Liver Transplant Management
Wael E.A. Saad
Interventional radiology plays an integral role in the care of patients after liver transplantation, which includes percutaneous interventions for treatment of vascular complications. Complications of the hepatic artery include hepatic artery stenosis (HAS), hepatic artery thrombosis (HAT), arterioportal fistula (APF), hepatic artery pseudoaneurysm (HAP), and nonocclusive hepatic artery hypoperfusion syndrome (NOHAH). The consequence of diminished hepatic artery flow is far more significant in hepatic transplants than native livers because the biliary tree is totally reliant on the hepatic artery (1,2). Hepatic outflow obstruction can be caused by either hepatic venous (HV) or inferior vena cava (IVC) stenosis/thrombosis, usually at an anastomosis. Portal inflow may be compromised by portal vein stenosis (PVS) usually at the anastomosis, portal vein thrombosis (PVT), and portal hypertension (3,4,5). On the rare occasion, portal vein inflow can be compromised by steal phenomenon from competing portosystemic collaterals.
Nonvascular complications of liver transplants are discussed elsewhere in this handbook and are dominated by postoperative fluid collections and biliary strictures or obstruction with similar indications, contraindications, end points, and complications as in nontransplant patients.
a. Hepatic graft dysfunction
b. Abnormal noninvasive imaging of the hepatic artery with or without hepatic graft dysfunction
2. Embolization of APFs
a. Symptomatic, for example, graft dysfunction, bleeding
b. Asymptomatic
(1) Rapidly growing
(2) Hemodynamic changes seen on Doppler ultrasound, for example, portal flow reversal
3. Embolization of HAPs
a. Intrahepatic—all regardless of size
b. Extrahepatic—temporizing prior to surgery
a. Hepatic graft dysfunction
b. Abnormal noninvasive imaging of the venous structures with or without hepatic graft dysfunction
c. Mean pressure gradient across anastomosis of >5 mm Hg
Contraindications
Relative
1. Uncorrectable coagulopathy
2. Renal insufficiency
3. Prior severe allergic reaction to iodinated contrast material
a. Consider use of gadolinium or CO2.
4. Unstable patient
a. Consider anesthesia consultation for assistance in patient management during intervention.
Preprocedure Preparation
1. Laboratory evaluation: Most patients will have had extensive blood testing. Ensure current complete blood count (CBC), platelet count, renal and hepatic function tests, and international normalized ratio (INR) are available. Correct platelet count to >50,000 and INR to <1.7 seconds when possible. It is preferred to transfuse platelets during the procedure and not before because many of these patients sequester platelets due to their large spleens.
2. No food by mouth except normal medications with a sip of water for at least 6 hours; clear liquids can be consumed up to 2 hours prior to the procedure.
3. Evaluate prior surgical operative notes, in particular the surgical transplant anatomy.
4. Review prior imaging. Careful study of surgical anatomy and imaging reduces angiographic time and inventory utilization (1).
Procedure
Hepatic Artery Interventions
1. General considerations
a. Review noninvasive imaging (duplex ultrasound, computed tomographic angiography [CTA], or magnetic resonance angiography [MRA]) prior to angiography, the gold standard for the diagnosis of arterial abnormalities.
b. Right common femoral artery access is preferred in most cases. Patients with significant atherosclerotic aortoiliac disease may require a long (20 to 30 cm) arterial sheath.
a. Arteriography
(1) Abdominal aortography can be performed; however, it may not be necessary if the patient has had a prior CTA. If there is suspicion of a proximal stenosis, perform a lateral aortogram (1).
(2) A celiac angiogram must be performed to evaluate the hemodynamics of the celiac trunk and to exclude an arterial steal syndrome. Nonfilling of the graft hepatic artery on a celiac angiogram does not suffice for the diagnosis of HAT. There may be a critical HAS with preferential flow to other celiac branches or arterial steal phenomena. A selective hepatic artery angiogram to confirm occlusion is required.
(3) Catheter selection for selective hepatic arteriography is based on the surgical hepatic artery anatomy (1,8,9).
(a) Supraceliac direct aortohepatic conduit can usually be catheterized with a Cobra (C-2) catheter.
(b) Infrarenal aortohepatic conduit off the aorta anteriorly and extending cephalad to the liver can be catheterized with a vertebral or similar shaped catheter.
(c) Graft hepatic artery anastomosis to recipient hepatic artery or other branch off the celiac trunk is the most common arterial anastomosis performed. An Sos Omni or C-2 Cobra catheter may be used.
(4) Collateral arteries should be documented. When intrahepatic arterial flow is demonstrated by Doppler ultrasound but occlusion of the hepatic artery is seen on angiography, there is collateral arterial supply (9).
(5) If HAS is seen, perform further imaging in multiple projections:
(a) To determine the angle orthogonal to the stenosis
(b) To assess the entire hepatic artery for tandem lesions, tortuosity, or kinking
b. Hepatic artery angioplasty/stent placement
(1) The hepatic artery is measured for angioplasty balloon or stent sizing.
(2) A 6 Fr. braided 45- to 70-cm sheath is advanced to the origin of the celiac axis or the proximal aortohepatic conduit.
(3) Administer heparin—3,000 units intravenous (IV) and 1,000 units every 20 to 30 minutes thereafter.
(4) Proximal lesions can be managed using a 0.035-in. coaxial platform. Smaller tortuous arteries and distal lesions usually require 0.014- to 0.018-in. platforms.
(5) Rather than primary stenting, the author prefers initial balloon angioplasty with stent placement reserved for refractory lesions, or when there are complications.
(6) If there are tandem lesions, the distal stenosis is treated first unless the proximal lesion hinders passage of the balloon. Predilation with an undersized balloon is often performed (11,12).
(7) A postangioplasty angiogram is done to assess results and exclude dissection or thrombus.
(8) If results are unsatisfactory or a complication results, a stent is placed.
(a) The author prefers 0.014-in. platforms with balloon-mounted low-profile stents.
(b) The femoral approach usually suffices, but uncommonly, a brachial approach is required.
(c) Always have nitroglycerine in the room ready during balloon angioplasty and/or stenting because vasospasm is not uncommon and can be detrimental leading to HAS and predisposing to hepatic artery dissection with wire and catheter manipulation.
a. Perform selective hepatic arteriography; however, seeing the fistulous tract is rare. Angiographic signs of a hemodynamically significant APF include:
(1) Filling of a portal venous radical in the early arterial phase
(2) Nonvisualization of the distal arterial branches (sump effect)
b. Microcatheters are used to get as selective as possible into the hepatic arterial branches, to reduce the risk of inducing HAT, and to minimize damage to normal liver.
c. Microcoils tailored to the size of the involved artery are deployed. Ideally, complete obliteration is the end point; however, enough occlusion to reduce flow into the PV will often suffice.
d. A hepatic arteriogram should be repeated to look for additional fistulas. Obliterating a dominant fistula may unmask others. The additional sites may be occluded in this or subsequent sessions. The mindset should be analogous
to managing complex vascular malformations, that is, the more one does in any single session, the greater the risk of complication—especially HAT and segmental ischemia of the graft.
to managing complex vascular malformations, that is, the more one does in any single session, the greater the risk of complication—especially HAT and segmental ischemia of the graft.
a. Spontaneous extrahepatic pseudoaneurysms are usually contained ruptures of mycotic aneurysms and require prompt open surgery. Stent grafts have a role in stabilizing and temporizing bleeding prior to surgery.
b. Iatrogenic extrahepatic or major branch pseudoaneurysms from balloon angioplasty can be treated with stent grafts or balloon tamponade.
c. Intrahepatic pseudoaneurysms of any size should be treated with superselective coil embolization, either sac obliteration or occlusion of the involved segmental artery distal and proximal to the pseudoaneurysm.
d. If endovascular access to an intrahepatic pseudoaneurysm is not possible or the pseudoaneurysm persists after embolization, direct percutaneous therapy should be considered (15).
(1) An ultrasound-guided 21-gauge needle puncture is performed and thrombin and/or microcoils can be deposited.
(2) An angiography/fluoroscopy-guided gun-site technique can also be used with or without ultrasound for deeper lesions or if there is concern of injury to larger vessels.
a. NOHAH is hepatic arterial hypoperfusion (slow flow) in the setting of a patent hepatic artery.
