TIPS is considered mainstay in managing complications from portal hypertension. However, ever since the first TIPS in 1969, the long-term efficacy of the intervention has been impeded by shunt dysfunction. (Rösch et al. 1969) The introduction of PTFE-covered stents replacing the use of bare metal stents has significantly improved longevity, yet patients often require multiple revisions of their TIPS (Triantafyllou et al. 2018). The major causes of bare metal stent TIPS dysfunction are in-stent thrombosis, intimal hyperplasia of the outflow hepatic vein and pseudointimal hyperplasia within the shunt lumen caused by biliary leakage from disrupted bile ducts. (Fanelli 2014) This may manifest as variceal bleeding, ascites, hydrothorax or hepatic encephalopathy, secondary to portal hypertension.
Parallel TIPS was first reported by Dabos et al. in 1998, prior to the availability of dedicated covered TIPS stents. The study assessed balloon angioplasty, re-stenting and creation of a parallel TIPS as interventions for TIPS dysfunction, recommending parallel TIPS for patients with early shunt dysfunction or severe recurrent pseudointimal hyperplasia. (Dabos et al. 1998) Parallel TIPS has since been predominantly reserved for when the primary TIPS is inaccessible or unfavourable for recanalization and for persisting portal hypertension despite verified patency on imaging. (Raissi et al. 2019) It has demonstrated similar patency rates in the mid-term compared to TIPS of patients who do not undergo parallel TIPS. (Raissi et al. 2019; Helmy et al. 2006)
Aside from the introduction of dedicated, covered TIPS stents, several factors contribute to maximising TIPS function. Some reports have suggested that entry of the stent at the left portal vein branch, compared to the right, is associated with improved longevity due to the straighter trajectory to the hepatic vein that allows for less turbulent blood flow. Puncturing the left portal vein may be more technically difficult given its location relative to the inferior vena cava. (Alwarraky et al. 2020; Chen et al. 2009; Luo et al. 2019; Chu et al. 2002) A study by Clark et al. also demonstrated longer patency in stents that extend to the hepatocaval junction rather than those terminating at the hepatic vein. (Clark et al. 2004) The TIPS stent in our patient terminated at the hepatic vein which could have contributed to the early stent occlusion in just over two months, requiring re-lining of the stent and commencement of apixaban. The use of prophylactic anticoagulation and antiplatelet therapy can reduce the incidence of both TIPS stenosis as well as de novo portal vein thrombosis occurring after TIPS. However, this carries the increased risk of rebleeding from varices. As such, certain patients may benefit from variceal embolization alongside parallel TIPS creation. (Tang et al. 2017)
He et al. describe a cohort of 10 patients undergoing parallel TIPS with non-TIPS-dedicated covered stents. (He et al. 2014) Nine patients suffered from persistent ascites and one patient had ongoing variceal bleeding despite patent primary TIPS. Reduction in PSG occurred in all patients, as well as clinical remission from portal hypertensive symptoms.
There is limited literature on parallel TIPS in which Viatorr stents, dedicated covered TIPS stents, are used for both procedures. One case report describes a patient with alcoholic cirrhosis who had two TIPS revisions before a parallel TIPS was inserted from the right hepatic to right portal vein. The PSG was reduced from 10 mmHg to 5 mmHg, however no follow-up data was included to describe the longevity of the parallel TIPS. (Larson et al. 2016) Another study reported two patients who experienced recurrent ascites, hydrothorax and elevated PSG despite venography indicating a patent primary TIPS. Both individuals demonstrated clinical improvement after parallel TIPS creation. (Parvinian and Gaba 2013) More recently, a case series by Raissi et al. followed three patients with failed endoscopic management of variceal bleeding after initial TIPS placement. Two of these patients also had patent TIPS and a PSG below 10 mmHg prior to parallel shunt insertion, comparable to our patient. (Raissi et al. 2019) Our findings concur with these latter two reports, suggesting that shunt patency may not necessarily correlate with the clinical features of TIPS dysfunction that necessitate parallel TIPS creation.
Hepatic encephalopathy is the most common complication of parallel TIPS. In most cases, this is adequately controlled with medical management. Rarer complications include biliary puncture, intraperitoneal haemorrhage and hepatic failure. (Alwarraky et al. 2020; Raissi et al. 2019) Overall, however, the parallel TIPS is considered a safe intervention for managing refractory portal hypertension, with a similar safety and adverse effect profile to a primary TIPS.