Truly Hybrid Interventional MR/X-Ray System: Investigation of in Vivo Applications

RATIONALE AND OBJECTIVES: The purpose of this study was to provide in vivo demonstrations of the functionality of a truly hybrid interventional x-ray/magnetic resonance (MR) system. MATERIALS AND METHODS: A digital flat-panel x-ray system (1,024(2) array of 200 microm pixels, 30 frames per second) was integrated into an interventional 0.5-T magnet. The hybrid system is capable of MR and x-ray imaging of the same field of view without patient movement. Two intravascular procedures were performed in a 22-kg porcine model: placement of a transjugular intrahepatic portosystemic shunt (TIPS) (x-ray-guided catheterization of the hepatic vein, MR fluoroscopy-guided portal puncture, and x-ray-guided stent placement) and mock chemoembolization (x-ray-guided subselective catheterization of a renal artery branch and MR evaluation of perfused volume). RESULTS: The resolution and frame rate of the x-ray fluoroscopy images were sufficient to visualize and place devices, including nitinol guidewires (0.016-0.035-inch diameter) and stents and a 2.3-F catheter. Fifth-order branches of the renal artery could be seen. The quality of both real-time (3.5 frames per second) and standard MR images was not affected by the x-ray system. During MR-guided TIPS placement, the trocar and the portal vein could be easily visualized, allowing successful puncture from hepatic to portal vein. CONCLUSION: Switching back and forth between x-ray and MR imaging modalities without requiring movement of the patient was demonstrated. The integrated nature of the system could be especially beneficial when x-ray and MR image guidance are used iteratively.     

Intravascular Ultrasound Guidance for Transjugular Intrahepatic Portosystemic Shunt Procedure in a Swine Model

A new method is described for guiding hepato-portal venous puncture using a longitudinal side-view intravascular ultrasound (L-IVUS) transducer to assist in the performance of transjugular intrahepatic portosystemic shunt (TIPS) in three Australian swine. Simultaneous L-IVUS with an AcuNav® 5–10 MHz 10 Fr transducer (Acuson Corporation, Mountain View, CA, USA) and fluoroscopy guidance was used to image and monitor the hepatic to portal venous puncture, dilatation of the tract, and deployment of the TIPS stent. Flow through the shunt could be demonstrated with both L-IVUS and angiography. TIPS was successful in all swine. The time for portal vein puncture once the target portal vein was identified was reduced at each attempt. The number of portal vein puncture attempts was 2, 1, and 1. No post-procedural complication was evident. L-IVUS-guided TIPS is practical and has the potential to improve safety by permitting simultaneous ultrasound and fluoroscopic imaging of the needle and target vascular structures. This technique allows for a more streamlined approach to TIPS, decreasing the fluoroscopic time (hence, decreasing the radiation exposure to the staff and patient) and anesthetic time. In addition, there are improved safety benefits obviating the need for wedged portography, facilitating avoidance of bile duct and hepatic arterial puncture, and minimizing hepatic injury by decreasing liver capsular puncture and the attendant risks.     

Evaluation of MR/fluoroscopy-guided portosystemic shunt creation in a swine model

PURPOSE: To evaluate three different percutaneous portosystemic shunts created with magnetic resonance (MR) imaging and fluoroscopy guidance in a swine model. MATERIALS AND METHODS: In stage 1 of the experiment, an active MR intravascular needle system was created for needle tracking and extracaval punctures. Twenty inferior vena cava (IVC)/superior mesenteric vein (SMV)/portal vein (PV) punctures were performed in 10 swine (weight, 40-45 kg) in a 1.5-T short-bore interventional MR imager. With use of a real-time MR imaging sequence, the needle was guided through the IVC and into the SMV or PV (N = 20 punctures). After confirmation, a wire was advanced into the portal venous system under MR imaging guidance (N = 20). In stage 2, animals were transferred to the radiographic fluoroscopy suite for deployment of shunts. Three different shunts were evaluated in this study: (i) a commercial stent-graft, (ii) a prototype bridging stent, and (iii) a prototype nitinol vascular anastomotic device. Postprocedural necropsy was performed in all animals. RESULTS: Successful MR-guided IVC/SMV punctures were performed in all 20 procedures (100%). All three shunts were deployed. Stent-grafts had the poorest mechanism for securing a shunt. The vascular anastomotic device and the bridging stent had more secure anchoring mechanisms but also had higher technical failure rates (50% and 40%, respectively). When deployed successfully, the vascular anastomotic device resulted in no bleeding at the sites of punctures at necropsy. CONCLUSION: Percutaneous shunts and vascular anastomoses between the portal mesenteric venous system and IVC were successfully created with use of a combination of MR imaging and conventional fluoroscopy for guidance.     

Intraluminal irradiation for TIPS stenosis: preliminary results in a swine model.

PURPOSE: To evaluate the ability of 32phosphorus intraluminal irradiation to reduce pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt (TIPS). MATERIALS AND METHODS: TIPS were successfully placed in 11 swine with normal portal pressures. Six animals received 15.2 Gy intraluminal irradiation to the hepatic parenchyma and venous outflow tract at the time of TIPS placement with use of a NA32P-filled balloon angioplasty catheter. Five control animals underwent TIPS and balloon angioplasty with saline. All animals were followed up for 28 days, at which time percutaneous portography was performed, the animals were killed, and the tissue around the TIPS stent was processed for histologic analysis. Maximum pseudointimal hyperplasia as a percentage of estimated TIPS diameter was calculated for each animal. RESULTS: At the time of euthanasia, all five control TIPS and all but one irradiated TIPS were occluded. Histologic analysis demonstrated considerable variability in the degree of pseudointimal hyperplasia within each TIPS and between animals. No statistically significant difference was found in the maximum pseudointimal hyperplasia, measured as a percentage of stent radius, between control (80.2%+/-17.4%) and irradiated animals (69.2%+/-25.2%). CONCLUSIONS: Irradiation of TIPS with 15.2 Gy 32P delivered at the time of TIPS placement did not significantly improve TIPS patency or reduce the degree of pseudointimal hyperplasia in swine with normal portal pressures.     

Pull-Through Technique for Recanalization of Occluded Portosystemic Shunts (TIPS): Technical Note and Review of the Literature

Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction is an important problem after creation of shunts. Most commonly, TIPS recanalization is performed via the jugular vein approach. Occasionally it is difficult to cross the occlusion. We describe a hybrid technique for TIPS revision via a direct transhepatic access combined with a transjugular approach. In two cases, bare metal stents or polytetrafluoroethylene (PTFE)-covered stent grafts had been placed in TIPS tract previously, and they were completely obstructed. The tracts were inaccessible via the jugular vein route alone. In each case, after fluoroscopy or computed tomography-guided transhepatic puncture of the stented segment of the TIPS, a wire was threaded through the shunt and snared into the right jugular vein. The TIPS was revised by balloon angioplasty and additional in-stent placement of PTFE-covered stent grafts. The patients were discharged without any complications. Doppler sonography 6 weeks after TIPS revision confirmed patency in the TIPS tract and the disappearance of ascites. We conclude that this technique is feasible and useful, even in patients with previous PTFE-covered stent graft placement.     

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.     

经颈静脉肝内门体分流术穿刺点的研究

为明确ＴＩＰＳＳ的最佳穿刺点，本文对正常肝脏和肝硬变患者各５０例的肝脏的ＭＲＩ或ＣＴ增强扫描图像进行了研究，并依此建立了空间直角坐标系。在该坐标系中，测量了肝静脉及肝内门静脉各主支的管径，计算了穿刺点间距离及穿刺角度，提出了最佳穿刺点，并初步用于临床。本方法和结果对指导ＴＩＰＳ操作有重要意义。     

Three-dimensional C-arm CT-guided transjugular intrahepatic portosystemic shunt placement: Feasibility,technical success and procedural time

Objectives

Establishment of transjugular intrahepatic portosystemic shunts (TIPS) constitutes a standard procedure in patients suffering from portal hypertension. The most difficult step in TIPS placement is blind puncture of the portal vein. This study aimed to evaluate three-dimensional mapping of portal vein branches and targeted puncture of the portal vein.

Methods

Twelve consecutive patients suffering from refractory ascites by liver cirrhosis were included in this retrospective study to evaluate feasibility, technical success and procedural time of C-arm CT-targeted puncture of the portal vein. As a control, 22 patients receiving TIPS placement with fluoroscopy-guided blind puncture were included to compare procedural time.

Results

Technical success could be obtained in 100 % of the study group (targeted puncture) and in 95.5 % of the control group (blind puncture). Appropriate, three-dimensional C-arm CT-guided mapping of the portal vein branches could be achieved in all patients. The median number of punctures in the C-arm CT-guided study group was 2?±?1.3 punctures. Procedural time was significantly lower in the study group (14.8?±?8.2 min) compared to the control group (32.6?±?22.7 min) (p?=?0.02).

Conclusions

C-arm CT-guided portal vein mapping is technically feasible and a promising tool for TIPS placement resulting in a significant reduction of procedural time.

Key Points

? C-arm CT-mapping of the portal vein for 3D TIPS guidance is feasible. ? Targeted punctures of the portal vein by C-arm CT reduce procedural time. ? A decreased number of punctures could improve patient safety.

     

Transjugular Intrahepatic Portosystemic Shunt Creation Using a Radiofrequency Wire: Acute Feasibility Study in Swine

The feasibility of a radiofrequency (RF) wire to replace the needle trocar for the creation of a transjugular intrahepatic portosystemic shunt (TIPS) was assessed in 3 swine by using fluoroscopy and intravascular ultrasonography (IVUS). RF wire passes were successful from hepatic to portal vein and from inferior vena cava to portal vein. Technical success was achieved using both IVUS guidance and carbon dioxide portography. The wire tracked a straight course under RF energy application without subjective deflection and, when centrally advanced, served as the working wire for completing the TIPS in 2 attempts with stent graft deployment. No procedural adverse events from the use of RF wire were observed.     

A new coaxial needle system,hepatic artery targeting wire,and biplane fluoroscopy to increase safety and efficacy of TIPS

To improve safety and efficacy of the transjugular intrahepatic portosystemic shunt (TIPS) procedure, we introduced a new, thin-needle (21-gauge long PTC needle) puncture technique using biplane fluoroscopy and targeting of a guidewire tip in the right hepatic artery. After puncture of the right portal vein, a 0.016-inch guidewire was inserted into the portal vein, followed by a 4 Fr dilator. The 4 Fr dilator allowed introduction of a 0.035-inch working guidewire. We successfully performed TIPS in seven patients with postnecrotic cirrhosis using this technique and encountered no technical difficulties or complications.     

经颈静脉肝内门体静脉内支架分流术术式改良的实验研究

目的：探讨建立改良式猪经颈静脉肝内门体静脉内支架分流术（TIPSS）模型的可行性及其意义。方法：11只家猪分成2组，7只采用改良术式（经肝段下腔静脉穿刺门脉）建立TIPSS模型，另4只行常规TIPSS作对照。共置入4枚进口覆膜镍钛合金支架，8枚国产覆聚氨酯膜支架。其中，改良组7只猪置入7枚支架（4枚进口支架，3枚国产支架）；对照组4只猪置入5枚国产覆膜支架（1只猪置入时支架发生移位，故加用1枚支架）。术后4周（5只），8周（2只）和12周（4只）进行门脉造影观察分流道通畅情况。动物处死后，行分流道大体和组织病理学检查。结果：术后4周，改良组2只分流道通畅（进口支架、国产支架各1枚），分流道表面均形成完整的假性内膜组织；另5只分流道在4至12周均闭塞，分流道内形成血栓，其中2只内支架伸入下腔静脉内不全，陷入肝实质内。常规组4只分流道在4、8和12周观察期内均闭塞。两组间分流道肝（下腔）静脉端，肝实质段和门静脉端各段的增生组织厚度对比差异均无显著性意义（t值分别为0．14、0．16和0．20，P值均＞0．05）。结论：改良式猪TIPSS模型的建立是安全和可行的。改良式TIPSS中应采用覆膜支架，并应有足够长度伸入至两端静脉内，有助于防止增生组织向分流道内长入。     

Influence of blood-pool contrast media on MR imaging and flow measurements in the presence of pulmonary arterial stents in swine

PURPOSE: To compare the effects of various stents on magnetic resonance (MR) imaging flow volume measurements and to determine the value of a blood-pool MR imaging contrast medium in assessment of vascular stents. MATERIALS AND METHODS: In 11 pigs, six nitinol stents (Memotherm), four platinum stents (NuMed), and one elgiloy stent (Wallstent) were placed in the main pulmonary artery under x-ray fluoroscopic guidance. MR imaging was performed 3 months after stent placement before and after injection of NC100150 contrast medium. Blood flow volumes were assessed with velocity-encoded cine MR imaging through and next to the stent. The signal-to-noise ratio and width of susceptibility artifacts of the stents also were determined. Measurements were analyzed with the paired Student t test and Bland-Altman test, where appropriate. RESULTS: Blood flow volumes measured through the nitinol and platinum stents disclosed no significant difference between velocity-encoded cine MR imaging measurements through and next to the stent. On cine MR images, small susceptibility artifacts were observed around the nitinol and platinum stents. Signal-to-noise ratio in the stent lumen was reduced in nitinol and platinum stents when compared with that next to the stent. The elgiloy stent produced severe susceptibility artifacts, making measurement of flow volumes impossible. NC100150 injection caused no significant effect on flow volume measurements. It improved the signal-to-noise ratio of the pulmonary arterial lumen outside and, to a lesser extent, inside the stent. CONCLUSION: Assessment of morphology and flow volumes through nitinol and platinum stents is feasible with MR imaging. Blood-pool contrast media provide persistent signal enhancement in the pulmonary artery and, to a lesser extent, in the lumina of nitinol and platinum stents.     

MR-guided percutaneous drainage of abdominal fluid collections in combination with X-ray fluoroscopy: initial clinical experience

The aim of this study was to examine the feasibility of a hybrid interventional MR system, which combines a closed bore magnet with a C-arm fluoroscopy unit for percutaneous drainage of abdominal fluid collections. During the past 2 years, we have performed four drainage procedures in four patients (mean age 47 years). Three patients had abscesses (psoas muscle, kidney, subphrenic location) and the fourth patient had a recurrent splenic cyst. All procedures were performed on an interventional MR system consisting of a 1.5-T ACS-NT scanner combined with a specially shielded C-arm. The drainages were guided by T1-weighted fast gradient-echo images, T2-weighted single-shot turbo spin-echo images or both. A standard 18 G (1.2 mm) nonferromagnetic stainless steel needle with a Teflon sheath was used for the punctures following which a 0.89 mm nitinol guidewire was inserted into the fluid collection. Thereafter, the patient was positioned in the immediate adjacent fluoroscopy unit and a drainage catheter was placed under fluoroscopic control. All drainage catheters were successfully placed into the fluid collections, as proven by fluid aspiration and resolution of the collection. The mean time needed for the entire drainage procedure (MR and fluoroscopy) was 110 min. No procedure-related complications occurred. It is feasible to perform drainage procedures on a closed-bore MR scanner. The multiplanar imaging capabilities of MR are particularly helpful for fluid collections in the subphrenic location. Received: 3 April 2000 Revised: 30 August 2000 Accepted: 31 August 2000     

Transjugular intrahepatic portosystemic shunting (TIPS) with balloon-expandable and self-expanding stents: Technical and clinical aspects after 3 1/2 years’ experience

Purpose To evaluate prospectively our experience with transjugular intrahepatic portosystemic shunt (TIPS) using four different metallic stents. Methods Between November 1991 and April 1995, 57 patients (41 men and 16 women; age 35–72 years, mean 54 years) underwent the TIPS procedure. Techniques for portal vein localization before and during TIPS were fluoroscopy, computed tomography (CT) studies, wedged hepatic venography, arterial portography, and ultrasound. After predilation we deployed balloon-expandable (n=48) and self-expanding (n=45) metallic stents. Fifteen patients underwent variceal embolization. Initial follow-up angiograms (mean 6.9 months, range 3–24 months) were obtained in 39 of these patients. Results Fifty-three patients (93%) had successful TIPS placement. The mean decrease in portal pressure was 42.7%. Besides fluoroscopy, the most helpful techniques for portal vein localization were venography and CT. Residual stenosis (n=1) and late shortening (n=4) of Wallstents resulted in shunt dysfunction. The technical problems encountered with the Palmaz stent resulted from its lack of flexibility. We combined balloon-expandable and self-expanding stents in 12 patients. The 30-day and late follow-up (mean 11.9 months) percutaneous reintervention rates were 11.3% and 64.2%, respectively. There were no clinically significant complications related to the TIPS insertions. Conclusion An ideal stent does not exist for TIPS, and the authors recommend combining a Palmaz stent with a flexible self-expanding stent.     

Percutaneous CT-guided superior mesenteric vein access for portal vein recanalization-transjugular intrahepatic portosystemic shunt

Portal vein recanalization-transjugular intrahepatic portosystemic shunt (PVR-TIPS) is a valuable technique in the treatment cirrhosis and portal vein (PV) thrombosis. Only a few studies have reported cases of utilizing the transmesenteric approach in the procedure''s initial portal access. Here, we report the successful utilization of a CT-guided percutaneous puncture of the superior mesenteric vein (SMV) for PVR-TIPS in a patient with splenic vein thrombosis. A 54-year-old male with a history of morbid obesity (BMI: 44.67), hepatitis C, NASH cirrhosis, esophageal varices, and complete PV thrombosis presented for PVR-TIPS. An initial percutaneous transplenic approach was attempted, but was aborted due to the discovery of a splenic vein thrombosis. Subsequently, the patient was brought back into the hybrid-angio CT suite, and the SMV was accessed percutaneously with a 21-gauge needle under 4D CT-guidance. A 5-Fr micropuncture sheath was then placed. Additional portal venogram confirmed PV thrombosis. Right internal jugular vein (IJV) access was then obtained, and the right hepatic vein was catheterized. A loop snare was advanced from the SMV access into the right PV. A Colapinto needle was later positioned in the right hepatic vein, and the right PV was accessed using the loop snare as a target. A wire was then advanced and captured by the snare, and brought down through the PV. The tract was dilated with a 10 mm balloon, and a Viatorr stent was deployed. Balloon embolectomy of the SMV, splenomesenteric vein, and TIPS were then performed with a CODA balloon with improvement in flow through the TIPS on final portal venogram. Portosystemic gradient was 11 mmHg initially and 10 mmHg post-TIPS. Follow-up TIPS venogram in 3 weeks showed a widely patent TIPS. CT-guided percutaneous SMV access may serve as valuable technique in PVR-TIPS when traditional modes of initial portal access for recanalization are unobtainable.     

Endovascular treatment of a portal vein tear during TIPSS

During a transjugular portosystemic stent-shunt (TIPSS) procedure a portal vein laceration occurred with subsequent intraperitoneal hemorrhage. A PTFE-covered nitinol stent was successfully placed eliminating the leak and creating a functioning portosystemic shunt. This case demonstrates both the importance of portal vein puncture more than 1 cm from the bifurcation and the necessity of maintaining a stock of available stent-grafts.     

Experimental TIPS with spiral Z-stents in swine with and without induced portal hypertension

Purpose To assess the suitability of spiral Z-stents for transjugular intrahepatic portosystemic shunt (TIPS) and the influence of portal hypertension on shunt patency in young swine. Methods TIPS were established using spiral Z-stents in 14 domestic swine. In 7 animals, the portal venous pressure was normal; in the other 7, acute portal hypertension was induced by embolization of portal vein branches. Follow-up portal venography and histologic evaluations were done from 1 hr to 12 weeks after TIPS. Results Follow-up transhepatic portal venograms showed progressive narrowing of the shunt, most priminent in the midportion of the tract. Ingrowth of liver parenchyma between the stent wires found after 3 weeks led to progressive shunt narrowing and shunt occlusion by 12 weeks. A pseudointima grew rapidly inside the stent, peaked in thickness around 4 weeks, and decreased later. Acutely created portal hypertension rapidly returned to normal and there was no difference in TIPS patency between the two groups of animals. Conclusion Although the spiral Z-stent can be used as a device for creation of TIPS in patients with cirrhotic livers, it is associated with extensive liver ingrowth in swine that leads to rapid shunt occlusion. Portal hypertension was only transient in this model.     

Transjugular intrahepatic portocaval shunt (TIPS) and hepatic vein-to-caval stenting as salvage treatment of portal hypertension secondary to neoplasm

A percutaneous transjugular intrahepatic portocaval shunt (TIPS) was successfully performed using Wallstents in a 53-year-old man with neoplastic disease causing portal hypertension and life-threatening variceal hemorrhage. Shortly after-wards, recurrent hemorrhage was investigated by shunt venography which showed that extrinsic narrowing of the hepatic vein and hepatic vena cava was causing shunt thrombosis. Shunt thrombosis was cleared by balloon occlusion of the shunt and forceful retrograde flushing of thrombus into the portal circulation. The compressed hepatic vein and vena cava were then dilated and stented using Gianturco “Z” stents. Bleeding recurred 3 months later due to focal narrowing within the shunt which possibly was due to intimal proliferation. Repeat dilatation and placement of a coaxial Palmaz stent again relieved portal hypertension. Creation of a TIPS for portal hypertension secondary to neoplasm can produce valuable palliation. Complete assessment of hepatic vein and vena cava patency is required to ensure shunt function.     

Experimental transjugular portacaval shunt. Use of a fine-needle puncture device for the implantation of Strecker stents.

A transjugular portacaval intrahepatic stented shunt was created in 16 pigs without induced portal hypertension. A fine needle (OD 0.7 mm) was used for the transjugular puncture of the portal vein. The puncture was done directly from the inferior vena cava in 5 cases and from the right liver vein in 11 cases. The puncture tract was dilated and subsequently supported by a Strecker stent. The stented shunt was patent in all cases immediately after the stent placement, but was obstructed by fibrous tissue in 7 of 8 cases reexamined by angiography and autopsy after 4 weeks. Complications seem to be related to the choice of the puncture site, with fewer complications when the puncture was done via the right hepatic vein.     

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.