Two-stage closure of a portosystemic shunt with covered balloon-expandable stents

An 11-year-old boy was admitted to our Department of Interventional Radiology with a rare and severe case of terminal portopulmonary hypertension (PPH) and right-sided heart dysfunction.

After multiple chest and cardiac function studies, an abdominal MR angiography was also performed. A congenital portosystemic shunt (CPSS) between the extrahepatic portal vein (PV) and the inferior cava vein (ICV), with a side-to-side anastomosis (Figure 1), was depicted on the MR T1-weighted imaging (WI) after contrast administration. Furthermore, a focal lesion was observed in the VII segment, which was later biopsied. A biopsy and a histopathology exam revealed that it was an adenoma.

A CT angiography afterwards showed the same findings (the CPSS and the adenoma), pneumoperitoneum and ascites related to the biopsy (Figures 2a and 2b).

A venography was performed, accessing the right jugular and common femoral veins. The CPSS was confirmed with phlebography through the superior mesentery vein (SMV). Notice the absence of intrahepatic portal venous branches since the blood flow bypasses the liver circulation and reaches systemic circulation unfiltered (Figure 3).

Background

Congenital portosystemic shunts (CPSS) are rare vascular malformations that consist of an abnormal connection between the portal vein (PV) and systemic veins. They can be intrahepatic or extrahepatic (type 1, end-to-side; or, type 2, side-to-side) [1,2].

Clinical Perspective

CPSSs are often asymptomatic or diagnosed because of two complications [3]:

• Portopulmonary hypertension (PPH) is the most feared complication and is produced by vasoconstriction of small vessels [4].
• Focal liver lesions (focal nodular hyperplasia, adenoma and hepatocellular carcinoma) appear because of arterial hyperflow since intrahepatic portal branches are inexistent or hypoplastic [5].

Imaging Perspective

Angiography is valuable for confirming the diagnosis and guiding the treatment. The occlusion test, which involves placing a balloon close to the CPSS and measuring superior mesentery vein (SMV) pressure and portosystemic gradient (PSG), determines the best approach for shunt closure (one-stage or two-stage) [6]. Abrupt closure of CPSSs with high pressures could result in intestinal ischaemia due to venous congestion.

Endovascular closure is indicated in all CPSSs when diagnosed. McLin et al. consider an SMV pressure > 30 mmHg or a PSG > 20 mmHg in the occlusion test as indicators for two-stage closure [3]. Franchi-Abella S et al. (SMV pressure > 32 mmHg) [1] and Kanazawa et al. (> 25 mmHg) [7] propose other cut-off values.

Outcome

Because the occlusion test in our case demonstrated high SMV pressure (47 mmHg) and PSG (30 mmHg), a two-stage closure was proposed (Figure 4). Since the shunt’s width was large (> 2.5 cm), no plugs or coils could be used. Two covered stents (BeGraft Bentley®) of 48 x 24 mm were instead placed.

During the partial closure, we firstly introduced an inner stent with a balloon, followed by an outer stent. Then, the balloon was expanded (Figure 5a). A smaller balloon expanded an 8 mm-diameter path between both stents to maintain access through the shunt, assuring flow from the main PV to the ICV (Figure 5b). Afterwards, we registered an SMV pressure of 25 mmHg (< 30) (Figure 6).

After two months, we performed a total closure (Figure 7). A new balloon was introduced through the inner stent and expanded, closing the 8 mm-diameter access (Figure 8). SMV pressure (< 30 mmHg) and PSG (< 20 mmHg) then showed adequate values.

In our case, PPH completely disappeared after the closure, a testament to the effectiveness of the treatment (Figures 9 and 10) [8].

Take Home Message

Interventional radiology plays a crucial role in the management of CPSSs. Through this case, we illustrate how two balloon-expandable stents can be an alternative option for a two-time closure.

Written informed patient consent for publication has been obtained.