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Friday, October 28, 2016

From the SIR Residents and Fellows Section (RFS)

Teaching Topic: Portal Vein Embolization via Percutaneous Transsplenic Access prior to Major Hepatectomy for Patients with Insufficient Future Liver Remnant

Ko HK, Ko G, Sung K, Gwon D, Yoon H. Portla vein embolization via percutaneous transsplenic access prior to major hepatectomy for patients with insufficient future liver remnant. J Vasc Interv Radiol 2016; 27:981–986.

Click here for abstract

In this recent article from JVIR, researchers evaluated the feasibility and safety of utilizing a transsplenic approach for portal vein embolization (PVE). The transsplenic approach was used in 16 patients due to anatomic difficulty secondary to tumor burden or trajectory of transhepatic access. In the remaining patients, a planned transsplenic approach was chosen prior to the start of the procedure. Embolization was performed with gelatin sponge particles followed by coils, amplatzer vascular plugs, or glue. There were 3 of 27 failed transsplenic accesses dues to splenic vein dissection (n=1) or failed splenic vein puncture (n=2). The remaining patients had successful planned liver resection at 4.9+/-3.5 weeks. The authors conclude that transsplenic PVE may be considered a safe and feasible treatment option in patients that have contraindications to a traditional ipsilateral approach.

Clinical Pearls

What patient population would benefit from portal vein embolization?

The patient population that benefit from portal vein embolization are those who are at significant risk of fulminant hepatic failure following total right hepatectomy for tumor resection due to the fact that their liver remnant following surgery is too small to function properly for the patient. In order to increase the size of this future liver remnant, portal vein embolization can be utilized to capitalize on the liver’s unique regenerative ability and increase the future liver remnant volume. The ratio of future liver remnant to total liver volume should be >40% in patients with chronic liver disease.

What are some contraindications to PVE?

While there are no absolute contraindications for PVE, there are a number of relative contraindications. Clearly metastatic disease with distal involvement or metastatic disease involving segment I, II, or III or involving the entire left lobe and segment VI or VII are not candidates for right or left trisegmentectomy, respectively and would not benefit from PVE. Other relative contraindications include biliary dilation, uncorrectable coagulopathy, tumor invasion of the portal vein, portal hypertension, and portal vein thrombus in the contralateral portal vein.

Morning Report Questions

How is the FLR calculated?

The percentage of liver left behind after surgery (future liver remnant, FLR) is a strong, independent predictor of postsurgical hepatic dysfunction and complications. CT with volumetrics is the cornerstone for planning surgical resection. There are different methods of calculating liver volumes. Many institutions will directly measure the FLR and estimate the TELV with a formula based on the patient’s body weight and body surface area (TELV = -794.41 + 1267.28 (BSA)) so that the FLR/TELV ratio can be calculated. This method allows uniform comparison of FLR volume prior to extended resection with or without preoperative PVE.

What are the embolic agents that can be used for PVE?

A variety of embolic agents may be used in PVE. Many have been investigated and show similar levels of effectiveness. Agents include: N-butyl cyanoacrylate (NBCA) & lipiodol; ethanol; PVA or Embospheres with coils or Amplatzer vascular plugs. A recent article from Jaberi et al. compared NBCA + AVP with PVA ± coils and found a greater degree of hypertrophy of the FLR, less fluoroscopic time and contrast volume, and similar complication rates. However, a full cost analysis and additional studies may need to be performed prior to any significant change in practice pattern.

What are the benefits and drawbacks for the various approach methods for portal vein embolization?

The standard approach method for portal vein embolization is the ipsilateral transhepatic approach (i.e. approaching from the same side of the liver that you are planning to embolize). The benefit of this approach is that you avoid damage to the future liver remnant. However, with the ipsilateral approach, there is increased risk of tumor seeding if there is a large tumor burden or a tumor lies within the trajectory of the puncture. Infection is also a concern as there is a risk of bile duct puncture.

The next most common is a contralateral transhepatic approach. The benefit with the contralateral approach is that you avoid possible tumor seeding of the tract. However, this runs the risk of damage to the future liver remnant as you are traversing the normal liver that you hope to maintain and grow. As with the ipsilateral approach, infection is a concern due to possible puncture of bile ducts.

Transsplenic approach is beneficial as it allows for avoidance of tumor seeding, damage to the future liver remnant and infection from bile duct puncture. However, the main drawback of a transsplenic approach is the risk of bleeding. The spleen is a highly vascular organ and small injuries can lead to significant bleeding. As can be seen in this associated manuscript, further investigation is warranted.

Additional Citations:

Jaberi A, et al. Comparison of clinical outcomes following glue versus polyvinyl alcohol portal vein embolization for hypertrophy of the future liver remnant prior to right hepatectomy. J Vasc Interv Radiol 2016. In press.

Andrew Niekamp, MD
Diagnostic Radiology Resident, PGY-3
UT Houston

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