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

Abstract 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.


Introduction
The ligament or vein of Marshall (VOM) is anatomical and electrical structures that are sometimes involved in macro-reentry and microreentry circuits. By bridging endocardial activation at the mitral isthmus, the VOM may be responsible for peri-mitral flutters that occur after atrial fibrillation (AF) ablation. 1,2 Ethanol (EtOH) 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. 3 The standard way of cannulating the VOM is through a femoral approach, which has been detailed in several case reports. 4,5 The jugular approach is also possible, but it has been less described. 5,6 Learning points • Ethanol infusion inside the vein of Marshall may be a complementary technique to complete mitral isthmus conduction block after endocardial and epicardial radiofrequency ablation.
• Right jugular vein approach may be of interest when the femoral approach is not feasible. *

Timeline
Case presentation A 45-year-old man was admitted to our unit for dyspnoea associated with an atypical atrial flutter with positive p waves in the inferior and precordial leads. He was already being treated with Disopyramide LP 125 mg and Bisoprolol 2.5 mg per day ( Figure 1). He had undergone an AF ablation procedure 7 months previously, during which a microreentry was ablated on the roof of the left atrium (LA) near the right superior pulmonary vein (PV). The procedure was then completed with antral PV isolation, and a complete roofline block was done in order to restore sinus rhythm. Transthoracic echocardiography revealed predominantly septal and posterior hypertrophic cardiopathy with intraventricular obstruction of flow (basic gradient at 45 mmHg up to 60 mmHg after Valsalva manoeuvres). The LA was found to be dilated, with a measured surface of 53 mL/m 2 . Computed tomography scan imaging showed a moderately dilated LA (42 cm 2 ) with normal PV anatomy and no thrombus in the left atrial appendage (LAA).
After informed consent was obtained, the patient underwent a new endocardial electrophysiology procedure. We used the same 3D navigation system as for the first procedure (CARTO 3D, Biosense Webster Inc., Johnson & Johnson, Irvine, CA, USA). At the beginning of the procedure, the rhythm was a stable atrial flutter with a cycle length of 320 ms. We observed a proximal to distal activation  At this stage, a new activation map showed that the mitral line was still permeable with an epicardial conduction bridge through the VOM (Figure 1). We then decided to use an ethanol infusion for the ablation of the VOM. The coronary sinus could not be thoroughly catheterized with femoral approach due to a winding and angular shape (Figure 2A) neither with a deflectable decapolar catheter Xtrem (Microport, Shangai, China) nor with two different sheaths (SL0 Abbott, Saint Paul, Minnesota, USA and Agilis TM NxT Steerable Introducer, Abbott, Saint Paul, MN, USA). So, we decided to try a right jugular vein approach with echo-guided puncture using an Agilis TM NxT Steerable Introducer (Abbott, Saint Paul, MN, USA). We had no problem finding the VOM ostium using a 5 Fr angiography catheter (5 Fr left internal mammary artery; Medtronic, Minneapolis, MN, USA) that was inserted into the CS via the steerable sheath. We then performed a selective venogram of the vein using a 1.5 mm balloon (1.5-2.5 mm diameter and 6-15 mm length, Abbott) that was progressively inflated (from 2 to 6 atm) inside the vein over an angioplasty wire (Whisper 0.014, Abbott). After we confirmed the complete occlusion of the VOM by injecting 1 mL of contrast medium, 3 mL of ethanol (96% ethanol 10 mL) was slowly injected over a period of 1 minute, and venography of the VOM was repeated. Following the initial injection and using the same technique, a complementary injection was performed with 3 mL of ethanol inside another branch of the VOM. A total of 9 mL of ethanol was used as a maximum dose. A final venogram showed the diffusion of ethanol around the VOM ( Figure 2B). Sinus rhythm was restored during the last ethanol infusion ( Figure 2C). A new voltage map confirmed the completion of the mitral line ( Figure 3). Activation maps sequentially paced in the distal CS and in the LAA confirmed a bidirectional atrial block (Figure 4).
At 1-month post-ablation, the patient was asymptomatic without recurrence of arrhythmia.

Discussion
Ethanol infusion is a new alternative approach to treat peri-mitral atrial flutters which are refractory to mitral isthmus endocardial RF ablation. 6 The ligament of Marshall is a unique anatomical structure electrically insulated by surrounding adipose tissue or vessels protecting it from endocardial RF energy applications. 7 Sometimes, it is still a vein (VOM) that can be followed retrogradely from its insertion into the main body of the CS, at the epicardial aspect of the mitral annulus, to the top of the ridge between the LA appendage and the leftsided PVs. Although this vein is usually too small to be targeted by a conventional ablation catheter, the atrial tissue drained by it may be efficiently ablated by retrograde EtOH infusion via the CS. Whereas the femoral vein approach is the regular technique to cannulate the VOM with an EtOH infusion success rate ranging from 89% to 92%, 5,8 to date, there are only a few reports using the jugular vein approach as a surrogate. Some authors are using the jugular vein approach as a regular technique which seems to be as efficient as the femoral vein approach (86%). 9 In our case, we have shown that this technique may be of interest whenever the femoral approach is not suitable. In addition, the right jugular vein approach may have several advantages: (i) the steerable sheath can also be useful to insert an RF ablation catheter in order to complete the epicardial conduction block after ethanol infusion if needed, (ii) one operator can perform the EtOH infusion while the other one is confirming the presence of a bidirectional endocardial conduction block, and (iii) the echoguided right jugular vein puncture may lead to simple post-operative follow-up.

Conclusion
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. This recently described technique appears to be suitable for obtaining a conduction block through the mitral isthmus. However, it must be noted that endocardial RF applications were also needed to complete the block.

Supplementary material
Supplementary material is available at European Heart Journal -Case Reports online.
Slide sets: A fully edited slide set detailing this case and suitable for local presentation is available online as Supplementary data.

Consent:
The author/s confirm that written consent for submission and publication of this case report including image(s) and associated text has been obtained from the patient in line with COPE guidelines.  (B) Clockwise peri-mitral block evidence by pacing at the left atrial appendage while recording at the distal coronary sinus.
A case report of ethanol infusion