Cumulative Stent Patency Research Articles

A Novel Double Stent System for Palliative Treatment of Malignant Extrahepatic Biliary Obstructions: A Pilot Study

The purpose of this study is to investigate the efficacy and safety of a novel double stent in patients with malignant extrahepatic biliary obstruction. This prospective pilot study enrolled 45 consecutive patients with malignant extrahepatic biliary obstructions from January 2008 to December 2009. All patients were treated with a novel double stent system (covered stent in uncovered stent). The double stents were successfully placed in all patients. Bilirubin levels decreased significantly after stent placement (p < 0.001). Median patient survival and stent patency times were 149 days (95% CI, 126-172 days) and 439 days (95% CI, 123-755 days), respectively. Cumulative stent patency rates at 3, 6, 9, and 12 months were 91%, 89%, 82%, and 82%, respectively. Five patients (11.1%) presented with stent occlusion due to tumor overgrowth (n = 3) or sludge incrustation (n = 2) and required repeat intervention. Tumor ingrowth, acute cholecystitis, pancreatitis, or stent migration was not observed in any of these patients. Preliminary results indicate that percutaneous treatment of malignant extrahepatic biliary obstructions using a novel double stent is feasible, safe, and effective in achieving internal biliary drainage.

Efficacy and safety of covered self-expandable metal stents for management of distal malignant biliary obstruction due to lymph node metastases

Distal malignant biliary obstruction (MBO) due to lymph node metastases (LNM) is a common problem in advanced malignant disease. However, the role of covered self-expandable metal stents (SEMS) in treating MBO has not been studied. The aim of this study was to evaluate the efficacy and safety of covered SEMS for the treatment of distal MBO due to LNM. Between November 1994 and December 2009, a total of 65 patients with distal MBO due to LNM underwent covered (n=44) and uncovered (n=21) SEMS placement. Successful drainage was achieved in all patients. There was no significant difference in patient survival. The cumulative stent patency of covered SEMS was significantly higher than that of uncovered SEMS (P=0.0020). Stent occlusion occurred in 5 patients (11%) with covered SEMS and in 8 (38%) with uncovered SEMS. There was no tumor ingrowth in covered SEMS, but seven in the uncovered SEMS group showed some ingrowth. Cholecystitis was not observed, but mild pancreatitis was observed in 6 (14%) of those with covered SEMS. No stent-insertion-related deaths occurred. Covered SEMS are safe and effective for treatment of distal malignant biliary obstruction due to LNM.

RESULTS OF A JAPANESE MULTICENTER, RANDOMIZED TRIAL OF ENDOSCOPIC STENTING FOR NON-RESECTABLE PANCREATIC HEAD CANCER (JM-TEST): COVERED WALLSTENT VERSUS DOUBLELAYER STENT

No study has compared covered metallic stents with Tannenbaum stents. We evaluated the efficacy of the DoubleLayer stent (DLS) and Covered Wallstent (CWS) in patients with pancreatic head cancer (PHC). This was a multicenter, prospective randomized study. Between October 2005 and December 2007, we enrolled 113 patients (58 DLS, 55 CWS) with unresectable PHC with distal biliary obstructions and observed them for at least 6 months. No significant difference in patient survival was found between groups, with a median survival of 231 and 248 days in the DLS and CWS groups, respectively. The cumulative stent patency was significantly higher (P = 0.0072) in the CWS group. The respective mean and median stent patency was 202 and 133 days in the DLS group and 285 and 419 days in the CWS group. The incidence of DLS occlusion (53.5%) was significantly higher than that of CWS (23.6%; P = 0.0019). The respective causes of occlusion were tumor overgrowth (0, 1), ingrowth (0, 2), sludge (24, 2), food impaction (3, 5), kinking bile duct (2, 0), and other (2, 3). Other complications were cholecystitis (0, 4), pancreatitis (0, 1), migration (1, 5), liver abscess (2, 0), and other (1, 2). No significant difference in the incidence of complications between groups was observed. CWS had significantly longer patency than DLS for the management of PHC with obstructive jaundice. The incidence of complications other than stent occlusion was higher in CWS, but this difference did not reach significance.

Endovascular Placement of Iodine-125 Seed Strand and Stent Combined with Chemoembolization for Treatment of Hepatocellular Carcinoma with Tumor Thrombus in Main Portal Vein

Purpose To study the safety and feasibility of endovascular placement of an iodine-125 ( 125I) seed strand and stent combined with chemoembolization to treat hepatocellular carcinoma (HCC) with tumor thrombus in the main portal vein (MPV). Materials and Methods From February 2008 to October 2009, 32 patients with HCC complicated by tumor thrombus in MPV were enrolled into this study (28 men and 4 women, mean age 53.2 years ± 8.8). After 125I seed strand and self-expandable stent had been placed in the obstructed MPV, chemoembolization was performed. All patients were followed up every 30 days. Patency of stent and response of HCC were evaluated by abdominal contrast-enhanced computed tomography (CT) scan. Results The technical success rate was 100% for placement of the 125I seed strand and stent in the obstructed MPV. No serious procedure-related complications occurred. During a mean follow-up of 217.5 days ± 151.6, the objective response rate of HCC to chemoembolization was 37.5%. The 90-day, 180-day, and 360-day cumulative survival rates were 96.4%, 67.4%, and 39.3%, and the cumulative stent patency rates were 96.7%, 83.4%, and 83.4%. Conclusions Endovascular placement of 125I seed strand and stent combined with chemoembolization was safe and feasible to treat HCC with tumor thrombus in the MPV.

A Comparative Analysis of PTFE-Covered and Uncovered Stents for Palliative Treatment of Malignant Extrahepatic Biliary Obstruction

The purpose of our study was to evaluate the outcomes of the newly designed partially polytetrafluoroethylene (PTFE)-covered stent and compare the outcomes of PTFE-covered and uncovered stents in patients with malignant extrahepatic biliary obstruction. From March 2006 to December 2008, 58 consecutive patients who underwent PTFE-covered stent placement were prospectively studied. Those data were compared with data obtained by retrospectively studying 58 consecutive patients who underwent self-expanding uncovered stent placement from March 2003 to February 2006. According to the Kaplan-Meier analysis, the cumulative stent patency of covered stents (98%, 98%, 91%, 76%, and 76% at 1, 3, 6, 9, and 12 months, respectively) was significantly better than that of uncovered stents (98%, 83%, 72%, 57%, and 57% at 1, 3, 6, 9, and 12 months, respectively) (p = 0.037). There was no significant difference in the patient survival between the groups (p = 0.479). The two groups also did not significantly differ in terms of complication rate (p = 0.717), with 8.6% (5/58) in the covered stent group and 5.2% (3/58) in the uncovered stent group. Partially PTFE-covered stents are effective and safe for the palliative treatment of malignant extrahepatic biliary obstruction. Moreover, PTFE-covered stents were significantly superior to uncovered stents in terms of stent patency for palliative treatment of patients with malignant extrahepatic biliary obstruction. In addition, there was no significant difference in patient survival and complication rate between the PTFE-covered and uncovered stent group.

Comparison of outcomes among secondary covered metallic, uncovered metallic, and plastic biliary stents in treating occluded primary metallic stents in malignant distal biliary obstruction

The self-expandable metallic stent (SEMS) has been widely used for unresectable malignant biliary obstruction but eventually becomes occluded by tumor ingrowth/overgrowth and sludge. Therefore, we aimed to determine the therapeutic effectiveness of secondary stents and to find differences according to various combinations of the first and second stents for the management of occluded SEMSs in patients with malignant distal biliary obstruction. Between 1999 and November 2008, 77 patients with malignant biliary obstruction underwent secondary biliary stent placement as "stent-in-stent" at three university hospitals in Korea (40 covered, 26 uncovered, and 11 plastic stents). The membrane of the covered SEMS was regarded as the barrier against tumor ingrowth. We categorized the patients into three groups based on whether the covered SEMS was either the first or the second stent: membrane-SEMS (18 covered-covered; 9 covered-uncovered; 22 uncovered-covered SEMS), bare-SEMS (17 uncovered-uncovered SEMS), and plastic stent (3 covered-plastic; 8 uncovered-plastic). The median patency of second stents was 138, 109, and 88 days (covered, uncovered, and plastic stents). The second covered SEMSs had a significantly longer patency than plastic stents (p=0.047). In a multivariate analysis including membrane-SEMS, bare-SEMS, and plastic stent groups, the bare-SEMS had a worse cumulative stent patency (HR=2.04, CI=1.08-3.86) and survival time (HR=2.37, CI=1.25-4.49) than the membrane-SEMS. Patients with ampulla of Vater cancer had better stent patency (HR=0.27, CI=0.08-0.98) and survival (HR=0.17, CI=0.04-0.77) than those with other pancreatobiliary malignancies. In addition, antitumor treatment prolonged survival time (HR=0.50, CI=0.26-0.99). The placement of additional biliary stents using the "stent-in-stent" method is an effective treatment for an occluded metallic primary stent. In addition, double biliary SEMS placement using at least one covered SEMS (in the primary and/or secondary procedure) might provide longer cumulative stent patency and survival than using uncovered SEMSs in both procedures.

Metallic Stent Placement in the Palliative Treatment of Malignant Gastric Outlet Obstructions: Primary Gastric Carcinoma Versus Pancreatic Carcinoma

The objective of our study was to compare the clinical effectiveness of metallic stent placement for relief of gastric outlet obstruction caused by gastric carcinoma and pancreatic carcinoma. A total of 207 patients with gastric outlet obstruction caused by inoperable gastric carcinoma (n = 147) or pancreatic carcinoma (n = 60) underwent metallic stent placement. Technical success of metallic stent placement was achieved in all patients. Clinical success was achieved in 97% and 93% of patients with gastric and pancreatic carcinoma, respectively (p = 0.286). The overall complication rate did not differ significantly between the gastric (29%) and pancreatic (23%) carcinoma groups (p = 0.441). Stent collapse was significantly more frequent in the gastric carcinoma group (11%) than the pancreatic carcinoma group (2%) (p = 0.027), whereas serious complications, including gastrointestinal bleeding and intestinal perforation, occurred more frequently in the pancreatic (7%) than the gastric (1%) carcinoma group (p = 0.026). The cumulative survival period was significantly longer in the gastric carcinoma (median, 153 days) than the pancreatic carcinoma (median, 90 days) group (p = 0.041), but cumulative stent patency did not differ significantly between the gastric carcinoma (median, 350 days) and pancreatic carcinoma (median, 385 days) groups (p = 0.415). Metallic stent placement was clinically effective in the palliative treatment of gastric outlet obstruction in patients with gastric and pancreatic carcinoma. The two groups differed significantly in the rates of stent collapse and serious complications and patient survival after stent placement.

The Result of Japanese Multicenter, Randomized Trial of Endoscopic Stenting for the Nonresectable Pancreatic Head Cancer (JM-Test) Retrospective Investigation

Background and Aim: Both DoubleLayer® stent (DLS) and Covered Wallstent® (CWS) are effective for management of malignant distal biliary obstructions, previously reported. DLS has tannenbaum type structure constructed 3 layers; perfluoro alkoxy (inner), polyamid elstmar (outer) sandwiched wire mesh layer. We estimated efficacy and safety of DLS compared with CWS in the patient with pancreas head cancer (PHC). Patients and Methods: Between May 2005 and April 2007, we enrolled 120 unresectable PHC with distal biliary obstructions. They were randomly assigned to DLS or CWS placement and observe at least 6 months. Results: we excluded 6 failed cases with digestive obstruction and 9 cases with imperfect data and follow up, finally we estimated 105 cases (53 DLS, 52 CWS). There are still alive cases; 10 in DLS (5 with patent stent) and 11 in CWS (8 with patent stent). There was no significantly difference in patient survival between 2 groups. The cumulative stent patency in CWS was significantly higher than that of DLS group (p=0.026). Median survival and stent patency were 250 and 130 days in DLS, and 215 and 419 days in CWS. Stent occlusion occurred in 31 (58.5%) after a median of 110 days in DLS group, and in 18 patients (34.6%) after a median of 144 days in CWS group. The incidence of DLS occlusion was significantly higher than that of CWS (p = 0.0190). The causes of occlusions were tumor overgrowth (0, 2), ingrowth (0, 2), sludge (24, 3), food impaction (1, 3) and kinking bile duct (2, 0). Other complications were pancreatitis (0, 1), cholecystitis (0, 4), migrations (0, 4), liver abscess (2, 0) and other (1, 2). There was no significantly difference in the incidence of complications between 2 groups. Conclusion: DLS did not show longer patency to CWS in the patients with pancreas cancer. Cholecystitis and migration were still unresolved complications in CWS, but the incidence did not significantly differed from DLS.

Unilateral versus bilateral endoscopic metal stenting for malignant hilar biliary obstruction

The extent of liver drainage for palliative treatment of malignant hilar biliary obstruction is controversial. The aim of this study was to compare endoscopic unilateral versus bilateral drainage in patients with malignant hilar biliary obstruction using a self-expanding metal stent (SEMS). We carried out a retrospective review of 46 consecutive patients with malignant hilar biliary obstruction who were treated by endoscopic biliary drainage using SEMS between 1997 and 2005. Unilateral metal stenting (group A) was performed in 17 patients between 1997 and 2000, and bilateral metal stenting (group B) was performed in 29 patients between 2001 and 2005. The successful stent insertion, successful drainage, early complications, late complications, stent patency, and survival rate for groups A and B were evaluated and compared retrospectively. There were no significant differences between the two groups in successful stent insertion (100% vs 90%, group A vs B, respectively), successful drainage (100% vs 96%), early complications (0% vs 10%), or late complications (65% vs 54%). Cumulative stent patency was significantly better in group B than in group A (P = 0.009). In cases of cholangiocarcinoma, cumulative stent patency was significantly better in group B than in group A (P = 0.009), whereas there were no inter-group differences for gallbladder carcinoma. Cumulative survival did not differ significantly between the groups. Endoscopic bilateral drainage using SEMS for malignant hilar biliary obstruction is more effective than unilateral drainage in terms of cumulative stent patency, especially in cases of cholangiocarcinoma.

Hepatocellular carcinoma with main portal vein tumor thrombus

Hepatocellular carcinoma (HCC) with main portal vein tumor thrombus (MPVTT) is often associated with poor prognosis. We retrospectively assessed the effectiveness of percutaneous transhepatic portal vein stenting and transarterial chemoembolization (PTPVS-TACE) combined with or without 3-dimensional conformal radiotherapy (3-DCRT) for HCC with MPVTT. Forty-five patients with HCC complicated by MPVTT were treated with PTPVS-TACE. Among them, 16 patients (group A) received 3-DCRT with 30-60Gy as daily 2Gy fractions. The remaining 29 patients (group B) received no radiotherapy. The tumor responses, complications, stent patency rates, and cumulative survival rates were evaluated, and the Kaplan-Meier method and log-rank test were used for survival analysis. No severe complications were associated with PTPVS-TACE and 3-DCRT. The objective response rate (CR and PR) was 35.6%. The 60-, 180-, and 360-day cumulative stent patency rates were 93.3%, 62.2%, and 34.6% in group A, and 58.6%, 21.7%, and 10.8% in group B, respectively, showing significant difference between the 2 groups (P<.01). The mean patency time was 475.20+/-136.97 and 199.58+/-61.40 days, respectively. The 60-, 180-, and 360-day cumulative survival rates were 93.8%, 81.3%, and 32.5%, respectively, for group A, 86.2%, 13.8%, and 6.9%, respectively, for group B. Significant statistical differences were detected between the 2 groups (P<.01). These findings suggest that sequential therapy by PTPVS-TACE-3-DCRT is possibly an effective treatment modality for HCC complicated by main portal vein tumor thrombus.

Hepatocellular carcinoma complicated by main portal vein tumor thrombus: treated by portal vein stenting,tansarterial chemoembolization and 3-dimensional conformal radiotherapy

Objective To retrospectively analyze the role of 3-dimensioual conformal radiotherapy (3-DCRT) after percutaneous transhepatic portal vein stenting and transcatheter arterial chemoembolization (PTPVS-TACE) in the treatment of patients with hepatocellular carcinoma (HCC) complicated by main portal vein tumor throw.bus (MPVTT).Methods Between July 2002 and July 2007,45 patients with HCC complicated by MPVTT were treated by PTPVS-TACE.Among them,3-DCRT were undertaken for MPVTT in 16 patients (group A),the other 29 patients were not treated with 3-DCRT(group B).The clinical effects,complication,stent patency rates,cumulative survival rates were evaluated among groups.The Kaplan-Meier method and log-rank test were used for survival analysis.Results No patient died during stent placement or within the preceding first 24 hours.No severe procedure-related complications were observed.The 60--,180--,360--day cumulative stent patency rates were 100.0%,62.2% and 34.6% in group A,and 58.6%,21.7% and 10.8% in group B,respectively,showing significant difference between the two groups (X2 =9.672,P <0.01).The mean patency time was(475±137) and (200±61)days,respectively.The 60--,180--,and 360--day cumulative survival rates were 93.8%,81.3% and 32.5% for group A,86.2%,13.8% and 6.9% for group B,respectively.There were significant statistical differences between the two groups(X2=9.672,14.596,P < 0.01).Conclusion Treatment with PTPVS-TACE-3-DCRT is a more effective modality than PTPVS-TACE for HCC complicated by MPVTT. Key words: Carcinoma,hepatocellular; Portal vein; Chemoembolization,therapeutic; Stent; Radiotherapy,conformal

Covered Versus Uncovered Wallstent for Malignant Extrahepatic Biliary Obstruction: A Cohort Comparative Analysis

We examined the use of both covered and uncovered Wallstents in patients with malignant extrahepatic biliary obstruction to determine whether use of covered Wallstents prolonged stent patency without increasing procedure-related complications. Commercially available silicone-covered Wallstents were prospectively evaluated in 98 patients who underwent insertion from December 2002-December 2004. Those data were compared with data obtained by retrospectively studying 108 consecutive patients who underwent endoscopic insertion of uncovered Wallstents between January 2000-November 2002, and for whom accurate and complete follow-up details were available. The mean stent patency was similar for both groups, 148.9 days (range, 3-667 days) for covered Wallstents and 143.5 days (3-910 days) for uncovered Wallstents (P = .531). The 2 groups also did not significantly differ in terms of cumulative stent patency according to the Kaplan-Meier lifetime table. The incidence of mild pancreatitis was similar in both groups, occurring in 6 patients with covered stents (6/98, 6.1%) and 2 patients with uncovered stents (2/108, 1.9%) (P = .154). Excluding those patients who had previously undergone cholecystectomy, acute cholecystitis occurred in 5 of 88 patients with covered Wallstents (6.1%) and 1 of 100 patients with uncovered stents (1%) (P = .104). Stent migration occurred in 6 patients with covered stents (6.1%) and 0 patients with uncovered stents (P = .011). Covered Wallstents might not prolong stent patency compared with uncovered Wallstents when used in the management of malignant extrahepatic biliary obstruction.

Is metallic stenting worthwhile for biliary obstruction due to lymph node metastases?

The indications for metallic stents have widened from primary hepatobiliary cancers to the other diseases such as lymph node metastases from distant organs. The present study aimed to evaluate the results and establish the efficacy of metallic stenting in patients with obstructive jaundice due to metastatic lymph nodes. Stent patency, survival and cost per patient until death were retrospectively compared between patients with primary carcinoma of the biliary tract (PC group; n = 71) and lymph node metastases from the gastric and colorectal carcinomas. (LN group; n = 26). Stent occlusion occurred in 17 patients in the PC group (24%). In contrast, stent occlusion was significantly more frequent in the LN group (P = 0.0293), occurring in 13 patients (50%). Cumulative stent patency was also significantly shorter in the LN group than that in the PC group (P = 0.0016). However, survival was almost the same between the two groups. The mean medical fee was 27% higher for the LN group than for the PC group, which was attributable to additional treatment for stent occlusion. The indications for metallic stent placement for biliary obstruction caused by lymph node metastases from the gastrointestinal tract seem limited. Further investigation of the treatments alternative to metallic stents would be required.

Percutaneous transluminal angioplasty (PTA) and venous stenting in hemodialysis patients with vascular access-related venous stenosis or occlusion

Aim of the study To present our experience with PTA and venous stenting in hemodialysis patients with vascular access (VA) related venous stenosis or occlusion. Patients – methods We studied retrospectively 22 hemodialysis patients with VA-related venous stenosis or occlusions that were treated with PTA and subsequent stenting. The following lesions were detected by digital subtraction venography: occlusion of the brachiocephalic and/or subclavian veins in four patients, stenosis (80–90%) of the same veins in 10 patients, stenosis (80–95%) of the axillary vein in four patients, brachial vein stenosis in two patients, and cephalic vein stenosis in two patients. The follow-up period ranged from 3 to 29 months (mean 15.4 ± 9.8 months). Primary and cumulative stent patency was recorded. Results Twenty-two primary venous PTA–stent implantation procedures were performed using 25 stents. The initial deployment of these 25 stents was technically successful, with complete opening (>80%) of the vein's lumen in all but one patient (95.4%). The patency of the vein immediately after the stenting procedure was greater than 90% in 13 patients, 80–90% in eight patients, and less than 40% in the case involving failure. Seventeen episodes of re-obstruction occurred in 13 patients (59%), and all were treated with the same PTA–stent procedures. At the end of the study period 47 stents had been placed in patients. The 3, 6, 12 and 24-month primary patency rates were 88.3%, 65.3%, 45.6% and 25.5%, respectively. Overall cumulative stent patency was 95.4% after 3 months, 79% after 6 months, 74% after 12 months, and 62.8% after 24 months. Conclusion PTA with primary venous stenting is an effective method for the treatment of VA-related stenosis or occlusion. However, repeat and sometimes multiple interventions are usually needed for the treatment of re-stenosis or re-occlusion episodes.

COVERED METALLIC STENTS FOR MANAGEMENT OF DISTAL MALIGNANT BILIARY OBSTRUCTION

ABSTRACTCovered metallic stent (covered MS) is useful to improve quality‐of‐life in patients with unresectable malignant distal biliary obstruction. We have managed 129 patients with three types of covered MS; polyurethane‐covered Wallstent (hand‐craft), polyurethane‐covered Diamond stent (hand‐craft), and silicone‐covered Wallstent (commercially available). They were compared with 115 cases treated with uncovered metallic stent (uncovered MS). There was no significant difference in survival between the two groups. The cumulative stent patency was significantly higher in the covered MS group than uncovered MS group (P = 0.0027). Stent occlusion occurred in 17 patients (13%) in the covered MS group, and in 48 patients (42%) in the uncovered MS group (P &lt; 0.0001). Complications of covered MS were 8 (6%) in acute cholecystitis, 10 (8%) in acute pancreatitis, and 10 (8%) in migration. We evaluated the risk factors for these complications of covered MS.

4643 A prospective randomized study of “covered” vs “uncovered” metallic stent for distal malignant biliary obstruction.

Purpose: This study was undertaken to determine the efficacy of polyurethane covered metallic stent in the treatment of patients with distal malignant biliary obstruction. Patients and Methods: From August 1998 to October 1999, we enrolled consecutive 50 patients with irresectable biliary malignancy of common bile duct. They were randomly assigned to polyurethane covered Diamond stent group (25) or original Diamond stent group (25). The prosthesis were implanted endoscopically. Stent patency represented from stent insertion to its occlusion or patient death. Cumulative stent patency and patient survival were estimated according to Kaplan-Meier analysis, supplemented by the log-rank test. Results: There was no significant difference between groups in patient survival. Effective biliary decompression was achieved in all patients initially. The stent patency rates at 3, 6, and 12 months were 100%, 83%, and 83% in the covered group, and 77%, 69%, and 52% in the uncovered group (p=0.055) respectively. Stent occlusion occurred in 1 patient (4%) in the covered group, and in 7 patients (28%) in the uncovered group, respectively. The cause of covered stent occulusion was tumor overgrowth over the tips of the metallic stent. On the other hand, the causes of occlusion in the uncovered group consisted of tumor ingrowth through the stent meshes in 5, tumor overgrowth in 1 and unknown cause in 1. Acute cholecystitis in 1 and mild pancreatitis in 3 occurred in the covered group. Percutaneously drainage was needed for management of cholecystitis. Pancreatitis conservatively improved. In the uncovered group, those complications did not occur. However, biliary bleeding in 1 occurred in uncovered group. Abdominal arteriography showed pseudoaneurysm in common bile duct and transcatheter arterial embolization with gelfoam was performed. Conclusions: Covered Diamond stent showed higher patency rates than the uncovered Diamond stent. Polyurethane cover may be effective to prevent against tumor ingrowth. However, this study is preliminary in nature and further investigations will be needed. Purpose: This study was undertaken to determine the efficacy of polyurethane covered metallic stent in the treatment of patients with distal malignant biliary obstruction. Patients and Methods: From August 1998 to October 1999, we enrolled consecutive 50 patients with irresectable biliary malignancy of common bile duct. They were randomly assigned to polyurethane covered Diamond stent group (25) or original Diamond stent group (25). The prosthesis were implanted endoscopically. Stent patency represented from stent insertion to its occlusion or patient death. Cumulative stent patency and patient survival were estimated according to Kaplan-Meier analysis, supplemented by the log-rank test. Results: There was no significant difference between groups in patient survival. Effective biliary decompression was achieved in all patients initially. The stent patency rates at 3, 6, and 12 months were 100%, 83%, and 83% in the covered group, and 77%, 69%, and 52% in the uncovered group (p=0.055) respectively. Stent occlusion occurred in 1 patient (4%) in the covered group, and in 7 patients (28%) in the uncovered group, respectively. The cause of covered stent occulusion was tumor overgrowth over the tips of the metallic stent. On the other hand, the causes of occlusion in the uncovered group consisted of tumor ingrowth through the stent meshes in 5, tumor overgrowth in 1 and unknown cause in 1. Acute cholecystitis in 1 and mild pancreatitis in 3 occurred in the covered group. Percutaneously drainage was needed for management of cholecystitis. Pancreatitis conservatively improved. In the uncovered group, those complications did not occur. However, biliary bleeding in 1 occurred in uncovered group. Abdominal arteriography showed pseudoaneurysm in common bile duct and transcatheter arterial embolization with gelfoam was performed. Conclusions: Covered Diamond stent showed higher patency rates than the uncovered Diamond stent. Polyurethane cover may be effective to prevent against tumor ingrowth. However, this study is preliminary in nature and further investigations will be needed.

4654 Biliary tube stents without sideholes and expandable metallic stents equally relieve middle and lower biliary tracts.

Background/Aim: The low cost and ease of handling of biliary plastic tube stents has led to their extensive use, however clogging of stents remains a major problem. While biliary expandable metallic stents (EMS) improved patency, they are unsuitable for primary biliary stenting because of their high cost and difficulty in replacement. Recently, biliary tube stents without sideholes were also reported to prolong patency. To evaluate the clinical utility and relative advantages of three types of biliary stents, we reviewed clinical results of three types of stents, including; 1) plastic tube stents with sideholes (PWS), 2) plastic tube stents without sideholes (PWOS) and 3) EMS. Patients and methods: 128 patients (M:F=72:56,mean age 69 years, range 34-91) consisting of 52 with pancreatic cancer, 24 with gallbladder cancer, 22 with biliary cancers, 18 with metastatic lymph nodes, 4 with Vater papilla cancer, and 8 with other malignant diseases. PWS (10 Fr), PWOS (double layer stents, Olympus, 10Fr or Soehendra tannenbaum stents, Wilson Cook, 10Fr), and EMS (Boston scientific, 30Fr) were inserted in 65, 25, and 38 cases, respectively. Cumulative stent patency of each stent was analyzed with Kaplan-Meier method, supplemented by Wilcoxon's method. Medical costs of each stent insertion were compared(as $1=105yen). Results: PWS and PWOS were inserted as the primary stenting whereas EMS were inserted as the secondary in all cases.Overall cumulative stent patency rates of EMS and PWOS were significantly higher than that of PWS, and their patency rates at 50, 100, and 200 days were: EMS; 94, 81, and 66%, PWOS; 95, 87, and 39%, and PWS; 70, 41, and 31%. In middle and lower biliary tract strictures, patency of EMS and PWOS were significantly higher than that of PWS, and their patency rates were: EMS; 93, 80, and 63%, PWOS; 94, 86, and 46%, and PWS; 77, 54, and 43%. In the cases with pancreas cancer, cumulative patency rates of EMS and PWOS were significantly higher than that of PWS. These patency rates were: EMS; 94, 72, and 60%, PWOS; 90, 90, and 61%, and PWS; 63, 49, and 37%. In Japan, PWS, PWOS, and EMS cost $24, $133, and $2,286, respectively and ERCP costs $721. Then the costs divided by mean patent period of PWS, PWOS, EMS were $9.3, $7.9, and $19.6/day, respectively. Conclusion:We recommend PWOS for the primary biliary stenting in the middle and lower biliary stricture, especially those due to pancreatic cancer, based on its lower price and sufficient patency without replacement after diagnoses of inoperability.

Prospective randomized trial comparing Tannenbaum Teflon and standard polyethylene stents in distal malignant biliary stenosis

Background: Our aim was to compare the clinical efficacy of the Tannenbaum (TB) biliary prostheses, a recently designed Teflon stent without side holes, with the Cotton-Huibregtse (CH) polyethylene stent. Methods: Fifty-seven patients (26 men, mean age 75.5 years) with unresectable malignant tumors and distal biliary stenosis were included (38 pancreatic head cancer, 17 cholangiocarcinoma, 2 ampullary cancer). Patients were prospectively randomized to have a 10F, 7 cm long TB (29 patients) or CH (28 patients) stent inserted endoscopically. Four patients (2 TB and 2 CH) were excluded: 3 because of the failure of stent insertion and 1 because of a protocol violation. The patients were evaluated clinically and, if necessary, with biochemical tests every month until death or until they needed surgery for symptoms of gastric outlet obstruction. When occlusion or dislocation occurred, the stent was replaced with one of the same type. Cumulative stent patency and patient survival were estimated with the Kaplan-Meier life-table analysis and compared by log-rank chi-square test. Results: The two groups were comparable in mean age, gender, and diagnosis. The patients were followed for a mean of 145.5 days (range 24 to 613); by the end of the study 47 patients (81%) had died or developed symptoms of gastric outlet obstruction. Median survival was 88 days (range 24 to 613) in the TB group and 75.6 days (23 to 486) in the CH group. Stent exchange (occlusion 16, dislocation 3) was necessary for 5 patients in the TB group and 7 in the CH group. No statistical difference was found on comparing the mean duration of function of the first, second, and third stents (analysis of variance, p = 0.80). The median duration of stent function was 96 days (range 11 to 613) in the TB group and 75.5 days (range 23 to 323) in the CH group. No significant difference was found in either survival time ( p = 0.48) or stent patency ( p = 0.12). Conclusion: This study found no significant advantage of the Tannenbaum prostheses over the standard polyethylene stent in the palliation for patients with distal malignant biliary stenosis with regard to survival or length of stent patency. (Gastrointest Endosc 2000;51:23-7.)

Percutaneous Microwave Coagulation Therapy Using Cholangioscopy for Recanalizing Self‐expanding Metallic Stents Occluded by Tumor Ingrowth: Preliminary Results

Abstract:Current ablative techniques for recanalizing self‐expanding metallic stents occluded by tumor ingrowth are limited by the risk of perforation or destruction of the stent filament. A previous experimental study revealed that microwave coagulation therapy for recanalizing occluded metal stents would be safe and effective, and we investigated the clinical application of this procedure. In this in vivo study, microwave coagulation therapy was performed for occluded metallic stents in 5 patients with pancreatic cancer and one patient with gallbladder cancer. This procedure was performed under percutaneous cholangioscopy and fluoroscopic control. Cumulative stent patency before and after microwave coagulation was estimated using the Kaplan‐Meier method supplemented with the log‐rank test. Tumor growing through the stent mesh was successfully removed without any complications using this technique. Analysis of stent patency did not reveal any significant difference between one session of coagulation therapy (115.0±18.4 days) and initial stent (102.3±.22.3 days). In contrast, none of the group after two sessions of this intervention was obstructed until their death. The results indicated that microwave coagulation therapy for recanalizing occluded metallic stent is effective and safe even in vivo. This procedure may be an alternative to placement of another stent through the occluded metallic stent. (Dig Endosc 1999; 11: 209–214)