Artificial urinary sphincter: current status and future directions

Abstract

Urge urinary incontinence (UUI) is one of the most troublesome complications of surgery of the prostate whether for malignancy or benign conditions. For many decades, there have been attempts to reduce the morbidity of this outcome with variable results. Since its development in the 1970s, the artificial urinary sphincter (AUS) has been the "gold standard" for treatment of the most severe cases of UUI. Other attempts including injectable bulking agents, previous sphincter designs, and slings have been developed, but largely abandoned because of poor long-term efficacy and significant complications. The AUS has had several sentinel redesigns since its first introduction to reduce erosion and infection and increase efficacy. None of these changes in the basic AUS design have occurred in the past three decades, and the AUS remains the same despite newer technology and materials that could improve its function and safety. Recently, newer compressive devices and slings to reposition the bladder neck for men with mild-to-moderate UUI have been developed with success in select patients. Similarly, the AUS has had applied antibiotic coating to all portions except the pressure-regulating balloon (PRB) to reduce infection risk. The basic AUS design, however, has not changed. With newer electronic technology, the concept of the electronic AUS or eAUS has been proposed and several possible iterations of this eAUS have been reported. While the eAUS is as yet not available, its development continues and a prototype device may be available soon. Possible design options are discussed in this review.

Keywords: artificial sphincter; bladder sling; prostate; sphincter; urinary incontinence.

Figure 1

Boston Scientific AMS 800 Artificial Urinary Sphincter with inhibizone coating of all parts except the pressure-regulating balloon.

Figure 2

Current possible designs for remote-controlled electronic artificial urinary sphincters. (a) “Closed” state: the cuff is inflated and the pump is unpowered; the pressure is equilibrated between the pressure-regulating balloon and the cuff, allowing to maintain a constant predetermined OCP as long as necessary. (b) Cuff deflation: as soon as a Bluetooth connection is established, the microcontroller activates the pump; the fluid is then transferred from the cuff to the balloon; the AUS#2 returns to an “open” status. (c) “Open state”: the cuff is deflated and the pump is unpowered. (d) Cuff inflation: as soon as decided via the control interface, the fluid progressively flows back to the cuff in 2–3 min thanks to the hydraulic resistor, returning to a “closed” status. Images are reproduced with pemission from Canadian Urological Association Journal.