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\begin{document}

\title{Evaluation of Conduit in Total Arterial Revascularization using Optical
Coherence Tomography (OCT) - A Case Report and Literature Review}



\author[1]{Angelo Citarella}%
\author[1]{Abdul  Sheikh Sheikh}%
\author[1]{Saqib Chowdhary}%
\author[1]{Nnamdi Nwaejike}%
\affil[1]{Wythenshawe Hospital}%


\vspace{-1em}



  
  \date{May 27, 2024}


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\selectlanguage{english}
\begin{abstract}
Coronary artery bypass grafting (CABG) remains the preferred
revascularization modality for the elective treatment of patients with
complex three vessel coronary artery disease. There is evidence that the
use of additional arterial grafts such as right internal mammary artery
(RIMA) and Radial Artery (RA); are associated with improved long-term
patency. Stenosis of arterial grafts can occur in some patients
postoperatively. We describe the first use of OCT in the evaluation of
suspected conduit stenosis in Total Arterial Revascularisation.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Coronary artery bypass grafting (CABG) remains the preferred
revascularization modality for the elective treatment of patients with
complex three vessel coronary artery disease. The left internal mammary
artery (LIMA) is routinely used for revascularization of the left
anterior descending artery. However, the choice of conduit used in
addition to the LIMA can be contentious. There is evidence that the use
of additional arterial grafts such as right internal mammary artery
(RIMA) and Radial Artery (RA); are associated with improved long-term
patency. LIMA grafting to the left anterior descending (LAD) artery and
use of a radial artery instead of the saphenous vein are Class I
recommendations in the 2018 ESC/EACTS guidelines on myocardial
revascularization. The use of bilateral IMA conduits is a Class IIa
recommendation. Stenosis of arterial grafts can occur in some patients
postoperatively. However, no reports have described an evaluation of
conduit using optical coherence tomography (OCT) to ascertain the
mechanism of stenosis. We describe the use of OCT in the evaluation of
suspected conduit stenosis in Total Arterial Revascularisation.

\textbf{Case Summary}

A 63 years old lady who was admitted with acute coronary syndrome. She
was referred for coronary artery bypass surgery. Risk factors included
previous PCI and stents to LAD and right coronary artery (RCA);
arteriopathy with peripheral vascular disease treated with stents in
both iliac arteries; persistent intermittent claudication; pulmonary
emphysema and current smoker. Left heart catheterization (LHC) showed
severe triple vessel disease with preserved left ventricular systolic
function. She underwent a triple vessel coronary artery bypass surgery
by Total Arterial Revascularization using cardio-pulmonary bypass. The
LIMA and the RIMA were harvested in skeletonized fashion and a
T-anastomosis (Tector) was performed. LIMA was grafted to LAD and RIMA
sequentially to distal Circumflex (LCx) and posterior descending artery
(PDA). (Figure 1)

Temporary atrial pacing wires were placed and the patient was
transferred to cardiothoracic intensive therapy unit in haemodynamically
stable condition. The patient had an asystolic cardiac arrest with no
pacemaker capture 2 hours later. There were no ECG changes suggestive of
myocardial ischaemia leading to the event. Cardiac surgery Advanced Life
Support (CALS) was initiated and the patient was stabilised on central
Veno-Arterial-Extra Corporeal Membrane Oxygenation (VA-ECMO). Bedside
transesophageal echocardiogram (TOE) showed a global severe depressed
left ventricular function which was confirmed on heart inspection when
the chest was reopened. When stabilized, emergency LHC was performed and
it showed patent LIMA to LAD with good run off distally. RIMA showed a
stenosis just distal to the Y-anastomosis. There was good run off into
PDA and obtuse marginal (OM) artery. (Figure 2) We did OCT to evaluate
the mechanism of stenosis. A large intramural haematoma was shown to be
compressing the lumen. There was no evidence of intimal dissection
(Figure 3). Patient was managed conservatively as there was no flow
limitation in the grafts.

\textbf{Discussion}

Likely mechanisms of intra-mural haematoma in this case include surgical
trauma perioperatively or trauma/bruising to the graft from cardiac
massage during the CALS protocol. We routinely use skeletonized mammary
arteries for CABG. Intra-operative surgical trauma seemed unlikely as
there was no visible evidence of damage to the conduit during the
operation. An evolving haematoma would more likely present as
progressive regional ischaemia on ECG with segmental wall motion
abnormality on echocardiogram. There were no ischaemic changes on ECG
post-operatively. This patient had no regional wall motion abnormality
on post-cardiopulmonary bypass transoesophageal echocardiogram (TOE).
Post-resuscitation TOE showed global LV impairment after stabilisation
on VA-ECMO. It could be that the cardiac arrest 2hrs after surgery was
unrelated to the intramural haematoma and the haematoma was as a result
of cardiac massage during CPR.

A much more common cause of early graft failure (failure within 1 month
of surgery) is technical failure or thrombosis which is usually at the
site of the anastomosis. LHC and OCT showed that all anastomoses were
intact with good flow and no sign of intra-lumnal thrombosis.

OCT is a catheter based invasive imaging system which allows for
high-resolution imaging of intra-luminal and trans-mural coronary
structures thus overcoming many of the limitations of angiography. Using
light rather than ultrasound, OCT produces high-resolution in-vivo
images of coronary arteries and deployed stents.

Accumulating data support a clinical role for OCT in a multitude of
clinical scenarios, including assessing the natural history of
atherosclerosis and modulating effects of therapies, mechanisms of acute
coronary syndromes, mechanistic insights into the effects of novel
interventional devices, and optimization of percutaneous coronary
intervention. We have found no previous reports of the use of OCT to
evaluate conduit post-CABG. Potential risks from the procedure include
that it can cause intimal dissection in fresh conduit.

Should OCT be used to routinely evaluate all conduit post-op? We can
advocate its usage when the LHC findings are unclear.

OCT to complement LHC can be a valuable tool to evaluate conduit post
CABG. The absence of proximal aortic anastomoses in total arterial
re-vascularization reduces the risk of graft disruption when early
post-operative LHC/OCT is indicated.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Fig-1/Fig-1}

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

\end{center}
\end{figure}\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/Fig-3/Fig-3}

\end{center}
\end{figure}

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