Portal Vein Embolization

Portal Vein Embolization

Thierry de Baère and Alain Roche

One of the prerequisites for partial hepatic resection is the presence of enough remaining functional liver parenchyma to avoid life-threatening postoperative liver failure. Therefore, the possibilities of curative resection of liver tumors are strongly dependent on the volume of the future remnant liver (FRL). In clinical practice, these possibilities are frequently limited when an extended hepatectomy is mandatory because the FRL is too small. The more frequent case is need for a right extended hepatectomy with a small left lobe. Major liver surgery is indicated in some patients with impaired liver function, whatever the cause (e.g., cirrhosis, cholestasis, fibrosis, steatosis), and this further limits the possibility of surgery because larger FRL volume is needed. It has long been demonstrated that liver trophicity closely depends on hepatic portal blood flow, and consequently portal branch ligation results in shrinkage of the corresponding lobe and hypertrophy of the contralateral one.1 In the same manner, liver atrophy occurs after surgical or spontaneous portocaval shunting, hypertrophy of the remnant liver occurs after partial hepatectomy, and the Spiegel lobe hypertrophies in Budd-Chiari disease when the caudate lobe remains the only one to still have hepatopetal portal blood flow.

It was established in the 1970s that portal venous blood flow promoted hepatic cell regeneration, and that blood arising from the duodenopancreatic area had strong hepatotropic properties. Insulin and glucagon were then soon recognized as growth regulatory factors that, when infused concomitantly, synergistically stimulated hepatic regeneration.2 More recently, hepatocyte growth factor (HGF) could be isolated in different laboratories and described to rise after partial hepatectomy.3 Multiple other peptides such as transforming growth factor (TGF)-α or serotonin have also been demonstrated to play a role in hepatic regeneration.

The aim of portal vein embolization (PVE) is to selectively induce hypertrophy of the FRL during the preoperative period. This is achieved by embolization of the intrahepatic portal branches of the future resected liver, leading to distribution of the entire portal blood flow containing hepatotropic factors exclusively toward the FRL.


Limits for hepatic resections, and consequently indications for PVE, depend on multiple factors, but FRL/total functional liver ratio for a given patient (according to age and liver function) is the main factor that determines possibilities for a safe resection. Depending on the authors, PVE is considered when this ratio is expected to be less than 25% to 40% in patients with normal liver function, and less than 40% to 50% in patients with liver dysfunction.1-3

Many studies have demonstrated that computed tomography (CT) estimations of liver volumes were correctly correlated to real volumes, despite partial volume effect, respiratory phase, or interobserver variations. Consequently, liver CT volumetry is a key examination to determine surgical possibilities and need for PVE. Because tumors do not contain functional hepatocytes, tumor volume must be subtracted from that of liver during CT volumetry. In the same manner, when radiofrequency ablation (RFA) is planned simultaneously with the hepatectomy for treating a tumor located in the FRL, one should pay attention to subtracting the volume of the future RFA lesion (tumor volume + safety margin) from the FRL volume. CT volumetry should be performed 1 month after PVE to evaluate hypertrophy of the FRL (Fig. 69-1).

Liver Metastases

Curative resection of liver metastases is mainly performed in patients presenting with colorectal primary cancer. Liver metastases are found in 40% to 70% of patients with colorectal cancer. In about one third of cases, the liver is shown to be the only site of cancer spread, even at autopsy. There is no spontaneous long-term survival in untreated patients, whose median survival time ranges from 6 to 24 months. At the time of diagnosis, the majority of patients present with unresectable tumors, and resection can be performed in less than 20% of all patients with colorectal liver metastases. The main limitation for resectability is the impossibility to be curative while leaving a sufficient residual amount of functional liver parenchyma. Consequently, preoperative PVE may dramatically improve the possibilities for a curative resection of liver metastases by increasing the volume and function of the FRL.


Ultrasound guidance is necessary for puncture of a small peripheral portal vein branch. We use a 27-cm 5F needle catheter (Transhepatic chlangiography catheter, DPLTH-5.0-27-ST, Cook Medical, Bloomington, Ind.) or a 20-cm 18-gauge EchoTip needle (Temno chiba needle, CHI1815, Carefusion, McGraw Park, Ill.) for entering the portal vein.

The procedure requires a digital subtraction angiography (DSA) suite with possible angulation of the C-arm that will aid intraportal navigation when venous anatomy is unusual and in atypical PVE before complex resections. In such complex embolization or atypical resection, three-dimensional (3D) reconstruction from cone beam CT acquisition and 3D roadmap renders catheterization easier (Fig. 69-2). On demand catheter tip can be shaped, alternatively Cobra shape can be used when approach is contralateral, or short sidewinder catheter can be used when approach is ipsilateral. Usually, a 0.035-inch hydrophilic guidewire suffices for the entire procedure. Microcatheters are used by some operators for particle embolization through ipsilateral access.

Embolic agents vary from center to center. We use cyanoacrylate (Histoacryl, B. Braun Medical, Bethlehem, Pa.) mixed with Lipiodol Ultra Fluid, 10 mL (Guerbet, Villepinte, France). Others use spherical embolic material ranging from 300 to 500 to 500 to 700 µm.

When cyanoacrylate is used, a 3-way stopcock resistant to Lipiodol is needed, as well as isotonic glucose solution for the sandwich technique. In addition, 1-mL syringes are needed for cyanoacrylate injection, and a 20-mL syringe is needed for flushing.


Anatomy and Approaches

A thorough knowledge of hepatic segmentation and portal venous anatomy is essential before performing PVE. The most frequent variation is slipping from right to left of segment V and VIII branches, separately or together. Therefore, two main variations are frequently encountered: (1) trifurcation of the portal vein into the left branch, segments V + VIII branch and segments VI + VII branch, when the slipping is limited and (2) bifurcation of the portal vein into a right vein limited to segments VI + VII, and left vein also giving rise to segments V + VIII branch, when the slipping is complete (Fig. 69-3). Besides knowledge of the anatomy, a clear knowledge of the plane of the hepatectomy is necessary before starting the procedure because the extent of PVE must mimic the extent of surgery, and because more and more atypical surgery is performed, many different types of PVE are possible4 (Fig. 69-4).

Technical Aspects

The procedure may be performed under intravenous sedation and analgesia, but most teams prefer general anesthesia, which provides more comfort for the patient and the operator.

Access can be obtained from a contralateral approach (i.e., puncture of the left portal branch and embolization of right portal branches) or an ipsilateral approach (i.e., puncture of the right to embolize right portal branches). The advantage of the contralateral approach is easier catheterization of the right lobe branches, but there is a risk of damage to the FRL. An ipsilateral approach allows for easier catheterization of segment IV branches when needed. The drawbacks of the ipsilateral approach are the difficulty of access to right portal branches in a retrograde fashion and difficulty in obtaining a good final portography, since the catheter has to pass through embolic material to be placed in the portal vein for the final contrast medium injection. Choosing the access also depends on the embolic material used. Glue can hardly be manipulated from the ipsilateral side, but large embolic materials like plugs require large-diameter access, which is less risky when obtained on the ipsilateral side. Ultimately, the choice between the ipsilateral and contralateral route should be based on their respective complication rates, which are similar and mainly related to puncture of unexpected structures like biliary branches or hepatic arteries. The largest series of contralateral PVE reviewed 188 cases performed in different centers using contralateral access as well as N-butyl cyanoacrylate as an embolic material.5 In the literature, the only factor increasing complications is puncture of the right posterior segment versus puncture of the right anterior segment,6 thus advocating puncture of the anterior segment when compatible with the location of the PVE to be performed.

When the goal of PVE is occlusion of right branches, we preferred access of the portal vein with the contralateral anterior subxiphoid left route, which allows antegrade catheterization of all right branches to be occluded and free-flow embolization, thereby enabling safe maneuvers. The puncture is achieved under ultrasonographic guidance with a 5F needle catheter. When branches for segment IV do not have to be occluded, the entry point in portal veins may be the Rex recess. If segment IV is affected by PVE, entering a peripheral segment III branch is recommended to facilitate catheterization of segment IV branches. Retrograde catheterization of the main portal trunk for performing portography is the first step of the procedure to identify individual intrahepatic branches and anatomic variations. In all patients with a known or suspected compromised liver, the portal pressure must be measured before embolization because it represents a prognostic parameter. Catheterization of every branch to be embolized is then performed with the 5F catheter of the needle catheter device. Depending on individual anatomy, a 1- to 2-cm length and 30- to 90-degree angulated tip is then shaped with steam in order to make further maneuvers easier. Every main trunk to be occluded is selectively catheterized for performing a distal and free-flow embolization.

The degree of selectivity (sectorial, segmental, or subsegmental) before each embolization depends on individual anatomy and local hemodynamics. It is chosen for each vein to ensure a stable selective positioning of the catheter, providing best conditions for free-flow embolization and preventing inadvertent reflux of embolic material. Massive reflux of embolic agent into the FRL would annihilate its hypertrophy or induce almost total portal occlusion and thereby fatal portal hypertension when the rest of the portal vasculature has already been totally embolized. Consequently, right branches originating close to the portal bifurcation should be superselectively catheterized. Caution should also be exercised to avoid reflux into left lobe veins when occluding veins in segment IV. Because of this potential risk, segment IV portal veins should be occluded first for added safety, and a particulate embolic agent must be preferred to cyanoacrylate.

Dec 23, 2015 | Posted by in INTERVENTIONAL RADIOLOGY | Comments Off on Portal Vein Embolization
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