Evaluation of the effects of temporary covered nitinol stent placement in the prostatic urethra: short-term study in the canine model.
OBJECTIVE
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).


CONCLUSIONS
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.
Crisóstomo
Verónica
V
Minimally Invasive Surgery Center, Avda. de la Universidad, s/n Campus Universitario, 10071, Cáceres, Spain. crisosto@ccmi.es
Song
Ho Young
HY
Maynar
Manuel
M
Sun
Fei
F
Soria
Federico
F
Lima
Juan Rafael
JR
Yoon
Chang Jin
CJ
Usón-Gargallo
Jesús
J
D000497:Alloys; D000818:Animals; D001284:Atrophy; D020099:Coated Materials, Biocompatible; D020878:Device Removal; D004195:Disease Models, Animal; D004285:Dogs; D005549:Foreign-Body Reaction / Q000473:pathology; D008297:Male; D011467:Prostate / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000150:complications* / Q000473:pathology; D015607:Stents; D014521:Urethra / Q000473:pathology; D014524:Urethral Obstruction / Q000473:pathology / Q000628:therapy*; D001748:Urinary Bladder Neck Obstruction / Q000473:pathology / Q000628:therapy*; D014563:Urodynamics / Q000502:physiology
D000497:Alloys; D020099:Coated Materials, Biocompatible; C013616:nitinol