URETEROILEAL ANASTOMOTIC STRICTURES: AN INNOVATIVE APPROACH WITH METALLIC STENTS

Ureteroenteric anastomotic stricture: novel use of a cutting balloon dilator

INTRODUCTION

Management of ureteroenteric strictures presents a significant challenge because of its intraabdominal location and morbidity associated with open surgical management. The peripheral cutting balloon microsurgical dilatation device (PCBD), approved by The United States Food and Drug Administration (USFDA) for use in coronary angioplasty, features a 2-cm noncompliant balloon with four microsurgical blades mounted longitudinally on its outer surface. We evaluated the feasibility and outcome of this cutting balloon dilator in the treatment of ureteroenteric anastomotic strictures.

MATERIALS AND METHODS

Three patients with a 1-cm or less ureteroenteric stricture underwent a transluminal incision under fluoroscopic guidance. Percutaneous access was obtained and a guidewire was introduced into the renal pelvis and ureter in antegrade fashion and passed through the stricture. The exact length of the strictured segment was measured. The PCBD was deployed over the guidewire and the balloon was inflated at the stricture site. The maximum diameter of the inflated balloon was 8 mm. Approximately 30 seconds later, the balloon was deflated and the enlarged passage from the ureter to the ileal loop was verified under fluoroscopy. A ureteral stent was placed and removed at 6 weeks after the procedure.

RESULTS

Postoperative computed tomography scans at 12 months revealed improved hydronephrosis. All patients were asymptomatic postoperatively. One patient had a solitary kidney and creatinine level decreased significantly following the procedure.

CONCLUSION

Dilatation and incision with PCBD is a novel approach for the treatment of the short ureteroenteric anastomotic strictures. Long-term data need to be obtained to establish the efficacy of this technique.

Case Report: Urothelial Hyperplasia Causing Recurrent Obstruction after Ureteral Metal Stent Placement in Treatment of Ureteroenteric Anastomotic Stricture

Initial experience utilizing metal stents in the treatment of ureteroenteric anastomotic strictures has yielded promising results. However, the long-term efficacy of metal stent placement remains unknown. Further, there is a paucity of literature to describe the technical considerations associated with the surgical management of obstruction after metal stent failure. We report the case of a 67-year-old man undergoing bilateral ureteral metal stent removal and ileal conduit creation following stent failure and recurrent obstruction.

Ureteral Metal Stents: A Tale or a Tool?

There are four types of ureteral metal stents: self expandable, balloon expandable, covered, and thermoexpandable shape-memory. Insertion of metal stents requires expertise with transurethral and percutaneous techniques. The stricture is traversed with the aid of a guidewire via a percutaneous nephrostomy, and the stenotic segment is dilated using a high-pressure balloon catheter. The stent is then inserted over the guidewire, such that the upper end bypasses the obstruction by at least 3 to 4 cm, while the lower end extends intravesically for 0.5 to 1 cm from the ureteral orifice. If necessary, two or more stents are placed in sequence, overlapping by at least 2 to 3 cm. Metal stents were initially used for the relief of end-stage malignant disease, and their role in the treatment of benign ureteral strictures is still undefined. Patients often complain of abdominal discomfort and mild pain after stent insertion, which soon resolve spontaneously. Hematuria usually stops after a few days and does not necessitate any treatment. Mild urothelial hyperplasia in the stent lumen is common but usually regresses after 4 to 6 weeks. Many authors suggest the use of a double-pigtail catheter for the first 4 to 6 weeks to avoid narrowing of the ureteral lumen. The influence of stents on ureteral peristalsis is a major but poorly documented issue. Encrustation is a significant problem that needs to be addressed. The characteristics of both the patient and the stent influence its likelihood. Migration of coated metal stents was seen in 81% of patients at our center. Virtual endoscopy has recently been introduced as a tool for the follow-up of patients with stented ureters. Further design development is necessary to obtain the ideal ureteral metal stent. In a recent study in female pigs, paclitaxel-eluting metal stents engendered less inflammation and hyperplasia of the surrounding tissues.

Endoscopic Management of Ureterointestinal Strictures after Radical Cystectomy

PURPOSE

To summarize the status of endoscopic treatment for ureterointestinal anastomotic strictures after radical cystectomy.

MATERIALS AND METHODS

We reviewed the English-language literature identified by PubMed and MEDLINE to evaluate the efficacy of various treatment options for these strictures.

RESULTS

Cumulative success rates from multiple studies analyzing patency after balloon dilation, endoureterotomy, and metal stenting specifically for ureteroenteric strictures were 18%, 63%, and 83%, respectively. Studies have not clearly shown any significant advantage over any specific cutting modality. The use of metal stents appears promising but is still fraught with complications of tissue ingrowth and recurrent obstruction. Clinical factors that appear to be associated with a poor prognosis are age >60 years, left-sided strictures, length >1 cm, stenting <4 weeks, and poor function in the affecting kidney.

CONCLUSION

Ureteroenteric strictures remain the most challenging and difficult of all ureteral strictures to treat. An evolution of technology has helped advance the therapeutic options available. Given the rarity of this condition, limited study designs, and small numbers of patients, conclusive statements regarding the optimal treatment for this condition are difficult. Given its patency rates and possible complications, endoureterotomy should be considered the initial treatment of choice in properly selected patients.

Percutaneous Placement of Permanent Metal Stents for Treatment of Ureteroenteric Anastomotic Strictures

PURPOSE

To evaluate the efficacy of permanent metal stent placement in the treatment of ureteroenteric anastomotic strictures following failed balloon dilation or laser endoureterotomy.

PATIENTS AND METHODS

Metal stents were placed in six ureteroenteric anastomotic strictures in four patients presenting with recurrent obstruction after balloon dilation or laser endoureteromy. Patients were evaluated at 1 week postoperatively with antegrade ureterography and at 3 to 6 months with renal ultrasound or CT scans. Serum creatinine assays and physical examination were performed at serial postoperative clinic visits.

RESULTS

At 1-week follow-up, antegrade studies demonstrated a patent anastomosis in all six strictures. With a mean follow-up of 10 months (range 7-12 months), no stricture recurrence has been seen. All patients have been clinically stable, without episodes of pyelonephritis, flank pain, or need for indwelling stents or nephrostomy tube placement. Serum creatinine concentrations have been stable in all patients.

CONCLUSIONS

Metal stents offer a useful treatment option in patients who develop ureteroenteric anastomotic strictures after urinary diversion. Further, such stents may be used in patients failing balloon dilation or laser endoureterotomy. Further study to assess the long-term durability of metal stent placement is needed.

Metal stents for the management of atherosclerotic renovascular disease

PURPOSE

We report on our experience with the use of metal stents for the treatment of atherosclerotic renovascular disease.

PATIENTS AND METHODS

Since 1996, 62 patients (mean age 67 years) with ostial atherosclerotic renal artery stenosis were treated successfully by placement of metal stents. All patients presented with renovascular hypertension, and eight had additionally impaired renal function. In 12 patients, stents were placed bilaterally. In 54 patients, the introduction of stents was performed as the primary mode of treatment, and in the remaining 8 patients, the positioning of the endoprosthesis was deemed necessary because of recurrence of stenosis previously treated by renal percutaneous transluminal angioplasty (PTA). The patients were followed for a mean period of 18 months (range 9-48 months).

RESULTS

Positioning of the endoprosthesis was successful in all patients. No major complications were reported. The 18-month patency rate was 77.4% (48 patients). Hypertension resolved in 39 patients and showed a trend to improvement in 15 patients. We observed no improvement of renal function in the eight patients who had impaired function prior to the procedure.

CONCLUSION

Implantation of metal stents is a safe and effective method for the treatment of atherosclerotic renal artery stenosis and certainly presents an important alternative to renal PTA.

Coated v noncoated ureteral metal stents: an experimental model

PURPOSE

The purpose of the present study was to compare the standard metal stents with internally and externally coated metal stents in the pig model.

MATERIALS AND METHODS

In nine female pigs weighing between 25 and 30 kg, the metal stents were randomly placed in either the right or left ureter, for a total of 18 stented ureters. Six ureters were stented with a Wallstent (Schneider, Zurich, Switzerland), six with a Passager stent (Boston Scientific, Natick, MA, USA), and six with a Corvita endoluminal graft (CEG) (Boston Scientific, Natick, MA, USA). Patency was examined by nephrostotomography 24 hours and 21 days after the initial procedure.

RESULTS

Free flow of urine through the stents into the bladder was revealed in all ureters with the exemption of four cases where a Passager stent migrated into the bladder, jeopardizing ureteral patency. The Wallstent generated mild inflammation with metaplasia of the urothelium; the CEG a more pronounced inflammatory response in the adjacent ureter; and the Passager stent severe inflammatory reaction with necrosis of the urothelium. The sections of the Wallstents revealed the presence of a mild polypoid reaction adherent to the internal surface of the devices. The coated stents showed no tissue ingrowth through the lining material into the ureteral lumen, and thus, the urothelium was compressed beneath the prostheses.

CONCLUSIONS

Our experimental results suggest that the standard Wallstent generates less inflammation of the surrounding tissues than coated stents. The coated stents have the advantage of minimal tissue ingrowth but have a tendency to migrate toward the bladder.

Treatment of benign ureterointestinal anastomotic strictures with permanent ureteral Wallstent after Camey and Wallace urinary diversion: long-term follow-up

BACKGROUND AND PURPOSE

Ureterointestinal anastomotic stricture follows urinary diversion in 4% to 8% of patients and may lead to a progressive deterioration of renal function. There are problems with all current management techniques: surgical revision, endourologic incision, nephrostomy drainage, external ureteral stents, and dilation with a high-pressure angioplasty balloon. The authors present their long-term results with permanent ureteral Wallstents for the treatment of benign ureterointestinal stricture.

PATIENTS AND METHODS

Eight patients with 10 strictures were treated by placement of self-expanding permanent indwelling stents via percutaneous nephrostomy between September 1993 and January 1998. The mean age of the group was 59.2 years. Development of strictures occurred a mean of 20.9 months after urinary diversion. There were seven complete and three partial strictures. Of 49 patients treated by the Camey procedure, 7 patients (14%) developed 9 (18%) strictures. Of 28 patients having the Wallace procedure, 1 patient (3.5%) developed one stricture. After recanalization of the distal ureter by a Terumo guidewire and dilation with a high-pressure angioplasty balloon, a Wallstent was placed across the stricture via a percutaneous approach.

RESULTS

The endourologic placement of the Wallstent was well tolerated by all patients. The hospital stay averaged 2 days. Seven patients with nine strictures after the Camey procedure are doing well with a follow-up of 7 to 68 months (mean 22.4 months). One major complication was observed in one patient necessitating an additional procedure (lithotripsy) because of stone formation at the lower part of the stent extending into the neobladder in order to maintain patency after 68 months. The other patient, who had a Wallace procedure, is doing well 1 year 8 months afterward.

CONCLUSION

An endourologic ureteral Wallstent approach to ureterointestinal stricture is a successful alternative, providing satisfactory management of the problem in most patients. No complication such as stent migration, hematuria, pain, or recurrent stricture was observed.

Liposome-coated metal stents: an in vitro evaluation of controlled-release modality in the ureter

PURPOSE

In vitro preparation of liposome-covered metal stents and loading of liposomal drug formulations that will slowly release the drug in the vicinity of the stent.

MATERIALS AND METHODS

Polytetrafluoroethylene-coated stents were used. Large multilamellar (MLV) liposomes (phosphatidylcholine:cholesterol 1:1 mol/mol), empty or entrapping the corticosteroid anti-inflammatory drug, dexamethasone, were prepared by the thin-film hydration method and applied to pieces of stent using a simple and mild evaporation technique. Initially, a freeze-drying method for applying liposomes to stents was also evaluated, but it failed to produce stents that efficiently retain liposomal lipid when incubated in an aqueous environment. The presence of liposomes on the stent surface was confirmed by scanning electron microscopy.

RESULTS

After analyzing the release of liposomal lipid (using a phospholipid assay) and liposomal drug (by a modified dexamethasone high-pressure liquid chromatography method) in an in vitro system developed to simulate in vivo conditions, it was found that 39.11+/-6.8% of the lipid and 50.84+/-5.48% of the drug was released from the stent pieces during 48 hours of incubation in the presence of artificial urine. The amount of dexamethasone released from stents during their application procedure was found to be negligible in an in vitro dry run.

CONCLUSION

The use of stent-associated liposomal drug formulations as slow-release depots could be an efficient method of treating the untoward event of ureteral stent obstruction.