| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1
Radiology Department, Rangueil Hospital, 1 Ave. Jean Poulhes, 31403 Toulouse,
France.
2
Gastroenterology Department, Purpan Hospital, 1, Pl. du Docteur Baylac, 31403
Toulouse, France.
Received March 26, 2001;
accepted after revision August 2, 2001.
Address correspondence to P. Otal.
Abstract
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
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.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Procedure
The Gore stent-graft (Fig.
1) is made of a two-part electropolished nitinol stent. The portal
side has "chain-link" struts, is noncovered, measures 2 cm in
length, and is constrained and free to deploy when the access sleeve is
removed. The length of the hepatic side depends on the device chosen according
to the careful measurement of the hepatic parenchymal length, measuring from
the ostium of the portal vein wall back to the inferior vena cava. The length
of the hepatic side can vary from 4 to 8 cm. This side is internally covered
with longitudinally sewn, highly porous expandable PTFE that is released by
pulling an internal string attached to the deployment knob, allowing the
hepatic part of the stent-graft to expand freely. In addition, the stent-graft
is externally covered with a bile-resistant expandable-PTFE film to avoid
biliary endoleaks. The beginning of the expandable-PTFE graft material can be
identified by a golden radiopaque marker attached to the graft material.
|
The procedure was performed in a dedicated sterile interventional radiology suite using general anesthesia (Fig. 2A,2B,2C,2D). The right internal jugular vein was punctured, and a 10-French, 30-cm-long sheath (Check-Flo; Cook, Charenton, France) was placed in the suprahepatic portion of the inferior vena cava. After catheterization of the right hepatic vein, a wedged hepatic venogram was obtained to guide portal puncture with a 16-gauge Colapinto needle (Cook). After puncture, a 0.035-inch Radiofocus guidewire (Terumo, Tokyo, Japan) was advanced, guiding a 5-French pigtail catheter into the portal vein. The portosystemic pressure gradient was measured and a portal venogram was obtained to outline the venous anatomy.
|
|
|
|
The intrahepatic parenchymal tract was then dilated with a balloon catheter over a 0.035-inch Amplatz Super Stiff guidewire (Boston Scientific, Watertown, MA). A calibrated 5-French pigtail catheter was used to perform accurate measurement of the length of the parenchymal tract. The device was chosen to cover the entire length of the parenchymal tract and the hepatic vein. When a TIPS revision was done, the old stent was recanalized and used as the new stent-graft tract.
After this standard TIPS procedure, further steps were different for Gore stent-graft placement. The 10-French sheath was exchanged for a 12-French sheath 45 cm long (Cook). The radiopaque tip of the sheath was then placed about 3 cm into the portal vein. The stent-graft delivery system was introduced as far as possible, and the stent-graft was pushed toward the portal vein. When the radiopaque sheath tip was reached, the whole system was positioned so that the golden ring of the stent-graft, which marks the border between the covered and the noncovered parts, corresponded to the portal venous wall. The stent-graft was then held in place, and the sheath was retracted into the parenchymal tract, allowing the noncovered part to deploy inside the portal system lumen. The position of the partially deployed stent-graft was checked using iodinated contrast material injected through the sheath. The stent-graft would eventually have to be slightly pulled to match the golden ring with the portal wall.
When this was done, the sheath was retracted into the hepatic vein, and the hepatic side of the stent-graft was also checked using an injection of contrast material. When proper positioning was confirmed, the sheath was pulled to the inferior vena cava, and the covered part was deployed by pulling the deployment knob. The same balloon used to create the parenchymal tract was then inflated inside the stent-graft to help it achieve a better expansion. No embolization of varices was done. A control venogram with portosystemic pressure gradient measurement (between portal vein and right atrium) was obtained at the end of the procedure, and the puncture site was closed by gentle hand compression.
Follow-Up
Patency was assessed by Doppler sonography at discharge, and then at 1, 3,
6, 9, 12, and 15 months, and by venography with portosystemic pressure
gradient measurement at 6 months and when TIPS dysfunction was suspected
clinically or sonographically (Fig.
3). Stenosis was suspected on Doppler sonography when midshunt
velocities were less than 50 cm/sec. Criteria of restenosis at venography were
a porto-systemic pressure gradient greater than 12 mm Hg and a caliber
reduction of 50% or more (using the stent diameter as a reference). One
patient was monitored by CT angiography because of poor echoic body habitus.
TIPS patency was evaluated by means of Kaplan-Meier survival analysis. Mean
pressure gradients were compared using the paired Student's t test
and Stat View software (SAS Institute, Cary, NC).
|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Procedural Results
A single device was used in 17 patients and two devices in three patients.
The caliber of the TIPS depends on the balloon used to create the parenchymal
tract. In our series, an 8-mm balloon was used in one patient, a 10-mm balloon
in 15 patients, and a 12-mm balloon in four patients. The selection of the
diameter of the balloon depended on the importance of the initial
portosystemic pressure gradient, with the aim of minimizing the risk of
encephalopathy. We placed 14 devices of 10-mm diameter and six of 12 mm
(Table 1). A total of four
devices (three 12 mm and one 10 mm) were placed in a smaller (10 and 8 mm,
respectively) tract, so as to keep a 2-mm-diameter reserve in case of
insufficient shunting caliber. After TIPS placement, portosystemic pressure
gradient dropped from 18 ± 5 to 5 ± 4 mm Hg, achieving a
statistically significant 100% hemodynamic success (reduction of portosystemic
gradient to < 12 mm Hg).
|
Follow-Up Results
After a mean follow-up period of 387 days (range, 272-454 days), two
asymptomatic 50% restenoses were found on follow-up tests. The first
restenosis was located at the junction between the covered and the noncovered
parts of the device and was successfully treated with balloon angioplasty, the
portosystemic gradient dropping from 16 to 9 mm Hg. The second restenosis was
of the outflow hepatic vein and was considered to be not so much an acquired
vein stenosis as a constitutional disparity of caliber between the new
parenchymal tract and the hepatic vein. Therefore, the patient was treated
with a 12-mm Memotherm (Bard, Karlsruhe, Germany) bare stent placement to
achieve complete coverage back to the inferior vena cava, and the
portosystemic gradient decreased from 15 to 6 mm Hg. The TIPS in a third
patient with a return of refractory ascites, who initially had a 10-mm
stent-graft in an 8-mm tract, also required repeated dilatation, first using a
10-mm balloon, then a 12-mm balloon, which resulted in overdilation. Good
results were obtained, with a final portosystemic gradient of 9 mm Hg versus
18 mm Hg before revision. The patient eventually underwent transplantation at
7 months.
Another patient had liver transplantation 7 months after TIPS placement, despite a normal clinical status and TIPS function on control venography. One patient had an episode of bloody stool and was found to have a 50% stenosis of the portal uncovered side of the device, which was dilated twice with no rebleeding afterward. Two patients died of non—device-related reasons, the first one of hepatic failure after hospitalization because of a motor vehicle crash, and the second one of renal failure. One patient experienced worsening encephalopathy 26 days after TIPS creation that required the reduction of the TIPS diameter by placing a 10-mm Gore stent-graft inside the 12-mm original device, anchored in place with a coaxial 12-mm bare stent.
Two cases of segmentary liver ischemia were reported. The first case was reported 24 hr after TIPS placement and involved the right posterior segment, drained by the same hepatic vein as the stent-graft. Sonography showed that a hepatic vein thrombosis above the stent-graft was responsible for this complication (Fig. 4). The second case was reported at 1 week and involved the caudate lobe. No explanation was found for this complication. Both patients responded to mild analgesia with no further clinical complications.
|
Histopathologically, the livers of the two patients with transplants showed patent stent-grafts internally lined with a thin layer of fibrin without evidence of endothelialization. The albumin side was surrounded by myofibroblasts with a collagen matrix that was prevented from gaining the shunt lumen by the expandable-PTFE graft (Fig. 5A,5B).
|
|
The primary patency rate of 80% was found in a mean follow-up time of 387 days. No definitive device failure has occurred, yielding a 100% secondary patency rate. Kaplan-Meier analysis showed a primary patency rate of 86% and a secondary patency rate of 100% (Fig. 6).
|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The major problem with TIPS placement is portal hypertension recurrence, found in 25-50% of patients 6-12 months after TIPS creation, and usually revealed by variceal rebleeding [9,10,11,12]. TIPS dysfunction may result from different causes: first, acute thrombosis, often caused by technical failure (e.g., stent shortening or migration), but sometimes due to a biliary—TIPS fistula; second, parenchymal stenosis resulting from a fibrotic healing response to the trauma of shunt creation; and third, intimal hyperplasia of the hepatic vein occurring between 3 months and 1 year after TIPS placement and mainly caused by chronic injury from increased blood circulation [3, 4, 9, 10, 13, 14]. Histologically, narrowing of the outflow hepatic vein usually indicates intimal hyperplasia, and stenosis in the stent indicates a thickened neointima composed of myofibroblasts and collagen and termed "pseudointimal hyperplasia" [1]. Accumulating evidence favors bile duct injury as a major stimulus of pseudointimal hyperplasia, which can result in stenosis or occlusion of the parenchymal tract. In addition to stimulating pseudointimal hyperplasia, bile may directly induce thrombosis, resulting in acute failure of the shunt [4].
To reduce the four factors described (thrombosis, pseudointimal hyperplasia, biliary endoleaks, and intimal hyperplasia of the hepatic vein), we decided to cover the stent, which we believed would achieve better shunt patency rates. To be effective, the coverage material must be biocompatible, microporous, non-thrombogenic, and impermeable to bile and tissue, and must provide a good substratum for endothelial lining [3].
Many types of graft material have been used in clinical and animal studies. Otal et al. [15] performed TIPS placement using polyester-covered stent-grafts in nine pigs. Those researchers found that polyester is highly thrombogenic and greatly induces inflammatory response. In addition to its high porosity, polyester results in low patency rates and would probably not be recommended in TIPS. Bloch et al. [13] covered the polyester with polyurethane to diminish its porosity; polyurethane, even though it prevented contact between bile and the shunt lumen and blocked pseudointimal hyperplasia, apparently did not suppress the thrombogenecity of polyester, which makes the material inadequate for TIPS. In 1995, Nishimine et al. [16] reported the first use of PTFE stent-grafts to prolong the patency of de novo TIPS in swine; 13 porcine TIPS were lined with handmade PTFE stent-grafts sewn to a combination of Z stents (Cook) and Wallstents (Schneider, Bülach, Switzerland) and were compared with 13 conventional TIPS with bare Wallstents. At 1 month's follow-up, nine of the 13 grafted shunts revealed a stenosis of less than 50%, whereas only one control TIPS was patent, showing that PTFE-covered stents dramatically improve primary TIPS patency when compared with uncovered stents.
Encouraging results were also obtained by Haskal et al. [9], who conducted an experimental study in a swine model and used a PTFE-covered Wallstent; those researchers found a patency rate of 91% at 4-6 weeks of follow-up. On the other hand, Saxon et al. [10] clinically evaluated PTFE-covered stent-grafts for revision of TIPS stenoses and occlusions. In six patients with an initial mean primary TIPS patency of 50 days, the TIPS was lined with Gianturco Z stent endoskeletons supporting a PTFE graft predilated to 14 mm. Noncovered TIPS had primary and secondary patencies of 50 and 53 days, respectively. The deployment of covered stents allowed a mean primary patency of 229 days. Clinical results for these patients were also excellent because none of those with variceal bleeding rebled after stent-grafting. The authors concluded that PTFE-covered stent-grafts were effective for TIPS revision in patients with tract stenosis or occlusion.
In a 1999 publication, Andrews et al. [2] described the treatment of eight patients awaiting liver transplantation with de novo stent-grafts. These prostheses were handmade, using two Z stents joined by struts and covered with PTFE, then supported by a Wallstent. Primary patency obtained with these stent-grafts was 75% at 294 days. Two patients developed a significant stenosis (>50%) at 127 and 460 days. Another study suggests that PTFE-covered stent-grafts for TIPS might provide both newly created and revised TIPS the durable uninterrupted patency they presently lack [3].
Our series assesses the safety and the clinical efficiency of a new expandable-PTFE—covered stent-graft that is commercially available in Europe. Ours is a prospective noncomparative phase I study, with a relatively limited number of patients. However, our study appears to show the benefit of expandable-PTFE—covered stent-grafts in TIPS. In addition, the device is specifically made for use in TIPS, with a bare self-expandable portion aimed at anchoring the device in the portal system, and a covered portion designed for lining the entire parenchymal tract, including the hepatic vein, as recommended by many authors who report hepatic vein stenosis as a major source of patency loss [9, 16]. Some authors mentioned the phenomenon of gas denucleation of the PTFE graft when expanded using a wet balloon, suggesting that microscopic gas bubbles would be then replaced with liquid droplets that act as a capillary ladder, allowing bile to pass across the PTFE [3].
In our series, we performed in vivo balloon inflation inside all devices, all of which were manufactured with expanded PTFE, and no biliary leak occurred with the dual layers of expandable PTFE: externally an impermeable layer resists parenchymal tract stenosis, and internally the more porous layer provides better endothelialization and is theoretically less thrombogenic.
Concerning follow-up, sonography has been shown to be an excellent method of screening for shunt stenosis because of its relatively high diagnostic accuracy, low cost, lack of ionizing radiation, and noninvasive nature [17]. We used sonography to perform follow-up after TIPS placement and found its results accurate and similar to venography results. However, when sonography was performed a few days after stent-graft implantation, an acoustic barrier prevented us from exploring the shunt lumen. This barrier resolved spontaneously 1 week later, and TIPS hemodynamics could be recorded as in bare stents. We think that the ultrasound barrier in the first days probably results from microbullae embedded inside the expandable PTFE. In one patient, sonography could not be performed because of poor echoic body habitus, and follow-up had to be performed using CT angiography, a method already used by some authors in these settings and known to be irradiating and to require the injection of a high level of iodinated contrast material [17].
Two of our patients developed ischemic hepatic lesions, one in the right posterior segment and one in the caudate lobe, at 1 and 7 days, respectively, after stent-graft deployment. Abdominal pain responded to mild analgesia and resolved a few days later. We think that these lesions result from hepatic vein thrombosis above the stent-graft and may be similar to a partial Budd-Chiari syndrome. Nevertheless, it does not seem to be of major concern because some authors have found that occlusion of a hepatic vein, even though it results in a partial Budd-Chiari syndrome, does not have any clinical effect [9, 18]. However, this hypothesis could not explain the second case of ischemia that affected the caudate lobe, in which venous drainage does not go through a major hepatic vein. An arterial compression or thrombosis could be another possible cause. To our knowledge, this type of complication was never reported with bare TIPS and might be related to the presence of expandable PTFE. To reduce the risk of occlusion of the hepatic vein by the stent-graft, it is probably appropriate to puncture the hepatic vein as close as possible to the inferior vena cava. Actually, implantation of a stent-graft in the widest portion of the hepatic vein is more likely to maintain the flow in the stent-bearing vein.
Two of our patients underwent liver transplantation, both 7 months after TIPS placement. One of these patients had a previously occluded bare TIPS parallel to the expandable-PTFE—covered stent, allowing a histologic comparison. Histopathologic studies showed patent stent-grafts in the two patients. We found the same myofibroblasts with collagen matrix around the covered and noncovered TIPS, except that this proliferation was prevented from gaining the shunt lumen in the PTFE-covered stents. The same findings were reported by Haskal et al. [9] in a study of pigs. In addition, we found a smooth thin layer of fibrin, with no evidence of endothelialization, lining the luminal surface of the PTFE, as opposed to the observation by Andrews et al. [2], in their de novo handmade PTFE-covered TIPS, of a thin layer of pseudointima. No procedural difficulty was encountered while performing the liver transplantation, even though our stent-grafts reached the inferior vena cava. The easy stent-graft removal is explained by the lack of tissue attachment to the device because proliferative fibrous reaction was due to the bile-resistant outer expandable-PTFE layer.
In conclusion, according to these preliminary results, the PTFE-covered endoprosthesis has good technical results and midterm patency rates. These patency rates are clearly better than those reported in the literature for bare stents. These results must be validated through larger, comparative randomized trials of covered and noncovered TIPS, as well as against other graft materials and therapeutic techniques, before accepting TIPS as a first-line therapeutic option of complicated portal hypertension.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Cura, A. Cura, R. Suri, F. El-Merhi, J. Lopera, and G. Kroma Causes of TIPS Dysfunction Am. J. Roentgenol., December 1, 2008; 191(6): 1751 - 1757. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Hoppe, S. L. Wang, and B. D. Petersen Intravascular US-guided Direct Intrahepatic Portocaval Shunt with an Expanded Polytetrafluoroethylene-covered Stent-Graft Radiology, January 1, 2008; 246(1): 306 - 314. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S W Park, S H Lee, C H Kim, G S Jeon, S J Hong, J G Yi, and H J Jeon Inhibition of pseudointimal hyperplasia in swine TIPS models: the efficacy of local delivery of paclitaxel using a perforated balloon catheter Br. J. Radiol., September 1, 2007; 80(957): 702 - 707. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Lake, M. Guimaraes, S. Ackerman, C. Hannegan, C. Schonholz, J. B. Selby, and R. Uflacker Comparative Results of Doppler Sonography After TIPS Using Covered and Bare Stents. Am. J. Roentgenol., April 1, 2006; 186(4): 1138 - 1143. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Vignali, I. Bargellini, M. Grosso, G. Passalacqua, F. Maglione, F. Pedrazzini, P. Filauri, R. Niola, R. Cioni, and P. Petruzzi TIPS with Expanded Polytetrafluoroethylene-Covered Stent: Results of an Italian Multicenter Study Am. J. Roentgenol., August 1, 2005; 185(2): 472 - 480. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G.-J. Teng and Q. Lu Bile Leakage during Transjugular Intrahepatic Portosystemic Shunt Creation: In Vitro Effect of Bile on Growth and Function of Human Umbilical Vein Endothelium Radiology, June 1, 2005; 235(3): 867 - 871. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Rossi, F. M. Salvatori, F. Fanelli, M. Bezzi, M. Rossi, G. Marcelli, D. Pepino, O. Riggio, and R. Passariello Polytetrafluoroethylene-covered Nitinol Stent-Graft for Transjugular Intrahepatic Portosystemic Shunt Creation: 3-year Experience Radiology, June 1, 2004; 231(3): 820 - 830. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hur, K.-H. Lee, J. H. Lee, J.-S. Yu, J. Y. Won, and D.-Y. Lee Stent-Graft for TIPS in a Hepatocellular Carcinoma Patient with Main Portal Vein Invasion Am. J. Roentgenol., May 1, 2004; 182(5): 1301 - 1304. [Full Text] [PDF]
|
|
|
|
 |
|
 D. C. Madoff, M. J. Wallace, K. Ahrar, and R. R. Saxon TIPS-related Hepatic Encephalopathy: Management Options with Novel Endovascular Techniques RadioGraphics, January 1, 2004; 24(1): 21 - 36. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Wallace, K. Ahrar, L. C. Stephens, and K. C. Wright Transvenous Extrahepatic Portacaval Shunt: Feasibility Study in a Swine Model Radiology, July 1, 2003; 228(1): 119 - 125. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
