Keywords
liver transplant - hepatic encephalopathy - portosystemic shunts - vascular plugs
- PARTO
Introduction
Liver transplant (LT) is a lifesaving procedure for patients with end stage liver
disease (ESLD). Improvement in technique and better postoperative intensive care have
improved both short- and long-term survival following LT.
Although spontaneous portosystemic (PS) shunts are a well-known cause of hepatic encephalopathy
(HE) in patients with ESLD, their occurrence in the posttransplant period has not
been highlighted.
Large PS shunts are often ligated during LT to direct the blood flow to the graft
liver and prevent portal steal, which may otherwise lead to inadequate perfusion and
graft failure.[1] The shunts that are not ligated or that develop after the LT may in some instances
contribute to HE. The initial treatment is usually medical management.
In cases of refractory HE, radiological shunt embolization may help. Herein we describe
the clinical presentation and management of two cases of posttransplant refractory
HE who presented to us 11 and 15 years after the transplant.
Cases
Patient A
A 65-year-old man underwent living donor liver transplant (LDLT) 11 years back for
cryptogenic decompensated cirrhosis with HE. Preoperative triple-phase computed tomography
(CT) scan revealed the presence of a large mesenterico-renal shunt that was ligated
intraoperatively. Follow-up imaging at 1 month showed complete thrombosis of the shunt.
One year back, the patient had atrial fibrillation (AF) for which he was started on
apixaban and amiodarone. One and half month back, the patient presented with waxing
and waning sensorium and deteriorated mental functions. On examination, he was drowsy
and disoriented, was unable to perform reverse counting and subtraction, and had flapping
tremors. CT and magnetic resonance imaging (MRI) of the brain showed no clinically
significant findings.
On evaluation, arterial ammonia was found to be elevated (127.9 µmol/L; cutoff value
of 60–90 µmol/L) and Doppler examination of the splenoportal axis showed reduced flow
velocity in portal vein (PV; 6.6 cm/s; normal: 20–40 cm/s). Based on these findings,
the possibility of HE was considered.
Triple-phase contrast CT of the abdomen revealed a large mesenterico-renal shunt arising
from the terminal part of the superior mesenteric vein and draining into the left
renal vein ([Fig. 1]).
Fig. 1 Maximum intensity projection image from contrast-enhanced computed tomography of
patient A shows a large shunt arising from the terminal part of the superior mesenteric
vein and draining into the left renal vein. The size of the shunt is approximately
14 mm (white arrow).
For the next 3 days, the patient was managed medically, but with little benefit. Given
the large diameter of the shunt and drainage into the left renal vein, plug-assisted
retrograde transvenous obliteration (PARTO) was considered for shunt embolization.
The benefits of the procedure and the risks involved, including worsening of portal
hypertension, were explained to the family.[2]
The procedure was done uneventfully in the angiography suite and the shunt was obliterated
with combination of a vascular plug (Amplatzer, Abbott, United States) and Gelfoam
injection ([Fig. 2]).
Fig. 2 (A) Left renal venogram of patient A taken via 5-Fr MPA catheter showing the shunt ostia
arising from the superior mesenteric vein (black arrow). (B) Venogram of the shunt after deployment of a plug (plug deployed via a long sheath
with a diameter of 8 Fr) showing occlusion. (C) Deployed vascular plug in place.
The next day, the patient showed neurological improvement with increased alertness,
absence of flapping tremors, and reduction in serum ammonia levels (103 µmol/L). Doppler
evaluation revealed hepatopetal flow with increased portal flow velocity (25 cm/s).
The patient was discharged in a hemodynamically stable condition 2 days later.
Follow-up after 2 months and 1 year, the patient was active with improved neurological
status and his serum ammonia level was 92 and 54 µmol/L, respectively.
Patient B
A 74-year-old man had undergone deceased donor liver transplant (DDLT) 15 years back
for hepatitis B virus (HBV) related decompensated chronic liver disease (CLD). He
was doing well till 1 month back when he developed generalized body weakness, decreased
sleep, and bilateral upper limb tremors. CT and MRI of the brain showed no clinically
significant changes.
The serum ammonia level was 110 µmol/L and liver function tests were within normal
limits. Doppler examination of the splenoportal axis showed decreased flow velocity
in PV (8 cm/s). Contrast-enhanced CT (CECT) abdomen showed normal graft size with
cirrhotic changes and multiple collaterals with a prominent lienorenal shunt (22 mm)
and gonadal venous shunt (12 mm; [Fig. 3A]).
Fig. 3 (A) Contrast-enhanced computed tomography of patient B shows multiple portosystemic
collaterals with a prominent lienorenal shunt. The shunt size is approximately 22 mm
(white arrow). (B) Left renal venogram using a 5-Fr MPA catheter of patient B showing the opacification
of the gonado-renal shunt (black arrow). (C) Venogram after the deployment of a plug via a long sheath with a diameter of 8 Fr
shows decreased flow through the shunt.
Medical management was done for 3 days but was of little benefit and as such embolization
of the lienorenal and gonadal vein shunt was considered. The procedure was done in
the angiography suite. Initial venograms revealed a gonadal venous shunt with low
flow volume. Subsequently after embolization of the lienorenal shunt, repeat interrogation
of the gonadal venous shunt revealed increase flow volume of shunt, which was then
embolized using a vascular plug (Amplatzer, Abbott, United States; [Fig. 3B, C]).
The next day, the patient showed improved neurological status and there was a decrease
in tremors, and the serum ammonia level went down to 105 µmol/L. He was discharged
after 2 days in a hemodynamically stable condition.
On follow-up at 1 and 2 months after discharge, there was sustained improvement in
mental status. The serum ammonia level went further down to 60 µmol/L.
Discussion
In cirrhotic patients, portal hypertension is known to cause splanchnic vasodilation
and hyperdynamic circulation. These factors cause the formation of PS collaterals
in approximately 40% cirrhotic patients.[3]
Post-LT, these collaterals may regress spontaneously.[4] If PS shunts persist, they jeopardize the portal inflow, which leads to inadequate
perfusion of the liver graft. Large shunt can lead to portal steal syndrome with graft
dysfunction and HE.[5] The estimated percentage of the patients with portal steal after LDLT is approximately
0.2%.[1]
There are different algorithms for management of spontaneous PS shunts before, during,
or after transplantation. A study from our center concluded that PS shunt ligation
may not be necessary if adequate portal flow, good vascular reconstruction, and good
graft quality have been ensured.[6]
Endovascular techniques described for PS shunt obliteration include antegrade embolization,
balloon-assisted retrograde transvenous obliteration (BRTO), coil-assisted retrograde
transvenous obliteration (CARTO)/PARTO, and use of vascular stent grafts.[1]
In our patients, intraoperative shunt ligation was done for patient A as it was large
and adequate portal flow was not seen intraoperatively. He presented with refractory
HE after 11 years post-LDLT. The development of late encephalopathy in our patient
can probably be attributed to various factors. First, the patient was on amiodarone
therapy (200 mg/d) for AF for the past 1 year. A cumulative dose of amiodarone as
low as 55 g has been shown to cause liver fibrosis or even cirrhosis.[7] Following the development of cirrhosis or fibrosis, small collaterals previously
present might have enlarged and precipitated encephalopathy. Second, following the
onset of AF, he was also started on apixaban, which might have recanalized any thrombosed
vein.[8]
Patient B presented 15 years after his LT with altered mental status and raised ammonia
levels.
The clue to HE in these patients was a raised ammonia level. Hyperammonemia is a relatively
sensitive marker for detection of PS shunt–related encephalopathy even in patients
without cirrhosis.[9] The presence of PS collaterals on CECT strengthened the diagnostic possibility of
HE.
In view of the presence of multiple comorbidities in the patients, a minimally invasive
endovascular procedure (PARTO) was chosen.
Shunt embolization can result in raised portal pressure, thus causing worsening of
gastroesophageal varices and ascites. This is more likely in patients with PV stenosis
(PVS) or hepatic venous outflow tract obstruction (HVOTO). In both our cases, there
was no imaging evidence of PVS or HVOTO.
To conclude, patent PS shunt should be kept in mind in the follow-up of transplanted
recipients with neurological symptoms even if there is no apparent evidence of graft
dysfunction. Elevated serum ammonia levels will give a clue and cross-sectional imaging
will delineate the shunt, and its obliteration may help in improvement of symptoms.
