Urinary sphincter based on electronics and artificial muscles

Objectives: The AMS 800TM is the current artificial urinary sphincter (AUS) for incontinence due to intrinsic sphincter deficiency. Despite good clinical results, technical failures inherent to the hydraulic mechanism or urethral ischemic injury contribute to revisions up to 60%. We are developing an electronic AUS, called ARTUS to overcome the rigors of AMS. The objective of this study was to evaluate the technical efficacy and tissue tolerance of the ARTUS system in an animal model.Methods: The ARTUS is composed by three parts: the contractile unit, a series of rings and an integrated microprocessor. The contractile unit is made of Nitinol fibers. The rings are placed around the urethra to control the flow of urine by squeezing the urethra. They work in a sequential alternative mode and are controlled by a microprocessor. In the first phase a three-rings device was used while in the second phase a two-rings ARTUS was used. The device was implanted in 14 sheep divided in two groups of six and eight animals for study purpose. The first group aimed at bladder leak point pressure (BLPP) measurement and validation of the animal model; the second group aimed at verifying mid-term tissue tolerance by explants at twelve weeks. General animal tolerance was also evaluated.Results: The ARTUS system implantation was uneventful. When the system was activated, the BLPP was measured at 1.038±0.044 bar (mean±SD). Urethral tissue analysis did not show significant morphological changes. No infection and no sign of discomfort were noted in animals at 12 weeks.Conclusions: The ARTUS proved to be effective in continence achievement in this study. Histological results support our idea that a sequential alternative mode can avoid urethral atrophy and ischemia. Further technical developments are needed to verify long-term outcome and permit human use.

Experimental evaluation of an electromechanical artificial urinary sphincter in an animal model.

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The AMS 800 urinary control system is the gold standard for the treatment of urinary incontinence due to sphincter insufficiency. Despite excellent functional outcome and latest technological improvements, the revision rate remains significant. To overcome the shortcomings of the current device, we developed a modern electromechanical artificial urinary sphincter. The results demonstrated that this new sphincter is effective and well tolerated up to 3 months. This preliminary study represents a first step in the clinical application of novel technologies and an alternative compression mechanism to the urethra. OBJECTIVES: To evaluate the effectiveness in continence achievement of a new electromechanical artificial urinary sphincter (emAUS) in an animal model. To assess urethral response and animal general response to short-term and mid-term activation of the emAUS. MATERIALS AND METHODS: The principle of the emAUS is electromechanical induction of alternating compression of successive segments of the urethra by a series of cuffs activated by artificial muscles. Between February 2009 and May 2010 the emAUS was implanted in 17 sheep divided into three groups. The first phase aimed to measure bladder leak point pressure during the activation of the device. The second and third phases aimed to assess tissue response to the presence of the device after 2-9 weeks and after 3 months respectively. Histopathological and immunohistochemistry evaluation of the urethra was performed. RESULTS: Bladder leak point pressure was measured at levels between 1091 ± 30.6 cmH2 O and 1244.1 ± 99 cmH2 O (mean ± standard deviation) depending on the number of cuffs used. At gross examination, the explanted urethra showed no sign of infection, atrophy or stricture. On microscopic examination no significant difference in structure was found between urethral structure surrounded by a cuff and control urethra. In the peripheral tissues, the implanted material elicited a chronic foreign body reaction. Apart from one case, specimens did not show significant presence of lymphocytes, polymorphonuclear leucocytes, necrosis or cell degeneration. Immunohistochemistry confirmed the absence of macrophages in the samples. CONCLUSIONS: This animal study shows that the emAUS can provide continence. This new electronic controlled sequential alternating compression mechanism can avoid damage to urethral vascularity, at least up to 3 months after implantation. After this positive proof of concept, long-term studies are needed before clinical application could be considered.

Artificial Urinary Sphincter based on smart materials

Objective: There are only a few established artificial urinary sphincters for treatment of incontinence. We have developed a new device composed by three parts: the actuator, three contractile rings and a control unit. The actuator is made of Nitinol fibers, driven by microprocessor. The fibers are linked to the rings placed around the urethra. They function with alternance in their open and closed position. This concept is called piano concept. With this set-up, the constant compression on the urethra is strongly reduced. Methods: Six male sheep have been used for this study. The sphincter was open each hour for a period of 10 min., to guaranty urination. The bladder was filled with water while one cuff was closed and bladder pressure was monitored. The animals were sacrificed. Two biopsies around two cuffs of each explant and all three cuffs from each explant including urethra were analyzed. Urethra not surrounded by a cuff was taken as control. Results: The pressure exerted by the sphincter around the urethra provided continence. Simulated incontinence occurred at a pressure of 1bar measured on the bladder wall using a pressure probe. The closing force of the cuff was approx. 0·7N. No difference in tissue structure and organization of the urethra with and without artificial sphincter was observed. Conclusions: This device has several advantages compared to other urinary sphincters. It is easy to implant, has no hydraulic nature and reduces ischemic injury of the urethra by the alternance of urethral part compressed. Proof of concept in vivo has been demonstrated. Other studies are planned to determine long-term outcome.

Urinary Sphincter Based on Electronics and Artificial Muscles

Objectives: The AMS 800 is the current artifi cial urinary sphincter (AUS) forincontinence due to intrinsic sphincter defi ciency. Despite good clinical results,technical failures inherent to the hydraulic mechanism or urethral ischemicinjury contribute to revisions up to 60%. We are developing an electronic AUS,called ARTUS to overcome the rigors of AMS. The objective of this study wasto evaluate the technical effi cacy and tissue tolerance of the ARTUS systemin an animal model.Methods: The ARTUS is composed by three parts: thecontractile unit, a series of rings and an integrated microprocessor. The contractileunit is made of Nitinol fi bers. The rings are placed around the urethrato control the fl ow of urine by squeezing the urethra. They work in a sequentialalternative mode and are controlled by a microprocessor. In the fi rst phase athree-rings device was used while in the second phase a two-rings ARTUS wasused. The device was implanted in 14 sheep divided in two groups of six andeight animals for study purpose. The fi rst group aimed at bladder leak pointpressure (BLPP) measurement and validation of the animal model; the secondgroup aimed at verifying midterm tissue tolerance by explants at twelve weeks.General animal tolerance was also evaluated.Results: The ARTUS systemimplantation was uneventful. When the system was activated, the BLPP wasmeasured at 1.038 ± 0.044 bar (mean ± SD). Urethral tissue analysis did notshow signifi cant morphological changes. No infection and no sign of discomfortwere noted in animals at 12 weeks.Conclusions: The ARTUS proved to beeffective in continence achievement in this study. Histological results supportour idea that a sequential alternative mode can avoid urethral atrophy andischemia. Further technical developments are needed to verify long-termoutcome and permit human use.

Artificial muscle: the human chimera is the future.

Severe heart failure and cerebral stroke are broadly associated with the impairment of muscular function that conventional treatments struggle to restore. New technologies enable the construction of "smart" materials that could be of great help in treating diseases where the main problem is muscle weakness. These materials "behave" similarly to biological systems, because the material directly converts energy, for example electrical energy into movement. The extension and contraction occur silently like in natural muscles. The real challenge is to transfer this amazing technology into devices that restore or replace the mechanical function of failing muscle. Cardiac assist devices based on artificial muscle technology could envelope a weak heart and temporarily improve its systolic function, or, if placed on top of the atrium, restore the atrial kick in chronic atrial fibrillation. Artificial sphincters could be used to treat urinary incontinence after prostatectomy or faecal incontinence associated with stomas. Artificial muscles can restore the ability of patients with facial paralysis due to stroke or nerve injury to blink. Smart materials could be used to construct an artificial oesophagus including peristaltic movement and lower oesophageal sphincter function to replace the diseased oesophagus thereby avoiding the need for laparotomy to mobilise stomach or intestine. In conclusion, in the near future, smart devices will integrate with the human body to fill functional gaps due to organ failure, and so create a human chimera.

A prospective study evaluating the efficacy of the artificial sphincter AMS 800 for the treatment of postradical prostatectomy urinary incontinence and the correlation between preoperative urodynamic and surgical outcomes

OBJECTIVES We have evaluated prospectively the long-term efficacy of the artificial urinary sphincter (AUS) AMS 800 for the treatment postradical prostatectomy urinary incontinence (PRPUI) patients. We also evaluated the correlation between preoperative urodynamic findings and surgical outcomes. METHODS From May 1997 to April 2003, 40 consecutive patients with PRPUI caused by intrinsic sphincter deficiency (ISD) were treated with the AMS 800. Mean age was 68.3 +/- 6.3 years. Continence status was evaluated on the basis of pad count, impact of urinary incontinence on the quality of life, complications, and surgical revisions. Preoperative urodynamic findings were correlated with surgical outcomes. RESULTS Follow-up ranged from 27 to 132 months (mean = 53.4 +/- 21.4 months). There was a significant reduction in pad count from 4.0 +/- 0.9 to 0.62 +/- 1.07 diapers per day (P <0.001) leading to continence in 90%. There was a significant reduction on the impact of incontinence decreasing from 5.0 +/- 0.7 to 1.4 +/- 0.93 (P <0.001) in a visual analogue scale (VAS). Surgical revision rate was 20%. Preoperative urodynamics was useful to identify sphincter deficiency. Except by a tendency of worse results in patients with reduced bladder compliance (RBC), other urodynamic parameters did not correlate with a worse surgical outcome. CONCLUSIONS The AMS 800 offers good long-term continence to most PRPUI patients. Preoperative findings like detrusor hyperactivity (DH), impaired detrusor contraction (IDC), low Valsalva leak point pressure, bladder outlet obstruction (BOO), and mild RBC were not associated with worse surgical outcomes.

Animal Tissue Response To Mid-Term Electronic Modular Artificial Sphincter Implantation

Introduction and objectives: The AMS 800TM is considered the gold standard for sphincter replacement. However, the one-ring design can erode the urethra and lead to severe complications. A mechanism that could alternatively compress successive segments of the urethra would limit such deleterious outcome. We report 12 weeks animal urethral tissue analysis following implantation of a new modular artificial sphincter. METHODS: The device is composed by three parts: the contractile unit, two rings and an integrated microprocessor. The contractile unit is made of Nitinol fibers. The rings are placed around the urethra to control the flow of urine by squeezing the urethra. They work in a sequential alternative mode and are controlled by a microprocessor connected to an external computer. The computer can reveal specific failure of device components. The device was impkanted in eight male sheep. The rings were positioned around the urethra and the control unit was placed 5cm away. The device was working twenty hours per day; it was open 10min. per hour to allow urination. The animals were sacrificed after 12 weeks. The urethra and the tissues surrounding the control unit were macroscopically and microscopically examined. Two transversal sections crossing the sphincter and two transversal sections crossing the urethra alone were obtained and stained with modified Paragon after resin embedding. Urethra was also embedded in paraffin. The first section was stained with safranin-hematoxylin-eosin, the second section was stained with Masson's Trichrome and the remaining eight sections were available for immunolabelling of the macrophages.Results: The chronic study went uneventful. No clinical infection or pain was observed. The computer registered no specific failure in ring function, Nitinol wires and tube connectors. At explantation, except for a slight grade of lymphocytes in two out of eight specimens, no urethral stricture or atrophy could be observed. Immunohistochemistry confirmed the absence of macrophages. Tissue structure and organization of the urethra with and without artificial sphincter were similar. No migration of the device was observed.Conclusions: The study clearly showed no tissue damage or inflammation of the urethra. Electronic design, preservation of urethral vascularisation and adjustability after implantation are the key ideas to improve the actual AUS. Further studies will be carried out to evaluate this potential.

Standardized pelvic floor exercises improve stress urinary incontinence in women with intrinsic sphincter deficiency.

OBJECTIVES Pelvic floor rehabilitation is the conservative therapy of choice for women with stress urinary incontinence (SUI). The success rate of surgical procedures in SUI patients with intrinsic sphincter deficiency (ISD) is low. The aim of this study was to analyse the effect of a standardized physiotherapy on patients with SUI and normotonic urethra and ISD. METHODS In this study, 64 patients with ISD and 69 patients with normotonic urethra were enrolled. Maximum urethral pressure (MUCP) >20 cm H2 O was considered as normotonic urethral pressure. Before and after physiotherapy MUCP was measured and cough testing was performed. Additionally, patient reported outcome was assessed using the King's Health Questionnaire (KHQ). For statistical analyses Excel 2010 (Microsoft Inc; Redmond, Washington) and SPSS 20 (SPSS Inc; Chicago, Illinois) for Windows were used. Power calculation was based on the primary endpoint incontinence impact and general health. For power calculation, GraphPad Statmate version 2.00 for Windows was used. RESULTS Sixty-four patients with ISD and 69 patients with normotonic urethra were included in the study. In SUI patients with normotonic and hypotonic urethra KHQ-scores regarding the primary endpoins "general health" and "incontinence impact" significantly improved following standardized physiotherapy. In both groups MUCP increased after physiotherapy. In SUI patients with ISD standardized physiotherapy resulted in a decreased incidence of a positive cough test. CONCLUSIONS Standardized physiotherapy should be offered to patients with SUI and ISD. Long-term results are subject to future studies. Neurourol. Urodynam. © 2015 Wiley Periodicals, Inc.

Pubovaginal sling versus transurethral Macroplastique for stress urinary incontinence and intrinsic sphincter deficiency: a prospective randomised controlled trial

Objective To compare the pubovaginal sling and transurethral Macroplastique in the treatment of female stress urinary incontinence (SUI) and intrinsic sphincter deficiency (ISD). Design A prospective randomised controlled trial comparing two surgical treatments for SUI and ISD. Setting Tertiary referral urogynaecology unit in Australia. Population Women with SUI and ISD who were suitable for either surgical technique. Methods Forty-five women with SUI and ISD were randomly allocated the pubovaginal sling (n = 22) or transurethral Macroplastique (n = 23). Subjective and objective success rates, patient satisfaction and cost measurements at six months and one year following surgery were the primary outcome measures. A telephone questionnaire survey was performed at a mean follow up period of 62 months (43-71). Main outcome measure Comparison of success rates, complications and costs. Results The symptomatic and patient satisfaction success rates were similar following the sling and Macroplastique with the objective success rate being significantly greater (P < 0.001) following the sling (81% vs 9%). Macroplastique had significantly lower morbidity but was more expensive than the sling (P < 0.001). Response rate at 62 months follow up was 60% in both groups with the sling group reporting better continence success (69% vs 21%) and satisfaction rates (69% vs 29%, P = 0.057). Conclusions The pubovaginal sling was more effective and economical than transurethral Macroplastique for the treatment of SUI and ISD. However, transurethral Macroplastique remains an appropriate treatment in selected cases of SUI and ISD.

Changes in urethral sphincter size following rehabilitation in older women with stress urinary incontinence

Introduction and hypothesis The purpose of this study was to evaluate the effects of a pelvic floor muscle (PFM) rehabilitation program on the striated urethral sphincter in women over 60 years with stress urinary incontinence (SUI). We hypothesized that the PFM rehabilitation program would also exercise the striated urethral sphincter and that this would be demonstrated by hypertrophy of the sphincter on magnetic resonance imaging (MRI). Methods Women with at least weekly episodes of SUI were recruited. Participants were evaluated before and after a 12-week group PFM rehabilitation intervention with T2-weighted fast-spin-echo MRI sequences recorded in the axial plane at rest to assess urethral sphincter size. Data on SUI symptoms and their bother were also collected. No control group was included. Results Seventeen women participated in the study. The striated urethral sphincter increased significantly in thickness (21 %, p < 0.001), cross-sectional area (20 %, p = 0.003), and volume (12 %, p = 0.003) following the intervention. The reported number of incontinence episodes and their bother also decreased significantly. Conclusions This study appears to demonstrate that PFM training for SUI also trains the striated urethral sphincter and that improvement in incontinence signs and symptoms is associated with sphincter hypertrophy in older women with SUI. These findings support previous ultrasound (US) data showing an increase in urethral cross-sectional area following PFM training and extend the previous findings by more specifically assessing the area of hypertrophy and by demonstrating that older women present the same changes as younger women when assessed using MRI data.

Changes in urethral sphincter size following rehabilitation in older women with stress urinary incontinence

Introduction and hypothesis The purpose of this study was to evaluate the effects of a pelvic floor muscle (PFM) rehabilitation program on the striated urethral sphincter in women over 60 years with stress urinary incontinence (SUI). We hypothesized that the PFM rehabilitation program would also exercise the striated urethral sphincter and that this would be demonstrated by hypertrophy of the sphincter on magnetic resonance imaging (MRI). Methods Women with at least weekly episodes of SUI were recruited. Participants were evaluated before and after a 12-week group PFM rehabilitation intervention with T2-weighted fast-spin-echo MRI sequences recorded in the axial plane at rest to assess urethral sphincter size. Data on SUI symptoms and their bother were also collected. No control group was included. Results Seventeen women participated in the study. The striated urethral sphincter increased significantly in thickness (21 %, p < 0.001), cross-sectional area (20 %, p = 0.003), and volume (12 %, p = 0.003) following the intervention. The reported number of incontinence episodes and their bother also decreased significantly. Conclusions This study appears to demonstrate that PFM training for SUI also trains the striated urethral sphincter and that improvement in incontinence signs and symptoms is associated with sphincter hypertrophy in older women with SUI. These findings support previous ultrasound (US) data showing an increase in urethral cross-sectional area following PFM training and extend the previous findings by more specifically assessing the area of hypertrophy and by demonstrating that older women present the same changes as younger women when assessed using MRI data.

The urethral pressure profile and ultrasound imaging of the lower urinary tract

In a prospective study 105 patients with symptoms of stress incontinence underwent video-urodynamic testing, including resting urethral pressure profilometry and translabial ultrasound. The urethral pressure profile (UPP) included maximum urethral closure pressure (MUCP), functional length (FL) and area under the curve (AUC). Ultrasound parameters included urethral thickness, urethral rotation and bladder neck descent, as well as funneling/opening of the internal urethral meatus on Valsalva maneuver. Levator contraction strength was assessed measuring the cranioventral displacement of the internal meatus. Negative correlations between UPP data and age, parity and previous surgery were observed which were consistent with literature data. There was a positive correlation :between the urethral AP diameter on ultrasound and the MUCP, which agrees with reports showing reduced sphincter thickness or volume in stress-incontinent women. Hypermobility on ultrasound did not correlate with UPP data. However, a lower MUCP correlated with extensive opening of the bladder neck. Finally, there was a trend towards poorer pelvic floor function with lower MUCP measurements.

Severe stress urinary incontinence: pelvic floor muscle training program

International guidelines recommend a first line therapy in the treatment of female stress urinary incontinence (SUI), the pelvic floor muscle (PFM) training. This case report assesses the effects of the PFM training program in treating women with severe SUI. The urodynamic parameters allow diagnosed intrinsic sphincter deficiency and urethral hypermobility. The subjective and objective parameters were assessed at the beginning and after six-month of PFM training program. This case report confirms the efficiency of the intensive training program in severe SUI. The medical implications of the PFM training as first treatment option reflect favourable individual results and additionally contribute to the selection of the non-invasive treatment, the reduction of the incidence collateral effects, low costs and that does not prevent future treatment options.