Efficacy of plastic tube stents without side holes for middle and lower biliary strictures

Biliary stenting in patients with malignant biliary obstruction: comparison of double layer, plastic and metal stents

BACKGROUND AND AIM

The double layer stent (DLS) has a unique design and has been used for palliation of malignant biliary obstruction, but literature on this stent is limited. Our aim was to compare plastic (PS), DLS and metal stents (MS) in terms of complication rates, time to occlusion, and patency rate in patients with malignant biliary obstruction (MBO).

METHODS

A retrospective review of stents placed for MBO at our institution in the period between January 2009 and April 2011 was conducted. A total of 114 stents were identified, of which 44 were MS (39 %), 37 DLS (32 %), and 33 PS (29 %). A stent was considered occluded when an unplanned stent removal or intervention occurred due to clinical suspicion of biliary obstruction.

RESULTS

Stents remained patent for 95 days (range 7-359 days) in the DLS group and 59 days (range 7-228 days) in the PS group (P = 0.014) and 128.7 days (range 4-602 days) in the metal stent group. Twenty-seven percent (n = 9) of PS occluded after a mean of 60 days while 16 % (n = 7) of MS occluded after a mean of 87 days and 5 % (n = 2) of DLS occluded after a mean of 85 days (DLS vs. PS P = 0.012, DLS vs. MS P = 0.13, MS vs. PS P = 0.22).

CONCLUSIONS

DLS are superior to PS in patients with MBO and appear to be comparable to MS. MS had a longer patency rate but were comparable to DLS in early and late complications. We speculate that the less expensive DLS may be a cost effective alternative in the palliation of MBO.

Biliary stent therapy for dominant strictures in patients affected by primary sclerosing cholangitis

The diagnosis and the treatment of dominant strictures (DS) in patients with primary sclerosing cholangitis (PSC) is challenging and the scientific literature on the subject is quite limited. Only level II and level III evidence is available to guide physicians managing patients with DS and PSC. For the diagnosis, intraductal endoscopic ultrasound is the most sensitive (64%) and specific (95%) test. However, the majority of cases require a combination of several different diagnostic tests, as there is no single investigation that can rule out malignancy in this group of patients. For the treatment, serial endoscopic or percutaneous dilatations provide 1- and 3-year biliary duct patency in 80 and 60% of patients, respectively. Dilatation and stenting are the most common interventions, although the optimal duration of treatment has still not been clearly defined. Bile duct resection and/or bilioenteric bypass are currently indicated only for patients with preserved liver function. For all other patients, benign DS can be treated with endoscopic dilatation with short-term stenting. This approach is effective and safe and does not increase the risk of malignant transformation or complications for liver transplant candidates. During the last decade, the use of self-expandable metallic stents for benign diseases has become an innovative option. The aim of this article is to review the diagnostic and therapeutic strategies for patients affected by PSC and DS with specific emphasis on the outcomes of patients treated with temporary stents.

Does heparin coating reduce encrustation of biliary plastic endoprostheses? A prospective randomized trial

OBJECTIVE

Common bile duct stenting is widely performed for bridging benign and malignant obstructions. A major limitation is early stent occlusion making regular stent exchange necessary. Covalent binding of glycosaminoglycanes to polyethylene stents proved to reduce encrustation in urological implants. Since development of urological and biliary stent occlusion shows parallels, the aim of the study was to evaluate the efficacy of heparin coating of biliary endoprostheses in preventing encrustation.

MATERIAL AND METHODS

In a prospective randomized trial, heparin-coated and native stents were endoscopically placed for almost 90 days on average. After removal, all stents were dried (50°C, 24 h), weighed and after longitudinal incision visible encrustation and discoloration recorded. Fifty-three patients (21 females/32 males, 70 ± 12 (42-87) years) were included; 13 patients (4 females/9 males, 58-79 years) completed the study according to the protocol.

RESULTS

After removal, mean weight of encrustation in native stents was more than double as high as of covered stents (native: 37.9 ± 19.8 (16-93) mg; covered: 17.6 ± 6.7 (9-33) mg). In 12 of 13 cases, the encrustation weight of the native stent was higher than that of the corresponding covered stent in the same patient. Premature stent explantation became necessary in 3 of 13 native stents, because of recurrent jaundice or cholangitis but only in 1 of 13 covered stents. After longitudinal incision, the three uncovered stents showed excessive encrustation whereas no significant encrustation was found in the covered prosthesis. Altogether, covered stents showed less visible accumulation of clogging material and discoloration than native stents.

CONCLUSIONS

Covalent bound heparin is highly effective in preventing encrustation of biliary polyethylene endoprostheses.

Impact of reducing duodenobiliary reflux on biliary stent patency: an in vitro evaluation and a prospective randomized clinical trial that used a biliary stent with an antireflux valve

BACKGROUND

The mechanisms leading to occlusion of plastic biliary stents (PBS) are not known.

OBJECTIVE

To evaluate the impact of reducing duodenobiliary reflux on stent patency rate.

DESIGN

A newly designed antireflux PBS (AR-PBS) was tested in vitro by using ox bile. A prospective randomized trial in human beings was conducted.

SETTING

Tertiary medical center.

PATIENTS

Patients with malignant bile-duct strictures were studied.

INTERVENTIONS

A PBS or an AR-PBS stent was placed by using standard techniques, and the patients were followed at regular intervals. Patients presenting with stent occlusion underwent re-stent placement with either a PBS or a metal stent.

MAIN OUTCOME MEASUREMENTS

In vitro: resistance to retrograde flow and comparison of the basal and peak antegrade flow pressures between the 2 stents. In vivo: stent patency rates, complications, and the efficacy of the stents in improving the liver test.

RESULTS

The AR-PBS stent could withstand a retrograde pressure gradient of >320 mm Hg compared with <1 mm Hg for the PBS. Secondary to the siphon effect of the valve, the antegrade flow resistance offered by the AR-PBS was on the negative side for all flow rates compared with PBS (P < .001). The median patency of the AR-PBS in human studies was 145 days (range, 52-252 days) compared with 101 days (range, 41-210 days) for the PBS (P = .002). Both stents were equally effective in improving the liver test, and complication rates were similar in the 2 groups.

LIMITATIONS

The occluded stents were not examined microscopically.

CONCLUSIONS

The antireflux biliary stent remains patent for a longer time and hence duodenobiliary reflux may be contributing to stent occlusion.

Plastic biliary stent occlusion: factors involved and possible preventive approaches

Endoscopic biliary stenting is today the most common palliative treatment for patients suffering from obstructive jaundice associated with malignant hepatobiliary tumors or benign strictures. However, recurrent jaundice, with or without cholangitis, is a major complication of a biliary endoprosthesis insertion. Thus, stent removal and replacement with a new one frequently occurs as a consequence of device blockage caused by microbial biofilm growth and biliary sludge accumulation in the lumen. Factors and mechanisms involved in plastic stent clogging arising from epidemiological, clinical and experimental data, as well as the possible strategies to prevent biliary stent failure, will be reviewed and discussed.

Antireflux biliary stents: are they the solution to stent occlusions?

Endoscopic insertion of plastic or metal stents is a well-established treatment for malignant biliary obstruction. The major limitation of this technique is stent occlusion. Duodenobiliary reflux has been considered a key contributor to stent occlusion. The presence of plant fibers in 35% to 60% of occluded stents on confocal laser microscopy has further confirmed the presence of reflux when the stent is placed across the papilla. Antireflux stents address this problem by allowing normal antegrade flow but preventing reflux. Recent studies comparing these antireflux stents with the standard Tannenbaum stents have shown significantly prolonged patency. Although initial results are encouraging, larger randomized trials are required to establish efficacy.

Endobiliary stents for palliation in patients with malignant obstructive jaundice

BACKGROUND

Endobiliary drainage for malignant obstructive jaundice presents a viable palliative alternative. Its role and efficacy depend on factors related to the stent, procedure, and patient.

GOALS

To review the evidence in the literature in which settings plastic or metal stents are cost-effective, and whether adjuvant measures or patient-related factors affect duration of stent patency.

STUDY

Using databases a literature search was performed for papers published from 1979 to April 2004. All retrieved papers reporting experimental or clinical observations were rated according to strength of evidence, and carefully analyzed.

RESULTS AND CONCLUSIONS

Metal stents (Wallstent) stay patent longer than plastic stents (large-bore polyethylene with side-holes), overall median 250 and 110 days, respectively, and seem cost-effective in patients with longer than about 6 months survival, which cannot be accurately predicted. Antibiotics or choleretic agents do not prolong stent patency in clinical settings. In case of stent occlusion, indicated stent exchanges and insertion of a plastic stent, respectively, seem cost-effective in patients initially treated with plastic and metal stents.

Biliary and pancreatic stents

The use of biliary and pancreatic stents has increased significantly during the last 2 decades because of improvements in available endoscopes and endoscopic accessories, as well as better techniques. The number of endoscopists who can successfully complete these demanding procedures has also increased, as have the indications for stent therapy in biliary and pancreatic diseases. Stents are now made in various shapes and configurations from different types of polymers (plastics), various expandable metallic alloys, and bioabsorbable materials. Most of the available data relate to plastic and metallic stents for biliary tract disease; the data for pancreatic disease are fewer and involve a smaller number of patients. This article reviews the most recent available data concerning biliary and pancreatic stents and discusses possible future developments. It does not attempt to cover all data reported in biliopancreatic stent therapy.