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\begin{document}

\title{LEFT SUBCLAVIAN ARTERY MANAGEMENT IN FROZEN ELEPHANT TRUNK: A NOVEL
TECHNIQUE}



\author[1]{Bashi Velayudhan}%
\author[2]{Mohamad Bashir}%
\author[1]{Mohammed Idhrees}%
\affil[1]{SRM Institutes for Medical Science Vadapalani}%
\affil[2]{Royal Blackburn Teaching Hospital}%


\vspace{-1em}



  
  \date{May 20, 2024}


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\selectlanguage{english}
\begin{abstract}
Proximilisation of Frozen Elephant Trunk (FET) necessitates the ligation
and reimplantation of the left subclavian artery (LSA), the origin of
which is distal and posterior, make rerouting difficult and cumbersome.
We describe a rather simple technique for subclavian artery exposure and
effective anatomical reconstruction in the mediastinum coupled with
hybrid FET utilisation for aortic aneurysm in elective and non-elective
settings. The division of the sternocleidomastoid coupled with the
sandbag behind the left shoulder brings the LSA superficial enabling
anastomosis without any difficulty.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Proximilisation of Frozen Elephant Trunk (FET) from zone 3 to zone 2
necessitates rapid evolving surgical skills to match device use and
technology application. However, ligation and reimplantation of the left
subclavian artery (LSA), the origin of which is distal and posterior,
make rerouting difficult and cumbersome. Despite, several methods being
described in the literature {[}1{]}, no single approach has been
ascribed to as providing optimal access and ease of use. We describe a
rather simple technique for subclavian artery exposure and anastomosis
coupled with hybrid FET utilisation for aortic aneurysm in elective and
non-elective settings.

\textbf{Surgical Technique}

The patient is positioned with a sandbag under the left shoulder and
head turned towards the right side. The upper end of the sternal
incision is extended cranially to the left side of the neck over the
sternocleidomastoid muscle. With the neck turned to right side, this
extension is almost in line with median sternal incision. The sternal
head of the sternocleidomastoid is divided from its origin (Figure 1B)
enabling the exposure of the left common carotid artery (LCCA) and the
LSA. The aorta is then pulled caudally and the supra-aortic arch vessels
are dissected and looped. When the desired body temperature is reached,
the hybrid prosthesis is deployed in zone 2 and the supra-aortic arch
vessels are~connected~to the hybrid prosthesis (Figure 1 C, D, E).
After achieving~haemostasis, the sternal head of the
sternocleidomastoid muscle is reattached using absorbable sutures and
chest closed in the usual manner.

When required, the following additional manoeuvres can be used to
increase the exposure of LSA. (i) Looping,~Ligation and division of the
innominate vein (Figure 1A) (ii) When the LCCA is used for arterial
inflow, both the incisions can be connected (Figure 1B) and (iii) during
the antegrade cerebral perfusion, the cross-clamp on the LCCA can be
applied in the neck to avoid any paraphernalia~in the~operative field
(Video 1).

\textbf{Discussion}

Although FET combines the advantage of open and endovascular surgery, it
is still major surgery with prolonged ischemia time. The perioperative
complication is similar to the classical total arch replacement, with
paraplegia proving to be the chink in armour for FET. Several steps
taken to reduce the complication include short stent graft,
reimplantation of the LSA artery, and reduction of the circulatory
arrest.

Reimplantation of the LSA in FET may be challenging in (i) Obese
individuals (ii) Patients with a deep chest (iii) Elongated aorta
(iv)Large aortic arch aneurysm (v) Re-operative procedures. Several
surgeons have tried different techniques to reimplant the LSA including
the LCCA-LSA artery bypass, extra anatomic aortic-axillary bypass
{[}1{]} and, clamping the descending thoracic aorta and compressing the
aortic arch to facilitate the exposure and anastomosis of LSA {[}2{]}.
An additional incision for extra-anatomic aortic-axillary bypass through
the left thorax may be cumbersome besides the risk of injury to brachial
plexus (1.5\%) during exposure of left axillary artery {[}3{]}. LSA is
often an elastic, thin fragile artery and when involved in aortic
dissection, it is even worse. Performing anastomosis on this artery in
the deep intrathoracic compartment is technically difficult making
future haemostasis further a challenge.

Some centers that perfuse the LSA during the cardiopulmonary bypass, a
tube graft can be anastomosed to the artery in an end to end fashion,
which can later be connected to the hybrid prosthesis. The advent of
Neo-Evita Spielvogel in the market will empower the surgeon for a
``no-arch-touch'' Zone 0 implantation {[}1{]}. The above exposure will
facilitate the LSA reimplantation during the same.

The incidence of direct aortic origin of left vertebral artery (LVA)
from the aortic arch varies from 2.4 - 5.8\% in different studies and in
50\% of individuals the LVA is dominant {[}4,5{]}. The LVA has to be
reimplanted directly or using an autologous vein, either to the LCCA or
the LSA to protect the posterior cerebral circulation and the spinal
cord {[}5,6{]}. Given the delicate nature of the LVA, meticulous
handling without stretching is essential to avoid intimal damage. We
believe, our technique will provide adequate exposure of the LVA for a
meticulous anastomosis to the LSA or LCCA.

Our technique provides excellent exposure of LSA for an effective
anatomical reconstruction in the mediastinum. The division of the
sternocleidomastoid coupled with the sandbag behind the left shoulder
brings the LSA superficial enabling anastomosis without any difficulty.
Additional manoeuvres described above will further aid in the exposure
and rerouting.~The division of the sternal head of sternocleidomastoid
will not cause any functional disability {[}7{]}. We agree that the scar
of the wound is a bit long and extends to the neck. In our experience,
there were no problems in wound healing.

\textbf{Declarations}

\textbf{Disclosures:} None of the authors have anything to disclose

\textbf{Ethical Statement:} An approval from the Institutional Review
Board~was obtained

\textbf{Informed Consent:} All the patients were explained about the
procedure and oral consent for the same was obtained.

\textbf{Reference}

1. Jakob H, Idhrees M, Bashir M. Frozen elephant trunk with straight
vascular prosthesis. Ann Cardiothorac Surg. 2020;9(3):164-169.
doi:10.21037/acs-2020-fet-60

2. Matalanis G, Koirala RS, Shi WY, Hayward PA, McCall PR. Branch-first
aortic arch replacement with no circulatory arrest or deep hypothermia.
J Thorac Cardiovasc Surg. 2011;142(4):809-815.
doi:10.1016/j.jtcvs.2011.01.020.

3. Sabik JF, Nemeh H, Lytle BW, et al. Cannulation of the axillary
artery with a side graft reduces morbidity. Ann Thorac Surg.
2004;77(4):1315-1320. doi:10.1016/j.athoracsur.2003.08.056

4. Yuan SM. Aberrant Origin of Vertebral Artery and its Clinical
Implications. Braz J Cardiovasc Surg. 2016;31(1):52-59.
doi:10.5935/1678-9741.20150071.

5. Brasiliense LB, Albuquerque FC, Spetzler RF, Hanel RA. Advances and
innovations in revascularization of extracranial vertebral
artery.\emph{Neurosurgery} . 2014;74 Suppl 1:S102-S115.
doi:10.1227/NEU.0000000000000218

6.Imparato AM. Vertebral arterial reconstruction: a nineteen-year
experience. \emph{J Vasc Surg} . 1985;2(4):626-634

7. Santoro GP, Luparello P, Lazio MS, Comini LV, Martelli F, Cannavicci
A. Myotomy of sternocleidomastoid muscle as a secondary procedure in
laryngectomized patients. Head Neck. 2019;41(10):3743-3746.
doi:10.1002/hed.25852.

\textbf{Legends}

Video 1: Surgical technique for exposure of Left subclavian artery:
Animated video explaining the surgical steps followed the surgical
procedure.

Figure 1:

Black dotted line: \emph{Crainal extension of the sternal incision} .
White dotted line: \emph{Skin between the sternal and neck
incision.}White arrow(\textgreater{}\textgreater{}): \emph{Innominate
vein.}Yellow arrow(\textgreater{}\textgreater{}): \emph{7mm arterial
inflow to the carotid artery.} M: \emph{Muscle- sternal head of
sternocledimastoid} . C: \emph{Left common carotid artery.} S:
\emph{Left subclavian artery}

(A) Left side cranial incision exposing the supraaortic arch vessel (B)
The sternal and the neck incision united. Note the division of the
sternal head of sternocleidomastoid muscle (C)Note the clear visibility
of the LCCA and LSA after implantation of the FET hybrid prosthesis
(D)Anastomosis of the LSA to the hybrid prosthesis (E) Anastomosis of
the LCCA to the hybrid prosthesis .\selectlanguage{english}
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