Placement of a Covered Retrievable Expandable Nitinol Stent with 8 Barbs in Patients with Metastatic Prostatic Cancer
Hyung Keun Park1, Choung-soo Kim1, Ho-Young Song1, jin Hyung Kim1, Deok Ho Nam2, Jae-Ik Bae3, In Gab Jeong1
Asan Medical Center, University of Ulsan College of Medicine 1, Kyung Hee University Hospital at Gangdong, Kyung Hee University2, Ajou University, College of Medicine & Hospital3
PURPOSE: To prospectively evaluate the technical feasibility and clinical effectiveness of a newly constructed, covered, retrievable, expandable nitinol stent with 8 barbs in patients with metastatic prostatic cancer.
MATERIALS AND METHODS: A stent 20mm in diameter when fully expanded and 20-50mm long was constructed from 0.01-inch-thick nitinol wires into a tubular configuration. To prevent stent migration, 4 barbs (2mm in length) were attached 5mm proximal to the distal (urethral) end of the stent and another 4 barbs to the middle body of the stent. To make the stent removable, two draw-strings were attached to the distal end of the stent crossing the lumen of the stent. The outside of the stent was covered with expanded polytetrafluoroethylene (ePTFE). The stent was placed with use of an 18-Fr stent delivery system in eight consecutive patients with symptomatic metastatic prostatic cancer. Patient age ranged from 55 to 76 (mean, 68) years. All of the eight patients have had hormone therapy, and two of them had palliative transurethral prostatectomy. In cases in which the stent caused complications, the stents was removed using a 21-Fr stent removal set. As for the follow-up study, we performed clinical examinations, uroflowmetry, and retrograde urethrography 1 day, 1 month, 3 months, and 12 months after stent placement.
RESULTS: No technical failure or procedural complications occurred. All patients could void immediately after stent placement. Maximum urine flow rates and post-void residual (PVR) volumes after stent placement were 5.6-10.2 mL/sec (mean, 8.2 mL/sec), and 5– 45 mL (mean, 27 mL), respectively. Urinary incontinence occurred in five of the eight patients, which gradually improved. During the mean follow-up of 192 days (range, 21 to 553 days), the stent was removed in one patient because of stone formation 233 days after stent placement. The patient did not need further intervention because of improvement of the mass after stent removal.
CONCLUSION: Although further studies are needed, our preliminary results show that the retrievable stent with 8 barbs seems to be both feasible and effective in patients with metastatic prostatic cancer.