Despite good, long-term clinical outcomes, a relatively high surgical revision rate of up to30% has been reported. Revisions are the result of urethral erosion or atrophy (which may be attributed to high occlusion pressures), mechanical failures such leaking connectors and infection. A new AUS has been designed by Anthony Mundy and colleagues from London to address these problems. A preliminary report of 9 patients implanted with the new AUS device with a 12 month follow-up period is reported in the September 2006 issue of European Urology.

he principal design features of the new implant include a self-sealing port in the pump assembly for in-situ pressure adjustment, a stress relief mechanism providing low resting occlusion pressure and conditional occlusion of the urethra, a one-piece assembly to facilitate implantation and minimize mechanical failures, improved cuff design to reduce potential for creasing and fracture, patient-activated rapid cuff re-inflation facility. The novel component of the new AUS device is a stress regulating balloon in addition to a pressure-regulating balloon that is placed extraperitoneally and transmits transient intraabdominal pressure changes to the urethral cuff to increase occlusion pressure during periods of stress (conditional occlusion). The new device is manufactured as a single unit from medical grade silicon rubber and supplied prefilled with sterile saline and ready for implantation. The cuff is different from the current AUS in that it is premoulded and has an adjustable circular occlusion cuff.

In the 12-month pilot study, 9 men with stress incontinence (8 after radical prostatectomy and one after pelvic trauma) were implanted with the new AUS device. The surgical procedure is not that different than the technique for the current AMS model although the device is implanted at atmospheric pressure and after adequate time has passed to allow for swelling to subside (2-4 weeks) the patient is brought back for device pressurization via the self-sealing port in the base of the pump which is accessed percutaneously via a 23-G short needle. A set volume of solution is initially injected and additional fluid can be injected at a later date if needed.

Analysis of results showed that a greater than 10-fold decrease in mean daily leakage volume from 770.6 grams to 55.1 grams. At 12 months of follow-up, 83% of patients achieved a continence index greater than 97% and could be described as dry or substantially dry. These continence levels are similar to those reported with the AMS device in which 73% of patients were dry or substantially dry and 88% showed improvement. The hope that the absence for the need for surgical revision with the ability to adjust the regulating pressure in situ can only be evaluated after longer follow-up.

Sarah L. Knight, Judith Susser, Tamsin Greenwell, Anthony R. Mundy, Michael D. Craggs

Eur Urol. 2006 September;50(3):574-80

Written by Michael J. Metro, MD, a Contributing Editor with UroToday.

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