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.     

Polydioxanone Biodegradable Stent Placement in a Canine Urethral Model: Analysis of Inflammatory Reaction and Biodegradation

PurposeTo investigate the inflammatory reaction and perform quantitative analysis of biodegradation after placement of a polydioxanone (PDO) biodegradable stent in a canine urethral model.Materials and MethodsPDO biodegradable stents were placed in the proximal and distal urethra of nine male mongrel dogs. The dogs were euthanized 4 weeks (group A; n = 3), 8 weeks (group B; n = 3), or 12 weeks (group C; n = 3) after stent placement. The luminal diameter of the stent-implanted urethra was assessed by follow-up retrograde urethrography, and histologic findings were obtained after the dogs were killed. Stents were removed after euthanasia, and their surface morphology and molecular weight were evaluated. Hematologic examination was performed to evaluate inflammatory reaction.ResultsStent placement was technically successful in all dogs. The average luminal diameter gradually decreased. The average number of epithelial layers (2.93 vs 4.42; P < .001), the average thickness of papillary projection (0.80 mm vs 1.28 mm; P < .001), and the average thickness of submucosal fibrosis (0.34 mm vs 0.49 mm ; P < .001) were significantly increased in group B versus group A. There were no significant differences between group B and group C. The average inflammatory cell infiltration did not differ significantly in the three groups. Molecular weight losses were 54% in group A and 84% in group B. In group C, PDO stents were completely decomposed.ConclusionsAn experimental study in a canine urethral model has demonstrated acceptable inflammatory reaction with gradually increasing granulation tissue but no luminal obstruction within 12 weeks.     

Renal cyst pseudoenhancement: evaluation with an anthropomorphic body CT phantom

PURPOSE: To evaluate the feasibility of using a retrievable urethral stent and to evaluate whether granulation tissue resolves after stent removal in a canine urethra. MATERIALS AND METHODS: Polyurethane-covered retrievable 0.10-mm-thick (n = 11) or 0.15-mm-thick (n = 10) nitinol wire stents were placed in the urethras of 20 dogs. In one dog, a second stent was placed in the urethra because of complete migration of the first stent into the urinary bladder. The stents were removed with retrieval hook wires 4 weeks (n = 10) and 8 weeks (n = 10) after placement. Fourteen dogs were sacrificed just after stent removal, and the other six dogs were sacrificed 2 weeks after stent removal. Information concerning procedure success, stent migration, and tissue response was obtained. RESULTS: Stent placement was technically successful in all dogs. Follow-up urethrograms showed partial (n = 4) or complete (n = 1) stent migration. Stent removal failed in two dogs due to partial or complete migration. Granulation tissue was observed at both ends of the stent in 17 dogs. Urethrograms and urethral specimens obtained 2 weeks after stent removal showed diminished granulation tissue and decreased thickness of the papillary projections of the epithelium compared with results obtained immediately after stent removal. CONCLUSION: Although some design modifications are necessary to reduce current complications, the polyurethane-covered retrievable nitinol stent seems feasible for use in the urethra. Stent-induced granulation tissue formation improved after stent removal.     

Reduction of tissue hyperplasia with a rhenium-188 mercaptoacetyltriglycine-3-filled balloon: preliminary study in a canine urethral model

PURPOSE: To evaluate the efficacy of beta-radiation therapy with rhenium-188 mercaptoacetyltriglycine-3 (MAG(3))-filled balloons to reduce tissue hyperplasia secondary to stent placement in 18 canine urethras. MATERIALS AND METHODS: Eight dogs were treated with 188-Re MAG(3)-filled balloon dilation immediately after stent placement and were killed 4 weeks later (group I, n = 4) or 8 weeks later (group II, n = 4). Five dogs were treated with 188-Re MAG(3)-filled balloon dilation 2 weeks after stent placement and were killed 4 weeks after stent placement (group III). The remaining five dogs were treated with conventional balloon dilation immediately after stent placement and were killed 4 weeks later; these animals formed the control group (group IV). Retrograde urethrography (RUG) was performed during follow-up and three histologic parameters were investigated: the number of epithelial layers, papillary projection thickness, and degree of submucosal inflammatory cell infiltration. The areas inside and outside the ends of the stents were evaluated in each case after animal sacrifice. After testing statistical significance of data for RUG and histologic findings in the four study groups, the Mann-Whitney U test was used to compare groups I and II to determine delayed effects of irradiation, groups I and III to determine benefits of delayed irradiation, groups I and IV to determine efficacy of immediate irradiation for reducing tissue hyperplasia, and groups III and IV to determine efficacy of delayed irradiation for reducing tissue hyperplasia. RESULTS: There were no significant differences in the four study groups on RUG before animal sacrifice. Between groups I and II, group II showed significantly lower mean values in five of six histologic comparisons. Between groups I and III, group III showed significantly lower mean values in only papillary projection thickness inside the stent ends. Between groups I and IV, group I showed significantly lower mean values in all three histologic parameters outside the stent ends. Between groups III and IV, group III showed significantly lower mean values in only two histologic parameters (papillary projection thickness in the in-stent area and inflammatory cell infiltration outside the stent edges). CONCLUSION: beta-Irradiation with use of a 188-Re MAG(3)-filled balloon shows the potential to reduce tissue hyperplasia secondary to stent placement in a canine urethral model. Treatment with 188-Re MAG(3)-filled balloons at the time of stent placement shows not only favorable outcomes for reducing tissue hyperplasia but also improved delayed effects until 8 weeks.     

Is a flared stent effective for decreasing stent migration in canine prostatic urethra?

Background: Prostatic urethral stents are effective in relieving obstructions caused by benign prostatic hyperplasia (BPH). However, migration of these stents occurs frequently.

Purpose: To evaluate the efficacy of a flared stent for decreasing the migration rate in comparison with a straight stent in a canine prostatic urethral model.

Material and Methods: The flared stent (15 mm in diameter and 20 mm in length) was flared up to 19 mm at both ends to prevent migration. A straight stent with the same size was straight without flaring. Both stents were made of a nitinol wire filament and covered with an expanded polytetrafluoroethylene (ePTFE) membrane. The flared stent was inserted in the prostatic urethra of 10 dogs (group 1) and the straight stent in the prostatic urethra of 12 dogs (group 2). Follow-up retrograde urethrography (RUG) was performed 1, 4, and 8 weeks after stent placement. Fisher's exact test was used to compare the migration rate between the two groups. When stent migration occurred during the follow-up period, the same type of stent was inserted again.

Results: Three of 10 (30.0%) flared stents migrated into the urinary bladder between 1 week and 4 weeks after placement. Seven of 12 (58.3%) straight stents migrated into the urinary bladder 1 (n = 3), 4 (n = 1), and 8 (n = 3) weeks following placement. The flared stent group showed lower migration rate than the straight stent group, but the migration rate did not reach statistical significance (P = 0.231). After the second stent placement, one of three (33.3%) flared stents migrated again after 4 weeks and two of seven straight stents (28.6%) after 1 week.

Conclusion: Although the migration rate was not statistically significant, the flaring of the stent seemed to reduce the migration rate in comparison with straight stents in a canine prostatic urethral model. However, the migration rate of the flared stent was still high, and further developments are required to decrease migration rate.     

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     

Influence of a dexamethasone-eluting covered stent on tissue reaction: an experimental study in a canine bronchial model

This study was designed to evaluate the feasibility and efficacy of a dexamethasone (DXM)-eluting, covered, self-expanding metallic stent to reduce tissue reaction following stent placement in a canine bronchial model. We placed a DXM-eluting, polyurethane-covered, self-expanding metallic stent (drug stent, DS) and a polyurethane-covered, self-expanding metallic stent (control stent, CS) alternately in each left main bronchus and left lower lobe bronchus in 12 dogs. The stents were 20 mm in diameter and length when fully expanded. The dose of DXM was approximately 36.7 mg in each DS, but was absent in the CS. The dogs were euthanased 1 week (n=4), 2 weeks (n=4) or 4 weeks (n=4) after stent placement. Histologic findings, such as epithelial erosion/ulcer or granulation tissue thickness, were obtained from the mid-portion of the bronchus, where the stent had been placed, and evaluated between DS and CS. There were no procedure-related complications or malpositioning of any of the bronchial stents. Stent migration was detected in one dog just before euthanasia 1 week following stent placement. Stent patency was maintained until euthanasia in all dogs. Epithelial erosion/ulcer (%) was significantly less in the DS (mean±standard deviation, 46.88±23.75) than in the CS (73.75±14.08) (P=0.026) for all time-points. There was a decrease in epithelial erosion/ulcer as the follow-up period increased in both DS and CS. The granulation tissue thickness (mm) was less in DS (2.63±2.05) than in CS (3.49±2.95), although the difference was not significant (P=0.751) for all time-points. There was a tendency toward an increase in granulation tissue thickness and chronic lymphocytic infiltration as the follow-up period increased in both DS and CS. In conclusion, DXM-eluting, covered, self-expanding metallic stent seems to be effective in reducing tissue reaction secondary to stent placement in a canine bronchial model.     

Effects of irradiation using a radioisotope-filled balloon on tissue hyperplasia caused by stent placement in a canine urethral model

PURPOSE: To evaluate 20 Gy and 40 Gy of intraluminal beta-irradiation using a 188Re-7mercaptoacetyltriglycine (MAG3)-filled balloon catheter to reduce tissue hyperplasia caused by covered stent placement for 12 weeks of follow-up in a canine urethral model. MATERIAL AND METHODS: Ten dogs underwent 188Re-MAG3-filled balloon dilatation immediately after stent placement; 20 Gy at 1-mm tissue depth in group I (n = 5) and 40 Gy in group II (n = 5), whereas 5 dogs (group III) underwent conventional balloon dilatation only. RESULTS: There were no significant differences among the three groups for percentage diameter of stenosis, although this was highest in group III. There was a tendency toward lower mean thickness of the epithelial layer and the papillary projection for out-stent area, and thickness of the papillary projection and degree of inflammatory cells for instent area in groups I and II compared with group III. Thickness of the papillary projection in out-stent area was significantly different among the three groups (P = 0.031). It was significantly less thick in group I than in group III (P < 0.05), whereas group II was not significantly different from group III. CONCLUSION: 188Re-MAG3-filled balloon dilatation has the potential to reduce tissue hyperplasia after 12 weeks of follow-up in a canine urethral model. The use of 20 Gy compared to 40 Gy did not show significant differences.     

尿道内支架置入术初步实验研究

目的：主要了解尿道粘膜对内支架置入后的反应。材料与方法：雄性犬５条。球囊扩张式钽丝支架（Ｓｔｒｅｃｋｅｒｓｔｅｎｔ），内支架扩张后内径６ｍｍ。先行逆行尿道造影后，支架置入前列腺部位尿道内，术后３天、２周和１个月造影复查，取病理检查。结果：造影复查显示尿道通畅，有１例内支架移位。病理巨检见支架与尿道结合紧密，支架网眼内粘膜增生，镜检示粘膜上皮细胞增生，结缔组织内有炎性细胞浸润及小血管增生，电镜下钽丝表面光滑。结论：粘膜上皮对该内支架无明显炎性反应，适用于前列腺成形术。     

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.     

Flared polyurethane-covered self-expandable nitinol stent for malignant biliary obstruction

PURPOSE: To determine the technical efficacy and safety of a flared polyurethane-covered self-expandable nitinol stent in the management of malignant biliary obstruction and to evaluate its clinical efficacy by estimating stent patency and patient survival rates. MATERIALS AND METHODS: Thirteen patients with common bile duct strictures (nonhilar) caused by malignant disease were treated by placement of 13 nitinol stents. The stents used include a flared section in the proximal portion (12 mm in diameter and 10 mm in length) and a section in the remnant portion that is fully covered with high-elasticity polyurethane, with an unconstrained diameter of 10 mm and a total length of 50-80 mm. Patient survival and stent patency rates were calculated with use of Kaplan-Meier survival analysis. The follow-up bilirubin and serum amylase and lipase levels were calculated, and the differences in means were evaluated with use of a Wilcoxon signed-rank test. The average follow-up duration was 22.9 weeks (range, 8-56 weeks). RESULTS: Placement was successful in all cases. The 30-day mortality rate was 0%. The survival rates were 38% and 24% at 20 and 50 weeks, respectively. Seventy-seven percent of study patients had adequate palliative drainage during their the remainder of their lives. The stent patency rates were 71% and 48% at 20 and 50 weeks, respectively. Three patients (23%) presented with stent occlusion requiring repeat intervention. There were no procedure-related complications such as proximal or distal migration. No complications occurred other than stent occlusion. One patient's stent was removed under endoscopic guidance 15 weeks after its insertion. Bilirubin levels had significantly decreased 1 week after stent insertion (P <.001). CONCLUSION: Preliminary results suggest that placement of a flared polyurethane-covered self-expandable nitinol stent is feasible and effective in achieving biliary drainage. The stents do not migrate, but there is tumor ingrowth into the flared portion of the stent. Treatment of a larger group of patients will be mandatory to validate these long-term results.     

Experimental arteriovenous fistulas: treatment with silicone-covered metallic stents.

PURPOSETo determine the efficacy of silicone-covered metallic stents in the treatment of experimentally created carotid-jugular fistulas.METHODSCarotid-jugular fistulas were surgically constructed in six mongrel dogs. Silicone-coated, self-expanding metallic stents were placed across the fistula holes within the carotid artery, and carotid angiography was performed before, immediately after, and 4 and 8 weeks after stent placement. Fistula specimens were resected 2 months after stent placement and analyzed by means of gross and light microscopy.RESULTSAngiography revealed complete closure of all fistulas immediately after stent deployment. The fistulas remained closed and all carotid arteries remained patent. Marked stenosis within the carotid lumen was seen along the proximal and distal ends of the stents. Gross and micropathologic specimens of the carotid-jugular fistulas revealed fibrous connective tissue and collagen across the fistula holes. Proliferative fibrous connective tissue, collagen, and fibromyoblasts were located at either end of the stents. The wires of the stents indented the intraluminal surface of the carotid arteries.CONCLUSIONSSilicone-covered stents were effective in closing all experimentally created carotid-jugular fistulas. With further refinements and variations in technique, covered stents may prove a viable alternative to current endovascular devices.     

Malignant gastroduodenal obstructions: treatment by means of a covered expandable metallic stent-initial experience

PURPOSE: To investigate the technical feasibility and clinical effectiveness of a polyurethane-covered expandable nitinol stent in the treatment of malignant gastroduodenal obstructions. MATERIALS AND METHODS: The stent was constructed in-house by weaving a single thread of 0.2-mm nitinol wire in a tubular configuration and was covered with polyurethane solution by means of a dipping method. With fluoroscopic guidance, the stent was placed in 19 consecutive patients with malignant gastric outlet obstruction (n = 15) or duodenal obstruction (n = 4). All patients had severe nausea and recurrent vomiting, and their obstructions were inoperable. RESULTS: Stent placement was technically successful in all but one patient. After stent placement, symptoms improved in all but one patient, who had another stenosis at the proximal jejunum. One patient with stent placement in the second portion of the duodenum became jaundiced. During the mean follow-up of 11 weeks, stent migration occurred in five patients 1-4 days after the procedure. All patients with stent migration were treated by means of placing a second, uncovered nitinol stent. Two of these five patients showed recurrence of stricture because of tumor ingrowth; they underwent coaxial placement of a third, covered nitinol stent with good results. CONCLUSION: Placement of a polyurethane-covered expandable nitinol stent seems to be technically feasible and effective for palliative treatment of inoperable malignant gastroduodenal obstructions. Stent migration, however, is problematic and requires further investigation.     

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.     

Fluoroscopically guided placement of a covered self-expandable metallic stent for malignant antroduodenal obstructions: preliminary results in 18 patients

OBJECTIVE: The purpose of this study was to investigate the technical feasibility and the clinical effectiveness of fluoroscopically guided placement of covered self-expandable metallic stents in the treatment of malignant antroduodenal obstructions. SUBJECTS AND METHODS: With fluoroscopic guidance, covered self-expandable metallic stents were placed in 18 consecutive patients with inoperable malignant antroduodenal obstructions. All patients were treated for severe nausea and recurrent vomiting. RESULTS: Stent placement was technically successful in all patients with or without gastrostomy (n = 2) and balloon dilatation (n = 3). After stent placement, symptoms improved in all but one patient, who had another stenosis in the proximal jejunum. During the follow-up of 2-73 weeks (mean, 12 weeks), stent migration occurred in three patients (16.7%) from 1 to 41 days after the procedure. These patients were treated successfully by means of placing a second covered metallic stent. Two patients, who were followed up for longer than 30 weeks, showed a recurrence of strictures because of mechanical failure of the stents; one of the patients was treated with coaxial placement of a second covered metallic stent, which had a positive clinical outcome. CONCLUSION: Fluoroscopically guided placement of covered self-expandable metallic stents is technically feasible and effective for the palliative treatment of inoperable malignant antroduodenal obstructions. The rate of stent migration in our study was lower than those in previous reports.     

Experimental study of the intraurethral placement of expandable metallic stents

Various types of Gianturco expandable metallic stents were implanted into the urethra of four dogs in order to evaluate the suitable expandability of the stents in urethra and also to determine the effect of the stents on the urethral wall. The stent of 1.5 cm in length and constructed of 0.010 inch round stainless steel wire with twelve zigzag bends showed the suitable expandability on the canine urethra compared to the other stents. The urethra remained patent and the inflammatory changes on the urethral wall were moderately noted. No hematuria or calcifications around the stents were noted in any dogs. The experimental data showed a potential clinical application.     

Metallic stent placement in patients with recurrent cancer after gastrojejunostomy

PURPOSE: To assess the technical feasibility and clinical effectiveness of placement of expandable metallic stents in patients with recurrent cancer after a gastrojejunostomy. MATERIALS AND METHODS: Data from 39 consecutive patients who had undergone metallic stent placement for recurrent malignant obstruction after a gastrojejunostomy were retrospectively analyzed. Thirty patients underwent a distal gastrectomy with a gastrojejunostomy with (n=10) or without (n=20) jejunojejunostomy, two patients underwent distal gastrectomy with a Roux-en-Y gastrojejunostomy, and seven patients underwent a palliative gastrojejunostomy with (n=5) or without (n=2) jejunojejunostomy. A total of 57 metallic stents were used in this study: four bare stents, 29 partially covered stents, and 24 fully covered stents. Types of obstruction were classified into 12 patterns and types of stent placement were classified into 16 patterns. RESULTS: Stent placement was technically successful in all patients. After stent placement, 35 of the 39 patients (90%) experienced improvement of their symptoms, two showed no change, and the remaining two showed aggravation of symptoms as a result of faulty stent placement. Two patients treated with stent placement only in the afferent loop died of aspiration pneumonia. In one of two patients who underwent stent placement according to pattern 6, afferent loop syndrome occurred 10 days after stent placement and was treated by percutaneous pigtail catheter drainage. Stent migration occurred in four of 24 fully covered stents, but in none of the bare or partially covered stents. Tumor ingrowth occurred in one of four bare stents, tumor overgrowth in one of 29 partially covered stents, and mucosal prolapse in one of 24 fully covered stents; all were treated with a second stent placement. CONCLUSIONS: Placement of expandable metallic stents in patients with recurrent cancer after a gastrojejunostomy seems to be feasible and effective, but accurate knowledge of the type of surgical procedure performed and determination of the pattern of tumor recurrence are important for successful stent placement.     

兔尿道细胞外基质修复尿道创伤缺损及组织相容性研究

目的 探讨尿道细胞外基质修复尿道创伤缺损的疗效及其组织相容性. 方法 实验组20只家兔手术切除一段长约1.0～1.5 cm的尿道,人工造成尿道缺损模型.再用一段等长的尿道细胞外基质修复尿道缺损.另设对照组(仅在游离尿道后关闭切口,10只)和异体尿道移植组(配对互换移植,10只).采用淋巴细胞转化实验及术后1,2,3,4周从兔耳缘静脉取血,应用流式细胞仪检测样本中T淋巴细胞亚群CD4+、CD8+及CD4+/CD8+动态变化,评估术后受体的免疫反应状态;术后10 d、3,6及24周取修复段尿道,行组织学观察;术后24周行尿道造影、尿道镜及尿流动力学检查. 结果 实验组术后淋巴细胞刺激指数及外周血淋巴细胞亚群CD4+、CD8+及CD4+/CD8+比值和对照组比较,差异无统计学意义;但异体尿道移植组则高于对照组(P<0.05).术后3周起实验组上皮细胞覆盖细胞外基质的整个管腔;24周尿道平滑肌数量明显增多,接近正常的尿道组织结构.尿道造影及尿道镜检查显示尿道基质管壁光滑通畅.尿流动力学检测显示实验组与对照组比较,差异无统计学意义. 结论 尿道细胞外基质具有较好的组织相容性,是一种安全有效的尿道修复材料.     

X线监视下经尿道植入支架治疗高龄前列腺增生症

目的评价植入网状记忆合金支架治疗高龄前列腺增生症尿道狭窄的临床效果和可行性。方法47例患者,年龄72~93岁,平均78.3岁,排尿困难7~21年。1%利多卡因尿道黏膜麻醉,DSA引导下经尿道将支架放置在前列腺尿道最狭窄处。结果47例患者均一次治疗成功(100%),其中43例支架植入后立即自行排尿,排尿通畅。本组无1例出现尿道再狭窄和结石等情况,排尿通畅率100%。结论记忆合金网状支架治疗前列腺增生引起的排尿困难临床疗效显著,值得临床推广应用。     

食管肿瘤引起的气管狭窄支架置入治疗

目的探讨气管内支架置入治疗由食管肿瘤或食管金属内支架放置术后引起的气管狭窄的疗效和安全性。方法本组11例气管狭窄患者,8例由食管恶性肿瘤引起,3例为食管金属内支架放置术后压迫气管造成。X线透视下在气管内共植入11枚镍钛合金支架,其中7枚为裸支架,4枚为带膜支架。支架直径16～18mm,长度40～60mm。结果所有患者均成功置入内支架(成功率100%)。术后患者气促、呼吸困难和窒息感均立即缓解或消失,血氧饱和度上升。部分患者在术后1～3d可有少量咳嗽和血痰,经对症治疗后消失,无其他并发症。结论采用气管内金属内支架置入的方法治疗由食管恶性肿瘤或食管金属内支架放置术后引起的气管狭窄是一种作用迅速且安全、有效的方法。