Cleaning of occluded biliary endoprostheses: is shockwave application an alternative to regular stent exchange?

Occlusion is the major limitation of plastic biliary endoprostheses (PBE), making regular stent exchange necessary. The aim of the in vitro analysis was to evaluate the cleansing effect of shockwave application (SWA) on occluded PBE. Thirty-five PBE removed from 24 patients were analyzed. Three hundred and fifty shockwave pulses were administered every 10 mm along the prosthesis stored in a liquid-filled latex balloon. Occlusion rates were measured before and after SWA. The cleansing rate was calculated in comparison to the native prosthesis. Mean occlusion rate was 76 ± 30% (Range 16-100%) before SWA. Cleansing effect was 47 ± 52% (0-100%) after SWA. Cleaning was complete (100%) in seven (20%) and satisfying (75-99%) in another seven prostheses. Degree of stent occlusion and indwelling time were significantly associated to the cleansing effect. In conclusion, SWA showed a limited cleaning effect in clogged PBE and is no suitable alternative for regular stent replacement to date.

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.

Cleaning of occluded pancreatic duct endoprostheses: a new indication for extracorporeal shock wave lithotripsy?

BACKGROUND: Pancreatic duct stenting is widely performed for bridging main pancreatic duct obstruction in patients with chronic pancreatitis. The major limitation is early stent occlusion, making regular stent exchange necessary. OBJECTIVE: To date, no measures are available to prevent stent occlusion. The aim of this study was to evaluate the cleansing effect of shock wave application (SWA) on occluded pancreatic duct stents in vitro. DESIGN: In vitro study. PATIENTS: We analyzed occlusion rates of 25 plastic endoprostheses removed from 21 patients with chronic pancreatitis. INTERVENTION: We administered 350 shock wave pulses every 10 mm along the prosthesis, which was stored in a latex balloon filled with gas-free physiologic saline solution, by using a pressure of 42 megapascals. MAIN OUTCOME MEASUREMENTS: After SWA, the occlusion rate was measured again, and the cleansing rate was calculated in comparison with the native prosthesis. RESULTS: The mean (± SD) occlusion rate was significantly reduced (64.7 ± 28.7 [15%-100%]) before SWA vs 9.8 ± 25.3 [0-100%]) after SWA; P = .038). In 16 of 25 prostheses (64%), cleaning was complete. Four of the remaining 9 prostheses (16%) showed satisfactory cleaning of 95%, on average. Residual clogging material was found mainly at the duodenal tip and the middle of the stent. No significant association was found between patient-related or stent-related parameters and the cleansing effect of SWA. LIMITATIONS: In vitro study design. CONCLUSION: SWA is effective in cleaning occluded pancreatic endoprostheses in vitro. Prolongation of stent placement seems possible if regular SWA is performed. Extracorporeal shock wave lithotripsy therefore might become a new indication for patients under treatment with pancreatic endoprostheses.

Interventional endoscopic therapy in chronic pancreatitis including temporary stenting: a definitive treatment?

OBJECTIVE: In the past 15 years there have been tremendous advances in endoscopic management of chronic pancreatitis (CP). However, the value of endoscopic pancreatic stenting is still debatable. MATERIAL AND METHODS: In 98 patients suffering from symptomatic CP (84 M, 14 F, 49+/-12, age range 23-83 years) endotherapy including temporary stenting of the pancreatic duct was performed. After final stent removal, indicating the primary end-point of endotherapy, 96 patients were followed for 35+/-28 (8 days-111) months. All data were assessed retrospectively. RESULTS: As well as other endoscopic procedures, a total of 358 prostheses were inserted in the pancreatic duct and left in place for 3+/-1 (1 day-11) months. Total stent treatment time was 10+/-10 (6 days-49) months. At 46+/-27 (4-111) months after limited endotherapy, 57 patients had no need for secondary intervention, two-thirds were even without further pain sensations. In 22 patients, surgical treatment and in 17 patients further endoscopic therapy became necessary, which was significantly correlated with continued alcohol consumption. CONCLUSIONS: Temporary stent placement as a part of interventional endoscopic therapy in CP shows a high rate of technical and long-term clinical success, with no need for secondary treatment in a remarkable number of patients. Continued cessation of alcohol consumption supports the treatment benefit significantly.

Pancreatic endoprostheses in chronic pancreatitis: criteria to predict stent occlusion.

BACKGROUND: Good clinical results of main pancreatic duct (MPD) stent placement in chronic pancreatitis (CP) are clouded by early stent occlusion. The aim of this study was to increase knowledge about stent occlusion and its effects on clinical symptoms, and to define criteria that enable the prediction of clogging. METHODS: A total of 100 pancreatic endoprostheses of 47 patients (32 men, 15 women; mean age, 53 years; standard deviation, 9 years) with CP were bench tested by simulating the pathophysiologically increased MPD pressure. The main study parameter was the reduction of water flow through clogged stents in comparison with native endoprostheses of identical type, length, and diameter. Major stent occlusion was defined as flow reduction by > or = 75%. The association between time to stent occlusion and stent- or patient-related variables was evaluated. RESULTS: Occlusion took place in nearly all endoprostheses (97%). No significant association of occlusion with clinical or blood parameters was found. Multifactorial analysis proved 4 risk factors for major stent occlusion: (A) stent diameter > 8.5F, (B) stent length > 8 cm, (C) female gender, (D) exocrine pancreatic insufficiency that required regular oral enzyme supplementation. According to the relative risk, these factors were given the following scores: A, 3 points; B to D, 2 points. Stents in patients with a score sum > 5 showed a significantly higher risk of major stent occlusion within 90 days. CONCLUSIONS: Stent clogging in CP seems to be an inevitable phenomenon. Because clinical and laboratory data do not reliably indicate clogging, stent removal or exchange should be performed in high-risk patients (score sum > 5) within 3 months.

Composition of clogging material in pancreatic endoprostheses.

BACKGROUND: Endoscopic management of chronic pancreatitis (CP), especially pancreatic stent placement, has made tremendous advances. However, good clinical results are hampered by rapid occlusion. The objective of this study was to understand mechanisms and materials that cause stent occlusion. METHODS: The clogging material of 50 lyophilized pancreatic endoprostheses (length 8.5 cm, range 5-14 cm, diameter 7-11F) from patients with CP was completely removed and weighed. Protein solubilization was achieved at pH 8.0 by using sodium dodecyl sulfate (SDS) and 2-mercaptoethanol in the presence of proteasome inhibitors. Proteins were separated by using a SDS-polyacrylamide gel electrophoresis. Protein identification was performed by the Western blot technique, as well as by mass spectrometry. Insoluble components were examined by polarized light microscopy and after staining (periodic acid-Schiff [PAS]). RESULTS: Clogging material was found in 49 prostheses, mainly at the duodenal flap (80%). More than a third of the prostheses contained visible calcium carbonate calculi. Light microscopy and PAS staining showed plant debris (80%), crystals (73.5%), and mucopolysaccharides (100%). The dry weight of clogging material (18 +/- 13 mg, range 3-72 mg) correlated significantly with the stent diameter ( p = 0.029) but not with any other stent- or patient-related criteria. Albumin, its degradation products, and lithostathine were identified as the main proteinaceous components. CONCLUSIONS: Almost all pancreatic stents had clogging material, predominantly located at the duodenal flap, which contained plant material, mucopolysaccharides, and crystals, as well as visible calcium carbonate calculi. Albumin and lithostathine may play an important role in the development of stent occlusion.

Extracorporeal shockwave lithotripsy of gallstones in cystic duct remnants and Mirizzi syndrome.

BACKGROUND: Although the efficacy of extracorporeal shockwave lithotripsy for treatment of bile duct calculi is established, there are few studies of the value of extracorporeal shockwave lithotripsy for cystic duct remnant stones and for Mirizzi syndrome. METHODS: Patients who required extracorporeal shockwave lithotripsy for cystic duct stones were identified in a cohort of 239 patients with bile duct stones treated by extracorporeal shockwave lithotripsy between January 1989 and December 2001 at a single institution. The medical records of these patients were reviewed. Follow-up information was obtained by telephone contact. OBSERVATIONS: Six women (age range 19-85 years) underwent extracorporeal shockwave lithotripsy for cystic duct stones after failure of endoscopic treatment measures. Three of the patients presented with retained cystic duct remnant calculi (one also had Mirizzi syndrome type I), and 3 presented with Mirizzi syndrome type I. The stones were fragmented successfully by extracorporeal shockwave lithotripsy in all patients; the fragments were extracted endoscopically in 5 patients. Endoscopy plus extracorporeal shockwave lithotripsy was definitive treatment for all patients except one who subsequently underwent cholecystectomy. CONCLUSIONS: Gallstones in a cystic duct remnant and in Mirizzi syndrome can be successfully treated by extracorporeal shockwave lithotripsy in conjunction with endoscopic measures. Extracorporeal shockwave lithotripsy is especially useful when surgery is contraindicated.

Pancreatic duct stones in chronic pancreatitis: criteria for treatment intensity and success.

BACKGROUND: The aim of the study was to evaluate interventional endoscopic management of pancreatic duct stones in patients with chronic pancreatitis by describing therapeutic methods and defining factors that predict technical success. METHODS: Records were retrospectively analyzed for 125 patients with symptoms caused by chronic pancreatitis with pancreatic duct stones (single 43, multiple 82) treated by interventional endoscopy, including extracorporeal shockwave lithotripsy. RESULTS: Technical success was achieved in 85% of patients (11 patients by mechanical lithotripsy, 114 by piezoelectric extracorporeal shockwave lithotripsy). There were no serious complications from lithotripsy. Univariate analysis disclosed a statistically significant association between treatment success and patient age as well as prepapillary location of stones. A greater therapeutic effort was necessary in patients with stones located in the tail of the pancreas, 2 or more stones, a stone 12 mm or more in diameter, or who have had a longer duration (>8 years) of the disease. However, with exception of the last parameter, correction for multiple testing of data removed statistical significance. CONCLUSIONS: Extracorporeal shockwave lithotripsy enhances endoscopic measures for treatment of pancreatic duct stones when mechanical lithotripsy fails. Middle-aged patients in the early stages of chronic pancreatitis with stones in a prepapillary location proved to be the best candidates for successful treatment. Unfavorable patient-related or morphologic factors can be compensated for through more intense efforts at therapy.

Complications of endoscopic sphincterotomy: can heparin prevent acute pancreatitis after ERCP?

BACKGROUND: An exploratory analysis of a prospective study of risk factors for acute pancreatitis after ERCP combined with endoscopic sphincterotomy showed that the frequency of acute pancreatitis was lower in patients who received heparin compared with patients not treated with heparin. The study was continued to further analyze the effect of heparin on the frequency of acute pancreatitis. METHODS: Potential risk factors for acute pancreatitis and outcomes were evaluated prospectively for all ERCP procedures with endoscopic sphincterotomy performed between September 1994 and December 1998. The results were analyzed by univariate and multivariate methods to determine risk factors for complications. Heparin was administered to 32.9% of the patients (heparin group [HEP group], n = 268) for various clinical reasons (low-molecular-weight heparin, n = 208, unfractionated heparin n = 60). A group of 547 patients who did not receive heparin served as control patients (CON group). RESULTS: Eight hundred fifteen patients underwent ERCP with endoscopic sphincterotomy; acute pancreatitis occurred in 6.4% (n = 52). The frequency of acute pancreatitis was significantly lower in the HEP group versus the CON group in the final multivariate model, which included significant risk factors for acute pancreatitis (HEP group: 3.4%, 9/268 vs. CON group: 7.9%, 43/547; p = 0.005). HEP did not increase the risk of hemorrhage (HEP group: 1.1%, 3/268, 2 severe, none fatal vs. CON group: 2.0%, 11/547, 3 severe, 2 fatal). HEP (p = 0.005; OR 0.3: 95% CI [0.16, 0.73]) and the number of risk factors present (p = 0.0001; OR 2.5: 95% CI [1.80, 3.50]) influenced the frequency of acute pancreatitis independently. CONCLUSIONS: Heparin was significantly associated with an extremely low frequency of post-ERCP pancreatitis without increasing the risk of hemorrhage after endoscopic sphincterotomy. Because this effect could not be attributed to other known or suspected confounders, our conclusion was that heparin administration before ERCP reduces the risk of pancreatitis.