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\begin{document}

\title{Minimally Invasive Approach to Cor Triatriatum Sinister}



\author[1]{Mohineesh Kumar}%
\author[1]{Francis Shannon}%
\affil[1]{Beaumont Health}%


\vspace{-1em}



  
  \date{May 04, 2024}


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\selectlanguage{english}
\begin{abstract}
Cor-triatriatum sinister (CTS) is a rare congenital condition in which
the left atrium is divided into two chambers. Patients can present as
infants or later in life, which is largely dependent on the size of
fenestration between these two chambers. Surgical excision of the
membrane is curative. This is traditionally performed through a median
sternotomy. Here we report of a case of a 60-year old man who presented
to his primary care physician with dyspnea and atrial fibrillation. He
was found to have CTS. We performed excision of the left atrial membrane
and maze procedure through a left anterolateral mini-thoracotomy with
femoral cannulation.%
\end{abstract}%



\sloppy


\textbf{Minimally Invasive Approach to Cor Triatriatum Sinister}

Mohineesh Kumar, MD and Francis L. Shannon, MD

Department of Surgery

Section of Cardiovascular Surgery

Oakland University William Beaumont School of Medicine

Royal Oak, Michigan

Corresponding author: Mohineesh Kumar, MD

3601 West Thirteen Mile Road

Royal Oak, Michigan 48073

Phone: 317-459-1058

e-mail: mohineesh.kumar@beaumont.org

\textbf{Abstract} :

Cor-triatriatum sinister (CTS) is a rare congenital condition in which
the left atrium is divided into two chambers. Patients can present as
infants or later in life, which is largely dependent on the size of
fenestration between these two chambers. Surgical excision of the
membrane is curative. This is traditionally performed through a median
sternotomy. Here we report of a case of a 60-year old man who presented
to his primary care physician with dyspnea and atrial fibrillation. He
was found to have CTS. We performed excision of the left atrial membrane
and maze procedure through a left anterolateral mini-thoracotomy with
femoral cannulation.

\textbf{Introduction:}

Cor-triatriatum Sinister (CTS) is a rare anomaly in which the left
atrium is divided into two distinct chambers separated by a
fibromuscular membrane and represents only 0.1\% of all congenital
cardiac anomalies. \textsuperscript{1} Patients develop symptoms
secondary to impaired venous return from the pulmonary
veins.\textsuperscript{2} The degree of a patient's symptoms is directly
related to the size of the left atrial opening and inter-atrial
gradient. \textsuperscript{1} Infants can present with heart failure or
death in infancy due to complete left atrial
obstruction.\textsuperscript{1} In adults, CTS is often asymptomatic due
to a large foramen in the membrane and minimal inter-atrial
gradient.\textsuperscript{2} CTS can present as a functional mitral
stenosis and can present with atrial fibrillation or mitral
regurgitation in adults.\textsuperscript{3} Patients presenting later in
life are more likely to have lower pressure gradients between the two
atria and lower pulmonary capillary wedge pressures.
\textsuperscript{3}. The most common associated anomalies include atrial
septal defect, anomalous pulmonary venous return, tetralogy of Fallot,
and bicuspid aortic valve.\textsuperscript{2}. Due to the increased
general use of imaging modalities, CTS is being more commonly diagnosed.
\textsuperscript{3}Incidental asymptomatic CTS may not require
treatment. Traditionally CTS has been managed with median sternotomy.
Here we report a case of CTS repair done minimally invasively through a
right anterolateral mini-thoracotomy.

\textbf{Case Presentation} :

A 60-year old Caucasian construction worker with no past medical history
presented to a primary care physician with a three month history of
increasing fatigability, particularly at the end of each day.
Electrocardiogram demonstrated atrial fibrillation. Echocardiography
(\textbf{figure 1} ) demonstrated severely enlarged right atrium as well
as a severely large left atrium with two atria consistent with
Cor-triatriatum sinister. There was a transmembrane gradient of 3 mm
between the two left atria. All four pulmonary veins drained into the
upper left atrium. The left atrial appendage also originated from the
lower left atrium. The mitral valve was normal in architecture. He had a
persistent left superior vena cava and ejection fraction was 60\%. CTA
was also used to further define anatomy and demonstrated a 1.6 x 1.5 cm
fenestration in the membrane between the two left atria (\textbf{figure
2} ).

An anterolateral mini-thoracotomy was made through the right fourth
intercostal space. The common femoral artery and vein were cannulated in
the right groin for cardiopulmonary bypass. The venous cannula position
in the right atrium was confirmed by trans-esophageal echo. The right
lung was collapsed with aid of bronchial blocker. This allowed us to
visualize the pericardium, which was incised 4 cm away from and parallel
to the phrenic nerve. A purse-string suture was placed in the superior
vena cava and 24 Fr single-stage venous cannula was inserted. An
anterograde cardioplegia catheter was placed in the ascending aorta. The
patient was placed on bypass and a flexible cross clamp occluded the
ascending aorta. The heart was arrested with antegrade Custodial
cardioplegia. A left atriotomy was made along Waterson's groove. The CTS
membrane extended from the fossa ovalis to the superior margin of the
left atrial appendage. There was a dime-sized fenestration in the CTS
membrane at a right angle to a patent foramen ovale (not seen in
pre-operative echo). A mitral lift retractor was used to gain exposure
to left atrium. The membrane excision was started at the fenestration
and extended circumferentially around the left atrium (\textbf{figure 3}
). A small cuff of membrane was left at the posterior wall. A running
3-0 prolene was used to close the ostium of the left atrial appendage. A
Cox Maze IV left atrial lesion set was done using Atricure bipolar
radiofrequency device and cryoprobe. The patent foramen ovale was closed
with a 3-0 pledgeted suture. The left atriotomy was closed and the
patient was taken off bypass without complication. Post repair TEE
showed no mitral valve regurgitation, no left to right shunting and
preserved pulmonary venous flow into the left atrium. The rhythm was
sinus. The patient's post-operative course was uneventful. Final
pathology demonstrated atrial myocardial and fibrous tissue with
dystrophic calcification (\textbf{figure 4} ).

\textbf{Discussion:}

Our patient had a large dime-sized fenestration in his CTS membrane with
minimal (3mm) intra-atrial gradient. Although there was small gradient,
there was a significant obstruction of flow. The patient also had a
patent foramen ovale, which allowed for left-to-right shunting and
allowed for left atrial decompression into the right atrium. This led to
a gradual left and right atrial dilation over 60 years and the
subsequent development of dyspnea and atrial fibrillation, which is the
most common trigger for presenting at a later age.\textsuperscript{3}

Minimally invasive anterior thoracotomy is a well-described technique
for repair and replacement of mitral valves. It provides reduced
post-operative pain, decreased infection, improved cosmesis, and reduced
length of stay.\textsuperscript{4} For repair of CTS, it provides
excellent exposure of the left atrium allowing for complete assessment
of the pulmonary veins, left atrial appendage and the CTS membrane. This
is only the second reported case of minimally invasive repair of CTS in
the literature to our knowledge. \textsuperscript{5} We believe that
minimally invasive anterolateral thoracotomy should be the preferred
method for treatment of CTS as well as other left atrial and mitral
pathology.

\textbf{Conflicts of Interest} :

There are no conflicts of interest

\textbf{Author Contributions:}

Concept/Design, Data analysis/interpretation, Drafting article:
Mohineesh Kumar

Concept/Design, Data analysis/interpretation, Critical revision and
approval of article: Francis Shannon

\textbf{Bibliography}

1. Jegier W, Gibbons JE and Wiglesworth FW. Cortriatriatum: clinical,
hemodynamic and pathological studies surgical correction in early
life.\emph{Pediatrics} . 1963;31:255-67.

2. Nassar PN and Hamdan RH. Cor Triatriatum Sinistrum: Classification
and Imaging Modalities. \emph{Eur J Cardiovasc Med} . 2011;1:84-87.

3. Slight RD, Nzewi OC, Buell R and Mankad PS. Cor-triatriatum sinister
presenting in the adult as mitral stenosis: an analysis of factors which
may be relevant in late presentation. \emph{Heart Lung Circ} .
2005;14:8-12.

4. Ward AF, Grossi EA and Galloway AC. Minimally invasive mitral surgery
through right mini-thoracotomy under direct vision. \emph{J Thorac Dis}
. 2013;5 Suppl 6:S673-9.

5. Gottschalk BH, Fujii S, Grant A, Iglesias I and Chu MWA. Minimally
Invasive Periareolar Approach to Cor Triatriatum
Repair.\emph{Innovations (Phila)} . 2018;13:445-447.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

\textbf{Figure 1:} Echocardiography demonstrating cor triatriatum
sinister\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

\textbf{Figure 2:} CTA of the heart demonstrating two atria and mitral
valve (A), 15 mm fenestration between the two champers (B), and
pulmonary veins draining into left atrium with a thick fibromuscular
portion of membrane (C)\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image8/image8}

\end{center}
\end{figure}

\textbf{Figure 3:} Intra-operative photos after left atriotomy and
placement of mitral lift retractor. A drainage catheter was placed in
the left atrial appendage. Picture A demonstrates the cor triatriatum in
situ. Picture B shows the left atrium after excision of the membrane.
Picture C shows the closure of the left atrial appendage\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image14/image14}

\end{center}
\end{figure}

\textbf{Figure 4:} Excised membrane measuring 2.5 x 2.5 x 0.4 cm. The
dime sized fenestration is the crescent at the superior part of image.

\selectlanguage{english}
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