The use of the AMS800 artificial urinary sphincter in combination with the gastric tube for continence in the canine model

An experimental canine model was designed to examine the potential use of the artificial urinary sphincter around a gastric tube. The artificial urinary sphincter was placed around a tubularized gastric flap as part of a continent gastric reservoir in 4 dogs and in 2 additional dogs the gastric tube was anastomosed to the native bladder. Two dogs underwent placement of the artificial urinary sphincter around the gastric tube 4 weeks postoperatively and the remainder had the sphincter placed simultaneously with creation of the gastric tube. All dogs with the gastric reservoir underwent urodynamics before and after activation of the sphincter. Only 61 to 70 cm. water pressure balloons were used. All dogs were continent postoperatively on clean intermittent catheterization every 8 hours. There were no erosions or problems with catheterization. Urodynamics confirmed a compliant system and an average increase of capacity of 410% after artificial urinary sphincter activation (4 dogs). There was no leakage at capacity. Histology of the artificial urinary sphincter and neighboring (control) regions, and of the reservoir at 1 (2 dogs), 3 (3 dogs) and 6 months (1 dog) was obtained. Microscopic examination of the cuff site showed mild serosal hyperplasia and fibrosis, a well preserved muscularis and mild to moderate focal mucosal atrophy. These changes were slightly more evident at 6 months. Mucosal folds were well preserved with normal submucosa and lamina propria. In the control region histology was well preserved and similar to native stomach. We conclude that the artificial urinary sphincter around a gastric tube can provide urinary continence. The minimal changes in histology under the cuff are encouraging and support the potential for use of the gastric tube with the artificial urinary sphincter, although longer term effects are unknown.