Vein of Marshall Ethanol Infusion: Beware the Left Atrial Appendage Isolation.

A 58-year-old woman was referred for atrial flutter ablation after atrial fibrillation ablation. Linear and reinforcement mitral isthmus ablation failed to terminate the perimitral flutter. During vein of Marshall ethanol infusion (VOMEI), the flutter was terminated and followed by left atrial appendage (LAA) isolation. Voltage mapping showed that a large low voltage area was created in the superior and anterior wall of left atrium. During the waiting time, the LAA activation recovered. It would be necessary to keep in mind that VOMEI would lead to uncontrolled lesion of left atrium.

Anatomical Treatment Strategies for Persistent Atrial Fibrillation with Ethanol Infusion within the Vein of Marshall-Current Challenges and Future Directions.

Currently, pulmonary vein isolation (PVI) is the gold standard in catheter ablation for atrial fibrillation (AF). However, PVI alone may be insufficient in the management of persistent AF, and complementary methods are being explored. One such method takes an anatomical approach-improving both its success rate and lesion durability may lead to improved treatment outcomes. An additional approach complementary to the anatomical one is also attracting attention, one that focuses on epicardial conduction. This involves ethanol ablation of the vein of Marshall (VOM) and can be very effective in blocking epicardial conduction related to Marshall structure; it is becoming incorporated into standard treatment. However, the pitfall of this "Marshall-PLAN", a method that combines an anatomical approach with ethanol infusion within the VOM (Et-VOM), is that Et-VOM and other line creations are not always successfully completed. This has led to cases of AF and/or atrial tachycardia (AT) recurrence even after completing this lesion set. Investigating effective adjunctive methods will enable us to complete the lesion set with the aim to lower the rates of recurrence of AF and/or AT in the future.

Case Report: Ethanol ablation of the Marshall vein as the first step for left atrial tachycardia ablation.

Electroanatomic mapping guides complex atrial tachycardia ablations; however, challenges may emerge after pulmonary vein isolation. 3D mapping systems can reveal the mechanism of tachycardia and critical areas that need to be ablated. Sometimes, however, these areas may be located deep inside, to the extent that they cannot be successfully reached by endocardial ablation. In this study, we present a unique case of a patient in whom vein of Marshall (VOM) ethanol ablation, a conventional secondary intervention, promptly terminated a Marshall bundle-related atrial tachycardia without further endocardial radiofrequency application, suggesting VOM ethanol ablation as a potential primary strategy.

Evaluation of posterior mitral isthmus ablation in the absence of a vein of Marshall.

AIMS: Achieving acute and durable mitral isthmus (MI) block remains challenging using radiofrequency (RF) catheter ablation alone. Vein of Marshall (VoM) ethanolization results in chemical damage along the MI resulting in the creation of a durable transmural lesion with a very high rate of procedural block. However, no studies have systematically assessed the efficacy of MI ablation alone when no anatomical VoM is present. METHODS AND RESULTS: Thirty seven patients without VoM evidenced after careful angiographic examination were included. Ablation parameters and result were compared with a matched control group in whom the posterior MI line was performed without assessing the presence of the VoM. Mitral isthmus block was achieved in 36 out of 37 patients without VoM (97%), with endocardial ablation only in 5/37 (14%) and combined endocardial and coronary sinus ablation in 32/37 patients (86%). There was a significant difference in the occurrence of block between patients without a VoM and the control group (97.3% vs. 65% respectively, P < 0.01), with a trend towards less needed RF {26 [interquartile range (IQR) 20-38] vs. 29 [IQR 19-40] tags [P = 0.8], 611 [IQR 443-805] vs. 746 [IQR 484-1193] seconds [P = 0.08]}. CONCLUSION: The absence of a VoM is associated with a very high rate of procedural block during posterior MI ablation. The higher rate of MI block in this specific population would also suggest the crucial role of the VoM (when present) in resistant MI block.

Combined ethanol and radiofrequency ablation for the elimination of focal atrial tachycardia originating from the Marshall bundle.

Introduction and importance: Atrial tachycardias (AT) originating from the Marshall bundle (MB) are rare and present significant challenges in diagnosis and management. The authors present the case of a 29-year-old male with recurrent AT successfully treated with a combined ethanol and radiofrequency ablation approach. This case highlights the effectiveness of this dual ablation strategy in resolving AT originating from the MB, contributing valuable insights into managing complex AT cases. Case presentation: A 29-year-old male with recurrent, symptomatic palpitations was initially suspected of orthodromic atrioventricular reentrant tachycardia, but an initial electrophysiological study (EPS) failed to induce arrhythmia. Subsequent spontaneous episodes led to a detailed EPS, revealing automatic AT originating presumably from an epicardial focus on the posterior wall of the left atrium (LA). Detailed mapping identified the earliest activation at the vein of Marshall (VoM) ostium within the coronary sinus (CS). Suspecting the involvement of MB structures, VoM ethanol ablation was performed. Complete arrhythmia elimination was achieved with radiofrequency ablation (RFA) at the VoM ostium within the CS, with no recurrence. Discussion: Most cases in the literature are associated with atrial fibrillation (AF) or AT within AF, typically involving re-entry mechanisms. The given case is unique as it presents a highly probable VoM origin of automatic AT with no concomitant AF. The VoM's anatomical and electrophysiological properties make it a potential source of refractory AT. In this case, ethanol ablation supplemented by targeted, limited RFA emerged as an effective strategy, highlighting the importance of comprehensive mapping and tailored ablation approaches in managing complex atrial arrhythmias. Conclusion: The potential implications for clinical practice include recognizing the VoM as a critical target in refractory AT cases and adopting a combined ablation strategy to improve patient outcomes in similarly challenging scenarios.

Beyond pulmonary vein isolation: approaches to treat patients with persistent atrial fibrillation.

INTRODUCTION: Atrial fibrillation (AF) is the most common arrhythmia. Catheter ablation is a successful rhythm control strategy in paroxysmal AF, but it has demonstrated dramatically lower AF-free survival rates in patients with persistent AF. In recent years, myriad novel rhythm control strategies have been developed, each with the promise of improved persistent AF ablation success. AREAS COVERED: This review discusses multiple novel techniques and approaches to persistent AF. Authors identified relevant papers by searching PubMed and Google Scholar databases and considered all papers identified, regardless of publication date. It begins by discussing recent advances in electrogram analysis that yielded improved AF-free survival following persistent AF catheter ablation. Next, it discusses several trials revealing the shortcomings of MRI in guiding persistent AF ablation. Finally, it discusses one nascent technique (Vein of Marshall ablation) and technology (AI-assisted electrogram analysis) who have shown promise in improving persistent AF ablation. EXPERT OPINION: In the authors' expert opinions, upcoming persistent AF ablations will utilize a stepwise approach of (1) ensuring PV isolation, (2) Vein of Marshall ablation and (3) AI-assisted ablation to optimize future persistent AF ablation outcomes. This approach systematically addresses arrhythmogenic sources beyond the pulmonary veins, the historical treatment target.

Mechanisms of Vein of Marshall-Related Tachyarrhythmias and the Impact of Ethanol Infusion.

The Ligament of Marshall (LOM) is a remnant of the embryonic sinus venosus and the left cardinal vein, containing a combination of fat, fibrous tissue, blood vessels, muscle bundles, nerve fibers, and ganglia. Various muscular connections exist between the LOM and the left atrium (LA) and the coronary sinus (CS). The LOM is richly innervated by autonomic nerves, with ganglion cells distributed around it. The unique characteristics of the LOM are responsible for generating focal electrical activities and enable it to serve as a substrate for micro- and macro-reentrant circuits. This, in turn, leads to the initiation and perpetuation of atrial fibrillation (AF) and atrial tachycardia (AT). Endocardial ablation in this region does not consistently succeed due to anatomical constraints within the left lateral LA, including the presence of a thicker and longer mitral isthmus (MI), anatomical variations between the MI and epicardial structures such as the CS and vein of Marshall (VOM) and circumflex artery, and the presence of fibrofatty tissue insulating the LOM. Furthermore, epicardial ablation is challenging for inexperienced institutions because of its invasive nature. Ethanol infusion into the VOM (EI-VOM) represents an effective and safe approach that can be employed in conjunction with radiofrequency ablation to eliminate this arrhythmogenic structure.

Vein of Marshall ethanol infusion for recurrent atrial fibrillation in patients with durably isolated pulmonary veins.

BACKGROUND: Vein of Marshall (VoM) ethanol ablation has a proven benefit in patients with persistent atrial fibrillation (AF) undergoing index procedure; however, its role in repeat ablation is unknown. We sought to evaluate the benefit of empiric VoM ethanol ablation in addition to posterior wall isolation (PWI) during the repeat procedure in patients with durable pulmonary vein (PV) isolation from prior ablation. METHODS: Twenty-three patients (age 67.1 + / - 7.4, 74% males) who received empiric VoM ethanol infusion in addition to PWI were matched for age, gender, ejection fraction, and left atrial size with forty-six patients receiving empiric PWI alone. All patients in the study group underwent additional ablation on mitral isthmus to complete the lateral mitral isthmus line. Additional ablation was based on program and trigger stimulation. Primary outcome was freedom from AF after a blanking period of 3 months by qualification of symptoms, EKG, wearable, or implantable monitor or device. RESULTS: The study group had a higher average BMI (35.07 + / - 8.98 vs. 30.85 + / - 5.65, p = 0.033) and rate of persistent AF (83.0% vs. 54.3%, p = 0.029) versus the control. The 1-year AF-free survival for the study and control groups was 20 (86.96%) and 28 (60.1%) patients (p = 0.027). Cox proportional hazard regression analysis showed a significant reduction in AF recurrence in the study group (HR 0.25, 95% CI 0.073-0.843, p = 0.026). CONCLUSION: Among patients undergoing repeat catheter ablation for recurrent AF with durably isolated PVs, the addition of VoM ethanol infusion increased the likelihood of remaining free from AF at 12 months.

Impact of Ethanol Infusion to the Vein of Marshall in Atrial Fibrillation and Atrial Tachycardia.

The ligament of Marshall is an epicardial structure characterized by its composition of fat, fibrous tissue, blood vessels, muscle bundles, nerve fibers, and ganglia. Its intricate network forms muscular connections with the coronary sinus and left atrium, alongside adjacent autonomic nerves and ganglion cells. This complexity plays a pivotal role in initiating focal electrical activities and sustaining micro- and macro-reentrant circuits, thereby contributing to the onset of atrial fibrillation and atrial tachycardia. However, endocardial ablation in this area may encounter challenges due to anatomical variations and insulation by fibrofatty tissue. Combining ethanol infusion into the vein of Marshall with radiofrequency ablation presents a promising strategy for effectively and safely eliminating this arrhythmogenic structure and terminating associated tachycardias.

Protocol modifications reduce risk of delayed pericardial effusions after vein of Marshall ethanol infusion: follow-up from the Maine experience.

BACKGROUND: While ethanol infusion into the vein of Marshall (VOM) as an adjunct to atrial fibrillation ablation has shown promise, adoption has been limited by the technical expertise required, unclear antiarrhythmic mechanism, and complication risk. Delayed pericardial effusions have been associated with ethanol infusion into the VOM in prior studies. Very little is known about how the procedural approach itself can impact the risk of delayed effusions. We sought to understand the incidence and influence of procedural technique on complications including delayed pericardial effusions from VOM ethanol infusion at a large single medical center. METHODS: A total of 275 atrial ablation cases wherein VOM ethanol infusion was attempted were identified from the time of the program's inception in 2019 at Maine Medical Center (Portland, ME) until October of 2023. Cases were classified into phase I cases (early experience) and phase II cases (later experience) based upon temporal programmatic changes in the ethanol dose and infusion rate as well as the use of routine VOM venography. Procedural details and complications were adjudicated from the medical record. RESULTS: The overall VOM ethanol infusion success was 91.4%. Nine complications (3.3%) occurred in eight patients (2.9% of patients). These were more frequent in phase I (5.8%) compared to phase II (1.3%, p = 0.047). This difference was driven by a difference in delayed presentations of tamponade, which occurred in four patients in phase I (3.3%) and in no patients in phase II (0%, p = 0.037). Twelve-month estimated atrial arrhythmia freedom did not differ between groups (73.8% phase I vs 70.4% phase II, p = 0.24). CONCLUSION: In our single-center experience, adjustments to the procedural approach with lower ethanol infusion rate and dosage, combined with utilizing selective VOM venography, associated with a lowering of complication rates and in particular, delayed pericardial tamponade.

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.

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.

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.

Clinical effect of vein of Marshall ethanol infusion on mitral isthmus ablation.

Purpose: This study aimed to investigate the effect of Marshall ethanol infusion (VOM-Et) in the vein on mitral isthmus (MI) ablation. Methods: Patients with persistent atrial fibrillation (AF) were grouped into vein of VOM-Et combined with radiofrequency (RF) ablation (VOM-Et-RF) and RF groups. The primary outcome was MI block immediate block rate after surgery. Stratified analysis was also performed for factors affecting the outcome measures. Results: A total of 118 consecutive patients underwent AF ablation at Taizhou Hospital of Zhejiang Province from January 2018 to December 2021. Successful bidirectional perimitral block was achieved in 96% of patients in VOM-Et-RF (69 of 72) and in 76% of patients in the RF group (35 of 46) (P < 0.01). In the subgroup analysis, male sex, elder than 60 years, Left atrial diameter <55 mm, and AF duration <3 years were associated with the benefits of VOM-Et in AF Patients. Conclusion: The vein of Marshall ethanol infusion for catheter ablation can improve the MI block rate. Male sex, elder age, smaller Left atrial diameter and shorter AF duration may have significant benefits for VOM-Et.