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\begin{document}

\title{Epicardial Ultrasound In A Case of Myocardial Bridge and Apical
Hypertrophic Cardiomyopathy}



\author[1]{Lindsey Whalen}%
\author[1]{Stephen Davies}%
\author[1]{Karen Singh}%
\author[1]{Gorav Ailawadi}%
\affil[1]{University of Virginia Health System}%


\vspace{-1em}



  
  \date{May 24, 2024}


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\selectlanguage{english}
\begin{abstract}
A 59-year-old male with a history of unstable angina was diagnosed with
a myocardial bridge of the left anterior descending artery (LAD) and
apical variant hypertrophic cardiomyopathy (AHCM). He underwent
unroofing of the myocardial bridge and a left ventricular apical
myectomy. Intraoperatively, epicardial ultrasound was used to identify
the myocardial bridge with systolic compression of the LAD and confirm
resolution of this compression postoperatively. Furthermore, epicardial
ultrasound was used for guiding the degree of apical resection of the
decompressed heart. This novel use of intraoperative epicardial
ultrasound can help guide surgeons preoperatively and confirm results
immediately after an operation.%
\end{abstract}%



\sloppy


\textbf{Title} : Epicardial Ultrasound In A Case of Myocardial Bridge
and Apical Hypertrophic Cardiomyopathy

\textbf{Running Head} : Epicardial US for Myocardial Bridge and Apical
HCM

\textbf{Authors} : L. Brett Whalen BS\textsuperscript{1}, Stephen W.
Davies MD\textsuperscript{1}, Karen Singh MD\textsuperscript{2}, Gorav
Ailawadi MD, MBA\textsuperscript{1}

\textbf{Institutions and affiliations} : University of Virginia Health
System Department of Surgery, Division of Cardiac Surgery
Charlottesville, VA, USA\textsuperscript{1},

University of Virginia Health System Department of Anesthesiology
Charlottesville, VA, USA\textsuperscript{2}

\textbf{Word count} : 1483

\textbf{Corresponding author} :

Gorav Ailawadi, MD, MBA

University of Virginia

1215 Lee Street

Charlottesville VA, 22908

Email: GA3F@hscmail.mcc.virginia.edu

Phone: (434) 924-5052

\textbf{Abstract} :

A 59-year-old male with a history of unstable angina was diagnosed with
a myocardial bridge of the left anterior descending artery (LAD) and
apical variant hypertrophic cardiomyopathy (AHCM). He underwent
unroofing of the myocardial bridge and a left ventricular apical
myectomy. Intraoperatively, epicardial ultrasound was used to identify
the myocardial bridge with systolic compression of the LAD and confirm
resolution of this compression postoperatively. Furthermore, epicardial
ultrasound was used for guiding the degree of apical resection of the
decompressed heart. This novel use of intraoperative epicardial
ultrasound can help guide surgeons preoperatively and confirm results
immediately after an operation.

\textbf{Introduction} :

Apical variant hypertrophic cardiomyopathy (AHCM,) characterized by
non-obstructive hypertrophy of the myocardium in the left ventricular
apex,\textsuperscript{1} accounts for just 3\% of hypertrophic
cardiomyopathy (HCM) cases in the United
States.\textsuperscript{2}Patients with AHCM, although often
asymptomatic, can present with chest pain, heart failure, dyspnea, or
syncope.\textsuperscript{2} A myocardial bridge, with resultant
compression of a coronary artery during systole, is often asymptomatic,
but can similarly lead to morbid events.\textsuperscript{3} Patients
with HCM who require myectomy are rare and only 15\% of patients with
HCM have a myocardial bridge.\textsuperscript{4} Since just 3\% of HCM
cases are of the apical variant, the combination of these pathologies as
reported here is exceedingly uncommon.

Herein, we present a patient who underwent surgical repair of a
myocardial bridge of the LAD and a myectomy for AHCM . We report the
novel use of a sterile, epicardial, high frequency ultrasound (HFUS)
with a 15 MHz imaging probe and MiraQTM system (Medistim ASA, Oslo,
Norway) to document the myocardial bridge throughout systolic LAD
compression as well as guide the amount of apical resection required on
a decompressed heart.

\textbf{Case Report} :

A 59 year-old male presented to us in 2018 with a 10-year history of
intermittent chest tightness, shortness of breath and fatigue now
reporting worsening, unstable angina over the last two years. A previous
cardiac MRI in 2016 demonstrated modest asymmetric thickening of the
apical septum, left ventricular free wall and apical lateral wall. His
history was significant for hyperlipidemia, hypertension, hypothyroidism
and nephrolithiasis.

A cardiac catheterization was done due to worsening exertional angina
and showed a left anterior descending artery (LAD) myocardial bridge
with 60\% mid LAD compression (Figure 1A). A subsequent CT coronary
angiography demonstrated a 1cm segment myocardial bridge with a short
segment of compression in the proximal LAD. Given his significant NYHA
Classification III symptoms and low surgical risk, he was referred to us
for surgical repair.

Intraoperatively, the transesophageal echo (TEE) exam revealed (Figure
2A) severe apical hypertrophy with an apical thickness measurement of
2.5 cm. The biplane method of disks calculated a low normal
end-diastolic volume, an ejection fraction of 50\%, and a low stroke
volume index of 19 ml/m\textsuperscript{2}. Given his severity of
symptoms unlikely to be explained by the myocardial bridge, the decision
was made to address the AHCM as well. Once the sternum had been opened
and the pericardial well created, HFUS was utilized to evaluate the
submyocardial LAD trajectory and left ventricle apical myocardial
thickness. Using this technology, the LAD was first identified lying
deep to a thick layer of epicardial adipose tissue. We then traced the
LAD more proximally to localize the overlying myocardial bridge. During
systole, the LAD was almost completely occluded, yet widely patent
during diastole (Video 1, Figure 1B). After crossclamp, the myocardial
bridge was released along the length of the compressed LAD with cautery.
Our attention was then turned to the left ventricular (LV) apex.

The hypertrophic apex was assessed and measured with the probe (Video 3,
Figure 2C) to help guide the extent of resection necessary, which was
roughly 1.5 cm depth circumferentially. The LV apex was opened using a
\#10 scalpel blade 2-3 cm parallel to the LAD. The apical septum and
walls were aggressively cored out with a \#10 blade and metzenbaum
scissors, taking care not to injure the papillary muscles. The LV apex
was widely opened leaving roughly 1 cm of residual LV wall thickness,
confirmed by HFUS. After thoroughly irrigating and clearing of residual
debris, the LV apex was closed using felt and a double layered, 2-0
prolene horizontal mattress, followed by running closure. The suture
line was further secured with Bioglue (CryoLife, Inc., Kennasaw, GA).
The patient was rewarmed and the aortic cross clamp was removed. TEE
demonstrated improved end-diastolic volume despite an underfilled left
ventricle immediately after cardiopulmonary bypass; however, a normal
contour of the LV apex was achieved (Figure 2B) and repeat Medistim
evaluation of the LAD now showed a widely patent vessel throughout its
course (Video 2, Figure 1C)\textbf{.}

The patient's postoperative course was unremarkable. Postoperatively, he
noted dramatically improved symptoms with resolution of his angina and
was able to resume all activities including returning to full-time work
by 2 months after surgery. Now at 1.5 years follow-up, he remains in
NYHA Class I functional class with no residual angina or shortness of
breath.

\textbf{Comment} :

Our patient underwent a rare combination of a myotomy of a myocardial
bridge and an apical myectomy. Although a previous case report
documented a patient with this combination,\textsuperscript{6} the
present report shows the utility of epicardial ultrasound to define the
extent and guide the resection of both pathologies. HFUS helped rapidly
identify the myocardial bridge, clearly demonstrating the
pathophysiology of the disease, as well as confirmed uninterrupted blood
flow after myotomy. HFUS was also highly useful in guiding the depth of
resection of the AHCM, allowing the surgeon to determine how much to
resect on an arrested, empty heart, unlike most preoperative imaging
modalities (MRI, TEE), which are in the setting of a full, beating
heart.

Preoperative diagnosis of both AHCM and myocardial bridging is commonly
performed with cardiac MRI.\textsuperscript{1,2} AHCM is also seen on
ventriculography and echocardiography as a ``spade-shaped''
end-diastolic volume\textsuperscript{1,2}. Myocardial bridging is
typically diagnosed via coronary
angiography.\textsuperscript{3,5}However, none of these modalities
provide real-time guidance to the surgeon intraoperatively, particularly
on a flaccid heart. In fact, HFUS may be further useful in more
conventional cases of hypertrophic cardiomyopathy to guide the resection
depth and avoid ventricular septal defects.

In summary, this case describes a rare combination of two distinct
pathologies. Similar to the real time feedback cardiologists get when
performing coronary or valvular procedures on the beating heart,
epicardial ultrasound gives the surgeon useful real-time guidance
intraoperatively that may provide a safer, more effective result.

\textbf{Keywords:} cardiovascular pathology; cardiovascular research;
perfusion

\textbf{Author contributions:}

L. Brett Whalen: drafting article

Gorav Ailawadi: concept/design, critical revision

Stephen W. Davies: critical revision

Karen Singh: data collection, analysis, interpretation

\textbf{References:}

\begin{enumerate}
\tightlist
\item
  Ates M, Kwong RY, Lipton MJ, Tatli S. Apical hypertrophic
  cardiomyopathy: diagnosed by cardiac magnetic resonance imaging. Texas
  Heart Institute Journal. 2006;33(3):408.
\item
  Mirabbasi SA, Khalighi K, Mukkamala S, Kodali A. A rare case of apical
  hypertrophic cardiomyopathy (AHCM). Journal of community hospital
  internal medicine perspectives. 2017 Apr 3;7(2):122-5.
\item
  Patel M, Swofford B, Distler E. Myocardial bridge: bridging the
  differential diagnosis. BMJ case reports. 2017 Oct 27;2017:bcr-2017.
\item
  Kunkala MR, Schaff HV, Burkhart H, Sandhu GS, Spoon DB, Ommen SR,
  Sorajja P, Dearani JA. Outcome of repair of myocardial bridging at the
  time of septal myectomy. The Annals of thoracic surgery. 2014 Jan
  1;97(1):118-23.
\item
  Arnaz A, Akansel S, Yalcinbas Y, Sarioglu T. Myocardial bridge of the
  left anterior descending artery. Journal of cardiac surgery. 2017
  May;32(5):288-9.
\item
  Giannitsis E, Haase H, SCHM\selectlanguage{ngerman}ÜCKER G, Sheikhzadeh A. Apical Hypertrophic
  Cardiomyopathy of the Japanese Type Coexistent with a Coronary Muscle
  Bridge. Japanese heart journal. 1997;38(5):741-8.
\end{enumerate}

\textbf{Figure legend:}

1. A. A cardiac catheterization image indicates compression (arrow) of
the left anterior descending artery (LAD) due to a myocardial bridge. B.
A frame of the Medistim video during systole shows the lumen of the LAD
(arrow) is compressed by myocardial bridge above (arrowhead). C. A frame
of the Medistim video post-myectomy shows the LAD (arrow) again in
systole, now with a patent lumen with no residual muscle above the
vessel.

2. A. The pre-apical myectomy TEE mid-esophageal 2 chamber view shows
hypertrophied apical myocardium with a classic spade-shaped LV cavity in
diastole. B. A Medistim probe image reveals the thickened apical
myocardium (arrow) overriding the narrowed LV chamber (thin line). C.
The post-CPB TEE mid-esophageal 2 chamber view shows an underfilled LV
with a slightly higher estimated end-diastolic volume, as compared to
pre-CPB imaging. The shape of the LV apical cavity appears normal after
surgical reduction of the apical myocardium.

\emph{TEE: transesophageal echocardiogram}

\emph{CPB: cardiopulmonary bypass}

Video 1. Medistim pre-myectomy LAD.

Video 2. Medistim post-myectomy LAD.

Video 3. Medistim pre-myectomy apical myocardium.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1/Figure-1}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-2/Figure-2}

\end{center}
\end{figure}

\textbf{Hosted file}

\verb`Video 1.mp4`  available at \url{https://authorea.com/users/312425/articles/443029-epicardial-ultrasound-in-a-case-of-myocardial-bridge-and-apical-hypertrophic-cardiomyopathy}

\textbf{Hosted file}

\verb`Video 2.mp4`  available at \url{https://authorea.com/users/312425/articles/443029-epicardial-ultrasound-in-a-case-of-myocardial-bridge-and-apical-hypertrophic-cardiomyopathy}

\textbf{Hosted file}

\verb`Video 3.mp4`  available at \url{https://authorea.com/users/312425/articles/443029-epicardial-ultrasound-in-a-case-of-myocardial-bridge-and-apical-hypertrophic-cardiomyopathy}

\selectlanguage{english}
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\end{document}

