Stent placement for benign pancreatic diseases: correlation between ERCP findings and clinical response.

OBJECTIVE. We performed a study to determine if the appearance of the pancreatic duct on ERCP before and after placement of pancreatic duct stents correlates with the therapeutic response in patients treated for impaired pancreatic drainage. MATERIALS AND METHODS. Findings in 29 consecutive patients with a variety of benign pancreatic diseases in whom pancreatic stents were placed and subsequently removed within a 3-year period were reviewed retrospectively. Early (1-5 days) and late (1-3 months) clinical outcomes after stent placement were assessed. These findings were correlated with a blinded interpretation of ERCP findings (Cambridge criteria were used) before and after stent placement. RESULTS. ERCP findings before stent placement were normal in 10 patients. At the end of stent therapy, ERCP showed changes associated with chronic pancreatitis in all 10; five had focal narrowing at the tip of the stent. Subsequent ERCP studies in five of these 10 patients showed that ductal changes induced by stents diminished after stent removal. Of the 19 patients with abnormal findings on ERCP at the time of stent placement, ERCP at the end of stent therapy showed some improvement in seven patients, no change in eight, and deterioration in four. Changes seen on ERCP had no statistically significant correlation with clinical outcome (p = .36). CONCLUSION. Our findings show that pancreatic duct stents can induce abnormalities on ERCP indicative of chronic pancreatitis. However, diminution of these abnormalities after stent removal in some patients suggests that these changes may be due to edema rather than to fibrosis. Ductal changes seen on ERCP are not a useful guide for determining the degree of response to pancreatic stents.     

Occlusive effect of metallic stents on canine ureters

A three-part study, with successive modifications based on preceding results, was conducted to evaluate ureteral placement of metallic stents. Gianturco self-expanding (10 mm and 4 mm diameter) and balloon-expanded (4 mm diameter) metallic stents were placed in normal and stenotic canine ureters. No migration or ureteral perforation occurred during the follow-up of 10 mm stents. Varying degrees of hydronephrosis and hydroureter were found on all 1-week pyelograms. At 4 weeks, complete occlusion of the stented ureter was noted in all cases because of mucosal hyperplasia around the stent wires. To prevent this reaction, 4 mm self-expanding stents constructed of smaller wire that was uncoated or coated with either Teflon or polyurethane were tested in five dogs. In all cases, results were similar to those obtained with the larger prostheses. Finally, 4 mm balloon-expanded stents were placed in a normal ureter of three dogs. In one dog, the stent migrated out of the ureter. No migration or ureteral perforation occurred in the two remaining dogs. In these animals, mucosal hyperplasia and complete ureteral occlusion occurred 6 and 8 weeks after placement. Therefore, ureteral placement of Gianturco self-expanding as well as balloon-expanded metallic stents leads to occlusion of the ureter instead of maintaining its patency. Stents, therefore, may be useful as ureteral occlusion devices.     

Expandable metallic biliary endoprostheses: preliminary clinical evaluation

A biliary endoprosthesis constructed of self-expanding metallic "Z" stents was placed in 23 patients with obstructive jaundice. The biliary obstruction was due to a malignant neoplasm in 21 patients and a postoperative biliary stricture in two patients. The lesions affected the intrahepatic biliary ducts in 13 patients. Twelve patients had undergone radiation therapy before stent placement. The endoprostheses consisted of 196 expandable metallic biliary stents placed singly (n = 10) or in tandem (n = 186). As many as 18 stents were used to relieve an obstruction in one patient. A transhepatic approach was employed in all patients except one in whom stents were placed through a T-tube tract. Within 1 week after placement, all stents expanded to at least 90% of their original diameter. Three misplaced, two deformed, and two dislodged stents caused no obvious clinical problems. At follow-up, which ranged from 2 to 59 weeks, five patients experienced recurrent jaundice. Two patients with recurrent jaundice due to obstruction of the bile duct containing the stent were treated with external catheter drainage. The expandable biliary endoprosthesis is suggested as an effective treatment for benign and malignant biliary obstruction.     

Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30–40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.     

Flexible tantalum stents: Effects in the stenotic canine urethra

Purpose Evaluate the effects of flexible tantalum stents (Strecker) implanted into stenotic canine urethras.Methods Eight conditioned, adult, German shepherd dogs, weighing 30–40 kg, were used. Strictures were created surgically in the bulbar urethra just proximal to the os penis. Two months postsurgery, strictures were documented radiographically and then balloon dilated. Following dilatation, a single Strecker stent was placed across the stricture. Stents were 7 mm in expanded diameter and either 2 or 4 cm in length. Retrograde urethrography was performed immediately after stent placement and then biweekly for up to 12 months. Two dogs were sacrificed at 2, 4, 6, and 12 months post-stenting, and necropsy was performed. The urethra was excised, fixed, and examined by scanning electron and light microscopy.Results Clinical success was achieved without complications in all animals. Hyperplasia of the urothelium was noted 4–6 weeks after stent placement and was most pronounced at 4–6 months. Mucosal folds were found between the stent struts. Restenosis occurred at the distal end of the stent in one dog. Histological alterations were noted in the deeper layers of the urethral wall.Conclusion Strecker stents were well tolerated in all animals and seem useful for the treatment of urethral strictures.Presented at CIRSE Annual Meeting and Postgraduate Course, Budapest, June 20–24, 1993     

经皮经肝内支架植入治疗恶性胆道梗阻(附35例报告)

目的:探讨国产金属胆道内支架治疗恶性梗阻性黄疸的疗效和安全性。材料和方法:恶性梗阻性黄疸病人35例,均采用经皮经肝途径植入胆道支架,其中16例采用两步法植入,19例采用一步法植入,5例同时施行了左肝管的球囊扩张术。结果:支架植入后即刻造影显示支架开通良好,内引流作用显著。血清胆红素水平降至正常者21例(60%),下降超过50%但未降到正常者7例,下降未过50%者3例,无改善者3例。3例病人术后一月内死亡,16例无黄疸生存6个月以上,半年生存率53.2%,3例生存12个月以上。8例病人半年内出现支架梗阻,占23.8%。一步法和二步法两种方法植入支架的病人住院天数和总的治疗费用统计学无显著性差异。结论:国产金属胆道内支架植入疗效显著,使用安全。     

Results of temporary placement of covered retrievable expandable nitinol stents for tuberculous bronchial strictures

Covered retrievable expandable nitinol stents were successfully placed in nine patients with tuberculous bronchial strictures refractory to balloon dilation. Complications included stent migration (n = 1) and tissue hyperplasia at the proximal portion of the stent (n = 2). During the follow-up period (5-52 months), stricture recurred in three of five patients (60%) after temporary stent placement for 2 months, whereas stricture did not recur in the other four patients after temporary stent placement for 6 months. Temporary placement of covered retrievable stents appears to be an effective method for the treatment of patients with tuberculous bronchial strictures refractory to balloon dilation.     

Palliation of malignant bile duct obstruction with metallic biliary endoprostheses: technique, results, and complications.

Expandable metallic stents were placed in 34 patients with pathologically proved malignant bile duct obstruction to determine ease of insertion, benefits of a one-stage insertion, and cost-effectiveness relative to conventional plastic stents. Thirty-eight strictures, ranging in length from 1 to 7 cm (mean, 3.2 cm), were present in the 34 patients. Strictures were located in the lower common bile duct (n = 22), middle of the common bile duct (n = 6), and hilar confluence (n = 10). In 13 patients (38%) metallic stents were placed at the time of initial biliary drainage (one-stage procedure), while the remaining patients underwent stent placement within 1-7 days of biliary drainage (two-stage procedure). Biliary obstruction was relieved in 31 of 34 patients (91%). Three patients died within 14 days of stent insertion of unrelated causes, without any change in biliary status. Mean duration of follow-up for all patients was 5.3 months (range, 0.5-14 months). Four episodes of stent occlusion occurred in three patients (12% occlusion rate); each episode was treated successfully. The average length of hospital stay for patients who underwent a one-stage procedure was 13 days (range, 3-33 days) and was 20 days (range, 9-42 days) for patients who underwent a two-stage procedure. The facility of one-step insertion, low occlusion rate, and the many strategies available for treatment of occluded stents make metallic stents an attractive alternative to conventional plastic stents in palliating patients with malignant biliary obstruction.     

Evaluation of the Effects of Temporary Covered Nitinol Stent Placement in the Prostatic Urethra: Short-Term Study in the Canine Model

Purpose To evaluate the effect of temporary stent placement on the canine prostatic urethra. Methods Retrievable PTFE-covered nitinol stents were placed in the prostatic urethras of 8 beagle dogs under fluoroscopic guidance. Retrograde urethrography was obtained before and after stenting. Retrograde urethrography and endoscopy were performed 1 and 2 months after deployment. The endoscopic degree of hyperplasia was rated on a scale of 0 to 4 (0 = absence, 4 = occlusion). On day 60, stents were removed and urethrography was performed immediately before euthanasia. Pathologic analysis was performed to determine the degree of glandular atrophy, periurethral fibrosis, and urethral dilation. Results Stent deployment was technically successful in 7 animals, and failed in 1 dog due to a narrow urethral lumen. Complete migration was seen in 2 animals at 1 month, and an additional stent was deployed. On day 30, endoscopy showed slight hyperplasia (grade 1) in 3 animals. On day 60, moderate hyperplasia (grade 2) was evidenced in 4 cases. No impairment of urinary flow was seen during follow-up. Retrieval was technically easy to perform, and was successful in all dogs. The major histologic findings were chronic inflammatory cell infiltrates; prostate glandular atrophy, with a mean value of 1.86 (SD 0.90); periurethral fibrosis, with a mean ratio of 29.37 (SD 10.41); and dilatation of the prostatic urethra, with a mean ratio of 6.75 (SD 3.22). Conclusion Temporary prostatic stent placement in dogs is safe and feasible, causing marked enlargement of the prostatic urethral lumen. Retrievable covered stents may therefore be an option for bladder outlet obstruction management in men.     

Self-expandable macroporous nitinol stents for transfemoral exclusion of aortic aneurysms in dogs: Preliminary results

This experimental study evaluated the feasibility of excluding artificially created aortic aneurysms in dogs with transfemorally inserted nitinol stents, serving as intraluminal bypass. Infrarenal aortic aneurysms were created in eleven dogs (28–35 kg) by end-to-end anastomosis of sacciform conduits. Single and double wire-knitted, macroporous, superelastic, self-expanding nitinol stents without any additional wrapping or in-between fabrics served as endovascular grafts. The pore size of the double-knitted stents was less than 0.7 mm². Angiography following stent placement showed immediate exclusion of the aneurysms for the double-knitted stents. For the single-knitted stents (2 cases), partial exclusion was achieved only after considerable delay. CT studies in the dogs with the double-knitted stents revealed patency of the grafts after 3 to 5 weeks with the aneurysms totally thrombosed. So far gross pathology of 1 dog at 24 h and 1 at 12 months revealed patency of the stents. At 12 months histopathology showed a neointima covering the inner stent surface with the aneurysm filled by an organized thrombus. It is concluded, that an “open” stent with a tight meshwork appears to be a suitable device to instantly exclude artificial aneurysms of the canine aorta.     

国产被膜网状支架治疗食管癌性狭窄初步研究

目的 评价国产被膜网状支架治疗食管癌性狭窄的价值,探讨支架置入的相关技术。方法 本组30例,置入支架前,行食管造影,并用X线显影尺精确定位,然后用超滑导丝、导引导管引入超硬导丝,对狭窄部扩张后,将支架置入预定部位。结果 30例共置入支架31枚,所有病例均一次成功,患者吞咽功能明显改善,未出现食管穿孔、大出血或死亡等严重并发症。结论 国产被膜网状支架治疗食管癌性狭窄安全、有效;相关技术的改进,可减少患者不适及并发症,提高支架放置的成功率及准确性。     

Malignant portal venous obstructions treated by stent placement: significant factors affecting patency.

PURPOSE: To identify factors affecting stent occlusion after stent placement in the portal vein in patients with malignant portal vein invasion. MATERIALS AND METHODS: Forty patients were studied. Twenty-three patients had hepatocellular carcinoma, nine patients had pancreatic cancer, and eight patients had bile duct cancer. Stents were placed in the portal venous system across stenotic (n = 28) or obstructive (n = 12) lesions after percutaneous transhepatic portography. Bare stents were used in 33 patients and covered stents were used in seven patients. Twenty-two variables were analyzed with use of univariate and multivariate analyses to identify significant factors affecting stent occlusion. RESULTS: Stents remained patent during a mean follow-up period of 11.9 months (range, 2-61 mo) in 60% of the patients. Stent occlusion was found in 40% of the patients, with a mean period until occlusion of 3.7 months (range, 0.2-16 mo). In the univariate analysis, the following five factors were significantly associated with a higher probability of stent occlusion: (i) splanchnic vein involvement, (ii) Child-Pugh class C, (iii) obstruction of the portal venous system, (iv) pancreatic cancer, and (v) lack of anticancer treatment after stent placement. In the multivariate analysis, the first three factors were found to have independent value for stent occlusion. CONCLUSIONS: Splanchnic vein involvement, severe hepatic dysfunction, and obstruction of the portal venous system are the most important factors affecting stent occlusion in patients with malignant portal vein invasion.     

Recurrent bronchobiliary fistula: unsuccessful management with repeated insertion of metallic biliary stent

This case of a recurrent bronchobiliary fistula was first managed temporarily with repeated metallic biliary stent placement, and finally required surgery. A 65-year-old man, who had undergone a hepatic resection for metastatic colon carcinoma, with a bronchobiliary fistula was treated with metallic biliary stent placement for a stenosis in the common bile duct. During 16 months of follow-up, the biliptysis recurred twice by a recurrent stricture of the common bile duct, which was managed by placement of a second and third stent in a coaxial manner. Three months after placement of the third stent, jaundice developed and the patient finally underwent a Roux-en-Y choledochojejunostomy.     

Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits

The purpose of this study was to evaluate the radiographic and biological effects of different polyurethane nasolacrimal duct stents in an animal model. Fifteen polyurethane nasolacrimal duct stents (n = 5 mushroom-type stents, n = 5 newly designed S-shaped TearLeader stents without hydrophilic coating, and n = 5 S-shaped TearLeader stents with hydrophilic coating) were implanted in the nasolacrimal ducts of eight unaffected New Zealand rabbits. One nasolacrimal system served as control. Clinical and radiographic follow-up was performed at 1-, 2-, and 4-week intervals, then after a 3-month interval, after which the animals were euthanized. All stents were implanted without major periprocedural complications. The stents proved to be patent by the end of the procedure. During follow-up, all mushroom-type stents were occluded at 4 weeks. None of these stents opened to forced irrigation. Clinically, all rabbits demonstrated severe dacryocystitis. Three out of five TearLeader stents without hydrophilic coating were blocked at 4 weeks; one out of five was open to irrigation. Best results were observed in the stent group with hydrophilic coating. Follow-up dacryocystography demonstrated patent stents in nasolacrimal ducts of all animals after 4 weeks. In only one of five cases, the coated stent became partially occluded after 2 months. These animals were free of clinical symptoms. After 3 months, at least three out of five stents still opened to forced irrigation and only one stent was completely blocked. Dislocation of the stents was not observed. Refinement of the stent surface and stent design improves the results of nasolacrimal duct stenting in this animal model. Implantation of hydrophilic-coated S-shaped stents is highly superior to conventional mushroom-type stents and noncoated stent types. Hydrophilic coating seems to prevent foreign-body reactions, resulting in maximized stent patency.     

Metallic stent placement for iliac artery occlusive disease

Since 1991, we have performed stent placement for 35 iliac artery lesions in 31 patients. The etiologic diseases were atherosclerotic in 34 patients and traumatic dissection in one. The indications of placement were total occlusion in 3, late restenosis after angioplasty in 5, dissection in 5, and residual stenosis due to inadequate angioplasty in 21. We also performed direct stent placement for one traumatic dissection. The stents used were Wallstents in 10, Palmaz stents in 14, Strecker stents in 9, and Memotherm stents in 2 lesions. Follow-up was performed clinically or angiographically with measurement of the ankle/arm pressure index. Stent placement was successful in all cases, and relief or improvement of symptoms was achieved. The follow-up period ranged from 6-85 months (mean, 37.3 months). Late stent stenosis or occlusion occurred in 6 cases, among which 4 occluded lesions were successfully recanalized by thrombolytic therapy with angioplasty or second stent placement. In total, the primary patency rates were 88% and 77% at two and four years, respectively, while the secondary patency rates were 94% and 94%. In conclusion, metallic stent placement may offer extended application of intravascular treatment for iliac artery occlusive disease, and good long-term patency rates can be expected.     

Stenosis of the vena cava: preliminary assessment of treatment with expandable metallic stents

To test the ability of Gianturco expandable metallic stents to dilate and maintain patency in stenotic venae cavae, stenosis of the inferior vena cava was created in seven mongrel dogs by the percutaneous injection of absolute ethanol into the paravascular retroperitoneal space. Gianturco stents, placed across the stenotic segment, resulted in successful dilatation with improved hemodynamics in four dogs. The stents failed to dilate an occluded vena cava in one dog; in the remaining dogs, stent placement was complicated by early migration and occlusion. Gianturco stents were placed in two patients, one with superior vena cava syndrome and one with retroperitoneal fibrosis that obstructed the inferior vena cava, and resulted in immediate relief of presenting symptoms. These results should be viewed cautiously, but further investigation into the clinical use of the stents is indicated, especially for patients for whom other treatments are difficult.     

Effects of a holmium-166 incorporated covered stent placement in normal canine common bile ducts

PURPOSE: A specially designed self-expandable covered metallic stent incorporated with beta-emitting radioisotope, Holmium-166 (Ho-166), was developed for delivering intraluminal brachytherapy as well as for internal bile drainage in malignant biliary stricture. The purpose of the study was to demonstrate the safety and tissue response of the radioactive metallic stent on the normal canine common bile duct (CBD) prior to the clinical application. MATERIALS AND METHODS: Nitinol self-expandable stents (diameter; 4 mm, length; 20 mm) were covered with polyurethane membrane (50 microm thick) containing 21 to 135 muCi of Ho-166 (mean, 77.9 microCi). To prevent migration of stent, the membrane covered only the middle 1 cm of the stent and the ends of the stent were left uncovered. The stents were placed in the CBD of 20 healthy beagle dogs. For control, non-radioactive covered stents were placed in another three dogs. The dogs were killed 3 to 6 months after stent insertion and histopathologic examination of CBD was performed. RESULTS: There was no stent migration in all cases. Varying degrees of papillary mucosal hyperplasia leading to significant narrowing of the lumen was observed within the lumen of the bare portion and under the mucosal surface of the non-radioactive covered stents. However, fibrosis was noted in Ho-166 coated area, instead of mucosal hyperplasia. Severity of fibrosis was correlated with estimated radiation dose. Despite high dose, there was no perforation of CBD wall. The membrane of Ho-166 coat was disrupted in some cases of 6 months follow-up. CONCLUSIONS: Holmium-166 incorporated covered stents demonstrated fibrosis of CBD wall and inhibition of ingrowth of mucosal hyperplasia without serious complication such as perforation, while control group showed severe mucosal hyperplasia.     

金属支架治疗恶性肿瘤引起的气管狭窄（附30例分析）

目的 评价金属支架治疗肺癌、食管癌等恶笥肿瘤引起的气管狭窄的可行性和疗效。方法 ３０例肺癌、管癌等恶性肿瘤压迫或侵犯气管，引起气管狭窄和严重的呼吸困难，分别置入自扩型金属支架。１１例患者进行了后续的化学治疗和放射治疗。结果 ３０例狭窄都位于主气管，共置入支架３０个（１２个ＧｉａｎｔｕｒｃｏＺ形支架，８个Ｗａｌｌｓｔｅｎｔ支架１０个Ｕｌｔｒａｆｌｅｘ支架）。所有患者呼吸困难得到立即缓解。１例杖后５６     

Gianturco self-expanding stents: Clinical experience in the vena cava and large veins

Twenty-five patients with stenosis of the vena cava (21) and other large veins (4) have been treated with self-expanding Gianturco metallic stents. Eighteen patients had superior vena cava syndrome. In 17, the stricture was due to malignant superior vena cava compression recurrent after maximum tolerance radiotherapy and/or chemotherapy. In 16 of these patients there was early symptomatic relief. In 1 patient with a benign posttraumatic superior vena cava stricture, the stenosis was not relieved, and occlusion occurred after 1 month. Stenoses associated with dialysis shunts were relieved in 2 other patients. Two malignant and one benign inferior vena cava stenoses were relieved either until death, or in the benign case, for 30 months. One malignant subclavian vein obstruction occluded after 24 h due to stent misplacement and another with extrinsic mediastinal compression remained patent until death, extensive thrombus having been lysed prior to stent placement. The results of this short series suggest that the Gianturco self-expanding stent in the vena cava and large veins is easy and safe to place, and in most cases produces almost immediate palliation of the distressing effects of venous obstruction, often in a preterminal and inoperable patient.     

Covered metallic stent placement in the management of cervical esophageal strictures

PURPOSE: To describe the authors' experience with self-expandable covered metallic stents in 16 patients with malignant and benign cervical esophageal strictures. MATERIALS AND METHODS: Sixteen expandable covered metallic stents were placed with fluoroscopic guidance in 16 patients (14 men, two women; mean age, 60 years; age range, 26-75 years) with malignant and benign strictures of the cervical esophagus. The causes of strictures were ingestion of corrosive agents (n = 3), biopsy-proved squamous cell carcinoma (n = 12), and postsurgical scarring (n = 1). The mean dysphagia scores at presentation were compared with those after stent placement by using the Wilcoxon signed rank test. RESULTS: Stent placement was technically successful in all patients. The reduction in the mean dysphagia score after stent placement was statistically significant (P = .0327). All patients complained of mild to severe foreign body sensation, with four reporting severe pain necessitating immediate stent removal. With the exception of one patient with limited follow-up, complications requiring intervention occurred in all patients, including migration in nine patients and tissue hyperproliferation in two. Of the 12 patients with a malignant stricture of the esophagus, four patients eventually underwent gastrostomy for the placement of a feeding tube and one patient underwent surgery. All four patients with a benign cervical stricture failed to achieve long-lasting improvement with temporary stent placement. CONCLUSIONS: Although the placement of covered metallic stents in the cervical esophagus provides adequate initial palliation, it is associated with poor patient tolerance and a high complication rate.