Primary implantation of polyester-covered stent-grafts for transjugular intrahepatic portosystemic stent shunts (TIPSS): A pilot study

Biological behavior exploration of a paclitaxel-eluting poly-l-lactide-coated Mg–Zn–Y–Nd alloy intestinal stent in vivo

As a new type of intestinal stent, the MAO/PLLA/paclitaxel/Mg–Zn–Y–Nd alloy stent has shown good degradability, although its biocompatibility in vitro and in vivo has not been investigated in detail. In this study, its in vivo biocompatibility was evaluated by animal study. New Zealand white rabbits were implanted with degradable intestinal Mg–Zn–Y–Nd alloy stents that were exposed to different treatments. Stent degradation behavior was observed both macroscopically and using a scanning electron microscope (SEM). Energy dispersion spectrum (EDS) and histological observations were performed to investigate stent biological safety. Macroscopic analysis showed that the MAO/PLLA/paclitaxel/Mg–Zn–Y–Nd stents could not be located 12 days after implantation. SEM observations showed that corrosion degree of the MAO/PLLA/paclitaxel/Mg–Zn–Y–Nd stents implanted in rabbits was significantly lower than that in the PLLA/Mg–Zn–Y–Nd stent group. Both histopathological testing and serological analysis of in vivo biocompatibility demonstrated that the MAO/PLLA/paclitaxel/Mg–Zn–Y–Nd alloy stents could significantly inhibit intestinal tissue proliferation compared to the PLLA/Mg–Zn–Y–Nd alloy stents, thus providing the basis for designing excellent biodegradable drug stents.

Mg–Zn–Y–Nd alloy stents coated with MAO/PLLA/paclitaxel coating were implanted into the New Zealand rabbits intestine to investigate the biocompatibility and degradation behavior.

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.

Transjugular intrahepatic portosystemic shunt with an autologous endothelial progenitor cell seeded stent: a porcine model

RATIONALE AND OBJECTIVES

To evaluate the efficacy of a self-expanding metal stent seeded with autologous endothelial progenitor cells (EPCs) for preventing in-stent stenoses in transjugular intrahepatic portosystemic shunt (TIPS) in a swine model.

MATERIALS AND METHODS

TIPS was performed in 18 young adult pigs, using a self-expanding nitinol stent (control, n = 8) and an autologous EPC-seeded stent (treatment, n = 10). All pigs were sacrificed at 2 weeks post-TIPS procedure. Portography was performed immediately before the euthanasia. Gross, microscopic, and immunohistochemistry of the TIPS tract specimens were examined. The proliferative response of the shunt was quantified histologically.

RESULTS

TIPS was performed successfully in 16 swine, 2 animals died during the procedure. Another pig died of unknown causes 2 days post-procedure. At day 14 follow-up, portography and necropsy of the 15 remaining swine demonstrated that five shunts occluded and one shunt was stenotic (80%) in the control group (n = 6). Five shunts remained patent, two shunts were stenosed (50%, 70%), and the remaining two shunts were occluded in the treatment group (n = 9). The patency rate was significantly lower in the control group than in the treatment group, 0% versus 55.6% (P = .03). Histological analyses showed a significantly greater pseudointimal hyperplasia in the TIPS track of the control group than that of the treatment group (P < .05). Intact endothelium was documented in the lumina of all the EPC-implanted stent group.

CONCLUSIONS

The EPC-seeded metal stent is feasibly fabricated in vitro and improves the patency in TIPS in a porcine model.

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.

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.

Acute Effects of Liver Vein Occlusion by Stent-Graft Placed in Transjugular Intrahepatic Portosystemic Shunt Channel: An Experimental Study

The purpose of this study was to evaluate the effects of hepatic vein occlusion by stent-graft used in transjugular intrahepatic portosystemic shunt (TIPS). The experiments were performed in six healthy pigs under general anesthesia. Following percutaneous transhepatic implantation of a port-a-cath in the right hepatic vein, TIPS was created with a stent-graft (Viatorr; W L Gore, Flagstaff, AZ, USA). The outflow from the hepatic vein, blocked by the stent-graft was documented by injection of contrast medium and repeated injections of (99)Tc(m)-labeled human serum albumin through the port-a-cath. After 2 weeks, the outflow was re-evaluated, the pigs were sacrificed, and histopathologic examination of the liver was performed. Occlusion of the hepatic vein by a stent-graft had a short and temporary effect on the outflow. Histopathological examination from the affected liver segment showed no divergent pattern. Stent-grafts used in TIPS block the outflow from the liver vein, but do not have a prolonged circulatory effect and do not affect the liver parenchyma.

Transjugular intrahepatic portosystemic shunt in refractory ascites: a meta-analysis

Transjugular intrahepatic portosystemic shunt (TIPS) is a more effective treatment for refractory ascites than large volume paracentesis (LVP), but the magnitude of its effect in terms of control of ascites, encephalopathy and survival has not been established.

AIM

This meta-analysis compare TIPS to LVP in terms of control of ascites at 4 and 12 months, encephalopathy and survival at 1 and 2 years.

RESULTS

Five randomized controlled trials involving 330 patients were included. In the TIPS group, control of ascites was more frequently achieved at 4 months (66% vs 23.8%, mean difference: 41.4%, 95% confidence interval (CI): 29.5-53.2%, P < 0.001) and 12 months (54.8% vs 18.9%, mean difference: 35%, 95% CI: 24.9-45.1%, P < 0.001), whereas encephalopathy was higher (54.9% vs 38.1%, mean difference: 17%, 95% CI: 7.3-26.6%, P < 0.001). Survival at 1 year (61.7% vs 56.5%, mean difference: 3.2%, 95% CI: -14.7 to 21.9%) and 2 years (50% vs 42.8%, mean difference: 6.8%, 95% CI: -10 to 23.6%) were not significantly different.

CONCLUSIONS

TIPS is a more effective treatment for refractory ascites than LVP. However, TIPS increase encephalopathy and does not improve survival.

[Increased long-term permeability of transjugular intrahepatic portosystemic shunt (TIPS) in 218 cirrhotic patients, with strict monitoring]

OBJECTIVE

To measure the impact of strict monitoring on long term permeability of TIPS.

METHODS

From November 1991 to December 2002, 208 patients (152 men and 66 women managed for the placing of a TIPS following failure with sclerotherapy or refractory ascites were included. The permeability of the prosthesis was controlled on the surgical piece. Revision of the TIPS was performed at the same time as the diagnosis of obstruction using trans-jugular angiography. The TIPS permeability was classified into 3 categories: primary permeability (duration of permeability recorded up until any intervention); assisted primary permeability (duration of continuous permeability with or without percutaneous intervention); secondary permeability (total duration of permeability with or without treated occlusion).

RESULTS

Among the 218 patients in the study, 108 had been monitored for less than one year (49.5%), 29 for between 1 and 2 years (13.5%), 27 between 2 and 3 years (12.5%), 16 between 3 and 4 years (7.5%), 15 between 4 and 5 years (7%) and 23 for more than 5 years (10%). The mean follow-up period was of 24.1 +/- 27.2 months (median: 13.7). Current survival of these patients was of 81.2 +/- 2.9% at 1 year, 62.9 +/- 4.2% at 3 years and 52 +/- 4.9% at 5 years. Thirty-four patients were lost to follow-up (16%), after a mean follow-up of 22.9 +/- 26.7 months (median: 9.7). All these patients exhibited a permeable TIPS during their last control. One hundred and thirty-five patients (62%) had never presented obstruction of the TIPS, with a mean follow-up of 19.5 +/- 26.2 months (median: 7.4); 83 patients (38%) exhibited 117 episodes of obstruction; 24 two episodes, 7 three and 3 more than three; 4 exhibited thrombosis provoked by an invalidating encephalopathy and contraindicating transplantation, 2 of them following a first episode of thrombosis. The current primary, primary assisted and secondary permeability rates were respectively: 67.7 +/- 3 and 514 +/- 3.7%, 79.9 +/- 2.3% and 69.3 +/- 3.4%, 94.4 +/- 1.8% and 91 +/- 2.6% at 1 and 3 years (p = 0.0001, Log Rank = 65.3). Univariate analysis revealed a relationship between the onset of an episode of early or late obstruction and the patients' age at the time the TIPS was inserted, Child's score before, and the pre- and post-surgical gradient. In multivariate analysis, none of these elements reached significance.

CONCLUSION

Although the use of TIPS in the treatment of portal hypertension follows the course of development of all surgery towards minimally invasive methods, it should not be considered as a surgical portal shunt or as a permanent treatment: long-term permeability is only obtained with strict and regular monitoring and the possibility of rapid intervention in the case of obstruction.

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.

Reversal of transjugular intrahepatic portosystemic shunt (TIPS)-induced hepatic encephalopathy using a strictured self-expanding covered stent

Hepatic encephalopathy is a known complication following percutaneous transjugular intrahepatic portosystemic shunt (TIPS) placement. We describe herein a simple and effective strategy of TIPS revision by creating an intraluminal stricture within a self-expanding covered stent, which is deployed in the portosystemic shunt to reduce the TIPS blood flow. This technique was successful in reversing a TIPS-induced hepatic encephalopathy in our patient.

Survival in patients undergoing transjugular intrahepatic portosystemic shunt: ePTFE-covered stentgrafts versus bare stents

In patients with liver cirrhosis, implantation of a transjugular intrahepatic shunt (TIPS) leads to reduction of portal pressure, but not of mortality compared with other therapies. The high stenosis rates of conventional bare stents causes high reintervention rates and costs and may be correlated with poor survival. ePTFE-covered stentgrafts provide much improved patency rates, but their impact on survival is unclear. All suitable patients receiving either bare TIPS (419/466) or undergoing implantation of ePTFE endoprostheses (89/100) in several centers in Austria up to 2002 were included in this retrospective analysis. Both patient groups were compared regarding survival with Kaplan-Meier and Cox regression analysis. Unmatched and 1:1-matched survival analyses were performed. Patients undergoing ePTFE stentgraft implantation had significantly higher survival rates in all analyses. The 3-month, 1-year, and 2-year survival rates were 93%, 88%, and 76% for the ePTFE-group and 83%, 73%, and 62% for conventional TIPS patients, respectively. The matched survival analyses validated these findings. The model of the stent, patient age, and Child-Pugh Class (CPC) were independent predictors of survival. In conclusion, patients undergoing ePTFE-endoprosthesis implantation had higher survival rates within 2 years after TIPS-implantation. This may be the result of improved patency rates after correct placement (up to the inferior caval vein [ICV]) of the ePTFE stentgraft. These data should be validated in a prospective series.

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.

Creation of a transrenal arteriovenous dialysis shunt: feasibility study in a swine model

PURPOSE

To investigate the feasibility of percutaneous renal artery and vein access for the creation of a transrenal arteriovenous hemodialysis graft.

MATERIALS AND METHODS

Renal-artery-to-ipsilateral-renal-vein conduits were constructed with use of entirely percutaneous techniques in seven swine. Renal artery and vein access was performed in six animals with use of a retrograde (inside-out) technique and in one animal with use of an antegrade (outside-in) technique. Modified 8-F sheaths were used in the first three animals and Wallgrafts were used in the final four animals to form the arterial and venous limbs of each shunt. The arterial and venous limbs were joined together by a subcutaneous segment of 6-mm reinforced polytetrafluoroethylene (PTFE) in five animals and by external conduits in two animals. Wallgrafts were deployed from the renal artery and vein into the segments of PTFE. The free ends of each conduit were tunneled and joined together to close the arteriovenous circuit. Post-shunt angiography was used in all animals to document successful shunt creation and demonstrate rapid arteriovenous shunting as a determinant of technical feasibility. Two of the seven animals received additional anticoagulation therapy and/or antiplatelet therapy to prevent shunt thrombosis during the follow-up period. The three initial animals were killed within 2 hours of shunt creation, and two of the remaining four animals returned for angiographic follow-up, one on day 2 and one on day 9. All animals underwent a complete necropsy to assess for potential complications including hemorrhage and vascular or bowel injury.

RESULTS

Retrograde renal arterial and venous access was successful in all six animals in which it was attempted. Five of six arterial accesses and four of six venous accesses traversed the peritoneum with two arterial accesses and one venous access penetrating a loop of large bowel. Antegrade access was performed and successfully accomplished in the final animal. Brisk arteriovenous shunting was demonstrated on completion angiography in all animals. Graft occlusion was present in the two animals that returned for follow-up and two animals died before follow-up as a result of graft leakage and subsequent hemorrhage. Minimal perinephric and intrarenal hemorrhage was demonstrated at necropsy after shunt insertion in the remaining five animals. Renal infarction was present in all kidneys used for transrenal access.

CONCLUSION

The transrenal approach for the creation of a percutaneous arteriovenous shunt is feasible after renal artery and vein access by either the retrograde or antegrade technique. Additional technical refinements of the procedure and the devices used will be necessary before follow-up studies are conducted.

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.

A new stent-graft for transjugular intrahepatic portosystemic shunts

The transjugular intrahepatic portosystemic shunt (TIPSS) has become an effective method of treatment for the complications of portal hypertension, however shunt dysfunction is common. Covered stent-grafts have been tested in animal models, and customized or "home-made" devices have been deployed in several institutions. We report the use of a new commercially available TIPSS stent-graft in six patients undergoing primary shunting as well as two cases of revision or secondary TIPSS. The device has proved relatively easy to handle and appears to have the technical features likely to improve primary patency. Further follow-up is required to properly assess shunt patency and re-intervention rates.