Uncovered Self-expandable Metal Stents Research Articles

Efficacy and safety of the covered Wallstent in patients with distal malignant biliary obstruction

The aim of this study was to evaluate the efficacy and the safety of the covered Wallstent, a commercially available silicone-covered, self-expandable metallic stent (covered Wallstent), for the treatment of distal malignant biliary obstruction. Sixty-nine consecutive patients with unresectable distal malignant biliary obstruction who underwent covered Wallstent placement between October 2001 and October 2003 were studied at 4 affiliated hospitals. Mean stent patency and mean survival were 139.1 days and 200.9 days, respectively. Stent occlusion occurred in 7 cases (10.1%), but tumor ingrowth was not observed. Seventeen complications, including 5 cholangitis (7.2%), 4 stent migration (5.8%), 4 cholecystitis (5.8%), and 4 pancreatitis (5.8%) were observed in 16 patients (23.2%). Stent misplacement was observed in 7 patients (10.1%). Covered Wallstent is effective in preventing tumor ingrowth for the treatment of distal malignant biliary obstruction. However, the overall complication rate may be higher than uncovered self-expanding metal stents and covered self-expanding metal stents of different design.

Common Bile Duct Strictures Due to Chronic Pancreatitis Managed by Self-Expandable-Metal Stents (SEMS): Results of a Long-Term Follow-Up Study

Background: Common bile duct (CBD) strictures are a common complication of chronic pancreatitis (CP). Successful dilation of these strictures by insertion of an increasing number of plastic stents is not effective as in the setting of postoperative bile duct stenoses. Aim: To evaluate long-term results of the management of CP-related CBD strictures by SEMS. Methods: From 1990 to 2002, 24 patients (21 M, mean age 48 yrs) with a symptomatic CP-related CBD stricture refractory to plastic stenting that refused surgery, were treated by placement of a biliary SEMS at our institution. Seven (29%) patients had pancreatic calcifications. All patients had a minimum follow-up of 2 years, and SEMS patency was assessed. Results: Eighteen (75%) uncovered SEMS were inserted. Eight (33%) patients still had a functioning SEMS after a mean period of 52 months (range 26-121). Sixteen (66%) patients developed a SEMS malfunction after a mean period of 39 months (range 5-103). Follow-up of patent covered SEMS was 35 months (range 33-37) while that for uncovered SEMS was 61 months (range 26-121). Patency of clogged SEMS according to stent features is summarized in the Table. Conclusions: Placement of SEMS in CBD strictures secondary to CP could be a valid alternative to surgery. Covered stents were placed only during recent years and longer follow-up is necessary to compare covered and uncovered SEMS in this kind of biliary stenoses.

A Randomized Controlled Comparative Study of Covered Versus Uncovered Self-Expandable Metal Stent for Malignant Biliary Obstruction

BACKGROUND/AIM: Self-expandable metal stents (SEMS) with various designs have been developed to improve clinical efficacy for treatment of malignant biliary obstruction. However, a lot of articles previously published for SEMS study reported a variety of efficacy of covered SEMS. We performed this study to compare the safety and clinical efficacy of membrane-covered SEMS (Shim-Hanarostent, M.I.Tech, Seoul, Korea) and uncovered SEMS (Hanarostent, M.I.Tech, Seoul, Korea) in a prospective randomized controlled trial. METHODS: There were 43 consequent patients, including 26 men and 17 women, with a mean age of 70 years (range, 49-87) who were diagnosed as malignant biliary obstruction. The etiology of the strictures included pancreatic cancer (17), cholangiocarcinoma (17), ampullary cancer (4), and gall bladder cancer (5). Patients were randomly assigned to covered or uncovered stent. After insertion of the stent, we followed up symptoms, LFT and abdominal US. We performed ERCP & mother-baby scopy in occluded cases. In case of stent malfunction, we inserted plastic stent into the metal stent. The survival rates of the patient and the stent's patency rates were calculated using Kaplan-Meier survival analysis. Serum bilirubin, amylase and lipase levels were evaluated in regular interval, and the mean differences of these data before and after stenting were evaluated using a Wilcoxon signed-rank test. The average follow-up duration was median 5.3 months (range, 0.8-29 months). RESULTS: Endoscopic procedures were successful (including complete relief of jaundice) in all cases. Late complications such as tumor ingrowth etc. occurred in 11 of 21 patients with uncovered stents, as compared with 4 of 22 patients in the covered group (p < 0.05). Median stent patency of covered and uncovered stent were 216 days (range 76 to 760 days) and 127 days (range 25 to 447 days), respectively (p < 0.05). Life table analysis showed similar survival in both groups. CONCLUSION: Membrane-covered self-expandable biliary metal stents have a significantly better palliation than uncovered metal stents in the treatment of patients with malignant biliary obstruction.

Early Complication of Endoscopic Biliary Stenting in Patients with Inoperable Malignant Biliary Stricture

BACKGROUND/AIM: Early complication rates and relative risk factor after endoscopic biliary stenting in patients with inoperable malignant biliary stricture has not yet been established. The aim of this study was to evaluate the occurrence rates of important early complication and it's relative risk factors after endoscopic biliary stenting in patients with inoperable malignant biliary stricture. METHODS: From Feb. 2001 to Aug. 2003, total 132 patients (men 90, women 42, mean age: 65.5 years) with inoperable malignant biliary stricture were performed endoscopic biliary stenting. Membrane covered self-expandable metal stent (MCSEMS) in 33 patients, membrane uncovered SEMS (UCSEMS) in 14 patients and plastic stent (PS) in 85 patients were inserted. Patients were retrospectively investigated the occurrence rates of cholecystitis and pancreatitis and it's relative risk factors. RESULTS: 1) Causes of malignant biliary stricture were Klatskin tumor; 44, pancreatic ca; 32, distal CBD ca; 23, AV ca; 14, GB ca; 13, and metastatic ca; 6 cases. 2) As an early complication (within 30 days), pancreatitis and cholecystitis were occurred in 11 (8.3%) and 5 (3.8%) cases, respectively. Pancreatitis and cholecystitis were developed in 9/85 (10.6%) and 4/85 (4.7%) cases of PS group and 2/33 (6.1%) and 1/33 (3.0%) cases of MCSEMS group, respectively. In UCSEMS group, pancreatitis and cholecystitis were not developed. Pancreatitis and cholecystitis were was developed in 4/ 44 (9.1%) and 2/44 (4.5%) cases of Klatskin tumor, 3/32 (9.4%) and 0 cases of pancreatic ca, 2/23 (8.7%) and 2/23 (8.7%) cases of distal CBD ca, 1/14 (7.1%) and 0 case of AV ca, 0 and 1/13 (7.7%) case of GB ca, 1/6 (16.7%) and 0 case of metastatic ca, respectively. The occurrence rate of pancreatitis or cholecystitis was not significantly different between the types of inserted stent and primary tumor. 3) Pancreatitis was significantly increased in the younger than 55 years old patients (p=0.009). 4) Cystic duct invasion of primary tumor significantly increased the occurrence rate of cholecystitis (p=0.01). CONCLUSIONS: Occurrence rate of pancreatitis or cholecystitis after endoscopic biliary stenting is not related to the types of stent and causes of malignant biliary stricture. Cystic duct invasion of tumor and patients with younger than 55 years old were relative risk factors for development of acute cholecystitis and pancreatitis, respectively. Further prospective studies with large number of cases will be needed.

Tracheobronchial obstruction in children: experience with endoscopic airway stenting

Background We reviewed our experience to determine the role of endoscopic airway stents in children with tracheobronchial obstruction. Methods Seventeen children (10 boys and 7 girls) aged 2 months to 16 years underwent tracheobronchial stenting. Etiology of the tracheobronchial obstruction included external vascular compression (n = 9); tracheobronchial anastomotic strictures after heart-lung/lung transplantation (n = 4); airway compression by malignant mediastinal mass (n = 2), and subglottic/high tracheal stenosis after prolonged intubation with a tracheostomy in situ (n = 2). Indications for airway stenting were failure to wean from ventilator after a mean of 82.5 days (range, 2 to 210) in 8 children; and dyspnea or stridor in the remaining 9 children. Results Ten children had a total of 24 uncovered self-expanding metal stents (either Magic Wallstent or Ultraflex Microvasive) and 7 children had silicone stents (2 straight, 3 Y and 2 T tube stents). At follow-up at 1 week to 72 months (median 21), only 8 of 17 (47%) children were alive but all the deaths were secondary to the underlying pathology and not related to tracheobronchial stenting. Six of 8 ventilator-dependent children were extubated after a mean of 5.3 days (range, 2 to 11) after airway stenting. For the 9 children stented for dyspnea, mean Medical Research Council dyspnea score decreased from 3.0 to 1.6 after stenting. Conclusions Tracheobronchial stenting in children is only rarely needed and often undertaken in dire circumstances. The procedure has led to significant symptomatic benefit in dyspneic children and has enabled ventilator-dependent children to be extubated. Medium-term outlook after stenting with self-expanding metal stents for vascular compression of the airway is encouraging. The long-term outcome remains uncertain, however, and is ultimately influenced by the underlying disease.

Self-Expandable Metal Stents in the Management of Cervical Oesophageal and/or Hypopharyngeal Strictures

AIM: To assess the usefulness of self-expandable metal stents in the recanalization of cervical and/or hypopharyngeal strictures. MATERIALS AND METHODS: We report our experience in 10 patients with inoperable cervical and/or hypopharyngeal strictures treated by implantation of 11 uncovered self-expandable metal stents inserted perorally under fluoroscopic guidance. The stent was placed in the hypopharynx and cervical oesophagus in 3 patients and cervical oesophagus alone in 7. There were 8 men and 2 women, mean age 70.2 years, range 45–85 years. All patients but two had malignant stricture caused by squamous cell carcinoma, in one case there was a benign postoperative stenosis secondary to laryngectomy, and in the last patient a local recurrence from thyroid cancer. RESULTS: Eleven stents were placed in 10 patients: technical success was achieved in 9 cases while clinical improvement was obtained in 8 cases. Seven of ten patients had a rapid improvement of dysphagia. One patient had a distal misplacement of the prosthesis, while in the other two cases stent position was very proximal and interfered with swallowing. A mean 9-month follow-up was obtained (range 3–24 months). Four patients with malignant stricture developed proliferation of neoplastic tissue after 2–5 months. The only patient treated for a benign stricture developed inside proliferation of granulation tissue after 4 months. CONCLUSION: Despite several technical difficulties and a high rate of late complications, recanalization of cervical oesophageal strictures by self-expandable metal stents allowed good palliation of symptoms. Stents proved to be effective and well tolerated palliative treatment also for hypopharyngeal stenoses. S. Profili et al. (2002). Clinical Radiology 57, 1028–1033.

Palliation of malignant esophageal strictures: initial results with self-expanding uncovered nitinol coil stents.

The purpose of this study was to determine the efficacy of the uncovered coil stents in patients with malignant dysphagia. Coiled spring-shaped uncovered self-expanding metallic Esophacoil stents (Instent, Eden Prairie, Minnesota) were placed in 11 patients (9 men and 2 women; age range 38-77 years, mean age 60.5 years) with malignant esophageal strictures and dysphagia, under fluoroscopic guidance. Dysphagia was graded on a scale of 0 to 4 (0 = no dysphagia; 1 = dysphagia to normal solids; 2 = dysphagia to soft solids; 3 = dysphagia to solids and liquids; 4 = complete dysphagia, inability to swallow saliva). Two patients had received radiation therapy, 4 had had chemotherapy, and 5 had had a combination of both radiation and chemotherapy before stent palliation. Control clinical examinations and endoscopic or barium swallow studies were performed every 4 weeks until the patient died. The stents were well tolerated by all patients and were effective in 9 of 11 patients with malignant dysphagia. Complications of the procedure included incomplete opening of the stent in 1 case, migration in 1 case, transient pain in 8 cases, reflux in 3 cases and minor gastrointestinal bleeding in 2 cases. Stent migration in 1 case resulted in surgical intervention and incomplete opening of the stent allowed only partial improvement of dysphagia in 1 case. The quality of life significantly improved in all other patients. Mean survival time of the patients was 73 days (range 34-125 days) and no significant tumor ingrowth was detected during the follow-up period. Insertion of an Esophacoil has a good palliative effect on dysphagia in patients with malignant esophageal strictures with few complications. Although the stent is uncovered, tumor ingrowth and overgrowth were not observed in our study, possibly because of previous treatments.

Silicone-covered Wallstent prototypes for palliation of malignant esophageal obstruction and digestive-respiratory fistulas

Background: Endoscopic palliation of malignant esophageal obstruction with uncovered self-expanding metal stents has been shown to have fewer complications than with conventional plastic stents. The addition of a membrane might prevent tumor ingrowth and allow treatment of digestive-respiratory fistulas. We report the clinical experience with a prototype silicone membrane-covered self-expanding metal stent. Methods: Twenty-three silicone membrane–covered Wallstent prototypes were used in 21 patients with dysphagia due to inoperable malignant tumors involving the esophagus and cardia. Results: Stent implantation was technically successful in all patients. There were no procedure-related perforations or deaths. The prototype stent was successful in sealing seven of the eight (87.5%) digestive-respiratory fistulas. As a group, the mean dysphagia grade improved significantly after stent placement (4.8 ± 0.9 vs 3.4 ± 1.6, p < 0.0005). However, 9 of 21 (42.9%) patients experienced no improvement in their dysphagia. Complications occurred in 13 of 21 (61.9%) patients. Tumor ingrowth was not observed in any patient. Conclusions: The prototype covered self-expanding metal stent was effective in sealing digestive-respiratory fistulas and provided palliation of dysphagia in slightly more than one half of the patients studied. A great deal has been learned from the preliminary experience, which has led to design modifications. The utility of the commercially available device should be evaluated in further prospective clinical trials. (Gastrointest Endosc 1997;45:31-7.)