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\begin{document}

\title{Transient left phrenic nerve paralysis after ethanol infusion into the
vein of Marshall}



\author[1]{Wataru Sasaki}%
\author[1]{Yosuke Nakatani}%
\author[1]{Yutaka Take}%
\author[1]{Shohei Kishi}%
\author[1]{Shigeto Naito}%
\affil[1]{Gunma Kenritsu Shinzo Kekkan Center}%


\vspace{-1em}



  
  \date{May 24, 2024}


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\selectlanguage{english}
\begin{abstract}
An 80-year-old man underwent catheter ablation for atrial tachycardia
(AT), which developed after catheter ablation for atrial fibrillation.
The AT was diagnosed as dual-loop tachycardia, which included
peri-mitral and roof-dependent ATs. An ethanol infusion into the vein of
Marshall resulted in left phrenic nerve paralysis. During the procedure,
the phrenic nerve paralysis was completely relieved.%
\end{abstract}%



\sloppy


\textbf{Transient left phrenic nerve paralysis after ethanol infusion
into the vein of Marshall}

Wataru Sasaki, MD; Yosuke Nakatani, MD; Yutaka Take, MD; Shohei Kishi,
MD; and Shigeto Naito, MD.

Division of Cardiology, Gunma Prefectural Cardiovascular Center, Gunma,
Japan

Funding: None

\emph{Disclosures:} None

Address for correspondence: Dr. Yosuke Nakatani, Division of Cardiology,
Gunma Prefectural Cardiovascular Center, 3--12 Kameizumi-machi Kou,
Maebashi, Gunma 371--0004, Japan. Telephone: +81-27-269-7455; Fax:
+81-27-269-1492; E-mail: yosuke3gbst@gmail.com

\textbf{ABSTRACT}

An 80-year-old man underwent catheter ablation for atrial tachycardia
(AT), which developed after catheter ablation for atrial fibrillation.
The AT was diagnosed as dual-loop tachycardia, which included
peri-mitral and roof-dependent ATs. An ethanol infusion into the vein of
Marshall resulted in left phrenic nerve paralysis. During the procedure,
the phrenic nerve paralysis was completely relieved.

\textbf{KEYWORDS}

Atrial tachycardia; the vein of Marshall; phrenic nerve paralysis;
catheter ablation.

\textbf{INTRODUCTION}

Ethanol infusion into the vein of Marshall (Et-VOM) is a promising
approach for treating atrial fibrillation (AF) and atrial tachycardia
(AT). Although this approach is highly feasible, several complications
have been reported.\textsuperscript{1} Here, we present a rare
complication of Et-VOM-induced left phrenic nerve paralysis.

\textbf{CASE PRESENTATION}

An 80-year-old man was referred to our facility for catheter ablation of
an atrial tachycardia (AT) that developed after atrial fibrillation (AF)
ablation. The previous procedure consisted of pulmonary vein isolation
and cavotricuspid isthmus ablation. An AT with a tachycardia cycle
length of 230 ms was detected on a baseline surface electrocardiogram
(Fig. 1A). A decapolar catheter was positioned in the coronary sinus.
The CARTO 3 system (Biosense-Webster, Inc., Diamond Bar CA) was used for
electroanatomical mapping. Contact mapping was performed using a 20-pole
high-density mapping catheter (PENTARAY; Biosense-Webster, Inc). The
activation map suggested a dual-loop tachycardia mechanism; one circuit
is a peri-mitral AT with a counterclockwise direction, and another is a
roof-dependent AT around the left pulmonary veins (Fig. 1B and 1C).
Since the lateral mitral isthmus was the common isthmus of the two
circuits, we performed Et-VOM to create a block line on the lateral
mitral isthmus. After occluding the vein of Marshall with an
over-the-wire balloon catheter, 10 ml of 98\% ethanol was injected in
three divided doses. We did not observe the leakage of ethanol into the
coronary sinus. During Et-VOM, the tachycardia cycle length was
increased to 290 ms. After Et-VOM, the local staining was observed
around the vein of Marshall (Fig. 2A). In the voltage map, an extensive
endocardial scar was visible on the left atrial ridge and lateral mitral
isthmus (Fig. 2B and 2C). Although the diaphragmatic motion was normal
at baseline (Fig. 3A and 3B, and Supplementary Movie 1), the left
phrenic nerve paralysis (PNP) was recognized after Et-VOM (Fig. 3C and
3D, and Supplementary Movie 2). A review of the fluoroscopic image
revealed that the motion of the left diaphragm weakened immediately
after the initial injection of ethanol. Seven minutes after the last
ethanol injection, the left PNP gradually started to relieve. Adjunctive
radiofrequency application to the lateral mitral isthmus terminated the
AT, and the block line was finally created. At the end of the procedure,
the left PNP was completely relieved, and no symptoms were observed
after the procedure.

\textbf{DISCUSSION}

Et-VOM may cause several complications, such as cardiac tamponade,
stroke, anaphylactic shock, atrioventricular block, and left atrial
appendage isolation.\textsuperscript{1} The left phrenic nerve injury,
however, has not been reported as a complication of Et-VOM. Catheter
ablation can injure the left phrenic nerve for its proximity to several
heart structures. The left phrenic nerve is at risk of injury during
radiofrequency application to a left posterolateral accessory
pathway,\textsuperscript{2} and the left PNP is one of the critical
complications during cryoballoon ablation of the left superior pulmonary
vein.\textsuperscript{3}

The left phrenic nerve runs dorsally to the left brachiocephalic vein
and anterolateral to the aortic arch and pulmonary
trunk.\textsuperscript{4} After that, it descends toward the cardiac
apex following three courses: (1) along a course related to the anterior
surface of the heart (anterior course), (2) pass leftward along a course
related to the apex of the left atrial appendage and obtuse margin of
the left ventricle (lateral course), or (3) pass posteriorly to the
inferior surface of the left ventricle (inferior course). In particular,
the inferior course shows the shortest distance to the left superior
pulmonary vein.\textsuperscript{4} Scarring caused by Et-VOM was
observed on the left lateral ridge anterior to the left superior
pulmonary vein in this case (Fig. 2B). This finding presumes that Et-VOM
directly injured the left phrenic nerve with an inferior course. Since
the vein of Marshall is an epicardial structure, ethanol exuding from it
may damage pericardial structures. The tissue staining around the vein
of Marshall (Fig. 2A) after Et-VOM supports this hypothesis. However,
epicardium insulation of the left phrenic nerve may have kept the left
PNP transient.

To our best of knowledge, this is the first case report of the
Et-VOM-related left PNP. Fortunately, the left PNP was transient in this
case; however, the persistent left PNP might be caused in patients with
a shorter distance between the left PNP and the vein of Marshall. We
should know the risk of the left PNP and keep a close observation of the
diaphragmatic movement during Et-VOM.

\textbf{REFERENCE}

1. Kamakura T, Derval N, Duchateau J, Denis A, Nakashima T, Takagi T,
Ramirez FD, Andr\selectlanguage{ngerman}é C, Krisai P, Nakatani Y, Tixier R, Chauvel R, Cheniti
G, Kusano K, Cochet H, Sacher F, Hocini M, Jaïs P, Haïssaguerre M,
Pambrun T. Vein of Marshall Ethanol Infusion: Feasibility, Pitfalls, and
Complications in Over 700 Patients. Circ Arrhythm Electrophysiol. 2021
Aug;14(8):e010001. doi: 10.1161/CIRCEP.121.010001. Epub 2021 Jul 19.
PMID: 34280029; PMCID: PMC8376276.

2. Rumbak MJ, Chokshi SK, Abel N, Abel W, Kittusamy PK, McCormack J,
Patel MM, Fontanet H. Left phrenic nerve paresis complicating catheter
radiofrequency ablation for Wolff-Parkinson-White syndrome. Am Heart J.
1996 Dec;132(6):1281-5. doi: 10.1016/s0002-8703(96)90477-9. PMID:
8969585.

3. Andrié RP, Schrickel JW, Nickenig G, Lickfett L. Left phrenic nerve
injury during cryoballoon ablation of the left superior pulmonary vein.
Pacing Clin Electrophysiol. 2012 Nov;35(11):e334-6. doi:
10.1111/j.1540-8159.2012.03470.x. Epub 2012 Jul 30. PMID: 22845556.

4. Sánchez-Quintana D, Ho SY, Climent V, Murillo M, Cabrera JA. Anatomic
evaluation of the left phrenic nerve relevant to epicardial and
endocardial catheter ablation: implications for phrenic nerve injury.
Heart Rhythm. 2009 Jun;6(6):764-8. doi: 10.1016/j.hrthm.2009.02.029.
Epub 2009 Feb 24. PMID: 19427272.

\textbf{FIGURES}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

\textbf{Figure 1. Surface electrocardiogram and activation map of atrial
tachycardia (AT)}

(A). Surface electrocardiogram of the AT. AT wave showed positive
deflection in inferior leads and V1. AT cycle length was 230 ms. (B, C)
The activation (white arrows) suggested a dual-loop tachycardia with a
circuit on the mitral annulus (MA) and another around the left pulmonary
veins (LPVs). Note that the lateral mitral isthmus was a common isthmus.
The blue tags and numbers on the map show entrainment-pacing sites and
the post-pacing interval minus the tachycardia cycle length. LAA, left
atrial appendage; RPV, right pulmonary vein.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

\textbf{Figure 2. The impact of ethanol infusion into the vein of
Marshall (Et-VOM)}

(A) A fluoroscopic image in the right anterior oblique (RAO) 35\selectlanguage{ngerman}° view
after Et-VOM. A circular catheter was positioned in the left atrial
appendage (LAA). The vein of Marshall was occluded with an over-the-wire
balloon catheter (arrow). Local tissue staining was observed around the
vein of Marshall (arrowheads). (B) Bipolar voltage map in the left
lateral view before Et-VOM. (C) Bipolar voltage map after Et-VOM. An
extensive scar appeared on the left atrial ridge and lateral mitral
isthmus. Note that the impact of Et-VOM extended to the basal left
atrial appendage (LAA). CS, coronary sinus. Other abbreviations are as
in Fig. 1.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

\textbf{Figure 3.} \textbf{The diaphragmatic motion before and after
ethanol infusion into the vein of Marshall.}

(A, B) Fluoroscopic images in the left anterior oblique (LAO) 45\selectlanguage{ngerman}° view
before Et-VOM. Compared to the expiratory phase (A), both the right and
left diaphragms sufficiently moved downward in the inspiratory phase
(B). Bars indicate the motion of diaphragms. (C, D) After Et-VOM.
Although diaphragmatic eventration was not observed in the expiratory
phase (C), the movement of the left diaphragm with inspiration weakened
after Et-VOM (D).

\selectlanguage{english}
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