Portal vein embolization
Portal vein embolization (PVE) is a technique used to selectively occlude the blood supply to one of the liver lobes, diverting portal blood flow to the other lobe, the future liver remnant (FLR).
This diversion will increase the size of the post-hepatectomy future liver remnant, which improves surgical outcomes by preventing liver insufficiency. The minimum limit of the future liver remnant is 20–40% of total liver volume dependent on the presence of background liver disease .
First published in 1990 by Makuuchi et al. .
- future liver remnant that would be too small for the patient's body mass, post-hepatectomy (typically <20%)
- elevated ICG-R15 serum values 15 minutes after injection
- ICG (indocyanine green) binds to albumin and is excreted by the biliary system
- elevated values imply decreased hepatic reserve
- patients who undergo hepatotoxic chemotherapy, if FLR<30%
- cirrhosis, Child-Pugh class A, ICG-R15 <10%, if FLR <40%
- patients with hepatic steatosis
- concomitant pancreas resection and patients with diabetes due to poor post-hepatectomy hypertrophy rates
- ipsilateral portal tumor thrombus precluding catheter placement
- clinically overt portal hypertension (procedure exacerbates portal hypertension)
Can be performed on an outpatient basis. The future liver remnant (on CT or MRI volume assessment) should be obtained prior to undertaking this procedure.
The right lobe is almost always targeted. The approach is usually through the right lobe, as well.
Different embolic agents have been used, including:
- n-butyl cyanoacrylate (NBCA)
- ethiodized oil
- fibrin glue
- microparticles (such as polyvinyl alcohol, PVA)
- microspheres followed by coils are used by some.
The portal vein can be approached surgically through a transileocolic approach, but interventional radiology usually approaches the portal vein transhepatically. Portal vein pressures are checked pre-procedure, to ensure that there is no portal hypertension.
- minor fluctuations in postprocedure liver function tests (50%)
- liver synthetic functions usually not affected
- nausea, fever, and pain are rare
- reported 0% procedure-related mortality
- reported overall morbidity of 2.2%
- non-target embolization
- complete portal vein thrombus
- risks similar to other transhepatic procedures
Patients with otherwise normal livers regenerate two weeks postprocedure at 12-21 mL/day (9 mL/day for cirrhotic patients) . 2-4 weeks is usually enough for most patients with normal liver function (>4 weeks for patients with cirrhosis).
There is some evidence from volumetric analyzes to indicate that right portal vein embolization (RPVE) + segment 4 embolization results in a greater degree of hypertrophy of segments 2/3 than RPVE alone in patients with colorectal liver metastases and this may become the recommended strategy in those with a relatively low FLR (<20%) and are planned to undergo an extended right hemihepatectomy .