The Use of the AMS-AS800 Artificial Sphincter for Continent Urinary Diversion. I. Investigations, Including Pressure-Flow Studies, Using Rabbit Intestinal Loops

The AS 800 genitourinary artificial sphincter was implanted in 40 New Zealand rabbits to evaluate its possible use for continent urinary diversion. This evaluation included the effects of varying closing pressures of the cuff implanted around isolated bowel loops. Six-weeks postoperative investigations included pressure/flow studies, autopsies, microangiographies and histologic evaluations. The sphincter was able to achieve continence during perfusion of the intestinal loop, maximum pressures being dependent on cuff pressures. Consistent changes were: 1) the formation of a thin fibrous capsule around the subcutaneously implanted pump, 2) the development of a fibrous sheath around the bowel beneath the cuff, and 3) fibrous and peritoneal reactions at the cuff site. In uncomplicated cases, the bowel wall tolerated the cuff pressure well, without macroscopic signs of atrophy. However, sphincter-related complications (1. infection, 2. erosion, 3. reduction of bowel circumference beneath the cuff) were pressure dependent and seen mainly in high pressure groups. Based on these results, the application of the sphincter for continent urinary diversion should include: low pressure urinary reservoirs, low pressure cuffs and most essentially, strict avoidance of infection.