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\begin{document}

\title{Lessons learned on a new procedure: Non-Sternotomy Minimally Invasive
Pulmonary Embolectomy}



\author[1]{Danuel Laan}%
\author[2]{Edwyn Assaf}%
\author[3]{John Fallon}%
\author[4]{Omar Lattouf}%
\affil[1]{Emory University}%
\affil[2]{American University of Beirut}%
\affil[3]{Emory University Hospital}%
\affil[4]{Emory University School of Medicine}%


\vspace{-1em}



  
  \date{June 17, 2024}


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\selectlanguage{english}
\begin{abstract}
Since publication of our initial experience with non-sternotomy
minimally invasive pulmonary embolectomy (MIPE) via a left mini
thoracotomy, we have expanded our experience, refined the operation and
streamlined the post-operative management of patients. Our initial
publication described three patients who underwent MIPE.1 We described
our technique which included peripheral cardiopulmonary bypass (CPB) via
femoral arterial and venous cannulation, left sided 5cm anterior
thoracotomy in the 3rd intercostal space, identification and incision of
the main pulmonary artery distal to the pulmonic valve, extraction of
clot with subsequent primary closure of the pulmonary artery, and use of
a 5mm, 30 degree laparoscope as an adjunct to assess clearance of the
pulmonary artery.2 The patients included in this series had no
post-operative complications, had a mean hospital length of stay of
three days with mid-term follow-up up to 8-months revealing no untoward
complications of the procedure. With early success of the MIPE at our
institution, we began employing it preferentially over sternotomy with
central CPB and pulmonary embolectomy. Since initial publication of our
results, we have performed the MIPE in two additional patients with
excellent outcomes. We herein present augmentations we've made to the
procedure with a case-presentation which highlights these adaptations.%
\end{abstract}%



\sloppy


7/15/20

Dear Editor(s) and Reviewers,

\emph{Journal of Cardiac Surgery}

Please find within our manuscript entitled `\textbf{Lessons Learned on a
New Procedure: Non-Sternotomy Minimally Invasive Pulmonary Embolectomy}
.'

Type of paper: Original Article

Conflicts of Interest and Source of Funding: The authors have no
relevant financial disclosures. This work has not been published
elsewhere. The work was not been presented at a conference.

Thank you for your time and consideration.

Sincerely,

Corresponding author:

Danuel Laan, MD

Division of Cardiothoracic Surgery

Emory University School of Medicine

550 Peachtree St NW

Suite 6D

Atlanta, GA 30308

email: danlaan21@gmail.com

Title: Lessons learned on a new procedure: Non-Sternotomy Minimally
Invasive

Pulmonary Embolectomy

Journal: Journal of Cardiac Surgery

Authors: Danuel Laan MD\textsuperscript{1}, Edwyn Jeremy Assaf
BS\textsuperscript{2}, John Fallon MD\textsuperscript{1}, Omar Lattouf
MD PhD\textsuperscript{1}

\begin{enumerate}
\tightlist
\item
  Division of Cardiothoracic Surgery, Department of Surgery; Emory
  University, Atlanta, GA
\item
  American University of Beirut; Beirut, Lebanon
\end{enumerate}

Keywords: Pulmonary embolism, Pulmonary Embolectomy, Minimally Invasive
Pulmonary Embolectomy

\textbf{Introduction:}

Since publication of our initial experience with non-sternotomy
minimally invasive pulmonary embolectomy (MIPE) via a left mini
thoracotomy, we have expanded our experience, refined the operation and
streamlined the post-operative management of patients.

Our initial publication described three patients who underwent
MIPE.\textsuperscript{1} We described our technique which included
peripheral cardiopulmonary bypass (CPB) via femoral arterial and venous
cannulation, left sided 5cm anterior thoracotomy in the
3\textsuperscript{rd} intercostal space, identification and incision of
the main pulmonary artery distal to the pulmonic valve, extraction of
clot with subsequent primary closure of the pulmonary artery, and use of
a 5mm, 30 degree laparoscope as an adjunct to assess clearance of the
pulmonary artery.\textsuperscript{2} The patients included in this
series had no post-operative complications, had a mean hospital length
of stay of three days with mid-term follow-up up to 8-months revealing
no untoward complications of the procedure.

With early success of the MIPE at our institution, we began employing it
preferentially over sternotomy with central CPB and pulmonary
embolectomy. Since initial publication of our results, we have performed
the MIPE in two additional patients with excellent outcomes. We herein
present augmentations we've made to the procedure with a
case-presentation which highlights these adaptations.

\textbf{Case presentation:}

\emph{Pre-operative Course:}

A 48 year old male with history of morbid obesity (BMI: 44 kg/m2), C4-C5
laminectomy and partial thyroidectomy one month prior presented to his
local emergency room with new dyspnea on exertion ongoing for two days
followed by a syncopal episode. He had no family history of clotting
disorders and denied alcohol or tobacco use. On presentation he was
normotensive, tachycardic and hypoxic requiring supplemental oxygen.
Pulmonary Embolism (PE) protocol- Computed Tomography (CT) demonstrated
a saddle pulmonary embolus extending into bilateral main pulmonary
arteries and into segmental and subsegmental pulmonary artery branches
bilaterally. Additionally, evidence of right ventricle strain was noted
with right ventricular size larger than left ventricle in diastolic
phase (Image 1). The patient was heparinized and transferred to our
institution. Upon arrival, he was persistently tachycardic and hypoxic.
Laboratory evaluation was notable for an elevated B-type natriuretic
peptide (BNP) of 620 ng/L. Transthoracic echocardiogram revealed
severely enlarged and poorly contractile right ventricle. Left
ventricular contractility and valvular assessment was grossly normal.
Bilateral lower extremities venous duplex ultrasound revealed a left
common femoral deep venous thrombosis. Based on his extensive clot
burden, evidence of acute right heart failure, pulmonary embolectomy was
advised, and the patient proceeded to the operating room urgently for
MIPE.

\emph{Operation:}

Our surgical approach was as previously described.\textsuperscript{1} We
positioned the patient supine with a bump underneath the left shoulder
blade to elevate the left hemithorax and extend the neck. Double lumen
endotracheal intubation was used to achieve left lung isolation and a
transesophageal echocardiography (TEE) probe was placed. A 5cm
parasternal anterior thoracotomy was made in the third intercostal space
(Image 2). Two inches of subcutaneous fat made visualization difficult.
A mini-mitral retractor (Estech, AtriCure Corporate Headquarters 7555
Innovation Way Mason, OH 45040 USA) was used to facilitate exposure. The
pericardium overlying the right ventricular outflow tract was identified
and opened in parallel direction to the Right Ventricular Outflow
Tract--Pulmonary Artery. Traction sutures were applied to the edges of
the incised pericardium.

With this exposure, we realized that our incision was too inferior, in
that the right ventricle was preferentially exposed rather than the body
of PA (Image 3). In hindsight a second intercostal space incision would
have been better for isolation of the main PA. In order to better
facilitate exposure, we placed a simple retraction suture in the main PA
to pull it inferior. We were also prepared to resect a portion of the
second rib, but such was not required.

The right common femoral vein and artery were exposed in a standard
fashion. The patient was fully heparinized and cannulation of the common
femoral vein (wire-guided 25-French Medtronic venous cannula extending
into the right atrium verified by transesophageal echocardiography) and
artery (wire-guided 18-French Femoral-Flex cannula ) was accomplished.
Due to the deep layer of subcutaneous fat encountered, we decided to
tunnel the cannuli through separate stab incisions. This facilitated the
insertion of needle and guide wire into target vessels followed by
dilation of each vessel and proper TEE guided placement of wires and
cannuli with minimal line kinking and enhanced ergonomics (Image 4).

Once the ACT (Activated Clotting Time) was confirmed to have reached
above 400 seconds, cardiopulmonary bypass (CPB) was initiated. At that
point, a one-inch incision was made in the main pulmonary artery in
order to insert ring forceps and extract the clots. Although full
cardiopulmonary bypass with approximately 5 L/min was ongoing, bleeding
from the PA incision was significant making visualization difficult thus
requiring simultaneous suctioning through the limited surgical incision
in order to identify the clots. Nevertheless, with vigorous suctioning
employed to clear the main PA, we were able to identify two large clots,
grasp each with endoscopic-type ring forceps and extract the target
clots each measuring about 8 inches (Image 5), from the right and left
pulmonary trunks.

Further investigation and review of the intraoperative TEE images
revealed that the venous cannula had slipped back toward the right
atrial (RA)-IVC junction rather than being high up in the mid RA, thus
leaving volume undrained and the right ventricle relatively full.
Furthermore, we suspected that the flow of 5 L/min was not adequate to
empty the heart in this large patient with BMI of 44 who had evidence of
fluid overload based on preoperative echocardiography and CT scan. With
this in mind, we should have deployed dual venous cannulas (placed via
the common femoral vein into the RA and a second percutaneously placed
superior vena cave (SVC) cannula inserted under TEE guidance via the
right internal jugular vein). We believe dual percutaneous cannulation
and confirmation of accurate position by TEE is advisable in large
patients and would prevent this undue hardship of exposure and clot
retrieval.

Once the two large clots were extracted, the pulmonary arteriotomy was
closed with multiple pledgetted 3-0 prolene stitches, instead of the
usual running two-layer closure. This technique facilitated repair of
the pulmonary artery while applying suction to clear the bleeding from
the surgical site, given inadequate venous drainage.

The patient was then weaned off cardiopulmonary bypass without
difficulty. Cardiac function was assessed via TEE and the right
ventricle remained dilated however function had improved to only mildly
depressed systolic function (compared with severely depressed systolic
function pre-operatively). Hemostasis was ensured and two chest tubes
were placed through separate entry points into the fourth intercostal
space. The anterior thoracotomy was closed in standard fashion and
decannulation followed by repair of femoral vessels with resultant
excellent distal pulses in the femoral artery.

In a follow-up case, and after learning from the aforementioned
experience, we modified our technical approach by making the anterior
thoracotomy incision in the second intercostal space, inserting a second
percutaneous cannula in the SVC, and placing a 2 cm purse-string suture
about the pulmonary arteriotomy prior to incision which was sufficient
to seal the pulmonary artery entry point at the end of the procedure.

\emph{Post-operative course} \textbf{:}

Aerosolized Epoprostenol Sodium (Flolan) was initiated in the operating
room prior to transport to the ICU to support right ventricular
function. The patient required inotropic and ventilatory support until
post-operative day (POD) 3 at which point he was extubated. Flolan was
weaned based on a combination of central venous gas oxygen saturation,
central venous pressure and echocardiographic assessment of RV function
given absence of a PA catheter to assess right heart function. Notably,
the patient had a known left femoral DVT pre-operatively, and an IVC
filter was placed on POD 3 as a safeguard for further pulmonary
embolism. His hospital course was further complicated by
thrombocytopenia and non-oliguric acute kidney injury with coinciding
hyperkalemia, requiring one session of hemodialysis. Given exposure to
heparin, a heparin-induced thrombocytopenia (HIT) immunoglobulin and
serotonin release assay were sent and both were positive. Heparin was
discontinued, Argatroban was initiated and ultimately transitioned to
coumadin. Extensive post-operative mobilization and physical therapy
were required for convalescence due to extended ICU stay, patient size,
and a recurrence of severe gout that immobilized him for several days.
Ultimately, the patient discharged on POD 19 not requiring dialysis or
supplemental oxygen, ambulating and tolerating a diet.

Our most recent patient who underwent MIPE for massive saddle PE, and
the fifth patient in our series total, underwent the procedure, was
extubated on POD 0, transferred to the general care floor on POD 1 and
discharged home on POD 3.

\textbf{Discussion:}

Pulmonary embolism is a major cause of cardiovascular
mortality.\textsuperscript{3} Most clinical guidelines only recommend
surgical embolectomy for massive PE and only when thrombolysis has
failed, is contraindicated, or for patients presenting in extremis with
cardiopulmonary collapse.\textsuperscript{1,4} Emerging data from our
institution and others support the extended utility of surgical
embolectomy for treatment of massive PE. As we previously wrote, recent
reports highlighting improved surgical techniques have shown that
surgical pulmonary embolectomy yields similar 30-day and 5-year
mortality rates compared to thrombolytic therapy.
\textsuperscript{5,6}However, compared to thrombolysis, surgical
pulmonary embolectomy was associated with lower rates of bleeding
complications, stroke, and requirement for re-intervention within 30
days.\textsuperscript{6}

Our introduction of the MIPE via a left mini thoracotomy highlights an
advancement in surgical embolectomy in that it avoids sternotomy and
related complications allowing for enhanced recovery. With continued
experience with the MIPE we offer the following as important lessons
learned after our initial description\textsuperscript{1}.

\begin{enumerate}
\tightlist
\item
  Location of the anterior thoracotomy should be based on pre-operative
  axial and sagittal imaging rather than adhering to a standardized
  third interspace. In the case presented the
  3\textsuperscript{rd}intercostal space was too inferior and created
  difficulty with exposure and visualization of the PA. The subsequent
  MIPE procedures done at our institution have been performed via the
  2\textsuperscript{nd} intercostal space with improved exposure and
  ease of surgery.
\item
  Appropriate venous drainage of the heart is important to successfully
  complete the operation. In the case presented, the single venous
  drainage catheter placed from the femoral vein going up into the right
  atrium may have slipped back into the IVC during surgery, or was not
  capable of sufficient drainage in the large patient, or combination of
  both factors, thus causing the right ventricle to not adequately
  decompress and forced us to rely on robust suctioning within the
  pulmonary arteriotomy to successfully complete the case. We now employ
  dual venous drainage (placed via the common femoral vein into the RA
  and the internal jugular vein into the SVC-RA junction) to ensure
  proper venous drainage which allowed for improved visualization and
  clot extraction.
\item
  Closure of the pulmonary arteriotomy can be much more easily
  facilitated by placement of a purse-string suture about the planned
  arteriotomy prior to incision. We intend to employ this technique,
  here forward, for PA closure.
\item
  Early utilization of Aerosolized Epoprostenol is an important adjunct
  to aid the recovering right ventricle.
\item
  Care of patients with massive pulmonary embolism requires a team
  based, multi-disciplinary approach. The care of this patient involved
  consulting services including vascular surgery, hematology,
  nephrology, physical therapy and social work services.
\item
  While we have demonstrated a low rate of complications, and zero
  mortality from this procedure in our previous
  report\textsuperscript{1}, the case presented highlights that while we
  were able to perform the MIPE, complications did still occur
  (prolonged ventilatory and inotropic support to aid the recovering
  right heart, AKI, HIT) and are to be expected with any patient who
  requires surgery for pulmonary embolus due to the inherent risk of
  cardiopulmonary bypass. Even so, we believe that recovery from the
  small mini anterior thoracotomy as described compared to a standard
  sternotomy may be easier and simpler for patients.
\end{enumerate}

In summary, we have detailed several augmentations to our original
description of the MIPE.\textsuperscript{1} We believe the operation and
results are reproducible and can be a valuable tool in the armamentarium
of the cardiothoracic surgeon.

References:

1. Fallon J, Luvika G, Zapata D, Lattouf O. Initial Experience with
Non-Sternotomy Minimally Invasive Pulmonary Embolectomy with
Thoracoscopic Assistance. Innovations 2020, Vol. 15(2) 180--184

2. Fallon J. Minimally Invasive Pulmonary Embolectomy With Thoracoscopic
Assistance. doi:10.25373/CTSNET.11964948

3. B\selectlanguage{polish}ĕ\selectlanguage{english}lohl\selectlanguage{ngerman}ávek J, Dytrych V, Linhart A. Pulmonary embolism, part I:
Epidemiology, risk factors and risk stratification, pathophysiology,
clinical presentation, diagnosis and nonthrombotic pulmonary
embolism.\emph{Exp Clin Cardiol} . 2013;18(2):129-138.
http://www.ncbi.nlm.nih.gov/pubmed/23940438. Accessed March 8, 2020.

4. Konstantinides S V., Torbicki A, Agnelli G, et al. 2014 ESC
Guidelines on the diagnosis and management of acute pulmonary
embolism.\emph{Eur Heart J} . 2014;35(43):3033-3080.
doi:10.1093/eurheartj/ehu283

5. Aymard T, Kadner A, Widmer A, et al. Massive pulmonary embolism:
surgical embolectomy versus thrombolytic therapy--should surgical
indications be revisited? \emph{Eur J Cardiothorac Surg} .
2013;43(1):90-94; discussion 94. doi:10.1093/ejcts/ezs123

6. Lee T, Itagaki S, Chiang YP, Egorova NN, Adams DH, Chikwe J. Survival
and recurrence after acute pulmonary embolism treated with pulmonary
embolectomy or thrombolysis in New York State, 1999 to 2013. \emph{J
Thorac Cardiovasc Surg} . 2018;155(3):1084-1090.e12.
doi:10.1016/j.jtcvs.2017.07.074

Image 1: Computed tomography showing: (A) saddle pulmonary embolus (B)
right ventricle strain with right ventricular size larger than left
ventricle in diastolic phase.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

Image 2: Pre-operative marking of incision at
3\textsuperscript{rd}intercostal space.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

Image 3: Anterior left thoracotomy with mini-mitral retractor in place
at 3\textsuperscript{rd} intercostal space. Right ventricle, not PA, is
immediately beneath and visualized, highlighting need for higher
incision at 2\textsuperscript{nd} intercostal space.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

Image 4. Femoral arterial and venous cannulation for peripheral
cardiopulmonary bypass.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image4/image4}

\end{center}
\end{figure}

Image 5: Pulmonary embolectomy specimen.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image5/image5}

\end{center}
\end{figure}

Image 6: Closed incision with two drainage chest tubes in place\selectlanguage{english}
\begin{figure}[H]
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\includegraphics[width=0.70\columnwidth]{figures/image6/image6}

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\includegraphics[width=0.70\columnwidth]{figures/Image-2/Image-2}

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\includegraphics[width=0.70\columnwidth]{figures/Image-3/Image-3}

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