Selective bladder denervation for overactive bladder (OAB) syndrome: From concept to healing outcomes using the ovine model.

AIMS

We evaluated a Selective Bladder Denervation (SBD) device, which uses radiofrequency ablation, for the treatment of overactive bladder syndrome in terms of its nerve denervation, ablation characteristics, and post-treatment healing.

METHODS

Using the SBD device, eight fresh extirpated ovine bladder trigones were treated (90°C set point for 60 s) and nitroblue tetrazolium viability stained to characterize the ablation. In addition, 12 trigones were treated in vivo with three adjacent ablations and divided into survival cohorts: Day 7, Day 30, and Day 90 to assess the ablations and their associated healing.

RESULTS

The ex vivo single trigone ablations had a 7.9 ± 0.9 mm width and 5.7 ± 1.0 mm thickness that involved the submucosa, detrusor muscle, adventitia, and vagina. Microscopic viability staining confirmed complete nerve necrosis within the targeted tissue. The in vivo Day 7 trigones supported the ex vivo ablation characteristics and showed up to minimal inflammation, granulation tissue, and collagen fibrosis. Day 30 trigones had essentially absent inflammation and granulation tissue with evolving collagen fibrosis at the ablation's periphery. Day 90 trigones had essentially absent acute inflammation, minimal chronic inflammation, essentially absent granulation tissue, and up to mild collagen fibrosis. No ureteral/urethral alterations, vesico-vaginal fistulas, or other complications were identified.

CONCLUSIONS

The SBD device provided a targeted trigone ablation with resultant denervation. The tissue healing timeline followed that expected for a hyperthermic ablation and was characterized by a fibroproliferative healing response with limited inflammation and granulation tissue. The ablations did not impact the overlying bladder mucosal surface.