophysiological defects. The intrinsic ANS of the heart consists of multiple ganglionated plexi (GP), commonly nestled in epicardial fat pads. These GPs contain both parasympathetic and sympathetic afferent and efferent neuronal circuits that control the electrophysiological properties of the myocardium. Pulmonary vein isolation and other cardiac catheter ablation targets including GP ablation can disrupt the fibers connecting GPs or directly damage the GPs, mediating the benefits of the ablation procedure. Ablation of GPs has been evaluated over the past decade as an adjunctive procedure for the treatment of patients suffering from AF. The success rate of GP ablation is strongly associated with specific ablation sites, surgical techniques, localization techniques, method of access and the incorporation of additional interventions. In this review, we present the current data on the clinical utility of GP ablation and its significance in AF elimination and the restoration of normal sinus rhythm in humans.

The ligament of Marshall and arrhythmias: A review

The ligament of Marshall (LOM) is a remnant of the embryonic sinus venosus and left cardinal vein, and contains fat and fibrous tissues, blood vessels, muscle bundles, nerve fibers, and ganglia. The complexity of LOM's structure makes it as a source of triggers and drivers as well as substrates of re-entry for atrial arrhythmias, especially for atrial fibrillation (AF). LOM also serves as a portion of left atrial macro-re-entrant circuit, especially peri-mitral isthmus re-entrant circuit. Experimental studies demonstrate that the LOM acts as a sympathetic conduit between the left stellate ganglion and the ventricles, and participates in the initiation and maintenance of ventricular arrhythmias. Endocardial or epicardial catheter ablation or ethanol infusion into the vein of Marshall may serve as an important adjunct therapy to pulmonary vein isolation in patients with advanced stage of AF, and may help alleviate ventricular arrhythmias as well.

Beyond Pulmonary Vein Isolation in Nonparoxysmal Atrial Fibrillation: Posterior Wall, Vein of Marshall, Coronary Sinus, Superior Vena Cava, and Left Atrial Appendage

The optimal ablation strategy for non-paroxysmal atrial fibrillation remains controversial. Non-PV triggers have been shown to have a major arrhythmogenic role in these patients. Common sources of non-PV triggers are: posterior wall, left atrial appendage, superior vena cava, coronary sinus, vein of Marshall, interatrial septum, crista terminalis/Eustachian ridge, and mitral and tricuspid valve annuli. These sites are targeted empirically in selected cases or if significant ectopy is noted (with or without a drug challenge), to improve outcomes in patients with non-paroxysmal atrial fibrillation. This article focuses on summarizing the current evidence and the approach to mapping and ablation of these frequent non-PV trigger sites.

Persistent atrial fibrillation in the setting of pulmonary vein isolation-Where to next?

Catheter ablation for atrial fibrillation (AF) is indicated in symptomatic patients who are intolerant or refractory to antiarrhythmic therapy. However, outcomes from catheter ablation remain suboptimal in patients with persistent AF. Pulmonary vein antral isolation (PVAI) is established as the cornerstone of AF ablation strategies. The landmark STAR AF II study demonstrated a lack of incremental benefit with adjunctive linear and complex fractionated electrogram ablation beyond PVAI. Randomized studies thus far have failed to consistently show favorable outcomes from other trigger/substrate-based ablation approaches over PVAI alone. In this issue of the journal, we pose an interesting clinical scenario-of a middle-aged female who presents with recurrent persistent AF but was found to have enduring PVAI on repeat electrophysiologic study. Which approach should be undertaken next? In this review article, we aim to provide an overview of ablation strategies beyond PVAI. Finally in light of scant randomized data to guide decision making we have approached leading experts in the field to provide their approach to this scenario.

Ethanol infusion for Marshall bundle epicardial connections in Marshall bundle-related atrial tachycardias following atrial fibrillation ablation: The accessibility and success rate of ethanol infusion by using a femoral approach

BACKGROUND

Ethanol infusion of the vein of Marshall (VOM) may be effective to treat Marshall bundle-related atrial tachycardia (MB-AT). However, methods and clinical results of ethanol infusion for MB-AT have been not established.

OBJECTIVE

To assess the accessibility of the VOM and the success rate of ethanol infusion using a femoral approach for MB-AT.

METHODS

A single-center observational study included consecutive patients who had MB-AT and in whom we attempted to treat MB-AT during AT by ethanol infusion. When the VOM was able to be cannulated following VOM venogram using a femoral approach, we systematically performed ethanol infusion with selective balloon occlusion of the VOM. We analyzed in detail the efficacy of ethanol infusion of VOM in patients who were in MB-AT during ethanol infusion.

RESULTS

We enrolled 54 consecutive patients in whom we attempted to treat MB-AT by ethanol infusion. Of those, the VOM was accessible in 92.5% of patients (50 of 54). Of the 50 patients treated by ethanol infusion during MB-AT, AT was successfully terminated in 56% percent of the patients (28 of 50) by solo treatment of ethanol infusion without RF ablation. The remainder required additional RF application to terminate the MB-AT. A mean of 6.2 ± 2.8 mL of ethanol was infused resulting in the low-voltage area significantly larger than that before ethanol infusion (12.7 ± 8.3 vs 6.6 ± 5.3 cm² , P < .001).

CONCLUSION

The present study demonstrated that the VOM was highly accessible and MB-AT was amenable to treatment by ethanol infusion by using a femoral approach.

Selective ablation of the ligament of Marshall attenuates atrial electrical remodeling in a short-term rapid atrial pacing canine model

INTRODUCTION

Cardiac sympathetic activation facilitates atrial electrical remodeling during atrial fibrillation (AF). Selective ablation of the distal part of the ligament of Marshall (LOM_LSPV ) could decrease cardiac sympathetic innervation. This study aimed to investigate the effects of LOM_LSPV ablation on atrial electrical remodeling in a short-term rapid atrial pacing (RAP) model.

METHODS

In 16 anesthetized dogs, 6 hours of RAP (20 Hz, 2 × threshold) was delivered before LOM_LSPV ablation (group 1, N  =  8) or after (group 2, N  =  8). Heart rate variability (HRV), serum norepinephrine (NE), atrial electrophysiological indices were analyzed. Six times of burst pacing (20 Hz, 2 × threshold, lasting for 5 seconds, were performed to induce AF, the number of episodes and the duration of AF were compared.

RESULTS

LOM_LSPV ablation decreased sympathetic indices of HRV and serum NE. Atrial effective refractory period (ERP) was shortened during RAP in both groups with higher reduction degrees in group 1. In group 1, the shortening of atrial ERP, elevating of ERP dispersion and sum of window of vulnerability (ΣWOV), facilitating of AF induced by RAP were subsequently reversed by LOM_LSPV ablation. In group 2, LOM_LSPV ablation prolonged atrial ERP, decreased ΣWOV, eliminated AF induction. The subsequent RAP failed to alter these indices. Histological studies showed abundant sympathetic nerve fibers in LOM_LSPV .

CONCLUSION

LOM_LSPV ablation could inhibit atrial electrical remodeling during short-term RAP by reducing the cardiac sympathetic activity. LOM_LSPV may be a potential target in AF ablation, especially in patients with highly cardiac sympathetic activation or atrial electrical remodeling.

Ablation of the Ligament of Marshall and Left Stellate Ganglion Similarly Reduces Ventricular Arrhythmias During Acute Myocardial Infarction

Background:

Sympathetic denervation exerts protective effects against ventricular arrhythmias (VAs) induced by acute myocardial infarction. The results of a previous study indicated that the distal part of the ligament of Marshall (LOM LSPV ) might be a sympathetic conduit between the left stellate ganglion (LSG) and the ventricles. The present study was designed to compare the effects between LSG and LOM LSPV ablation on ischemia-induced VAs.

Methods:

Twenty-nine dogs were randomly divided into sham ablation group (group 1, n=9), LOM LSPV ablation group (group 2, n=10), and LSG ablation group (group 3, n=10). Ablation was performed before occlusion of the left anterior coronary artery. Changes in the heart rate variability, serum norepinephrine, ventricular effective refractory period, and blood pressure induced by LSG stimulation were observed, and the occurrence of VAs was recorded. Immunostaining examinations of LOM LSPV were performed in dogs without ablation.

RESULTS:

In group 2, LOM LSPV ablation evidently attenuated blood pressure elevation induced by LSG stimulation. Both LOM LSPV ablation and LSG ablation similarly prolonged ventricular effective refractory period and reduced the concentration of serum norepinephrine, the sympathetic index of heart rate variability, and the incidence of VAs compared with sham ablation. Abundant sympathetic nerve fibers were observed in LOM LSPV .

Conclusions:

LOM LSPV ablation prevented acute myocardial infarction–induced VAs with the same efficiency as LSG ablation, potentially by blocking the sympathetic pathway from the LSG to the heart.

The Human Left Atrial Venous Circulation as a Vascular Route for Atrial Pharmacological Therapies: Effects of Ethanol Infusion

OBJECTIVES

This study catalogued the human venous left atrium (LA) circulation system and the ablative effects of ethanol in different branches.

BACKGROUND

Vascular routes to target the LA could have significant therapeutic potential. Beyond the vein of Marshall (VOM), the fluoroscopic LA venous anatomy has not been described.

METHODS

Patients undergoing ethanol infusion in the VOM as adjunctive therapy to atrial fibrillation (AF) catheter ablation were included in this study. Balloon occlusion venograms of the VOM and other LA veins were obtained in 218 patients.

RESULTS

Sequentially from the coronary sinus (CS) ostium, LA veins included: 1) proximal septal vein draining the inferior septum; 2) inferior LA vein in the annular inferior LA; 3) VOM; 4) LA appendage vein; and 4) anterior LA vein. Additionally, venous sinuses not connected to the CS included roof veins and posterior wall veins, which drained into the right and left atria, respectively. Venous connections between LA veins through capillaries and with pulmonary veins were abundant. Extracardiac collateral vessels were present in 38 patients (17.4%). Ethanol infusion in LA veins led to tissue ablation in their corresponding regions.

CONCLUSIONS

The atrial venous anatomy is amenable to selective cannulation. Consistent anatomical patterns are present. Targeting atrial tissues through atrial veins can be used for therapeutic purposes.