High occlusion rate in experimental transjugular intrahepatic portosystemic shunt created with a Dacron-covered nitinol stent

Creation of 6- to 10-mm-Diameter Transjugular Intrahepatic Portosystemic Shunts Using a Novel Transjugular Intrahepatic Portosystemic Shunt Stent Graft in a Swine Model

PURPOSE

To assess the delivery, function, and patency of a new expanded polytetrafluoroethylene-encapsulated transjugular intrahepatic portosystemic shunt (TIPS) stent graft ("Liverty") in an animal model.

MATERIALS AND METHODS

TIPS were created in 2 successive groups: (a) 14 single and (b) 10 overlapping devices, in swine weighing 52-64 kg. Explants occurred at 30 (n = 10) and 60 (n = 14) days. These were evaluated by histomorphometric and histopathologic evaluations and electron microscopy.

RESULTS

Seven 6-mm-diameter, 5 7-mm-diameter, and 12 10-mm-diameter TIPSs were created using varied human TIPS access sets without adverse events, both sheathed and unsheathed advancement and deployment of the devices within liver tracts. One animal was sacrificed at 35 days due to encephalopathy; the remainder survived to endpoints. Twenty-two of 24 TIPSs were patent at 30-day and 60-day endpoints. The mean stenosis at 30 days was 13.3% (SD ± 10.1), and that at 60 days was 18.4% (SD ± 5.0). Two shunts were occluded by tissue overgrowth at the stent-free native hepatic vein end and downgrowth into TIPS. Histology and electron microscopy showed well-apposed, incorporated devices lined with smooth, uniform neointimal tissue averaging 0.48 mm (single devices) and 0.74 mm (overlapped devices) thick with minimal adventitial inflammation.

CONCLUSIONS

The new Liverty TIPS stent graft was straightforward to deploy for TIPS creation and resulted in patent 6-mm-diameter, 7-mm-diameter, and 10-mm-diameter shunts in both single and overlapping configurations. One- and 2-month histology showed desired tissue healing without in-stent stenosis.

Transjugular Intrahepatic Portosystemic Shunt: Devices Evolution, Technical Tips and Future Perspectives

Portal hypertension (PH) constitutes a pivotal factor in the progression of cirrhosis, giving rise to severe complications and a diminished survival rate. The transjugular intrahepatic portosystemic shunt (TIPS) procedure has undergone significant evolution, with advancements in stent technology assuming a central role in managing PH-related complications. This review aims to outline the progression of TIPS and emphasizes the significant influence of stent advancement on its effectiveness. Initially, the use of bare metal stents (BMSs) was limited due to frequent dysfunction. However, the advent of expanding polytetrafluoroethylene-covered stent grafts (ePTFE-SGs) heralded a transformative era, greatly enhancing patency rates. Further innovation culminated in the creation of ePTFE-SGs with controlled expansion, enabling precise adjustment of TIPS diameters. Comparative analyses demonstrated the superiority of ePTFE-SGs over BMSs, resulting in improved patency, fewer complications, and higher survival rates. Additional technical findings highlight the importance of central stent placement and adequate stent length, as well as the use of smaller calibers to reduce the risk of shunt-related complications. However, improving TIPS through technical means alone is inadequate for optimizing patient outcomes. An extensive understanding of hemodynamic, cardiac, and systemic factors is required to predict outcomes and tailor a personalized approach. Looking forward, the ongoing progress in SG technology, paired with the control of clinical factors that can impact outcomes, holds the promise of reshaping the management of PH-related complications in cirrhosis.

Comparison of the Covered Self-Expandable Viatorr CX Stent with the Covered Balloon-Expandable BeGraft Peripheral Stent for Transjugular Intrahepatic Portosystemic Shunt (TIPS) Creation: a Single-Centre Retrospective Study in Patients with Variceal Bleeding

PURPOSE

This study compares the safety and efficacy of the ePTFE-covered self-expansible nitinol stent (VIATORR® Controlled Expansion, Gore, Flagstaff, USA) with the ePTFE-covered, balloon-expandable, metallic stent (BeGraft peripheral, Bentley, Hechingen, Germany) for the creation of the transjugular intrahepatic portosystemic shunt (TIPS).

MATERIAL AND METHODS

From September 2016 to December 2020, 72 consecutive patients receiving TIPS for acute variceal bleeding (rescue and early TIPS, n = 15) or for prophylaxis of variceal rebleeding (n = 57) were enrolled. The main contraindications were patients with vascular liver disease (portal vein thrombosis and Budd-Chiari syndrome). Forty patients (55.6%) received a Viatorr CX stent and 32 patients (44.4%) a BeGraft peripheral stent. Safety endpoints were technical and clinical adverse events and early deaths within 30 days after TIPS implantation. Efficacy endpoints were rebleeding rates, recurrence of large varices requiring endoscopic band ligation, or TIPS revision.

RESULTS

Groups receiving the Viatorr CX or BeGraft peripheral stent were comparable in all respects except the TIPS indication for acute variceal bleeding (5% vs. 25%, p = 0.015). All patients had a successful intervention, and the physical variables of stent implantation (intervention and fluoroscopy time, reduction of the portosystemic pressure gradient) as well as adjunctive embolization of varices were similar in both groups. Severe clinical complications (Viatorr CX: 5% vs. BeGraft peripheral: 3.1%, p = 0.692), post-TIPS hepatic encephalopathy (12.5% vs. 18.8%, p = 0.743) and death (5% vs. 0%, p = 0.793) were not different between Viatorr CX and BeGraft peripheral groups. With respect to efficacy, freedom from rebleeding and from variceal band ligation during follow-up (100% vs. 100%, p = 1.0), as well as the need for shunt revision (10.5% vs. 18.8%, p = 0.327), was comparable.

CONCLUSION

Compared to the present gold standard, the Viatorr CX stent, the balloon-expandable BeGraft peripheral stent, showed similar results with respect to safety and efficacy.

Shunt stenosis or occlusion after transjugular intrahepatic portosystemic shunt

Transjugular intrahepatic portosystemic shunt (TIPS) has been extensively used to treat the complications of portal hypertension and should be considered the first-line treatment for hemorrhage of acute esophagogastric varices caused by portal hypertension. However, stent stenosis or occlusion after TIPS is the main cause of shunt dysfunction and surgical failure. This paper aims to make a comprehensive review of stents, with the focus being on the development of stents and stent coat material, the reason of shunt stenosis or occlusion, and the revision of shunt.

The Evolution of Transjugular Intrahepatic Portosystemic Shunt: Tips

Since Richter's description in the literature in 1989 of the first procedure on human patients, transjugular intrahepatic portosystemic shunt (TIPS) has been worldwide considered as a noninvasive technique to manage portal hypertension complications. TIPS succeeds in lowering the hepatic sinusoidal pressure and in increasing the circulatory flow, thus reducing sodium retention, ascites recurrence, and variceal bleeding. Required several revisions of the shunt TIPS can be performed in case of different conditions such as hepatorenal syndrome, hepatichydrothorax, portal vein thrombosis, and Budd-Chiari syndrome. Most of the previous studies on TIPS procedure were based on the use of bare stents and most patients chose TIPS 2-3 years after traditional treatment, thus making TIPS appear to be not superior to endoscopy in survival rates. Bare stents were associated with higher incidence of shunt failure and consequently patients required several revisions during the follow-up. With the introduction of a dedicated e-PTFE covered stent-graft, these problems were completely solved, No more reinterventions are required with a tremendous improvement of patient's quality of life. One of the main drawbacks of the use of e-PTFE covered stent-graft is higher incidence of hepatic encephalopathy. In those cases refractory to the conventional medical therapy, a shunt reduction must be performed.

Reduced stents and stent-grafts for the management of hepatic encephalopathy after transjugular intrahepatic portosystemic shunt creation

Hepatic encephalopathy (HE) is a common complication encountered by patients after transjugular intrahepatic portosystemic shunt (TIPS) creation. Although most patients respond well to conservative medical therapy, up to 7% of patients do not and require more invasive therapeutic approaches. One option is emergent liver transplantation; however, most patients are not suitable candidates. During the past decade, various percutaneous techniques have been described that alter the hemodynamics through the TIPS by occluding it with coils or balloons or by reducing its diameter using constrained stents or stent-grafts. These endovascular techniques have produced symptomatic improvement in many patients with refractory HE, with either complete resolution or substantial reduction of HE symptoms that can be controlled with additional medical therapy. Unfortunately, despite all attempts, some patients remain incapacitated and ultimately die. Further research is necessary to improve our understanding of HE after TIPS creation so that less invasive and safer procedures can be developed to treat this difficult clinical problem.

Should stent-grafts replace bare stents for primary transjugular intrahepatic portosystemic shunts?

Transjugular intrahepatic portosystemic shunt (TIPS) creation using bare stents is a second-line treatment for complications of portal hypertension due in part to the relatively high number of reinterventions and the occurrence of new or worsened encephalopathy. Initially, custom-made stent-grafts were used for TIPS revision in cases of biliary fistulae. Subsequently, custom stent-grafts were used for de novo TIPS creation. With the introduction of the VIATORR(®) TIPS endoprosthesis a dedicated stent-graft became available for TIPS creation and revision. The VIATORR(®) demonstrated its efficacy and superiority to uncovered stents in retrospective analyses, case-matched analyses, and randomized studies. The improved patency of stent-grafts has led many to requestion the role of TIPS as a second-line therapy. Currently, randomized trials are warranted to redefine the role of TIPS in the treatment of complications of portal hypertension.

The transjugular intrahepatic portosystemic shunt (TIPS)

The creation of an intrahepatic portosystemic shunt via a transjugular approach (TIPS) is an interventional radiological procedure used to treat the complications of portal hypertension. TIPS insertion is principally indicated to prevent or arrest variceal bleeding when medical or endoscopic treatments fail, and in the management refractory ascites. This review discusses the development and execution of the technique, with focus on its clinical efficacy. Patient selection, imaging surveillance, revision techniques, and complications are also discussed.

Causes of TIPS dysfunction

OBJECTIVE

Transjugular intrahepatic portosystemic shunt (TIPS) creation is an effective method to control portal hypertension. TIPS creations with bare stents have shown limited and unpredictable patency. In nearly all cases of rebleeding or recurrent ascites after TIPS creation, there is shunt stenosis or occlusion. The purpose of this article is to review the biologic and technical factors that predispose to TIPS failure and how the use of an expandable polytetrafluoroethylene (PTFE)-covered-stent has significantly improved TIPS patency.

CONCLUSION

Biologic and technical factors may predispose to shunt failure. The combination of improved technique and expandable PTFE has significantly improved TIPS patency. The need for follow-up venography and secondary interventions has been reduced significantly as a result of improved shunt patency.

Bidirectionally adjustable TIPS reduction by parallel stent and stent-graft deployment

Excessive shunting through transjugular intrahepatic portosystemic shunts (TIPS) can cause life-threatening hepatic encephalopathy and insufficiency. Intentional reduction of flow may be effective but difficult to control. The present report describes refinements of the parallel stent/stent-graft technique of flow reduction that is adjustable in either direction. Six patients underwent TIPS reduction with varying stent positioning and a variety of commercial products. Flow was adjusted by iterative balloon dilatation of the stent and stent-graft, resulting in a mean gradient increase of 8 mm Hg. All cases were technically successful, but 1-year survival was seen in only the patient who underwent liver transplantation.

Intravascular US-guided direct intrahepatic portocaval shunt with an expanded polytetrafluoroethylene-covered stent-graft

PURPOSE

To retrospectively evaluate the midterm patency rate of the nitinol (Viatorr, W.L. Gore and Associates, Flagstaff, Ariz) stent-graft for direct intrahepatic portacaval shunt (DIPS) creation.

MATERIALS AND METHODS

Institutional Review Board approval for this retrospective HIPAA-compliant study was obtained with waiver of informed consent. DIPS was created in 18 men and one woman (median age, 54 years; range, 45-65 years) by using nitinol polytetrafluoroethylene (PTFE)-covered stent-grafts. The primary indications were intractable ascites (n = 14), acute variceal bleeding (n = 3), and hydrothorax (n = 2). Follow-up included Doppler ultrasonography at 1, 6, and 12 months and venography with manometry at 6-month intervals after the procedure. Shunt patency and cumulative survival were evaluated by using the Kaplan-Meier method and survival curves were plotted. Differences in mean portosystemic gradients (PSGs) were evaluated by using the Student t test. Multiple regression analysis for survival and DIPS patency were performed for the following parameters: Child-Pugh class, model of end-stage liver disease score, pre- and post-DIPS PSGs, pre-DIPS liver function tests, and pre-DIPS creatinine levels.

RESULTS

DIPS creation was successful in all patients. Effective portal decompression and free antegrade shunt flow was achieved in all patients. Intraperitoneal bleeding occurred in one patient during the procedure and was controlled during the same procedure by placing a second nitinol stent-graft. The primary patency rate was 100% at all times during the follow-up period (range, 2 days to 30 months; mean, 256 days; median, 160 days). Flow restrictors were deployed in two (11%) of 19 patients. The 1-year mortality rate was 37% (seven of 19).

CONCLUSION

Patency after DIPS creation with the nitinol PTFE-covered stent-graft was superior to that after TIPS with the nitinol stent-graft.

Endovascular shunt reduction in the management of transjugular portosystemic shunt-induced hepatic encephalopathy: preliminary experience with reduction stents and stent-grafts

OBJECTIVE

The purpose of this study was to retrospectively evaluate the safety, feasibility, and midterm clinical outcome of the use of three types of reduction stents inserted to manage transjugular intrahepatic portosystemic shunt (TIPS)-induced hepatic encephalopathy refractory to medical treatment.

CONCLUSION

The use of a covered reduction stent-graft results in a greater increase in portosystemic gradient immediately after reduction than does use of a bare reduction stent. Relief of TIPS-induced hepatic encephalopathy tends to be greater in patients with reduction stent-grafts than in those with bare reduction stents.

[Covered transjugular intrahepatic portosystemic shunts]

Transjugular intrahepatic portosystemic shunts (TIPS) consist of a connection created by methods of interventionist radiology between the vena porta and the vena cava through the hepatic parenchyma. By markedly decreasing the portal pressure gradient, TIPS are highly effective in controlling the complications of portal hypertension such as bleeding due to esophageal varices and refractory ascites. Nevertheless, with the use of uncovered stents, the probability of shunt dysfunction -with the consequent reappearance of portal hypertension and its complications- is very high. The use of expandable polytetrafluoroethylene (e-PTFE)-covered stents markedly reduces the incidence of dysfunction, thus decreasing the number of clinical recurrences of portal hypertension and the reinterventions required to maintain shunt patency. The greater effectiveness of e-PTFE-covered stents is not accompanied by a higher incidence of complications or hepatic encephalopathy. Therefore, e-PTFE-covered stents should be preferred over uncovered stents in the management of the complications of portal hypertension.

A modified procedure for transjugular intrahepatic portosystemic shunt flow reduction

The authors present a modified transjugular intrahepatic portosystemic shunt (TIPS) flow reduction procedure to treat TIPS-related refractory hepatic encephalopathy, giving the results and follow-up on six patients. A 6-mm-diameter Uni Wallstent was introduced over a guide wire and deployed beyond the angulated portion of the TIPS. A Wallgraft was then introduced over the same guide wire, pushed through the Uni Wallstent coaxially, and deployed in the TIPS. All cases were technically and clinically successful. There were no deaths in the first month after the procedure. In this study, three patients had more than 1 year's patency.

Efficacy of a dexamethasone-eluting nitinol stent on the inhibition of pseudo-intimal hyperplasia in a transjugular intrahepatic portosystemic shunt: an experimental study in a swine model

OBJECTIVE

We wanted to evaluate the feasibility and efficacy of using a dexamethasone (DM)-eluting nitinol stent to inhibit the pseudo-intimal hyperplasia following stent placement in the transjugular intrahepatic portosystemic shunt tract (TIPS) of a swine.

MATERIALS AND METHODS

Fifteen stents were constructed using 0.15 mm-thick nitinol wire; they were 60 mm in length and 10 mm in diameter. The metallic stents were then classified into three types; type 1 and 2 was coated with the mixture of 12% and 20%, respectively, of DM solution and polyurethane (PU), while type 3 was a bare stent that was used for control study. In fifteen swine, each type of stent was implanted in the TIPS tract of 5 swine, and each animal was sacrificed 2 weeks after TIPS creation. The proliferation of the pseudo-intima was evaluated both on follow-up portogram and pathologic examination.

RESULTS

One TIPS case, using the type 1 stent, and two TIPS cases, using the type 2 stent, maintained their luminal patency while the others were all occluded. On the histopathologic analysis, the mean of the maximum pseudo-intimal hyperplasia was expressed as the percentage of the stent radius that was patent, and these values were 51.2%, 50% and 76% for the type 1, 2, and 3 stents, respectively.

CONCLUSION

The DM-eluting stent showed a tendency to reduce the development of pseudo-intimal hyperplasia in the TIPS tract of a swine model with induced-portal hypertension.

Improved clinical outcome with transjugular intrahepatic portosystemic stent-shunt utilizing polytetrafluoroethylene-covered stents

BACKGROUND AND AIMS

Transjugular intrahepatic portosystemic stent-shunt (TIPSS) with standard uncovered stents has a 50% one-year primary patency rate, and is complicated by hepatic encephalopathy in 35% of patients. Newer covered stents appear to have improved patency. This large study aimed to assess the shunt function and clinical efficacy of polytetrafluoroethylene-covered stents in a single centre.

METHODS

A total of 316 patients with uncovered stents before the introduction of covered stents (group 1) and 157 patients with the Viatorr Gore polytetrafluoroethylene-covered stents at the time of TIPSS creation (group 2) were studied.

RESULTS

The mean follow-up was 22.8+/-25.4 and 13.1+/-12.5 months, respectively (P<0.01). Shunt insufficiency was greater in group 1 [54 versus 8% at 12 months; relative hazard (RH) 8.6; 95% confidence interval (CI) 4.8-15.5; P<0.001]. The incidence of variceal rebleeding was greater in group 1 (11 versus 6% at 12 months; RH 2.4; 95% CI 1.1-5.1; P<0.05). The incidence of hepatic encephalopathy was greater in group 1 (32 versus 22% at 12 months; RH 1.5; 95% CI 1.1-2.3; P<0.05). Mortality was similar in the two groups.

CONCLUSION

The Viatorr type of polytetrafluoroethylene-covered stent results in vastly improved patency compared with uncovered stents, with reduced rates of variceal rebleeding and hepatic encephalopathy. This type of covered stent has the potential for superior clinical efficacy compared with uncovered stents.

TIPS with expanded polytetrafluoroethylene-covered stent: results of an Italian multicenter study

OBJECTIVE

Our objective is to describe the results of a multicenter prospective trial on the safety and efficacy of transjugular intrahepatic portosystemic shunts (TIPS) using the Viatorr stent-graft.

SUBJECTS AND METHODS

From 2001 to 2003, 114 patients (75 men and 39 women; mean age, 59.3 years) with portal hypertension underwent TIPS with the Viatorr stent-graft. Indications for treatment were variceal bleeding (n = 49, 43.0%), refractory ascites (n = 52, 45.6%), hypertensive gastropathy (n = 10, 8.8%), Budd-Chiari syndrome (n = 1, 0.9%), and hepatorenal syndrome (n = 2, 1.7%). Eight patients (7.0%) had Child-Pugh class A cirrhosis; 60 (52.6%), Child-Pugh class B; and 46 (40.4%), Child-Pugh class C. Patients were monitored by color Doppler sonography and phlebography.

RESULTS

The procedure was successful in 113 (99.1%) of 114 patients; in one patient, creation of the track was not feasible. The mean portosystemic pressure gradient decreased from 21.8 to 8.7 mm Hg. Three minor immediate complications (2.6%) occurred (two cases of self-limiting hemoperitoneum and one extrahepatic portal puncture requiring covered stenting). At a mean follow-up of 11.9 months, the overall mortality rate was 31.0% (35/113), with a 30-day mortality rate of 8.8% (10/113). Mortality was significantly higher in patients in Child-Pugh class C with refractory ascites and with post-procedural encephalopathy. Cumulative primary patency rates were 91.9%, 79.9%, and 75.9% at 6, 12, and 24 months' follow-up, respectively. Restenosis occurred in 15 patients (13.3%) within the stent (n = 8, 53.3%) or at the ends of the portal (n = 1, 6.7%) or hepatic (n = 6, 40%) veins and was solved by percutaneous transluminal angioplasty (n = 11), stenting (n = 3), or parallel TIPS (n = 1). The secondary patency rate was 98.2%. Post-procedural encephalopathy occurred in 27 patients (23.9%).

CONCLUSION

The Viatorr stent-graft is safe and effective in TIPS creation, with high primary patency rates. Covering the entire track up to the inferior vena cava can increase patency.

Dacron-covered stent-grafts in transjugular intrahepatic portosystemic shunts: initial experience

PURPOSE

To retrospectively review the authors' experience with use of a Dacron-covered stent-graft in transjugular intrahepatic postosystemic shunts (TIPS).

MATERIALS AND METHODS

The need for internal review board approval was waived. Informed consent was obtained from all patients. The study was compliant with the Health Insurance Portability and Accountability Act. A retrospective analysis was performed of 16 patients who received a Dacron-covered stent-graft during revision or de novo creation of TIPS. There were 13 men and three women aged 44-80 years (mean age, 61 years). Primary unassisted and assisted patency rates and secondary patency rates were estimated. The primary unassisted patency of patients who underwent de novo placement of stent-grafts (n = 10) was compared with that of patients with stent-grafts placed during shunt revision (n = 6); in all patients, stent-grafts were placed within stents. Primary unassisted patency was also compared between patients in whom the covered stent was confined to the parenchymal tract (n = 7) and those in whom the stent extended 1 cm or more into the portal vein (n = 9). Patency was estimated with the Kaplan-Meier method, and group comparisons were performed with the log-rank test.

RESULTS

Primary unassisted patency rates following stent-graft placement at 4, 12, and 24 months (+/- standard error) were 64% +/- 14, 54% +/- 15, and 40% +/- 16, respectively. The rates for primary assisted patency were 78% +/- 12, 67% +/- 14, and 67% +/- 14 and those for secondary patency were 91% +/- 9, 81% +/- 12, and 54% +/- 23. At 12 months, primary unassisted patency with de novo stent-graft placement was 90% +/- 9, whereas that with stent-grafts placed during TIPS revision was 17% +/- 15 (P = .005). At 12 months, the primary unassisted patency in patients with stent-grafts confined to the parenchymal tract was 75% +/- 22, and that of patients with stent-grafts extending at least 1 cm into the portal vein was 40% +/- 17 (P = .21).

CONCLUSION

In this small series, satisfactory long-term patency was observed among patients in whom Dacron-covered stent-grafts were placed during revision or de novo creation of TIPS. More favorable outcomes were observed when the stent-graft was placed during de novo TIPS creation and when the device was confined to the parenchymal tract.

Intravascular ultrasound-guided direct intrahepatic portacaval shunt: midterm follow-up

PURPOSE

To describe the midterm patency and clinical results of the intravascular ultrasound (US)-guided direct intrahepatic portacaval shunt (DIPS) procedure for the treatment of intractable ascites and variceal bleeding.

MATERIALS AND METHODS

From February 23, 1999, to December 18, 2002, inferior vena cava (IVC)-to-portal vein (PV) shunts were created in 40 patients for ascites (n = 35) and bleeding (n = 5). Intravascular US was used to guide direct puncture from the IVC to the PV. The shunts were completed with the use of single (n = 15) or overlapping (n = 25) polytetrafluoroethylene (PTFE)-covered Palmaz stents. These stent-grafts were deployed primarily at diameters of 8 mm. The diameter of the shunt was increased in three cases to achieve a target portosystemic gradient (PSG) of 15 mm Hg or lower. All patients were followed clinically and with portography with manometry.

RESULTS

All DIPSs were created successfully. Mean PSGs were reduced from 23 mm Hg before DIPS creation to 9 mm afterward. During the follow-up period of a maximum of 38 months, 22 of 40 patients died or underwent liver transplantation (mean follow-up, 9 months; median, 6 months). At the time of this report, 18 of 40 patients remain living after follow-up ranging in duration from 8 to 38 months (mean, 22 months; median, 16.5 months). During the follow-up period, there was one stent-graft occlusion and three stenoses. These four patients were successfully treated by additional stent-graft placement. In addition, two patients developed IVC stenosis cephalad to the DIPS, which required IVC stent placement. The primary patency rates by Kaplan-Meier analysis were 100% at 6 months and 75% (95% CI, 53%-97%) at 12 months.

CONCLUSION

Intravascular US-guided direct IVC-to-PV shunts may be created successfully with minimal complications. Primary patency of the shunt is greater than that with conventional TIPS with a bare wire stent and appears equal to that with TIPS with a PTFE-covered stent-graft.

Bile Resistance of Coated Transjugular Intrahepatic Portosystemic Shunt Stents in a Flow-Model

PURPOSE

We sought to test the bile resistance of transjugular intrahepatic portosystemic shunt (TIPS) stents with 3 different coatings.

MATERIALS AND METHODS

Three stents with different coating materials (monolayer polyethylene terephthalate [PETP], monolayer polytetrafluoroethylene [PTFE], and double layer [PTFE]) were tested in a flow model. After testing the sealing of the system with isotonic saline solution, fresh human bile was circulated. Constant pressure was 50 cm H2O. Bile resistance of the stent membranes was analyzed.

RESULTS

Two of the 3 stents proved completely resistant to water. Only the PETP stent was resistant to bile. The PTFE-coated stents were not bile resistant.

CONCLUSION

The bile resistance of coated TIPS stents and, thus, the dependency of TIPS shunt patency is called into question. The stent with the reported superior patency rates does not show experimental bile resistance.

TIPS-related hepatic encephalopathy: management options with novel endovascular techniques

Hepatic encephalopathy is a common complication that develops after creation of a transjugular intrahepatic portosystemic shunt (TIPS). Although most patients respond well to conservative medical therapy (ie, protein-restricted diet, nonabsorbable disaccharides, nonabsorbable antibiotics), a small percentage of patients (3%-7%) do not benefit from these methods and require more invasive therapeutic approaches. One option is emergent liver transplantation, but the majority of patients are not suitable candidates. Recently, various percutaneous techniques have been described that alter the hemodynamics through the shunt by occluding it with coils or balloons or by reducing its diameter by inserting constrained stents or stent-grafts. Other techniques have been used for patients with TIPS-related hepatic encephalopathy in whom spontaneous splenorenal shunts are present. In many patients with refractory hepatic encephalopathy, these percutaneous techniques have produced symptomatic improvement, with either a complete resolution or a substantial reduction in hepatic encephalopathy symptoms that can be controlled with medical therapy. Unfortunately, despite all attempts, some patients remain incapacitated and ultimately die. Further research is necessary to improve our understanding of TIPS-related hepatic encephalopathy so that newer, less invasive and safer procedures can be developed to treat this difficult clinical problem.

Polytetrafluoroethylene-covered stent grafts for TIPS procedure: 1-year patency and clinical results

OBJECTIVES

Polytetrafluoroethylene (PTFE)-covered stent grafts appear to have the potential to improve TIPS patency, but data available are few and controversial. The aim of this prospective nonrandomized trial was to assess TIPS safety and 1-yr patency with a new commercially available PTFE-covered stent graft in comparison with a group of historical controls treated with conventional stents.

METHODS

Between July 1992 and December 1999, 87 consecutive cirrhotics underwent TIPS with conventional stents, while from January 2000 to November 2001, 32 consecutive cirrhotics were treated with PTFE-covered stent grafts. All patients were followed by the same medical team according to a prospective protocol for a diagnostic work-up and a surveillance strategy.

RESULTS

The two groups were comparable for age, sex, etiology, and severity of cirrhosis. The 1-yr probability of remaining free of shunt dysfunction tended to be higher in the covered stent group: 76.3% (95% CI = 58.7-93.9%) versus 57.5% (95% CI = 46.6-68.4%); log rank test: p = 0.055. However, stenoses inside the stent were significantly higher in patients with bare stents (88% vs 17%), while stenoses at the hepatic or portal vein were more frequent in PTFE-covered stent-graft group (50% vs 9% and 33% vs 3%, respectively), (chi2 = 15.42; df = 2.0; p = 0.0004). Stenoses inside the covered portion of the stent did not occur. One-year cumulative rebleeding, encephalopathy, and survival were similar.

CONCLUSIONS

PTFE-covered stents are able to solve pseudointimal hyperplasia within the stent tract, but have a high incidence of hepatic or portal vein stenosis. Improvements in stent design and insertion techniques are necessary to fully achieve the potential benefit of this new device.

Improved clinical outcome using polytetrafluoroethylene-coated stents for TIPS: results of a randomized study

BACKGROUND & AIMS

A 50% dysfunction rate at 1 year is one of the main drawbacks of the transjugular intrahepatic portosystemic shunt procedure. Preliminary experimental and clinical studies suggest that the use of stents covered with polytetrafluoroethylene could tremendously decrease this risk.

METHODS

Eighty patients with cirrhosis and uncontrolled bleeding (n = 23), recurrent bleeding (n = 25), or refractory ascites (n = 32) were randomized to be treated by transjugular intrahepatic portosystemic shunts with either a polytetrafluoroethylene-covered stent (group 1; 39 patients) or a usual uncovered prosthesis (group 2; 41 patients). Follow-up Doppler ultrasound was scheduled at day 7, at 1 month, and then every 3 months for 2 years. Angiography and portosystemic pressure gradient measurements were performed 6, 12, and 24 months after the transjugular intrahepatic portosystemic shunt procedure and whenever dysfunction was suspected. Dysfunction was defined as a >50% reduction of the lumen of the shunt at angiography or a portosystemic pressure gradient >12 mm Hg.

RESULTS

After a median follow-up of 300 days, 5 patients (13%) in group 1 and 18 (44%) in group 2 experienced shunt dysfunction (P < 0.001). Clinical relapse occurred in 3 patients (8%) in group 1 and 12 (29%) in group 2 (P < 0.05). Actuarial rates of encephalopathy were 21% in group 1 and 41% in group 2 at 1 year (not significant). Estimated probabilities of survival were 71% and 60% at 1 year and 65% and 41% at 2 years in groups 1 and 2, respectively (not significant).

CONCLUSIONS

The use of polytetrafluoroethylene-covered prostheses improves transjugular intrahepatic portosystemic shunt patency and decreases the number of clinical relapses and reinterventions without increasing the risk of encephalopathy.

Transvenous extrahepatic portacaval shunt: feasibility study in a Swine model

PURPOSE

To evaluate the feasibility of intravascular ultrasonography (US)-guided access to the extrahepatic segment of the main portal vein (PV) to create a transvenous extrahepatic portacaval shunt (TEPS) as an easier and more durable alternative to transjugular intrahepatic portosystemic shunt.

MATERIALS AND METHODS

PV access from the inferior vena cava (IVC) to the main PV was performed in eight pigs by using intravascular US guidance. Either a prototype stent-graft (n = 6) or Wallgraft (n = 2) was used to create the shunt. Intravascular US demonstrated the main PV to be in direct contact with the IVC in all animals. A mean of 1.75 needle passes were needed to enter the PV. Immediate postprocedure computed tomography (CT) of the abdomen helped identify and quantify the presence of hemoperitoneum. Shunt venography was performed at 2 weeks, followed by necropsy.

RESULTS

PV access and TEPS creation were successful in all animals. Contrast medium extravasation, due to inadequate coverage of the portacaval tract, was identified in four procedures and addressed by the placement of additional devices in three cases and prolonged balloon inflation in one. Abdominal CT demonstrated small amounts of hemoperitoneum in five animals and moderate to large amounts in three. Two animals did not live to the 2-week follow-up study. One animal was sacrificed on the day of the procedure owing to intraperitoneal hemorrhage; the second died of intussusception-related bowel necrosis 10 days after TEPS creation. Shunts were occluded or severely stenotic at venography and necropsy in the remaining six animals.

CONCLUSION

TEPS is technically feasible after intravascular US-guided PV access.

Covered stents in transjugular portosystemic shunt: healing response to non-porous ePTFE covered stent grafts with and without intraluminal irradiation

The aim of this study was to evaluate the healing response to a new commercially available ePTFE-covered stent graft used to create transjugular intrahepatic portosystemic shunts (TIPS) in an animal model with and without intraluminal irradiation. The study was designed for ten domestic normotensive pigs. The TIPS was created using a ePTFE-covered stent graft (Viatorr, Gore, Flagstaff, Ariz.). Five animals were scheduled for intraluminal irradiation with iridium 192 immediately after TIPS creation with a dosage of 18 Gy. Shunt venograms were performed every 2 weeks. Animals from the irradiated and non-irradiated group were killed at 2-week intervals. Maximum follow-up was planned for 8 weeks in each group, with two animals in reserve. Gross specimen evaluation and histological examination, including scanning electron microscopy, was performed. Two animals died from interventional complications. In the irradiation group, one shunt occlusion and one stenosis occurred after 2 weeks. The stenosis regressed until the end of the 8-week follow-up period and probably was caused by a resolving thrombus. In the non-irradiated group, no shunt dysfunction was observed. One animal died early due to encephalopathy. Histology revealed an increased inflammatory reaction in the irradiation group, a lesser degree of incorporation of the stent graft, and a lesser degree of endothelialization of the inner surface compared with the non-irradiated group. No significant foreign body reaction was found at any time in any of the animals. The Viatorr stent graft was well tolerated in the pig model. Intraluminal irradiation seemed to have an adverse effect on the healing response. The TIPS patency was prolonged in both the irradiated and non-irradiated group compared with data from the literature; however, seemingly better results were observed in the non-irradiated group.

Management of TIPS-related refractory hepatic encephalopathy with reduced Wallgraft endoprostheses

The purpose of this study is to evaluate the feasibility of constrained endografts used for the treatment of transjugular intrahepatic portosystemic shunt (TIPS)-related refractory hepatic encephalopathy (HE). Because the clinical status of two patients worsened (return of intractable ascites requiring transplantation, n = 1; death, n = 1) after complete balloon occlusion, six patients were treated with constrained/modified Wallgraft endoprostheses placed within the preexisting TIPS. Shunt reductions were technically successful in all six patients, as shown by an immediate mean portosystemic gradient increase of 9.3 mm Hg. Clinical improvement was achieved in five patients within 72 hours of reduction. The remaining patient continued to decline and died 3 weeks later. Two endografts completely occluded within 8 months without HE recurrence. This technique offers an attractive alternative to previously described shunt reduction methods.

Recurrent TIPS thrombosis after polyethylene stent-graft use and salvage with polytetrafluoroethylene stent-grafts

Increasing data support the use of polytetrafluoroethylene (PTFE) stent-grafts for de novo and revision transjugular intrahepatic portosystemic shunt (TIPS) applications. Animal experiments have indicated that polyethylene terephthalate (PET) stent-grafts provide no improvement or actually worsen TIPS patency compared with controls, but human TIPS experience with PET grafts is more limited. Herein we describe three patients who underwent de novo creation of TIPS with PET-covered stent-grafts at outside institutions, which resulted in immediate and recurring TIPS thromboses despite repeated thrombectomies. After the failed TIPS were revised with PTFE stent-grafts, the presenting symptoms resolved and uninterrupted patency was achieved.

Percutaneous inferior vena cava-to-portal vein shunt (PIPS) using a stent-graft: preliminary results

PURPOSE

To present preliminary results of an inferior vena cava (IVC)-to-portal vein shunt (PIPS) that is created through the caudate lobe of the liver.

METHODS

Sixteen patients (13 men; mean age 50 years, range 32-63) were referred for PIPS procedures because of bleeding varices (n = 11), intractable ascites (n = 4), and hepatorenal syndrome (n = 1). The severity of liver disease was Child's B in 2 and Child's C in 14. The PIPS was created by a transhepatic puncture through the IVC and the portal vein; an endograft made of polytetrafluoroethylene sutured to a Palmaz stent was placed through a jugular approach.

RESULTS

In 13 (81%) patients, the portal vein-to-IVC tracts were successfully created. The postprocedural portal vein-IVC gradients varied from 1 to 9 mm Hg (mean 5). There were 2 deaths in the 30-day periprocedural period from adult respiratory distress syndrome and hepatorenal syndrome. A third patient died at 31 days from liver failure owing to continuing alcohol abuse. In addition, there was 1 case of peritoneal bleeding treated with blood product replacement. The follow-up period ranged from 14 to 671 days (mean 343). None of the patients treated for variceal bleeding had another bleeding episode, but 2 patients who had a PIPS procedure for refractory ascites did not benefit from the procedure. Postprocedure, 46% (6/13) of the patients had hepatic encephalopathy, which was unchanged from baseline. The primary and secondary patency rates at 365 days were 60% and 65%, respectively.

CONCLUSIONS

The preliminary results using a stent-graft to create an IVC-portal vein shunt are encouraging and support further work to better determine the role of this procedure.

Preliminary results of a new expanded-polytetrafluoroethylene-covered stent-graft for transjugular intrahepatic portosystemic shunt procedures

OBJECTIVE

The purpose of our study was to evaluate the feasibility and the safety of transjugular intrahepatic portosystemic shunts (TIPS) with a new expanded-polytetrafluoroethylene-covered stent and the influence of the covering on occlusion rate.

SUBJECTS AND METHODS

Twenty cirrhotic patients (57 +/- 11 years old) admitted with a history of esophageal variceal bleeding (n = 11), refractory ascites (n = 5), or both (n = 4) were included. Five of the patients were treated for TIPS revision, and 15 as de novo TIPS placements. The endoprostheses used were composed of a 2-cm noncovered nitinol stent and a 4- to 8-cm expanded-polytetrafluoroethylene graft covering, and were placed from the portal vein to the ostium of the hepatic vein. Patients underwent Doppler sonography at discharge and again at 1, 3, 6, 9, 12, and 15 months and underwent venography with portosystemic pressure gradient measurement at 6 months and whenever necessary.

RESULTS

At the time of this writing, complications included three TIPS restenoses and one recurrent ascites successfully treated by balloon dilation, two cases of segmentary liver ischemia, and one patient with encephalopathy that required shunt reduction. After TIPS placement, the portosystemic pressure gradient dropped from 18 +/- 5 to 5 +/- 4 mm Hg. Primary and secondary patency rates were 80% and 100%, respectively, at 387 days.

CONCLUSION

These results clearly show the feasibility of TIPS placement with the Gore TIPS endoprosthesis stent-graft and its improved patency compared with results in the literature for bare stents. These preliminary results must be certified further with randomized comparative trials between covered and noncovered TIPS stents.

Transjugular intrahepatic portosystemic shunt with an autologous vein-covered stent: results in a swine model

PURPOSE

To investigate the feasibility, safety, and efficacy of an autologous vein-covered stent (AVCS) to prevent shunt stenosis in a porcine transjugular intrahepatic portosystemic shunt (TIPS) model.

MATERIALS AND METHODS

TIPS were created with an AVCS in 12 healthy domestic swine and with a bare stent in 10 additional swine. Tissue response was compared with use of venography, histology, and computerized morphometry analysis 2 weeks after implantation. Differences between AVCS and noncovered stents (established by a t-test), as well as regional differences within a single stent (established by an f test), were considered significant at P <.05.

RESULTS

Twenty of 22 TIPS procedures were technically successful. Ten of 12 shunts with an AVCS (83%) and two of 10 with bare stents (20%) remained patent (<50% diameter narrowing) at euthanasia 2 weeks later (P <.01). Histologic evaluation of harvested bare stents showed marked intimal hyperplasia (IH), composed of smooth muscle cells, myofibroblasts, and fibroblasts. In contrast, the AVCS were remarkably free of IH and thromboses. In patent TIPS in both groups, endothelial coverage of the luminal surface was present histologically. IH accounted for 57% (26.27/45.79) of total stent cross-sectional lumen area in the control group and 21% (8.34/39.54) in the AVCS group (P <.01), with no intrashunt differences (P >.05).

CONCLUSION

Based on short-term follow-up, AVCS significantly improved TIPS patency by prevention of both IH and in-stent thrombosis. TIPS created with an AVCS was feasible and safe in our porcine model.

Creation of transjugular intrahepatic portosystemic shunts with stent-grafts: initial experiences with a polytetrafluoroethylene-covered nitinol endoprosthesis

PURPOSE

To evaluate the safety and performance of a recently developed expanded polytetrafluoroethylene (ePTFE)-covered nitinol stent-graft to create transjugular intrahepatic portosystemic shunt (TIPS) in patients with portal hypertension and related complications.

MATERIALS AND METHODS

The ePTFE-covered nitinol stent-graft was used to create TIPS in 16 patients with recurrent variceal bleeding (n = 13) or refractory ascites (n = 3). Follow-up was performed with duplex ultrasonography, clinical assessment, and venography at 6 months. Technical success and portosystemic pressure gradients (PPGs) before and after stent-graft implantation and at follow-up were assessed. Two patients died during follow-up. Histopathologic follow-up data were available for one patient at autopsy and for the other after liver transplantation.

RESULTS

The implantation technical success rate was 100%. Mean (+/- SD) PPG was reduced from 24 mm Hg +/- 5 to 9 mm Hg +/- 2. Histopathologic analysis of the explanted endoprostheses revealed no inflammatory response or neointima formation. The venographic follow-up data available for 10 patients demonstrated 100% in-graft patency (mean follow-up, 289 days +/- 26). Revisions with implantation of a new ePTFE-covered nitinol stent-graft or another commercially available stent in 10 patients were necessary because of hepatic vein stenosis above the grafted portion and/or relative diameter mismatch causing TIPS dysfunction.

CONCLUSION

The ePTFE-covered nitinol stent-graft was used successfully to create TIPS and has the potential to prolong TIPS patency upon complete coverage to the hepatocaval junction.

Improved patency of transjugular intrahepatic portosystemic shunts in humans: creation and revision with PTFE stent-grafts

PURPOSE

To determine whether polytetrafluoroethylene (PTFE) stent-grafts yield longer patency for creation or revision of transjugular intrahepatic portosystemic shunts (TIPS).

MATERIALS AND METHODS

Fourteen PTFE-covered Wallstents were placed in 13 patients with TIPS: seven at shunt creation and seven during revision of TIPS with one to five prior thromboses at 1 day to 1 year after initial TIPS formation. In six cases, prior to stent-graft placement persistent biliary-TIPS fistulas were demonstrated despite repeated shunt revisions with additional metallic stents.

RESULTS

All but one graft-lined TIPS were widely patent at a mean duration of venographic follow-up of 19 months (median, 17 months; range, 5-32 months). The limiting percentage of stenosis within the grafted shunts was 0%-10%. One patient developed stent-graft thrombosis; the prior biliary-TIPS fistula was seen despite the graft. A second, parallel PTFE-lined transcaval shunt was created in this patient; it was widely patent at 11-month follow-up. In two asymptomatic patients, stenoses developed in the short, nongrafted portions of the outflow hepatic veins.

CONCLUSION

PTFE stent-grafts can markedly prolong TIPS patency, potentially reducing the need for shunt follow-up and revision and the risk of recurrent symptoms associated with shunt stenosis or occlusion.

Porous and nonporous polycarbonate urethane stent-grafts for TIPS formation: biologic responses

PURPOSE

To evaluate the biologic response to transjugular intrahepatic portosystemic shunts (TIPS) lined with polycarbonate urethane endografts and the effects of different porosity formulations.

MATERIALS AND METHODS

Seventeen TIPS were created in non-modified portal hypertensive miniswine with use of porous (n = 6), nonporous (n = 7) polycarbonate urethane stent-grafts, and control Wallstents TIPS (n = 4). Eight-week venography, histology, scanning electron microscopy, and immunohistochemical analyses were performed.

RESULTS

The mean 8-week percent parenchymal tract shunt stenosis was 75%, 46%, and 26% in the control, porous, and nonporous groups, respectively. Occlusions developed in one control, one porous, and two nonporous shunts. The biologic response to porous grafts included marked inflammation and encapsulation and permeation of the grafts by a thick fibrous pseudointima. Nonporous grafts evoked little inflammation or pseudointima. Mature thrombus lined the occluded shunts (under which little luminal pseudointima or endothelium was present). The control group showed typical pseudointimal hyperplasia enveloping the intraparenchymal portions of the stents.

CONCLUSIONS

The healing response of the porous and nonporous grafts markedly differed. Unlike the porous grafts and control stents, the nonporous endografts elicited little inflammation or luminal pseudointimal hyperplasia, although sporadic thrombosis was problematic in this normotensive model. Graft use in high-flow situations (ie, human TIPS, possibly in concert with antiplatelet agents) may allow desired shunt patency prolongation.