A new generation of urethral stents--Allium in the therapy of symptomatic prostatic enlargement of various etiology

A number of urethral stents made of different materials, with different time of indwelling and different designs, primarily based on the vascular stent concept, have been applied in the clinical practice so far. According to the published studies, urethral stents have justified their clinical application, however with certain limitations. Within an attempt to overcome the limitations, a covered, temporary urethral stent was initially designed by Daniel Yachie and Ijko Markovi in Allium corporation from Israel. With its triangular shape, the stent is a replica of the obstructive prostatic urethral lumen. In has been applied in a series of 14 patients with lower urinary tract symptoms caused by the obstruction at the level of the prostatic urethra. The subjects were averagely aged 77.4 +/- 5.1 years. Allium prostatic stent remained in place in the patients for 4.93 +/- 3.17 months, at the average.     

自制国产化支架-移植物腔内治疗腹主动脉瘤的实验研究

目的 探讨自制国产化支架、移植物在治疗犬腹主动脉瘤中的作用。方法 以国产镍钛合金丝纺织成网状管型支架,外套以国产真丝涤纶交织人造血管,装入导鞘制成支架-移植物系统;用胰蛋白酶灌注犬肾下腹主动脉段形成动脉瘤模型;用血管腔内技术将支架-移植物置入腹主动脉内,隔绝血流分别于第1周、1个月、3个月和6个月末观察通畅度及新生内膜生长。结果 20条模型犬接受手术,成功19条,支架置入后能充分展开并恢复形状,1个月末,支架内表面90%被新生内膜覆盖,3个月末几达100%,6个月末,79%的支架保持通畅,无移位、内漏等并发症。结论 自制国产化支架、移植物有良好的生物相容性和较高的通畅率,可用于腹主动脉瘤的治疗。     

Outcome of dual flange metallic urethral stents in the treatment of neuropathic bladder dysfunction after spinal cord injury

Abstract Purpose: To review the results of metallic urethral stents used in patients with neuropathic bladder dysfunction after spinal cord injury (SCI). Patients and Methods: In a rehabilitation unit for SCI and stroke in Cape Town, South Africa, we performed a case note review of dual flange Memokath stents placed from March 2008 until October 2011. Stents were placed rather than performing an external sphincterotomy in selected patients. With the patient under deep general anesthesia, a thermosensitive expandable metallic stent was positioned over the internal and external urethral sphincters. Results: In total, 33 stents were placed in 28 male patients. SCI was cervical in 23 patients and thoracic in 5. Average follow-up was 18 months (range 1-40 months, median 18 months). The most common indications were repeated catheter blockage in eight patients and urinary tract infection in six. The average time from SCI to stent insertion was 79 months (range 1-468 months, median 21 months). Severe autonomic dysreflexia was present in 17 cases before stent placement and in 7 after stents were placed (P=0.003). Stents failed in 15 patients (45%) and were removed. The most common reason for failure was stone formation. Comparing the group of patients with stents lasting >20 months (n=11) to the group with stent removal before 20 months (n=10), the mean time between SCI and stent placement was 31 vs 119 months (P=0.057). Medium term results (up to 27 months) were significantly influenced by earlier stent placement (P=0.0484). One major complication was stent migration that caused an urethrocutaneous fistula.     

UroLume stents: lessons learned

PURPOSE: The UroLume (American Medical Systems, Minnetonka, Minnesota) endoprosthesis has been commercially available since 1990 and has been advocated for use in men with urethral stricture disease and detrusor-sphincter dyssynergia due to spinal cord injury. Despite reports of its success and ease of removal, we have noted management problems in several complex cases. MATERIALS AND METHODS: We retrospectively analyzed the outcome of 10 men who required several additional procedures or experienced complications following UroLume placement. RESULTS: Of the patients 4 had detrusor-sphincter dyssynergia and 6 had urethral stricture disease. All patients with detrusor-sphincter dyssynergia required hospitalization for management of urosepsis within 4 to 10 months of stent placement, and all 4 experienced stent migration requiring placement of a tandem stent (3), bladder neck resection (3) or sphincterotomy (1). Two men were in retention following placement of a second stent and required stent explantation. Of the other 6 men 2 had bulbar and 3 had membranous urethral disease, and 1 had a severe bladder neck contracture following radical retropubic prostatectomy. Strictures recurred within the stent lumen in all 6 men and/or adjacent to it in 3. At least 1 repeat procedure was required in all 6 men (within 6 months in 5), and 1 experienced significant bleeding during open explantation which required perineal urethrostomy. CONCLUSIONS: In our referral experience stent migration and recurrent stenosis were noted following UroLume insertion. Placement of a tandem stent was associated with urethral obstruction. In many cases these adverse outcomes may be secondary to improper patient selection. Therefore, judicious use of the UroLume stent and proper case selection are essential since stent removal is not always straightforward.     

Use of a shape-memory alloy (nitinol) in a removable prostate stent

An easily removable prostate stent would be useful in various clinical situations but is not currently available. Thus, we studied the safety, tolerability, and ease of removal of a nitinol (nickel-titanium alloy) prostate stent in 10 men with symptomatic benign prostatic hyperplasia. The circular-coil stent becomes hourglass in shape following deployment, with the narrowest diameter approximately 35F. A working hypothesis was that the temperature-sensitive shape memory of nitinol would allow for its easy removal vis-à-vis other available stents. Using several modifications of a prototype insertion device, we found that the nitinol stents were easily inserted, retained their shape during retention periods of 1 to 4 weeks, caused no gross tissue reaction, and were removed easily with gentle traction after in situ cooling with iced saline lavage. Stent migration was observed in two patients, but otherwise, the stents were well tolerated. Nitinol prostate stents appear to fulfill a theoretical promise of being biologically inert, "superelastic," and pliable when cooled, allowing for easy removal. Further clinical investigation appears warranted.     

镍钛记忆合金尿道支架管在尿道下裂修复中的应用（附128例报告）

目的：探讨镍钛记忆合金尿道支架管在尿道下裂修复中的优点及应用前景。方法：2007年1月～2010年6月应用镍钛记忆合金尿道支架管作为尿道支架修复128例尿道下裂患者,均为一期尿道重建。结果：术后1～3个月自行脱落或拔除尿道支架,所有患者随访6～24个月,7例出现尿瘘,1例术后发生尿道狭窄,其余均获成功,手术成功率为93．75％（120／128）。结论：镍钛记忆合金尿道支架管可有效预防尿道下裂术后尿瘘及尿道狭窄的发生。     

镍钛尿道支架管在尿道下裂修复术中的作用

目的探讨镍钛记忆合金尿道支架管在预防尿道下裂术后尿瘘及尿道狭窄中的作用.方法 2001年1月～2004年12月,应用镍钛记忆合金尿道支架管作为尿道支架修复63例尿道下裂,其中阴茎近端型19例,阴茎阴囊型22例,阴囊会阴型8例,为一期尿道重建;尿道下裂术后尿瘘行尿瘘修补术10例;尿道下裂术后尿道狭窄再次重建尿道4例.结果 63例伤口均Ⅰ期愈合,术后获随访2个月～2年,排尿通畅,均无尿瘘和尿道狭窄发生.其中62例于术后2～3个月后拔除尿道支架,1例于12个月后拔除.结论镍钛记忆合金尿道支架管可有效预防尿道下裂术后尿瘘及尿道狭窄的发生.     

Long-term safety and tolerance of silicone and self-expandable airway stents: an experimental study

BACKGROUND: A variety of respiratory stents are currently available, but the ideal airway prosthesis seems far from being recognized. The objective of this study was to verify safety and long-term effect on the bronchial wall of three different types of airway stents. METHODS: Twelve healthy adult sheep were divided in three groups, scheduled to receive: (1) bare self-expandable metallic stents (Gianturco); (2) silicone stents (Dumon); and (3) covered self-expandable synthetic stents (Polyflex). Insertions were performed through a rigid bronchoscope under general anesthesia. Chest roentgenogram was performed 1 and 6 months after surgery, and flexible bronchoscopy after 6 months. Twelve months postoperatively, the animals were killed and a postmortem examination was carried out. RESULTS: All Polyflex stents migrated during the observation period; one late migration was observed in the Dumon group. Microscopic study showed: (1) Gianturco stents: full-thickness perforation of the bronchial wall covered by a thick layer of a chronic inflammatory infiltrate. Infection by Candida at the bottom of some ulcerations; (2) Dumon stents: mild bronchial inflammation (squamous metaplasia, submucosal inflammatory infiltrates; granuloma-like infiltrates). In case of displacement, no significant changes of the previously stented bronchus occurred; and (3) Polyflex stents: no changes of the previously stented bronchi. CONCLUSIONS: Gianturco stents proved unsafe in the long term, owing to the risk of severe airway wall damage. The Polyflex stent is well tolerated but presents a high migration rate. Silicone stents show several limitations but appear to be well tolerated by the host mucosa.     

‘Stent in a Stent’—An Alternative Technique for Removing Partially Covered Stents Following Sleeve Gastrectomy Complications

Endoscopic stenting is a relatively new technique for the treatment of post sleeve gastrectomy complications. Partially covered stents are used in this method to minimise the risk of migration but they are associated with difficulties with removal. Patients requiring emergency stenting following sleeve gastrectomy underwent insertion of a partially covered metallic stent. One month later, if the stent was not easily removable, a fully covered overlapping stent was inserted and the patient was readmitted 2 weeks later for removal of both stents. Four patients required stenting following sleeve gastrectomy leaks, and one patient required stenting for a stricture. In these cases, a ‘stent in a stent’ technique was used for removal. This technique allows the safe removal of partially covered stents inserted following sleeve gastrectomy complications.     

Recanalization of urethral strictures using a temporary curved biocompatible new generation metal endoprosthesis]

The male urethral stricture treatment is actual clinical issue with its resolution being increasingly frequently based on application of minimum invasive therapeutic interventional uroradiology methods. Since the methodology is applied over the last two decades, the most reasonable therapeutic algorithm has not been defined yet with respect to the correlation with the contemporary surgical treatment. The results of application of the temporary covered self-expandable nitinol Allium stents, which have been applied for the first time ever at our Institution in October 2003. Over the last 3 years, the method was applied in 40 males, averagely aged 54 years with urethral strictures previously treated by urological methods. In four cases, stent placement was performed after endourethral incision. The most common etiology of the stricture was the posttraumatic (55%), post-inflammatory (32%) and iatrogenic (10%). In all the cases, stents were removed 12-14 months after their insertions. The results are evaluated using uroflowmetry and urethrocystography, revealing in 85% of the cases permanent recanalization free of dysuric complaints. Development of a stricture on the anterior stent end was evidenced in 15% of the cases.     

Expandable metallic stents in the management of malignant oesophageal obstruction

BACKGROUND: Malignant oesophageal obstruction with an advanced disease presents a difficult challenge. A new class of metal stents have been developed to overcome the limitations of existing treatment modalities. METHODS: We present our first 58 patients, who have been treated with self-expandable metallic stents, using sedation anaesthesia, with fluoroscopic and endoscopic control. Both kinds of stents, covered and uncovered, were applied. RESULTS: There was no procedure-related mortality. The immediate relief of dysphagia was 98%. All four oesophageal fistulas were successfully sealed with covered stents. Due to stent migration, tumour overgrowth, or ingrowth, twelve (21%) of the patients needed re-intervention. Restenting or laser therapies were used against recurrent dysphagia. CONCLUSION: The palliation of oesophageal malignant obstruction with metal stents is a rapid, effective, and relatively safe single treatment which can be employed as part of a multimodal treatment program.     

Retrieval of migrated ureteral stents by coaxial cannulation with a flexible ureteroscope and paired helical basket

PURPOSE: Retrieval of a proximally migrated ureteral stent is a technically challenging endoscopic procedure. We describe the use of a paired wire helical stone retrieval basket through a flexible ureteroscope to remove proximally migrated ureteral stents. MATERIALS AND METHODS: Five ureteral stents were lost in the proximal (1) and distal (4) ureter after lithotripsy or stent exchange. Once the location of the distal aspect of the ureteral stent was identified by either fluoroscopy or ureteroscopy, a safety guidewire was placed alongside the migrated stent. A flexible ureteroscope was brought to the distal end of the stent under direct visualization. Through the working port of the ureteroscope, the paired wire helical basket was deployed to grasp or coaxially cannulate the lumen of the migrated stent. Once inside the stent, the basket was then opened. The outward resistance of the deployed basket is sufficient to provide enough lateral force to reposition the stent into the bladder. RESULTS: All stents were successfully retrieved without complication. No patient had visual evidence of ureteral injury, and all patients were discharged on the same day as their procedure. CONCLUSION: While proximal migration of a ureteral stent is usually caused by technical error, the ideal technique to reposition the stent should require the least time, trauma to the ureter, and expense to the patient. We describe a simple technique to retrieve migrated stents anywhere along the urinary tract.     

Temporarily implanted urethral coil stent for the treatment of recurrent urethral strictures: a preliminary report

A new urethral stent developed for use in recurrent urethral strictures is presented. This metallic coil is self-expanding when released from its introducing catheter. The stent was used in 18 patients with recurrent strictures necessitating frequent dilation or urethrotomy. The stent is introduced under fluoroscopic guidance after internal urethrotomy or simple dilation. Strictures of 5 to 60 mm. were treated successfully with this device. All strictures were distal to the external sphincter. No serious complications attributed to the device were recorded. When necessary, the stent could be repositioned either under fluoroscopic control or endoscopically. This device can hold the stenotic area of the urethra open for long intervals allowing for complete healing. Even after 6 months the stent is not covered with urethral epithelium and does not become incorporated into the urethral wall. It can be removed easily without an operation by simple manipulation. The large internal caliber permits passage of endoscopes up to 17F in patients who require cystoscopy. The device can be removed before transurethral resections and then a new stent can be inserted at the end of the procedure. Mean followup of our patients with the stent indwelling was 8 months (range 4 to 11 months). Followup after removal of the stent (6 patients) was 3 to 8 months (mean 5 months). The patients voided well during followup and were fully continent. No incrustations were noted in the removed stents even after 6 months and no stent became obstructed due to tissue proliferation or incrustation. In 1 patient the stricture recurred after 3 months and a new stent was inserted. Urine sterilization was obtained in 7 patients with infected urine after relatively short courses of antibiotics. This stent seems to be a promising tool for the nonoperative treatment of recurrent urethral strictures.     

Biodegradable braided poly(lactic-co-glycolic acid) urethral stent combined with dutasteride in the treatment of acute urinary retention due to benign prostatic enlargement: a pilot study

OBJECTIVE

To evaluate, in a pilot study, the efficacy and safety of combining a braided poly(lactic‐co‐glycolic acid) (PLGA, a copolymer of l ‐lactide and glycolide) urethral stent and dutasteride in the treatment of acute urinary retention (AUR) due to benign prostatic enlargement (BPE).

PATIENTS AND METHODS

Ten men with AUR due to BPE were treated as outpatients. A biodegradable braided PLGA urethral stent was inserted into the prostatic urethra, using a specially designed insertion device under visual control. Dutasteride treatment was started and the patients were followed up for 3 months after insertion of the stents.

RESULTS

In all patients the stents were placed successfully with the new insertion device. All men were able to void after inserting the stent. At 1 month five patients voided freely with a low residual urine volume (<150 mL), two voided but had a high residual urine volume and a suprapubic catheter was placed, and three needed a suprapubic or an indwelling catheter before 1 month, due to AUR or comorbidities. At 3 months five patients were voiding with no problems.

CONCLUSIONS

We have developed a new and effective insertion device for biodegradable braided prostatic stents. The new braided‐pattern stent overcomes the earlier problems of migration and sudden breakage into large particles associated with biodegradable spiral stents. However, the mechanical properties of the new stent need to be improved and tested in a longer follow‐up. We consider that this new biodegradable braided‐pattern urethral stent could provide a new option in the future treatment of AUR.     

Outcome analysis of the urethral stent (Memotherm®)

A number of patients with benign prostatic hyperplasia can not undergo surgical therapy because of advanced age, concomitant diseases, and other reasons. Since 1980, various types of urethral stents have been used for high-risk patients with benign prostatic hyperplasia. We report our experience with the use of urethral stents (Memotherm?). Between July 2002 and December 2010, we implanted urethral stents in 36 patients. The average follow-up period was 24.0 months. After stent implantation, 34 of the 36 patients were able to micturate. The average residual urine volume was 24.7 ml (0-250 ml), and the maximal urinary flow rate was 10.7 ml/s (3-24 ml/s). One stent had to be removed due to bladder tamponade, and one had to be exchanged due to dislocation. In 2 patients, a stone formed at the bladder end of the stent, and one of these patients underwent transurethral lithotripsy. Our results suggest that therapy with the Memotherm? urethral stent is a good option for patients suffering from urinary retention due to benign prostatic hyperplasia.     

Self-expanding polytetrafluoroethylene covered nitinol stents for the treatment of ureteral stenosis: preliminary report

PURPOSE: We evaluated the treatment of ureteral stenosis using a self-expanding nitinol stent covered with expanded polytetrafluoroethylene (ePTFE). MATERIALS AND METHODS: Between January 2001 and April 2003, 37 ePTFE covered metal stents were implanted in 20 patients with a total of 29 ureteral stenoses due to various causes. In general the stents were introduced by using a retrograde approach under combined endoscopic and fluoroscopic guidance with patients under spinal block and sedation. Followup assessments in 18 patients, including urography, were done 3, 6, 12, 18 and 24 months after the procedure. Followup endoscopic examinations were performed at 6 and 12 months in 8 patients. RESULTS: Immediate ureteral patency was achieved during all insertion procedures and maintained in most patients. Four patients died of the neoplastic process 3 to 12 months after implantation. Four stent migrations occurred in 3 patients (22.2%), which was resolved by implanting a new stent. Nonobstructive mucous hyperplasia was observed in 5 patients (27.7%) at the end of the stent, although there was no internal calcification. In all cases the stents remained patent until the current time or until patient death. CONCLUSIONS: We found that ePTFE covered nitinol stents were safe and effective for ureteral stenosis. Their resistance to calcification was high with nonobstructive hyperplasia developing in only a few cases and only at the stent ends. The ideal material for covering stents would produce no mucous hyperplasia.     

气管支架置入术治疗气管恶性狭窄的并发症分析

目的探讨应用气管支架治疗气管恶性狭窄的并发症。方法回顾性分析1999年11月—2011年6月在局麻和数字减影血管造影机下应用气管支架治疗气管恶性狭窄的25例患者资料,其中6例置入Z型不锈钢支架,19例置入镍钛记忆合金支架,观察支架相关并发症。结果置入Z型不锈钢支架的6例患者中,所有支架置入后即刻完全扩张,2例出现支架移位,随访期中支架再狭窄3例,其中肿瘤增生性狭窄1例,黏稠痰液阻塞性狭窄1例,支架断裂伴肉芽增生性狭窄1例;置入镍钛记忆合金支架的19例患者中,术中无支架移位,2例即刻完全扩张,17例术后3天～3个月扩张完全,随访期内支架再狭窄2例,其中肿瘤增生性狭窄1例,肉芽增生性狭窄1例。所有患者术后呼吸困难即刻明显改善。结论应用气管支架治疗气管恶性狭窄有一定并发症,但仍是一种作用迅速、效果显著的治疗措施。     

Stenting and interventional radiology for obstructive jaundice in patients with unresectable biliary tract carcinomas

Together with biliary drainage, which is an appropriate procedure for unresectable biliary cancer, biliary stent placement is used to improve symptoms associated with jaundice. Owing to investigations comparing percutaneous transhepatic biliary drainage (PTBD), surgical drainage, and endoscopic drainage, many types of stents are now available that can be placed endoscopically. The stents used are classified roughly as plastic stents and metal stents. Compared with plastic stents, metal stents are of large diameter, and have long-term patency (although they are expensive). For this reason, the use of metal stents is preferred for patients who are expected to survive for more than 6 months, whereas for patients who are likely to survive for less than 6 months, the use of plastic stents is not considered to be improper. Obstruction in a metal stent is caused by a tumor that grows within the stent through the mesh interstices. To overcome such problems, a covered metal stent was developed, and these stents are now used in patients with malignant distal biliary obstruction. However, this type of stent has been reported to have several shortcomings, such as being associated with the development of acute cholecystitis and stent migration. In spite of these shortcomings, evidence is expected to demonstrate its superiority over other types of stent.     

具有防移位设计的可压缩性肺动脉支架瓣膜动物置入手术及体内测试

目的 探讨具有防移位设计的可压缩性肺动脉支架瓣膜的防移位效果.方法 将带瓣牛颈静脉缝在3个"Z"字型镍钛合金支架上,制作成喇叭口型肺动脉支架瓣膜.非体外循环下用推送器将其经右心室置入羊肺动脉瓣位置(n=6),分别于术后早期、术后2个月采用右心导管、心脏彩超、血流动力学测定、大体病理等方法评价置入瓣膜的位置和功能.结果 6只羊支架瓣膜均在正确位置释放.超声、右心导管造影以及血流动力学检查显示,术后早期、术后2个月置入瓣膜支架固定好,无移位,1例瓣膜收缩期跨瓣压差24 mm Hg,1例瓣膜轻度关闭不全,其他瓣膜功能良好.结论 喇叭口型支架有助于防止瓣膜移位.     

A novel dedicated endoscopic stent for staple-line leaks after laparoscopic sleeve gastrectomy: a case series

BackgroundStaple-line leak is the most serious complication of laparoscopic sleeve gastrectomy (LSG) occurring in .5−7% of cases. Patients with this complication are often managed with an esophageal covered, self-expandable metal stent positioned at endoscopy. Unfortunately, migration of these stents has been reported in 30–50% of cases. A novel fully-covered, self-expanding metal stent (Megastent), specifically designed for post-LSG leaks is now available. The objective of this study was to describe the first case series of patients with a staple-line leak after LSG who were endoscopically managed with such a novel stent.MethodsFour patients who developed a staple-line leak after LSG were treated by positioning a Megastent at endoscopy. The stents were removed after 8 weeks.ResultsA complete leak repair was achieved in all patients. No stent migration occurred. Prokinetic therapy was needed to treat vomiting episodes during stent presence. At endoscopic evaluation after stent removal, a decubitus lesion at the distal part of the duodenal bulb was observed.ConclusionThese preliminary results would suggest the use of the Megastent as an option for stenting of a staple-line leak after LSG. Further studies are still necessary.