Measurement of radial and axial forces of biliary self-expandable metallic stents

Arterial repair after bare-metal stent implantation in peripheral arteries is delayed compared to that in coronary arteries: A case report of pathological evaluation

Despite widespread use of endovascular therapy with bare-metal stent (BMS) implantation in patients with peripheral artery disease (PAD), arterial healing has not been well examined in this setting. An 84-year-old man with PAD received BMS implantation at the right external iliac artery (EIA, Epic 8.0 mm × 100 mm) and superficial femoral artery (SFA, SMART Control 8.0 mm × 150 mm). However, he died of lobar pneumonia 81 days later. Pathological evaluation was conducted at BMS implantation sites. At the distal part of Epic site in the EIA, neointimal formation was seldom observed. A small amount of fibrin deposition was seen around stent struts without apparent smooth muscle cell proliferation or surface endothelial cell coverage. In contrast, at the middle part of distal SMART site in the SFA, most of the stent struts were completely covered with moderate amount of neointima which was composed of a lot of smooth muscle cells and extracellular matrix on the plaque-free wall. However, on the contralateral calcified plaque site, a lot of fibrin components were still observed over the surface of thin neointima and only rough smooth muscle cells were scatteringly infiltrated. Furthermore, incomplete endothelial cell coverage was seen on the surface. Arterial repair after BMS implantation in peripheral arteries was extremely delayed. <Learning objective: An 84-year-old man with peripheral artery disease received bare-metal stent (BMS) implantation in peripheral arteries. Pathological evaluation 81 days later showed heterogeneous neointimal coverage formation with incomplete coverage, especially at the vessel portions with significant plaque burden. In these portions, endothelial cell coverage was also incomplete. Moreover, some malapposed struts were observed. Arterial repair after BMS implantation in peripheral arteries was extremely delayed.>.

Partially covered versus uncovered self-expandable nitinol stents with anti-migration properties for the palliation of malignant distal biliary obstruction: A randomized controlled trial

OBJECTIVE

Covered self-expandable metal stents (SEMSs) are increasingly used as alternatives to uncovered SEMSs for the palliation of inoperable malignant distal biliary obstruction to counteract tumor ingrowth. We aimed to compare the outcomes of partially covered and uncovered SEMSs with identical mesh structures and anti-migration properties, such as low axial force and flared ends.

MATERIALS AND METHODS

One hundred and three patients who were diagnosed with inoperable malignant distal biliary obstruction between January 2006 and August 2013 were randomly assigned to either the partially covered (n = 51) or uncovered (n = 52) SEMS group.

RESULTS

There were no significant differences in the cumulative stent patency, overall patient survival, stent dysfunction-free survival and overall adverse events, including pancreatitis and cholecystitis, between the two groups. Compared to the uncovered group, stent migration (5.9% vs. 0%, p = 0.118) and tumor overgrowth (7.8% vs. 1.9%, p = 0.205) were non-significantly more frequent in the partially covered group, whereas tumor ingrowth showed a significantly higher incidence in the uncovered group (5.9% vs. 19.2%, p = 0.041). Stent migration in the partially covered group occurred only in patients with short stenosis of the utmost distal bile duct (two in ampullary cancer, one in bile duct cancer), and did not occur in any patients with pancreatic cancer.

CONCLUSIONS

For the palliation of malignant distal biliary obstruction, endoscopic placement of partially covered SEMSs with anti-migration designs and identical mesh structures to uncovered SEMSs failed to prolong cumulative stent patency or reduce stent migration.

Technical and Anatomic Factors Influencing the Success of Inferior Vena Caval Stent Placement for Malignant Obstruction

PURPOSE

To evaluate the outcomes of inferior vena cava (IVC) stent placement for malignant obstruction and to identify anatomic and procedural factors influencing technical and clinical success.

MATERIALS AND METHODS

A total of 57 patients (37 male, 20 female; age range, 22-86 y) underwent 62 IVC stent placement procedures using 97 stents (47 Wallstents, 15 S.M.A.R.T. stents, 18 Wallflex stents, 17 others) from 2005 to 2016 for malignant IVC obstruction caused by hepatic metastases (n = 22; 39%), primary hepatic malignancy (n = 16; 28%), retroperitoneal metastases (n = 16; 28%), or other primary malignancy (n = 5; 9%). Presenting symptoms included lower-extremity edema (n = 54; 95%), ascites (n = 28; 50%), and perineal edema (n = 14; 25%). Sixteen percent (n = 10) and 10% (n = 6) of the procedures involved tumor and bland thrombus, respectively.

RESULTS

Stent placements resulted in 100% venographic patency and significantly decreased pressure gradients (P < .0001). Lower-extremity swelling, perineal swelling, and abdominal distension improved within 7 days in 83% (35 of 42), 100% (9 of 9), and 40% (6 of 15) of patients, respectively, and at 30 days after the procedure in 86% (25 of 29), 89% (8 of 9), and 80% (4 of 5) of patients, respectively. Increased pre- and post-stent placement pressure gradients were associated with worse outcomes. A 4% stent misplacement rate (4 of 97) was related to the use of Wallstents with caudal stent tapering, asymmetric deployment superior to the obstruction, suprahepatic IVC involvement, and decreased stent adherence to the IVC wall as a result of local mechanical factors.

CONCLUSIONS

Stent placement is reliable, rapid, and durable in improving malignant IVC syndrome. Understanding of technical and anatomic factors can improve accuracy and avoid complications of stent misplacement.

Endoscopic management of unresectable malignant gastroduodenal obstruction with a nitinol uncovered metal stent: A prospective Japanese multicenter study

AIM: To determine the safety and efficacy of endoscopic duodenal stent placement in patients with malignant gastric outlet obstruction.

METHODS: This prospective, observational, multicenter study included 39 consecutive patients with malignant gastric outlet obstruction. All patients underwent endoscopic placement of a nitinol, uncovered, self-expandable metal stent. The primary outcome was clinical success at 2 wk after stent placement that was defined as improvement in the Gastric Outlet Obstruction Scoring System score relative to the baseline.

RESULTS: Technical success was achieved in all duodenal stent procedures. Procedure-related complications occurred in 4 patients (10.3%) in the form of mild pneumonitis. No other morbidities or mortalities were observed. The clinical success rate was 92.3%. The mean survival period after stent placement was 103 d. The mean period of stent patency was 149 d and the patency remained acceptable for the survival period. Stent dysfunction occurred in 3 patients (7.7%) on account of tumor growth.

CONCLUSION: Endoscopic management using duodenal stents for patients with incurable malignant gastric outlet obstruction is safe and improved patients’ quality of life.

Randomized controlled exploratory study comparing the usefulness of two types of metallic stents with different axial forces for the management of duodenal obstruction caused by pancreatobiliary cancer

BACKGROUND

Very few studies have examined effectiveness of duodenal stent placement (DSP) for duodenal obstruction (DO) caused specifically by pancreatobiliary cancer. We compared two types of stents with different axial forces (AF) for DO with pancreatobiliary cancer.

METHODS

The patients were randomly assigned to two stent groups with different AF (high AF stent, WallFlex™: W-group or low AF stent, Niti-S™: N-group). The primary endpoint was improvement in the Gastric Outlet Obstruction Scoring System (GOOSS) score. This study was registered at UMIN000009061.

RESULTS

The GOOSS scores significantly improved in both W-group (0.9 before vs. 2.7 after; P = 0.002) and N-group (1.0 before vs. 2.5 after; P = 0.001). The change in the GOOSS score after DSP did not differ significantly between the groups (P = 0.482). The median time to recurrent DO (RDO) was significantly shorter in W-group than in N-group (89 days vs. 421 days; P = 0.025). The incidence of RDO was significantly higher in W-group than in N-group (64% vs. 24%; P = 0.027). Stent kinking occurred only in W-group.

CONCLUSIONS

The GOOSS scores significantly improved after DSP, but effectiveness did not differ significantly between groups. The use of stents with high AF was related to short-term stent patency, but did not influence survival time.

Basic Knowledge about Metal Stent Development

Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque markers, are discussed in this review. What we know about the physical and mechanical properties of the SEMS is very important. With an understanding of the basic knowledge of metal stents, hurdles such as stent occlusion, migration, and kinking can be overcome to develop more ideal SEMS.

Small cell- versus large cell-sized metal stent in endoscopic bilateral stent-in-stent placement for malignant hilar biliary obstruction

BACKGROUND AND AIM

Although the large cell-sized biliary stent facilitates contralateral stent deployment through the mesh of the first metallic stent for stent-in-stent (SIS) technique, there are concerns about its vulnerability to tumor ingrowth. The aim of the present study was to compare the clinical outcomes of endoscopic bilateral SIS placement according to the cell size of a self-expandable metallic stent (SEMS).

METHODS

A total of 58 patients were enrolled who underwent endoscopic bilateral SIS placement of SEMS for malignant hilar biliary obstruction as a result of cholangiocarcinoma or gallbladder cancer. Finally, 43 patients who underwent successful stent insertion were included in the analysis and divided into the small cell-sized stent (SCS; n = 21) and the large cell-sized stent (LCS; n = 22) groups. We retrospectively compared comprehensive clinical and laboratory data in both groups.

RESULTS

There were no significant differences between the two groups in successful drainage (SCS vs LCS, 100% vs 100%, respectively), early complications (38.1% vs 18.2%), late complications (14.3% vs 22.7%), stent occlusion (42.9% vs 45.5%), tumor ingrowth (33.3% vs 45.5%) or overgrowth (9.5% vs 0%). Duration of stent patency and overall survival were not significantly different between the two groups (P = 0.086 and P = 0.320, respectively).

CONCLUSIONS

Endoscopic bilateral SIS placement for malignant hilar biliary obstruction shows no differences in stent patency, survival, complications and clinical course according to the cell size of SEMS.

Topic controversies in the endoscopic management of malignant hilar strictures using metal stent: side-by-side versus stent-in-stent techniques

Endoscopic management of unresectable hilar malignant biliary stricture (MBS) is currently challenging, and the best approach is still controversial. Liver volume is the key to adequate biliary drainage in hilar MBS and multiple stenting is mandatory to drain over 50% of liver volume in most cases. The self-expandable metallic stent (SEMS) has shown superior patency to plastic stents in recent reports. There are two methods of multiple stenting for hilar MBS: stent-in-stent (SIS) and side-by-side (SBS). Advantages of SIS include multiple SEMS placement in one stent caliber at the common bile duct (CBD), which is considered physiologically ideal. The through-the-mesh (TTM) technique with guidewires and the SEMS delivery system can be technically difficult in SIS, although the recent development of dedicated SEMSs having a loose portion facilitating the TTM technique makes SIS technically feasible both at stent deployment and re-interventions. Conversely, the SBS technique, if placed across the papilla, is technically simple at initial placement and re-intervention at stent occlusion. However, SBS has potential disadvantages of overexpansion of the CBD because of parallel placement of multiple SEMS, which can lead to portal vein thrombosis. Given the limited evidence available, a well-designed randomized controlled trial comparing these two techniques is warranted.

Cholangiocarcinoma and malignant bile duct obstruction: A review of last decades advances in therapeutic endoscopy

In the last decades many advances have been achieved in endoscopy, in the diagnosis and therapy of cholangiocarcinoma, however blood test, magnetic resonance imaging, computed tomography scan may fail to detect neoplastic disease at early stage, thus the diagnosis of cholangiocarcinoma is achieved usually at unresectable stage. In the last decades the role of endoscopy has moved from a diagnostic role to an invaluable therapeutic tool for patients affected by malignant bile duct obstruction. One of the major issues for cholangiocarcinoma is bile ducts occlusion, leading to jaundice, cholangitis and hepatic failure. Currently, endoscopy has a key role in the work up of cholangiocarcinoma, both in patients amenable to surgical intervention as well as in those unfit for surgery or not amenable to immediate surgical curative resection owing to locally advanced or advanced disease, with palliative intention. Endoscopy allows successful biliary drainage and stenting in more than 90% of patients with malignant bile duct obstruction, and allows rapid reduction of jaundice decreasing the risk of biliary sepsis. When biliary drainage and stenting cannot be achieved with endoscopy alone, endoscopic ultrasound-guided biliary drainage represents an effective alternative method affording successful biliary drainage in more than 80% of cases. The purpose of this review is to focus on the currently available endoscopic management options in patients with cholangiocarcinoma.

TOKYO criteria 2014 for transpapillary biliary stenting

It is difficult to carry out meta-analyses or to compare the results of different studies of biliary stents because there is no uniform evaluation method. Therefore, a standardized reporting system is required. We propose a new standardized system for reporting on biliary stents, the 'TOKYO criteria 2014', based on a consensus among Japanese pancreatobiliary endoscopists. Instead of stent occlusion, we use recurrent biliary obstruction, which includes occlusion and migration. The time to recurrent biliary obstruction was estimated using Kaplan-Meier analysis with the log-rank test. We can evaluate both plastic and self-expandable metallic stents (uncovered and covered). We also propose specification of the cause of recurrent biliary obstruction, identification of complications other than recurrent biliary obstruction, indication of severity, measures of technical and clinical success, and a standard for clinical care. Most importantly, the TOKYO criteria 2014 allow comparison of biliary stent quality across studies. Because blocked stents can be drained not only using transpapillary techniques but also by an endoscopic ultrasonography-guided transmural procedure, we should devise an evaluation method that includes transmural stenting in the near future.

Clinical outcomes of secondary gastroduodenal self-expandable metallic stent placement by stent-in-stent technique for malignant gastric outlet obstruction

BACKGROUND AND AIM

To evaluate the efficacy and safety of secondary gastroduodenal stent placement after first stent dysfunction for malignant gastric outlet obstruction.

METHODS

We conducted a retrospective analysis to investigate the efficacy and safety of secondary stent-in-stent gastroduodenal stent placement.

RESULTS

Among 260 patients who had been treated with first gastroduodenal stent placement for malignant gastric outlet obstruction, 29 patients (11.2%) were treated with secondary gastroduodenal stent placement because of first stent dysfunction. Pancreatic cancer was the major primary cancer (55.2%). A WallFlex duodenal stent was the most frequently inserted stent both as a first stent (75.9%) and as a secondary stent (62.1%). There were 22 patients (75.9%) that received gastroduodenal stents at the bending site (supraduodenal angle or infraduodenal angle). Technical and clinical success rates were 100% and 86.2%, respectively. Median eating period was 3.0 months, and median survival time was 3.5 months. As for related complications, gastrointestinal perforation, insufficient stent expansion, tumor ingrowth, tumor overgrowth, and cholangitis were experienced in 13.8% (four cases), 6.9% (two cases), 6.9% (two cases), 3.4% (one case), and 3.4% (one case), respectively.

CONCLUSION

Secondary gastroduodenal stent placement might be effective for managing first stent dysfunction in malignant gastric outlet obstruction. However, gastrointestinal perforation was the major complication.

Late complications of self-expandable metallic stent placement for malignant gastric outlet obstruction

The patient was a 68-year-old man with pancreatic cancer exhibiting invasion into the superior mesenteric artery and stenosis of the third part of the duodenum. He subsequently received a duodenal stent for malignant gastric outlet obstruction. On day 43 after the placement of the duodenal stent, he reported feeling poorly, with hypotension and hematemesis. High-density areas were observed from the stomach to the rectum on computed tomography. We diagnosed the origin of bleeding as the last third of the duodenum; unfortunately, the patient died. This is the first report of massive gastrointestinal tract bleeding as a late complication of self-expandable metallic stent placement for malignant gastric outlet obstruction.

Risk factors for technical failure of endoscopic double self-expandable metallic stent placement by partial stent-in-stent method

BACKGROUND

Endoscopic double self-expandable metallic stent (SEMS) placement by the partial stent-in-stent (PSIS) method has been reported to be useful for the management of unresectable hilar malignant biliary obstruction. However, it is technically challenging, and the optimal SEMS for the procedure remains unknown. The aim of this study was to identify the risk factors for technical failure of endoscopic double SEMS placement for unresectable malignant hilar biliary obstruction (MHBO).

METHODS

Between December 2009 and May 2013, 50 consecutive patients with MHBO underwent endoscopic double SEMS placement by the PSIS method. We retrospectively evaluated the rate of successful double SEMS placement and identified the risk factors for technical failure.

RESULTS

The technical success rate for double SEMS placement was 82.0% (95% confidence interval [CI]: 69.2-90.2). On univariate analysis, the rate of technical failure was high in patients with metastatic disease and unilateral placement. Multivariate analysis revealed that metastatic disease was a significant risk factor for technical failure (odds ratio: 9.63, 95% CI: 1.11-105.5). The subgroup analysis after double guidewire insertion showed that the rate of technical success was higher in the laser-cut type SEMS with a large mesh and thick delivery system than in the braided type SEMS with a small mesh and thick delivery system.

CONCLUSIONS

Metastatic disease was a significant risk factor for technical failure of double SEMS placement for unresectable MHBO. The laser-cut type SEMS with a large mesh and thin delivery system might be preferable for the PSIS procedure.

Risk factors for covered metallic stent migration in patients with distal malignant biliary obstruction due to pancreatic cancer

BACKGROUND AND AIM

Covered metallic stents (CMSs) were developed to overcome tumor ingrowth in uncovered metallic stents (UMSs) for malignant biliary obstruction, but superiority of CMSs over UMSs is still controversial due to the high migration rate in CMS. Therefore, we conducted this retrospective analysis to clarify risk factors for stent migration, including mechanical properties of CMSs.

METHODS

Patients with unresectable pancreatic cancer, receiving CMS for distal malignant biliary obstruction in five tertiary care centers, were retrospectively studied. Univariate and multivariate analyses to identify prognostic factors for early (< 6 months) stent migration were performed using a proportional hazards model with death or stent occlusion without stent migration as a competing risk. Two mechanical properties were included in the analysis: axial force, the recovery force that leads to a CMS straightening, and radial force (RF), the expansion force against the stricture.

RESULTS

Among 290 patients who received CMS placement for distal malignant biliary obstruction, stent migration rate was 15.2%. CMS migrated early (< 6 months) in 10.0% and distally in 11.7%, respectively. In the multivariate analysis, significant risk factors for early stent migration were chemotherapy (subdistribution hazard ratios [SHR] 4.46, P = 0.01), CMS with low RF (SHR 2.23, P = 0.03), and duodenal invasion (SHR 2.25, P = 0.02).

CONCLUSION

CMS with low RF, chemotherapy, and duodenal invasion were associated with CMS migration from our study.

Metallic stent with high axial force as a risk factor for cholecystitis in distal malignant biliary obstruction

BACKGROUND AND AIM

Tumor involvement to the orifice of cystic duct (OCD) is a risk factor for cholecystitis after self-expandable metallic stent (SEMS) placement, but its prevention is still difficult. We conducted this multicenter analysis to clarify a type of SEMS or a method to place SEMS which would decrease the incidence of cholecystitis after SEMS placement.

METHODS

The incidence of cholecystitis was studied in consecutive patients receiving SEMS for distal malignant biliary obstruction in five tertiary care centers. Multiple logistic regression analysis was performed to evaluate risk factors for cholecystitis.

RESULTS

A total of 376 patients who received SEMS placement for distal malignant biliary obstruction were analyzed. Tumor involvement to OCD was diagnosed in 25.3%. Overall incidence of cholecystitis was 6.9%. Cholecystitis was observed in 8.0% of 300 patients with covered SEMS, 16.8% of 95 patients with tumor involvement to OCD, 10.8% of 234 patients with SEMS of high axial force (AF), and 12.0% of 158 patients with SEMS length ≤ 60 mm. In the multivariate analysis, tumor involvement to OCD (odds ratio [OR] 5.40, P < 0.001), SEMSs with high AF (OR 5.33, P = 0.002), and SEMS length ≤ 60 mm (OR 3.19, P = 0.010) are risk factors. Among patients with tumor involvement to OCD, the incidence of cholecystitis in SEMS with high and low AF was 25.0% and 5.0%, respectively.

CONCLUSION

This study with an expanded cohort reconfirmed tumor involvement to OCD as a risk factor for cholecystitis after SEMS placement. SEMS with low AF might decrease cholecystitis.

High single-session success rate of endoscopic bilateral stent-in-stent placement with modified large cell Niti-S stents for malignant hilar biliary obstruction

BACKGROUND

Endoscopic bilateral self-expandable metallic stent (SEMS) placement in a stent-in-stent method for malignant hilar biliary obstruction is technically challenging. Technical difficulties in the initial placement and reinterventions for stent occlusion are disadvantages inherent to this stent-in-stent method. We previously reported the feasibility of Niti-S large cell D-type biliary stents (LCD). This multicenter prospective consecutive study evaluated the efficacy of bilateral SEMS placement using modified LCD with large and uniform cells, a slimmer delivery system and high radial force.

PATIENTS AND METHODS

From July 2010 to June 2011, 26 consecutive patients with unresectable malignant hilar biliary obstruction underwent endoscopic bilateral placement of modified LCD in a stent-in-stent method at three tertiary hospitals. Ten patients had gallbladder cancer, eight had cholangiocarcinoma, four had lymph node metastasis, two had intrahepatic cholangiocarcinoma, and two had liver metastasis.

RESULTS

Single-session and final technical success rate was 96% and 100%, respectively. Functional success rate was 89%. Stent occlusion occurred in 11 patients (42%) because of sludge (n = 7) or tumor ingrowth (n = 4). Endoscopic bilateral reintervention was technically easy and successful: six patients had stent clearance by balloon sweeping and five had plastic stent placement. According to Kaplan-Meier analysis, median survival and stent patency were 220 days and 157 days, respectively.

CONCLUSIONS

Modified LCD achieved a high technical success rate both in the initial stent-in-stent placement and in bilateral reinterventions in patients with malignant hilar biliary obstruction.

A novel, fully covered laser-cut nitinol stent with antimigration properties for nonresectable distal malignant biliary obstruction: a multicenter feasibility study

BACKGROUND/AIMS

Stent migration occurs frequently, but the prevention of complications resulting from covered self-expandable metal stents (C-SEMSs) remains unresolved. We prospectively assessed a newly developed C-SEMS, a modified covered Zeo stent (m-CZS), in terms of its antimigration effect.

METHODS

Between February 2010 and January 2011, an m-CZS was inserted into 42 patients (31 initial drainage cases and 11 reintervention cases) at a tertiary referral center and three affiliated hospitals. The laser-cut stent was flared for 1.5 cm at both ends, with a 1 cm raised bank located 1 cm in from each flared end. The main outcome of this study was the rate of stent migration, and secondary outcomes were the rate of recurrent biliary obstruction (RBO), the time to RBO, the frequencies of complications, and overall survival.

RESULTS

Of the 31 patients with initial drainage, stent migration occurred in four (12.9%, 95% confidence interval, 5.1% to 29.0%), with a mean time of 131 days. RBO occurred in 18 (58%), with a median time to RBO of 107 days. Following previous C-SEMS migration, seven of 10 patients (70%) did not experience m-CZS migration until death.

CONCLUSIONS

m-CZSs with antimigration properties effectively, although not completely, prevented stent migration after stent insertion.

Management of dysfunctional covered self-expandable metallic stents in patients with malignant distal biliary obstruction

BACKGROUND

Endoscopic placement of covered self-expandable metallic stents (CSEMSs) is effective for distal malignant biliary obstruction. However, management of dysfunctional CSEMSs has not been established.

METHODS

Between March 1998 and July 2007, a total of 74 patients who underwent endoscopic re-interventions for CSEMS dysfunction were analyzed. Second stent insertion (CSEMS or plastic stent) or mechanical cleaning of the occluded CSEMS was performed endoscopically. The period between second stent insertion and stent dysfunction or patient death (time to dysfunction; TTD) was calculated. The cleaned initial CSEMSs were analyzed as second stents.

RESULTS

Dysfunction of the second stent occurred in 17 of 37 patients (45.9%) in the CSEMS group, 16 of 20 (80.0%) in the plastic stent group, and 13 of 17 (76.5%) in the cleaning group. The median TTD of each group was 176, 57, and 46 days, respectively. The cumulative TTD was significantly higher in the CSEMS group than in the plastic stent and cleaning groups (P = 0.08). From the multivariate analysis, sludge occlusion of the first CSEMS was identified as a significant risk factor for second stent dysfunction (HR, 2.51; 95% CI, 1.19-5.46), and placement of the second CSEMS significantly reduced the risk of dysfunction (HR, 0.39; 95% CI, 0.18-0.79).

CONCLUSIONS

Insertion of a new CSEMS should be considered as the treatment of choice for the management of dysfunctional CSEMSs.

Covered self-expandable metal stents with an anti-migration system improve patency duration without increased complications compared with uncovered stents for distal biliary obstruction caused by pancreatic carcinoma: a randomized multicenter trial

OBJECTIVES

The requirements of biliary stents used in the palliation of malignant biliary obstruction are a long duration of patency and minimal adverse effects. Covered self-expandable metal stents (SEMSs) have been shown to prevent tumor ingrowth, which is the most frequent complication of uncovered SEMSs. However, because they are prone to migration, the superiority of covered SEMS has yet to be convincingly demonstrated. The aim of this study was to evaluate the superiority of covered over uncovered SEMSs in the palliation of distal biliary obstruction due to unresectable pancreatic carcinoma, using both stent types with relatively low axial force and uncovered flared ends to prevent their migration.

METHODS

From April 2009 to December 2010, 120 patients who were admitted to 22 tertiary-care centers because of distal biliary obstruction from unresectable pancreatic carcinomas were enrolled in this prospective randomized multicenter study. Patients were randomly assigned to receive a covered or uncovered SEMS deployed at the site of the biliary stricture during endoscopic retrograde cholangiopancreatography. Stent patency time, patient survival time, patient survival time without stent dysfunction (time to stent dysfunction or patient death), cause of stent dysfunction (ingrowth, overgrowth, migration, or sludge formation), and serious adverse events were compared between covered and uncovered SEMS groups.

RESULTS

Patient survival time in the two groups did not significantly differ (median: 285 and 223 days, respectively; P=0.68). Patient survival time without stent dysfunction was significantly longer in the covered than in the uncovered SEMS group (median: 187 vs. 132 days; P=0.043). Stent patency was also significantly longer in the covered than in the uncovered SEMS group (mean±s.d.: 219.3±159.1 vs. 166.9±124.9 days; P=0.047). Reintervention for stent dysfunction was performed in 14 of 60 patients with covered SEMSs (23%) and in 22 of 60 patients with uncovered SEMSs (37%; P=0.08). Stent dysfunction was caused by tumor ingrowth, tumor overgrowth, and sludge formation in 0 (0%), 3 (5%), and 11 (18%) patients in the covered SEMSs group, and in 15 (25%), 2 (3%), and 6 (10%) patients in the uncovered SEMSs group, respectively. Stent migration was not observed in either group. Rates of tumor overgrowth and sludge formation did not significantly differ between the two groups, whereas the rate of tumor ingrowth was significantly lower in the covered than in the uncovered SEMS group (P<0.01). Acute pancreatitis occurred in only one patient in the covered SEMS group. Acute cholecystitis occurred in one patient in the covered SEMS group and in two patients in the uncovered SEMS group. There was no significant difference between the two groups in the incidence of serious adverse events.

CONCLUSIONS

By preventing tumor ingrowth and migration, covered SEMSs with an anti-migration system had a longer duration of patency than uncovered SEMSs, which recommends their use in the palliative treatment of patients with biliary obstruction due to pancreatic carcinomas.

Self expandable metal stents for anastomotic stricture following liver transplant

BACKGROUND

Endoscopic treatment for biliary strictures with plastic stent placement has been used widely. The use of covered self-expandable metal stents (CSEMS) has been reported in anastomotic strictures post liver transplant. The aim of this study was to evaluate the efficacy of different CSEMS in these subjects.

METHODS

A total of 55 patients with anastomotic stricture received CSEMS, which were removed after 3-4 months. There were 19 patients in group A (partially covered SEMS), 21 patients in group B (fully covered SEMS with fins) and 15 patients in group C (fully covered SEMS with flared ends). Technical success, stricture resolution, follows up, and complications were documented.

RESULTS

CSEMS were successfully deployed in all 55 cases. There was no evidence of significant difference with regards to stricture resolution (14 [74%] vs. 15 [71%] vs. 9 [60%] p=0.6630, df=2) or complications between groups. Stent-related complications were as follows: three in group A (2 migration, 1 occlusion), five in group B (4 occlusions, 1 migration), and one proximal migration in group C (p=0.3894, df=2). Three cases required surgery (hepatico-jejunostomy) due to refractory strictures.

CONCLUSIONS

The observed clinical success rate of CSEMS (70.4%) proved to be below the reported one for multiple plastic stents, while no significant differences between CSEMS types were observed.

Comparison of the utility of covered metal stents versus uncovered metal stents in the management of malignant biliary strictures in 749 patients

BACKGROUND

Self-expandable metal stents (SEMSs) are used to relieve malignant biliary obstruction.

OBJECTIVE

To compare outcomes between covered self-expandable metal stents (CSEMSs) and uncovered self-expandable metal stents (USEMSs) in malignant biliary obstruction.

DESIGN

Retrospective cohort study.

SETTING

Tertiary cancer center.

PATIENTS

Patients with malignant biliary obstruction.

INTERVENTIONS

Placement of CSEMS or USEMS.

MAIN OUTCOME MEASUREMENTS

Time to recurrent biliary obstruction (TRO), overall survival (OS), and adverse events.

RESULTS

From January 2000 to June 2011, 749 patients received SEMSs: 171 CSEMSs and 578 USEMSs. At 1 year, there was no significant difference in the percentage of patients with recurrent obstruction (CSEMSs, 35% vs USEMSs, 38%) and survival (CSEMSs, 45% vs USEMSs, 49%). There was no significant difference in the median OS (CSEMSs, 10.4 months vs USEMSs, 11.8 months; P = .84) and the median TRO (CSEMSs, 15.4 months vs USEMSs, 26.3 months; P = .61). The adverse event rate was 27.5% for the CSEMS group and 27.7% for the USEMS group. Although tumor ingrowth with recurrent obstruction was more common in the USEMS group (76% vs 9%, P < .001), stent migration (36% vs 2%, P < .001) and acute pancreatitis (6% vs 1%, P < .001) were more common in the CSEMS group.

LIMITATIONS

Retrospective study.

CONCLUSIONS

There was no significant difference in the patency rate or overall survival between CSEMSs and USEMSs for malignant distal biliary strictures. The CSEMS group had a significantly higher rate of migration and pancreatitis than the USEMS group. No significant SEMS-related adverse events were observed in patients undergoing neoadjuvant chemoradiation or surgical resection.

Comparison of uncovered and covered stents for the treatment of malignant duodenal obstruction caused by pancreaticobiliary cancer

BACKGROUND

Few clinical studies to date have compared different types of self-expandable metallic stents (SEMS) and their outcomes in patients with pure duodenal obstruction caused by pancreaticobiliary cancer. The aim of this study was to compare the clinical effectiveness and side effects of uncovered and covered SEMS for the palliation of duodenal obstruction caused by pancreaticobiliary cancer.

METHODS

We retrospectively analyzed all patients with pancreaticobiliary cancer who underwent upper endoscopy with SEMS placement for malignant duodenal obstruction at the National Cancer Center of Korea between April 2003 and December 2010. The technical and clinical success rates of the procedure, complications, and durations of stent patency and overall survival were evaluated.

RESULTS

We identified 70 patients with a mean age of 51.2 years (range = 39-81 years); of these, 46 (65.7 %) had pancreatic cancer, 9 (12.9 %) had bile duct cancer, 11 (15.7 %) had gallbladder cancer, and 4 (5.7 %) had cancer of the ampulla of Vater. Twenty-four patients (34.3 %) received covered SEMSs and 46 (65.7 %) received uncovered SEMSs. Technical and clinical success rates were similar for the covered and uncovered stent groups. The complication rate was higher in the covered than in the uncovered group (62.5 vs. 34.8 %, P = 0.025), due primarily to a significantly higher stent migration rate (20.8 vs. 0 %, P = 0.004). Perforation as a late complication occurred in four patients, two in each group (8.3 vs. 4.3 %, P = 0.425). Stent patency tended to be shorter for covered than for uncovered duodenal stents (13.7 ± 8.6 weeks vs. not reached, P = 0.069).

CONCLUSIONS

The use of uncovered stents may be a preferred option for duodenal obstruction secondary to pancreaticobiliary malignancies, since they were effective in preventing stent migration and tended to have longer patency than covered stents. Careful attention should be paid to signs and symptoms of perforation during follow-up.

Biliary self-expandable metallic stent for unresectable malignant distal biliary obstruction: which is better: covered or uncovered?

Self-expandable metallic stents (SEMS) are a widely accepted biliary endoprosthesis for patients with unresectable malignant distal biliary obstruction. There are two types of SEMS: covered and uncovered. Uncovered SEMS (UCSEMS) embed into the biliary wall due to their mesh structure and self-expandability, and are resistant to migration. However, the disadvantage of UCSEMS is occlusion due to tumor ingrowth (TI) via the stent mesh, and TI is the main cause of UCSEMS occlusion. To overcome this, covered SEMS (CSEMS) were developed and showed longer patency than UCSEMS. However, migration due to the non-embedded stent body is the main cause of CSEMS dysfunction. There are some randomized studies comparing CSEMS and UCSEMS; however, the results are different according to each study. From one meta-analysis, CSEMS showed longer patency than UCSEMS. A literature review revealed that covered SEMS showed longer patency than UCSEMS. Some studies cannot clearly demonstrate the superiority of CSEMS, as the CSEMS used did not prevent TI or migration. Mechanical properties of SEMS may influence the occurrence of complications. A recent clinical study comparing the Covered Wallstent and the Covered WallFlex revealed superiority of the WallFlex for the prevention of migration. Reducing the axial force and increasing the radial force may lead to good results. Migration of CSEMS should be prevented by taking into consideration the mechanical properties of stents and development of anti-migration systems.

Feasibility of a new self-expandable metallic stent for patients with malignant colorectal obstruction

AIM

Stent migration due to peristalsis of the colon is one of the unresolved complications of colonic self-expandable metallic stent (SEMS) placement. Axial force (AF), a recovery force of the stent to a straight position after bending, has been considered a factor influencing the conformability of the digestive tract. An uncovered SEMS (Niti-S Enteral Colonic Uncovered Stent, D-type; Taewoong, Inc., Gimpo, South Korea) with improved conformability is considered to decrease migration.

METHODS

Thirty three consecutive patients with symptomatic colorectal obstruction between March 2006 and December 2011 underwent endoscopic stent placement for palliation to estimate the efficacy and safety of Niti-S stents prospectively in four tertiary referral centers.

RESULTS

Technical and clinical success rates were 100% and 97%, respectively. Seventeen patients had the following complications: ingrowth (n = 6), overgrowth (n = 1), collapse of the SEMS (n = 1), stool impaction (n = 2), migration (n = 1), bleeding (n = 3), and tenesmus (n = 3). The patient with migration had no recurrent symptoms until death. Of these 17 patients, 10 required re-interventions. Seven patients underwent an additional SEMS implantation. One patient underwent surgery for stoma creation. Two patients had stool impaction, and they underwent endoscopic cleaning. The median duration of patency was 347.0 ± 65.5 days. The mean survival time after stent insertion was 240.1 ± 39.9 days.

CONCLUSION

The new SEMS effectively relieves malignant colorectal obstruction. Good conformability, according to the very low AF, may contribute to the low incidence of migration.

What is the ideal stent as initial intervention for malignant gastric outlet obstruction?

BACKGROUND

Self-expandable metal stents are effective palliation for malignant gastric outlet obstruction. The aims of study were to evaluate efficacy and safety of double-layered Comvi, uncovered and covered stent to find out protocols which enhance stent patency.

METHODS

We retrospectively analysed data from 224 patients who underwent endoscopic stent placement for malignant gastric outlet obstruction caused by stomach cancer from 2006 to 2011. Technical and clinical success rates were evaluated and clinical outcomes were compared according to stent types and chemotherapy.

RESULTS

The overall technical and clinical success rates were achieved in 99.6% and 80.4%, respectively without immediate complications. The clinical success rate was not significantly different between three groups. The median stent patency time was 156 days [interquartile range 66-279] without differences between groups. The 4-, 8-, and 12-week patency rates were 89.4%, 77.3%, and 61.2%, respectively with no differences between groups. The re-stenosis of stent frequently occurred in the case of the uncovered stents, while migration was more likely to be observed for the covered and Comvi stent. Chemotherapy significantly lowered re-intervention rates, especially in uncovered stents.

CONCLUSIONS

Patency rates are significantly improved by combining the use of uncovered stent with follow-up chemotherapy treatment, which retains the advantages of the mechanical and chemical aspects of stent and chemotherapy, respectively.

Japanese multicenter estimation of WallFlex duodenal stent for unresectable malignant gastric outlet obstruction

AIM

This retrospective study estimated the efficacy and safety of the WallFlex duodenal stent for malignant gastric outlet obstruction (GOO) in Japan.

METHODS

Forty-two consecutive patients with symptomatic malignant GOO were treated using WallFlex duodenal stents between January 2010 and October 2010.

RESULTS

The technical and clinical success rates were 100% and 83.3%, respectively.The median gastric outlet obstruction scoring system increased significantly, from 0 to 2, after stent placement (P < 0.01).The median survival time was 3.3 months (95% confidence interval (CI), 1.8-6.0 months), and the median eating period was 3.0 months (95% CI, 1.1-4.3 months). Re-intervention was required in 11 patients (26.2%). The complication rate was 26.2%. The major complication was stent occlusion (23.8%) by tumor ingrowth, which occurred in nine (21.4%) patients, and tumor overgrowth, which occurred in one (2.4%) patient. Stentmigration, perforation, and food impaction without stent occlusion were not observed.The median survival time of the patients with stent occlusion was 11.7 months (95% CI, 2.2 months - not reached), and the median stent patency of these patients was 4.0 months (95% CI, 0.8-4.7 months).These patients were successfully treated with additional stent insertion using a stent-in-stent procedure.

CONCLUSION

Duodenal stent placement using a WallFlex duodenal stent was safe and effective for managing malignant GOO.This stent is an uncovered metallic stent, and the major problem was stent occlusion due to tumor ingrowth. However, the occluded stent could be corrected by inserting an additional duodenal stent.

Predictive factors for pancreatitis and cholecystitis in endoscopic covered metal stenting for distal malignant biliary obstruction

BACKGROUND AND AIM

Pancreatitis and cholecystitis are major complications after self-expandable metal stent (SEMS) placement in distal malignant biliary obstruction. We aimed to clarify predictive factors for pancreatitis and cholecystitis after covered SEMS placement.

METHODS

We retrospectively reviewed 74 consecutive patients with distal malignant biliary obstruction who underwent initial endoscopic drainage using covered SEMS. Predictive factors for pancreatitis and cholecystitis were evaluated in the 74 patients described above and in 66 patients who had not undergone cholecystectomy.

RESULTS

The incidences of pancreatitis and cholecystitis were 10.8% (8/74) and 6.1% (4/66), respectively. Univariate analysis revealed that non-pancreatic cancer (P = 0.018) and contrast injection into the pancreatic duct (P = 0.030) were significant predictive factors for pancreatitis. Multivariate analysis revealed that non-pancreatic cancer (odds ratio [OR], 4.21; 95% confidence interval [CI], 1.63-14.18; P = 0.007) and contrast injection into the pancreatic duct (OR, 3.34; 95% CI, 1.33-9.60; P = 0.016) were significant independent predictive factors for pancreatitis. On the other hand, univariate and multivariate analyses revealed that tumor involvement to the orifice of the cystic duct (OCD) was a significant independent predictive factor for cholecystitis (OR, 5.85; 95% CI, 1.91-27.74; P = 0.005).

CONCLUSIONS

Non-pancreatic cancer and contrast injection into the pancreatic duct were predictive factors for pancreatitis, and tumor involvement to the OCD was a positive predictive factor for cholecystitis after endoscopic covered SEMS placement for distal malignant biliary obstruction.

Favorable long-term clinical outcome of uncovered D-weave stent placement as definitive palliative treatment for malignant colorectal obstruction

BACKGROUND

Most self-expandable metallic stents for colorectal placement are uncovered because of the high migration rate of covered stents. However, the optimal stent design for colorectal use remains unclear.

OBJECTIVE

The purpose of this study was to evaluate the efficacy and safety of a double-wire woven uncovered stent for definitive palliative treatment of malignant colorectal obstruction.

DESIGN

This study was a prospective, single-arm, observational clinical study of patients enrolled between December 2005 and September 2010.

SETTINGS

This study was conducted at a referral hospital in Japan.

PATIENTS

Twenty-four consecutive patients with malignant colorectal obstruction were included in the study.

INTERVENTIONS

A double-wire woven uncovered stent was placed by use of a standard through-the-scope endoscopic placement technique.

MAIN OUTCOME MEASURES

Technical, initial clinical, and long-term clinical success were measured. Long-term clinical success was defined as sustained relief of obstructive symptoms without reintervention until the patient's death.

RESULTS

The Karnofsky performance status score before stent placement was 60 (median, interquartile range, 42.5-67.5). Twenty of 24 patients had primary colorectal cancer, and 4 had extracolorectal malignancies. The site of obstruction was the ascending colon in 10 patients, descending colon in 4 patients, sigmoid colon in 7 patients, and rectum in 3 patients. Technical, initial, and long-term clinical success rates were 100%, 100%, and 83%. Median stent patency time was 149 days (interquartile range, 45-198 days). Median survival time after stent placement was 155 days (interquartile range, 68-231 days). Four patients (17%) had negative outcomes including stent occlusion by tumor ingrowth (8%) and stent migration (8%). The highest Karnofsky performance status score after stent placement was 70 (median; interquartile range, 50-70). The Karnofsky performance status score improved after stent placement (p = 0.002).

LIMITATIONS

This study was limited because it was a single-arm, single-center study, and it had a small sample size.

CONCLUSIONS

Endoscopic placement of double-wire woven uncovered stents is effective and safe as definitive palliative treatment for patients with malignant colorectal obstruction.

Endoscopic retrograde cholangiopancreatography for distal malignant biliary stricture

Endoscopic biliary stent placement is widely accepted as palliation for malignant biliary obstruction or as a treatment of benign biliary stricture. Although various biliary stent designs have become available since self-expandable metallic stents were introduced, no single ideal stent has been developed. An ideal stent should be patent until death, or surgery, in patients with resectable malignant biliary obstruction. Fewer complications, maneuverability, cost-effectiveness, and removability are also important factors. Alternatively, should we develop a novel method for biliary drainage other than biliary stenting via endoscopic retrograde cholangiopancreatography? This article reviews the current status of biliary stenting for malignant biliary obstructions.

Comparison of partially covered nitinol stents with partially covered stainless stents as a historical control in a multicenter study of distal malignant biliary obstruction: the WATCH study

BACKGROUND

Covered self-expandable metal stents (CSEMSs) were developed to prevent tumor ingrowth, but stent migration is one of the problems with CSEMSs.

OBJECTIVE

To evaluate a new, commercially available CSEMS with flared ends and low axial force compared with a commercially available CSEMS without the anti-migration system and high axial force.

DESIGN

Multicenter, prospective study with a historical cohort.

SETTING

Twenty Japanese referral centers.

PATIENTS

This study involved patients with unresectable distal malignant biliary obstruction.

INTERVENTION

Placement of a new, commercially available, partially covered SEMS.

MAIN OUTCOME MEASUREMENTS

Recurrent biliary obstruction rate, time to recurrent biliary obstruction, stent-related complications, survival.

RESULTS

Between April 2009 and March 2010, 141 patients underwent partially covered nitinol stent placement, and between May 2001 and January 2007, 138 patients underwent placement of partially covered stainless stents as a historical control. The silicone cover of the partially covered nitinol stents prevented tumor ingrowth. There were no significant differences in survival (229 vs 219 days; P = .250) or the rate of recurrent biliary obstruction (33% vs 38%; P = .385) between partially covered nitinol stents and partially covered stainless stents. Stent migration was less frequent (8% vs 17%; P = .019), and time to recurrent biliary obstruction was significantly longer (373 vs 285 days; P = .007) with partially covered nitinol stents. Stent removal was successful in 26 of 27 patients (96%).

LIMITATIONS

Nonrandomized, controlled trial.

CONCLUSION

Partially covered nitinol stents with an anti-migration system and less axial force demonstrated longer time to recurrent biliary obstruction with no tumor ingrowth and less stent migration.

Biliary leak in post-liver-transplant patients: is there any place for metal stent?

Objectives. Endoscopic management of bile leak after orthotopic liver transplant (OLT) is widely accepted. Preliminary studies demonstrated encouraging results for covered self-expandable metal stents (CSEMS) in complex bile leaks. Methods. Thirty-one patients with post-OLT bile leaks underwent endoscopic temporary placement of CSEMS (3 partially CSEMS , 18 fully CSEMS with fins and 10 fully CSEMS with flare ends) between December 2003 and December 2010. Long-term clinical success and safety were evaluated. Results. Median stent indwelling and follow-up were 89 and 1,353 days for PCSEMS, 102 and 849 for FCSEMS with fins and 98 and 203 for FCSEMS with flare ends. Clinical success was achieved in 100%, 77.8%, and 70%, respectively. Postplacement complications: cholangitis (1) and proximal migration (1), both in the FCSEMS with fins. Postremoval complications were biliary strictures requiring drainage: PCSEMS (1), FCSEMS with fins (6) and with flare ends (1). There was no significant differences in the FCSEMS groups regarding clinical success, age, gender, leak location, previous treatment, stent indwelling, and complications. Conclusion. Temporary placement of CSEMS is effective to treat post-OLT biliary leaks. However, a high number of post removal biliary strictures occurred especially in the FCSEMS with fins. CSEMS cannot be recommended in this patient population.

Management of malignant gastric outlet obstruction with a modified triple-layer covered metal stent

BACKGROUND

A high incidence of migration with covered metal stents has been reported in malignant gastric outlet obstruction (GOO). A newly modified, partially covered, triple-layer nitinol stent was developed that has a longer uncovered portion (5-15 mm) to prevent stent migration.

OBJECTIVE

To estimate the efficacy and safety of the modified covered, triple-layer metal stent.

DESIGN

Multicenter, prospective cohort study.

SETTING

Three tertiary referral centers.

PATIENTS

Fifty consecutive patients (26 with pancreatic carcinoma, 14 with gastric carcinoma, 9 with cholangiocarcinoma, 1 with a metastatic node) who presented with symptomatic unresectable malignant GOO between April 2007 and March 2010.

INTERVENTIONS

Endoscopic placement of the modified covered, triple-layer metal stent.

MAIN OUTCOME MEASUREMENTS

The primary endpoint was to improve the GOO scoring system (GOOSS) score. Secondary endpoints were success rate, patency, and complications.

RESULTS

The median GOOSS score improved significantly (P < .0001) after stenting (from 0 to 3). The technical and clinical success rates were 100% and 90%, respectively. Stent occlusion by tumor overgrowth or ingrowth at the uncovered portion developed in 5 patients (10%). Asymptomatic stent migration occurred in 3 patients (6%) receiving chemotherapy at 95, 230, and 553 days after stent placement, but these patients tolerated solid food 68, 260, and 142 days after stent migration, respectively. Other complications occurred in 1 patient with insufficient expansion, cholangitis, and pancreatitis. No procedure-related deaths occurred.

LIMITATIONS

A single-arm study in tertiary-care centers.

CONCLUSIONS

The modified covered, triple-layer metal stent was effective and safe for managing malignant GOO and can prevent tumor ingrowth and stent migration. (

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000004566.).

Self-expandable metal stents in malignant biliary obstruction

Malignant biliary obstruction can be due to direct tumor infiltration, extrinsic compression, adjacent inflammation, desmoplastic reaction from tumors or, more commonly, a combination of the above factors. Pancreatic cancer is the most common cause of malignant biliary obstruction, and jaundice occurs in 70-90% of the patients during the course of the disease. Compared with the uncovered metal stents, covered metal stents have longer patency and a lower rate of tumor ingrowth, but have a higher rate of stent migration. To combat the occlusion and provide an antitumor effect, drug-eluting stents were developed. A duodenal stricture complicates biliary stent placement in 10-20% of patients with distal biliary obstruction due to pancreatic cancer. When both strictures are considered, a biliary stent can be placed either preceding or following duodenal stent placement. Complications of self-expandable metal stents include stent occlusion, stent migration, cholecystitis and pancreatitis.

Endoscopic bilateral metallic stenting for malignant hilar obstruction using newly designed stents

BACKGROUND/PURPOSE

Whether unilateral or bilateral drainage should be performed for malignant hilar biliary obstruction is controversial. Moreover, endoscopic placement of bilateral metallic stents is difficult and complicated.

METHODS

New metallic stents, such as the Niti-S Y-type stent (Y-stent), BONASTENT M-Hilar, and Niti-S large cell D-type stent (LCD), have recently been developed for bilateral stent-in-stent procedures to facilitate contralateral stent deployment through the interstices of the first metallic stent. We review the features and efficacy of these metallic stents designed for bilateral drainage in patients with hilar biliary obstruction.

RESULTS

The newly designed stents examined exhibited high technical success rates, low stent-related complications, and good stent patency. Endoscopic reinterventions for occluded stents could be performed easily, particularly in patients with bilateral LCD placement.

CONCLUSION

Endoscopic bilateral stenting using newly designed metallic stents is feasible, safe, and effective in patients with unresectable malignant hilar biliary obstruction.

Risk factors for pancreatitis following transpapillary self-expandable metal stent placement

BACKGROUND

Pancreatitis is one of complications after self-expandable metal stent (SEMS) placement. The purpose of this study was to evaluate risk factors for pancreatitis after endoscopic SEMS placement for malignant biliary obstruction (MBO).

METHODS

We retrospectively reviewed 370 consecutive patients who underwent initial transpapillary SEMS placement for biliary decompression. The characteristics of inserted SEMSs were classified according to axial and radial force.

RESULTS

Pancreatitis following SEMS insertion was observed in 22 patients (6%). All of them were mild according to consensus criteria. Univariate analysis indicated that injections of contrast into the pancreatic duct (frequency of pancreatitis, 10.3%), the placement of an SEMS with high axial force (8.3%), and nonpancreatic cancer (16.1%) significantly contributed to the development of pancreatitis, whereas female gender, a younger age, a covered SEMS, and a SEMS with high radial force or without a biliary sphincterotomy did not. In a multivariate risk model, SEMSs with high axial force (odds ratio [OR], 3.69; p = 0.022) and nonpancreatic cancer (OR, 5.52; p < 0.001) were significant risk factors for pancreatitis.

CONCLUSIONS

SEMSs with high axial force and an etiology of MBO other than pancreatic cancer were strongly associated with a high incidence of pancreatitis following transpapillary SEMS placement in patients with distal MBO.

Results of a Japanese multicenter, randomized trial of endoscopic stenting for non-resectable pancreatic head cancer (JM-test): Covered Wallstent versus DoubleLayer stent

BACKGROUND

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).

PATIENTS & METHODS

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.

RESULTS

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.

CONCLUSION

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.

Complex biliary stones: treatment with removable self-expandable metal stents: a new approach (with videos)

BACKGROUND

Complex biliary stones often require temporary stent placement before a repeat attempt at extraction. To date, covered self-expandable metal stents (CSEMSs) have not been formally investigated for this indication.

OBJECTIVE

To evaluate the efficacy and safety of CSEMSs in patients with retained complex biliary stones.

DESIGN

Retrospective case series.

SETTING

Large quaternary-care center.

PATIENTS

Thirty-six patients (24 women) with complex biliary stones with incomplete stone clearance after endoscopic retrograde cholangiography (ERC) with biliary sphincterotomy.

INTERVENTIONS

Patients with incomplete stone clearance after ERC with biliary sphincterotomy underwent temporary placement of CSEMSs, with subsequent removal before repeat stone extraction.

MAIN OUTCOME MEASUREMENTS

Success achieving immediate biliary drainage and eventual complete duct clearance. Procedure-related complications were also assessed.

RESULTS

CSEMS placement was successful in establishing immediate biliary drainage in all 36 patients. Complete duct clearance at repeat ERC was achieved in 29 of 35 patients after a mean duration of 6.4 weeks. Four of the remaining 6 patients underwent sequential CSEMS placement, with eventual duct clearance after multiple ERCPs. There were no complications related to biliary obstruction. One patient died of a nonbiliary cause. Of the total 42 CSEMSs placed, there were 4 cases (9.5%) of clinically insignificant stent migration.

LIMITATIONS

Single-center experience, retrospective design.

CONCLUSIONS

CSEMSs permit management of complex biliary stones, but require multiple sessions. The cost-effectiveness of this technique needs further investigation.

Duodenal invasion is a risk factor for the early dysfunction of biliary metal stents in unresectable pancreatic cancer

BACKGROUND

Although the placement of self-expandable metal stents (SEMSs) has been widely accepted as palliation for distal malignant biliary obstruction, the risk factors for their early dysfunction remain unclear.

OBJECTIVE

To identify risk factors for early (<3 months) SEMS dysfunction in unresectable pancreatic cancer.

DESIGN

A multicenter retrospective study.

SETTING

Five tertiary referral centers.

PATIENTS

Patients were included who underwent first-time SEMS placement for distal malignant biliary obstruction caused by pancreatic cancer between April 1994 and August 2010.

MAIN OUTCOME MEASUREMENTS

Rates and causes of early dysfunction were evaluated, and risk factors were analyzed.

RESULTS

In all, 317 eligible patients were identified. Covered SEMSs were placed in 82% of patients. Duodenal invasion was observed endoscopically in 37%. The median time to dysfunction was 170 days. The rates of all and early SEMS dysfunction were 55% and 31%, respectively. The major causes of SEMS dysfunction were food impaction and nonocclusion cholangitis (21% each) in early dysfunction and sludge (29%) in nonearly dysfunction. The rate of early dysfunction was 42% with duodenal invasion and 24% without duodenal invasion (P = .001). Early dysfunction caused by food impaction was more frequent in patients with duodenal invasion (10% and 4%, P = .053). Duodenal invasion was a risk factor (odds ratio 2.35; 95% CI, 1.43-3.90; P = .001) in a multiple logistic regression model.

LIMITATIONS

A retrospective design.

CONCLUSIONS

Duodenal invasion is a risk factor for early SEMS dysfunction in patients with pancreatic cancer.

Fully covered self-expanding metal stents placed temporarily in the bile duct: safety profile and histologic classification in a porcine model

BACKGROUND

Fully covered Self-Expanding metal stents (FCSEMS) have been shown efficacious in palliating malignant biliary obstructions. There is little data analyzing mucosal response to their temporary placement in the bile duct.

METHODS

Ten mini pigs underwent endoscopic placement of a FCSEMS (Wallflex, Boston Scientific). FCSEMS were kept in place for three months. At the end of the 3 months, FCSEMS were removed endoscopically. Five pigs were euthanized and their bile ducts harvested. The other five were kept alive for another month post removal. A single pathologist, created a scoring system (to determine degree of inflammation, fibrosis, and epithelial injury), examined all specimens in a blinded fashion.

RESULTS

Four FCSEMS spontaneously migrated in the duodenum. On post mortem examination, mild mucosal thickness was noted in three bile duct specimens while superficial inflammation of the bile duct was noted in five animals. Histologic examination of the bile duct revealed focal acute inflammation in both groups. For the 5 animals euthanized immediately after stent removal, there was a tendency to have superficial mucosal erosion and fibrosis. In contrast, increased chronic inflammation was more commonly seen in the animals 1 month post stent removal, with all animals in this group showing moderate degrees of mononuclear inflammatory cell mucosal infiltrates. No severe inflammatory or fibrotic duct injury was observed in any of the study animals, with degree of injury graded as mild to moderate.

CONCLUSION

FCSEMS appear to induce minimal tissue overgrowth or fibrosis post placement. Ease of removability and no significant histologic injury are advantages noted with FCSEMS., however, further studies are needed to evaluate treating benign biliary strictures with FCSEMS in humans.

Fully-covered, self-expandable metal stents (CSEMS) in malignant distal biliary strictures: mid-term evaluation

BACKGROUND AND AIMS

Limited data exist regarding fully-covered, self-expandable metal stents (CSEMS) with anchoring fins for the management of malignant distal biliary strictures. The aim of this study is to evaluate their safety and patency.

METHODS

Over a period of 2 years, 70 patients (45 males, 66 ± 13 years) underwent endoscopic retrograde cholangiopancreatography (ERCP) with placement of a 10-mm (67 patients) or 8-mm diameter (3 patients) CSEMS for the palliation of distal malignant biliary obstruction (pancreatic [53] or other [17]). Data were collected prospectively for survival and stent patency; complications were evaluated retrospectively.

RESULTS

After CSEMS placement, 17 patients proceeded to surgery, and 53 patients were deemed unresectable. Mean survival for non-surgical candidates was 180 days (range: 15-1091), and 170 days (range: 9-589) for patients who underwent surgical management. CSEMS were left in place and remained patent for a mean of 163 days (range: 15-1091) in non-surgical candidates, and a mean of 55 days (range: 5-126) in surgical candidates. Complications during placement included wire perforations (4) and proximal deployment requiring repositioning (4), one of which was complicated by a bile leak. Post-procedure complications were observed in 24 cases (34%) and included post-ERCP pancreatitis (8, with 2 of them severe), post-procedure pain (5, with 3 requiring admission), cholecystitis (3), stent occlusion (3), cholangitis (2), proximal migration (1), post-sphincterotomy bleeding (1), and sepsis leading to death (1).

CONCLUSION

CSEMS appear to provide acceptable short-term patency rates; however, their limited long-term patency and high complication rate might limit their widespread use. Further long-term prospective data are required to confirm this observation.

A multicenter prospective study of the short-term outcome of a newly developed partially covered self-expandable metallic biliary stent (WallFlex(®))

BACKGROUND

Self-expandable metallic stent (SEMS) placement is a widely used, effective therapy for unresectable malignant stricture of the lower bile duct.

AIMS

We evaluated the short-term outcome of the newly developed WallFlex(®) Biliary RX Partially Covered Stent in patients with malignant lower and middle biliary stricture in five tertiary referral centers.

METHODS

The subjects of this study were 52 patients in whom WallFlex(®) Biliary RX Stents were inserted into the bile duct for malignant stenosis of the middle and lower bile duct at five medical facilities between April 2009 and November 2009.

RESULTS

The stent placement success rate was 100%. Effective biliary decompression was achieved in all patients. The incidence of early complications was 7.7% (4/52). Stent occlusion occurred in two patients (3.8%) (one dislocation, one migration); cholecystitis occurred in two patients (3.8%). Neither acute pancreatitis nor stent kinking in the bile duct occurred.

CONCLUSIONS

The present results revealed that the new WallFlex(®) Biliary RX Partially Covered SEMSs were useful for the short-term relief of biliary obstruction due to unresectable distal biliary malignancies.

A multicenter analysis of safety and outcome of removal of a fully covered self-expandable metal stent during ERCP

BACKGROUND

Fully covered self-expandable metal stents (FCSEMSs) have been used for palliation of both malignant and benign biliary strictures. Limited data are available about safety and outcome of endoscopic removal of these stents.

OBJECTIVE

To evaluate safety and efficacy of endoscopic removal of FCSEMSs.

DESIGN

Retrospective review of patients who underwent endoscopic removal of Viabil FCSEMSs.

SETTING

Four centers with experience in using FCSEMSs.

PATIENTS

Thirty-seven patients who had stents endoscopically removed.

INTERVENTION

ERCP with endoscopic removal of FCSEMSs.

MAIN OUTCOME MEASUREMENTS

Feasibility, safety, and complications associated with endoscopic removal of FCSEMS.

RESULTS

All 37 stent removal attempts were successful and were achieved without difficulty. Indwelling stent-related complications occurred in 4 of 37 patients, including secondary strictures in 3 and minor bile leak in 1. Two of 3 secondary strictures occurred at the distal stent margin of oversized intraductal stents, and another stricture occurred at a proximal stent margin of an oversized transpapillary stent. One case of minor confined intratumoral bile leak also occurred in a patient with metastatic urothelial cancer of the bile duct. All of these cases were successfully treated with repeat stenting and resolved without sequelae. No free perforations or significant bleeding occurred.

LIMITATIONS

Retrospective study.

CONCLUSION

Endoscopic removal of Viabil FCSEMSs placed for benign or malignant conditions is feasible and easily accomplished. Secondary strictures may be found at the time of stent removal or with a delayed presentation in patients with oversized stents who may require repeat stent placement.