Sphincter System Research Articles

Power flow control of TET system for a novel artificial anal sphincter system

This paper presents an adaptive transcutaneous energy transfer system (TETS) integrated with a novel elastic scaling artificial anal sphincter system (ES-AASS) for treating severe faecal incontinence (FI). The ES-AASS is based on a novel executive mechanism that uses a spring scalable structure to clamp the rectum. To deliver the correct amount of power (i.e. to match the load demand under variable coupling conditions or different operation stages of the implanted device) for internal battery charging and ensure safety for the human body, theoretical analysis was conducted as a control rule with respect to the relationship between the phase of driver signals and output voltage. An easy regulating procedure to stabilize output voltage with a phase shift controller is also presented. To validate the phase control rules, a prototype of the TETS was constructed and its performance was validated across the whole coupling coefficient range (0.09 ∼ 0.29) as well as load resistance (50 ∼ 120 Ω). The results show that the output voltage of the secondary side can be maintained at a constant 7 V with a phase regulation range of 78.7–178.2° and the proposed controller has reached a maximal end-to-end power efficiency of 74.2% at 1 W.

IMPACT DE L’IMATINIB EN NEOADJUVANT SUR LA PRESERVATION SPHINCTERIENNE, LA SURVIE SANS RECIDIVE ET LA SURVIE GLOBALE DANS LES GIST DU RECTUM

Objective: To evaluate the impact of neoadjuvant imatinib in sphincter preservation and survival in GIST rectum. Patients and Methods: Retrospective study of four patients treated in the department of Surgery at Tenon Hospital for rectal GIST between 2005 and 2012. All tumors strongly expressed the C-Kit. Were included, patients treated with neoadjuvant imatinib. The impact of imatinib on the surgery was obtained by comparing the initial indication and the gesture made after imatinib. Results: The mean tumor size at diagnosis was 4.62 (3 and 6) and 2.45 cm (0 to 6) cm respectively at diagnosis and at the end of treatment with imatinib. The average duration of neoadjuvant imatinib was four months The indication for surgery was abdominoperineal resection in three cases because of reports of tumors with sphincter system. After treatment with imatinib, no amputation was performed. We performed a local resection of the tumor in two cases and a low anterior resection in one case. In the latter case, no action has been made. Urticaria was noted in one case requiring discontinuation of treatment after a month. In the latter case, the reduction in tumor size was not significant, but the rectal signs had disappeared. All patients are alive with disease-free survival (DFS) average of 22 months. Conclusion: The neoadjuvant imatinib allows sphincter preservation in rectal GIST. It decreases the risk of recurrence and improves overall survival (OS). GIST of the rectum are rare and reported primarily by clinical case studies, it is necessary to undertake large studies to better understand the impact of preoperative imatinib on surgery, SRH, and OS. Keywords: GIST - Rectum - Imatinib - sphincter preservation

A novel artificial anal sphincter system in an in vitro and in vivo experiment.

This paper presents some of the latest progress in the development of a novel artificial anal sphincter system (AASS) to treat severe fecal incontinence. We have redesigned and integrated an intelligent, remote-controlled artificial anal sphincter based on biological signal feedback mechanisms. The device consists of an external telemetry unit, an internal artificial anal sphincter (IAAS), and a transcutaneous energy transfer system (TETS). The mechanical medical micropump of the IAAS can realize bidirectional flow with a maximum flow rate of 8.5 ml/min and can build backpressure up to 170 kPa. The design of the prosthesis reduces occlusion pressure and allows for low inflation volumes (9 mL-10.5 mL); operating pressures between 4.05 kPa and 7.16 kPa indicate that the risk of ischemic injury to the bowel is minimal. Furthermore, the rechargeable battery based on TETS puts the operation time at an estimated 2 days. The performance characteristics of the AASS and its efficiency in achieving continence and sensing the stool inside the anorectum were evaluated in vitro and in vivo in a pig model. Experimental results confirm that the system can maintain continence and build the sense of defecation successfully. Moreover, this innovation can be integrated into not only severe fecal incontinence, erectile dysfunction, and therapy-resistant reflux disease, but also morbid adiposity therapeutic AASS applications.

Feedback control of TET system with variable coupling coefficients for a novel artificial anal sphincter

For treating severe faecal incontinence, the authors developed an intelligent artificial anal sphincter system (AASS) equipped with a feedback sensor that utilized a transcutaneous energy transfer system (TETS). To deliver the correct amount of power (i.e. to match the load demand under variable coupling conditions caused by changes in positioning between the coils due to fitting and changes in posture), a regulating method to stabilize output voltage with a closed loop variable-frequency controller was developed in this paper. The method via which the voltage gain characteristics of a voltage-fed series-tuned TETS were derived is also described. The theoretical analysis was verified by the results of the experiment. A numerical analysis method was used as a control rule with respect to the relationship between operating frequency and output voltage. To validate the feedback control rules, a prototype of the TET charging system was constructed, and its performance was validated with the coupling variation between 0.12–0.42. The results show that the output voltage of the secondary side can be maintained at a constant 7 V across the whole coupling coefficient range, with a switching frequency regulation range of 271.4–320.5 kHz, and the proposed controller has reached a maximal end-to-end power efficiency of 67.5% at 1 W.

Assessment and in vitro Experiment of Artificial Anal Sphincter System based on Rebuilding the Rectal Sensation Function

In this paper, a novel artificial anal sphincter (AAS) system based on rebuilding the rectal sensation function is proposed to treat human fecal incontinence. The executive mechanism of the traditional AAS system was redesigned and integrated for a simpler structure and better durability. The novel executive mechanism uses a sandwich structure to simulate the basic function of the natural human anal sphincter. To rebuild the lost rectal sensation function caused by fecal incontinence, we propose a novel method for rebuilding the rectal sensation function based on an Optimal Wavelet Packet Basis (OWPB) using the Davies-Bouldin (DB) index and a support vector machine (SVM). OWPB using a DB index is used for feature vector extraction, while a SVM is adopted for pattern recognition.Furthermore, an in vitro experiment with the AAS system based on rectal sensation function rebuilding was carried out. Experimental results indicate that the novel executive mechanism can simulate the basic function of the natural human anal sphincter, and the proposed method is quite effective for rebuilding rectal sensation in patients.

Novel Artificial Anal Sphincter System Based on Transcutaneous Energy Transmission System Tested in vivo

This paper proposes a novel artificial anal sphincter system (AASS) for severe fecal incontinence. The AASS is composed of an artificial anal sphincter (AAS), an external transcutaneous energy transmission system (TETS), and an external control device. The AAS is composed of a cuff, a micropump, a reservoir, and a remote control device. It is designed to be implanted into the body of the patient. The function of the AAS is to open and close the patient's natural anus. Patients suffering from loss of their natural sphincter lose rectal sensation and are thus unable to perceive imminent fecal incontinence. In order to restore rectal sensation, a pressure sensor in the AAS cuff is designed to detect pressure in the colon. The pressure reflects the present quantity of colon contents, allowing patients to control the AAS to open or close the anus according to the pressure. The TETS is designed to provide electrical energy to the implanted AAS without wire connections. The external control device is designed to receive the pressure information from the AAS and send the patient's command to the implanted device. This paper provides a thorough discussion of the design of the novel AASS and describes the performance of the AASS when tested in vivo on two Beagle dogs who were chosen to be the subjects for receiving the implant. The experimental results verified that the performance of the AASS met the functional requirements it was designed for; however, the trial also revealed some challenges to be further studied.

Experience with a new prosthetic anal sphincter in three coloproctological centres

BackgroundFecal incontinence is a common and severely disabling disorder. For patients with severe fecal incontinence, surgery may prove to be the only adequate treatment option.MethodsThis study reports on 43 patients that were treated with a prosthetic sphincter system between 2005 and 2009 in three coloproctological centres. Main Outcome Measures: complications, anal pressures before and after surgery, fecal continence score.ResultsThe new artificial sphincter system significantly improves continence but leads to some complications in clinical practice. After implantation of the device, continence improved significantly (Keller & Jostarndt continence score 2.6 to 14.3 (P < 0.01)). With the band activated, resting pressure improved significantly as compared to baseline (10.7 mmHg vs. 66.1 mm Hg, P < 0.01). The same holds for anal sphincter squeeze pressure (32.2 mmHg versus 85.9 mm Hg, P < 0.01). Complications occurred in 21 patients (48.8%): 10 surgical and 13 technical. Two patients were affected by both technical and surgical problems. The median time of the occurrence was 3 months postop. In five patients difficulties arose within the first postoperative month leading to explantation of the device in three patients. 90% of complications occurred in the first year.ConclusionsThe soft anal band of AMI (AAS), a new artificial anal sphincter, improves severe anal incontinence, but it must be regarded as a last treatment option to avoid a stoma.

Electromagnetic assessment of embedded micro antenna for a novel sphincter in the human body

This paper presents a wireless, miniaturized, bi-directional telemetric artificial anal sphincter system that can be used for controlling patients' anal incontinence. The artificial anal sphincter system is mainly composed of an executive mechanism, a wireless power supply system and a wireless communication system. The wireless communication system consists of an internal RF transceiver, an internal RF antenna, a data transmission pathway, an external RF antenna and an external RF control transceiver. A micro NMHA (Normal Mode Helical Antenna) has been used for the transceiver of the internal wireless communication system and a quarter wave-length whip antenna of 7.75 cm has been used for the external wireless communication system. The RF carrier frequency of wireless communication is located in a license-free 433.1 MHz ISM (Industry, Science, and Medical) band. The radiation characteristics and SAR (Specific Absorption Rate) are evaluated using the finite difference time-domain method and 3D human body model. Results show that the SAR values of the antenna satisfy the ICNIRP (International Commission on Nonionizing Radiation Protection) limitations.

Das krurale Zwerchfell gehört zum ösophagokardialen Kontinenzorgan (PET-CT und Impedanzmessung am Dehnverschluss und seine Verankerung im Hiatus oesophageus des Zwerchfells)

This paper provides evidence that pharyngeo-cardial propulsion in the oesophagus follows similar principles as translocation of luminal contents in other locations in the body. In brief, the following statements are discussed in the paper: 1. Only animals with a lung-based respiratory system have an oesophagus. 2. Its bulky muscular wall is made up of the elastic fibres which ensure that the oesophagus stays elastic during an entire lifetime. 3. While short-segment ring sphincter systems exist in several locations in the body, the lower oesophageal sphincter is maximally elongated. This configuration helps with the propulsion of luminal contents in addition to this sphincter's opening and occlusive functions. 4. The musculature of the diaphragm is genetically related to the cervical muscles. The crural portion of the diaphragm works in coordination with the lower oesophageal stretch sphincter. 5.Gastro-oesophageal reflux disease is fairly common. In patients with this disorder, the oesophagus is too short and the stretch sphincter remains patent for abnormal periods of time. 6.When the stretch sphincter is surgically retightened by transposition of the oesophageal cardia into the abdomen, a proper function of the regulatory lower oesophageal stretch sphincter can be restored. 7.-9. All fundoplication procedures place the lower oesophageal sphincter under stretch, squeeze and create an oesophageal wrap out of gastric fundus tissue. X-ray images confirm in many patients undergoing fundoplication that the anatomic stretch sphincter already starts above and proximally to the plicated cuff.

Inkontinenzmanagement beim orthotopen Blasenersatz

Orthotopic urinary diversion (OUD) is performed in almost half of all radical cystectomies. This review presents an overview of the incidence, pathophysiology, and management of urinary incontinence (UI) after OUD. Daytime and nighttime UI are reported in up to 15% and 45% of cases after OUD, respectively. UI after OUD is more frequent in women. Stress incontinence is the most common reason for daytime urinary leakage, while an absent vesicourethral reflex with reduced external sphincter muscle tone is associated with nighttime UI. Conservative management has limited therapeutic value in UI after OUD. Surgical approaches include adjustable and nonadjustable slings as well as the ProACT® system in mild stress UI. Implantation of the artificial urinary sphincter system AMS 800® is the standard treatment for stress UI after OUD. Very limited data exist regarding results after implantation of newer artificial urinary sphincter systems such as the FlowSecure® and the Zephyr® ZSI 375 after OUD.

Study on reconstruction of rectal sensation based on wavelet packet analysis and SVM strategy

To control anal incontinence, we have developed an artificial anal sphincter system with sensor feedback. The artificial anal sphincter system is a novel hydraulic-electric muscle which mainly comprises an artificial anal sphincter, a wireless power supply subsystem, and a rectal sensation reconstruction subsystem. To investigate the features of the patients’ rectal sensation, we have developed an in vitro experimental platform of artificial anal sphincter. In vitro experiments have been performed, and demonstrate that the traditional threshold method is not suitable for predicting the time for defecation. The traditional threshold method only uses single-dimensional pressure time series which may contain a few interdependent components simultaneously. A wavelet packet analysis algorithm is employed to extract the feature vector of the rectal pressure signal, then the rectal sensation prediction model is constructed based on a support vector machine for defecation pattern recognition. The results show that the proposed method is an effective approach for the reconstruction of patients’ rectal sensation.

Neurophysiology and therapeutic receptor targets for stress urinary incontinence

Stress urinary incontinence is the most common type of urinary incontinence in women. Stress urinary incontinence involves involuntary leakage of urine in response to abdominal pressure caused by activities, such as sneezing and coughing. The condition affects millions of women worldwide, causing physical discomfort as well as social distress and even social isolation. This type of incontinence is often seen in women after middle age and it can be caused by impaired closure mechanisms of the urethra as a result of a weak pelvic floor or poorly supported urethral sphincter (urethral hypermobility) and/or a damaged urethral sphincter system (intrinsic sphincter deficiency). Until recently, stress urinary incontinence has been approached by clinicians as a purely anatomic problem as a result of urethral hypermobility requiring behavioral or surgical therapy. However, intrinsic sphincter deficiency has been reported to be more significantly associated with stress urinary incontinence than urethral hypermobility. Extensive basic and clinical research has enhanced our understanding of the complex neural circuitry regulating normal function of the lower urinary tract, as well as the pathophysiological mechanisms that might underlie the development of stress urinary incontinence and lead to the development of potential novel strategies for pharmacotherapy of stress urinary incontinence. Therapeutic targets include adrenergic and serotonergic receptors in the spinal cord, and adrenergic receptors at the urethral sphincter, which can enhance urethral reflex activity during stress conditions and increase baseline urethral pressure, respectively. This article therefore reviews the recent advances in stress urinary incontinence research and discusses the neurophysiology of urethral continence reflexes, the etiology of stress urinary incontinence and potential targets for pharmacotherapy of stress urinary incontinence.

Ninety and still active in research

Here, we review Prof. Stelzner's career and scientific achievements, which include his personal attitude to genuine creative thinking and its application to surgery and research. The stations of his clinical career are highlighted together with his excursions into philosophical and historical topics. From the vast number of publications and research activities, we describe major contributions to morphology including recent contributions through functional examination techniques. We reflect on his research on perianal fistulas. Modern-day understanding of continence of the anal sphincter apparatus and other visceral sphincter systems were fields of his research. His efforts in comparative anatomy and morphology are commended. An open mind throughout his life with sharp scientific reasoning opened him a world of solid arguments based on evidence to prove his view, sometimes after decades. Exemplary are the discussions about the adenoma-carcinoma sequence or his views on anatomical structures limiting the spread of cancer cells. We note his continuing research activities well beyond normal pension age. At the age of over 90, he is still a very sought-after conference speaker.

Sakrale Neuromodulation in der Urologie – Entwicklung und aktueller Stand

Sacral neuromodulation (SNM) in urology is employed to treat refractory lower urinary tract dysfunction as well as chronic pelvic pain. Electrical stimulation of the sacral afferents (S2 - S4) causes activation and conditioning of higher autonomic and somatic neural structures and thereby influences the efferents controlling the urinary bladder, the rectum and their related sphincter systems. It is therefore possible to treat overactivity as well as hypocontractility and functional bladder neck obstruction. SNM treatment is conducted biphasically. Initially, test electrodes are placed to evaluate changes in micturition and pain parameters. If, in this first phase - called peripheral nerve evaluation (PNE test) - sufficient improvements are observed, the patient progresses to phase two which involves implantation of the permanent electrodes and impulse generator system. In recent years, the "two stage approach" with initial implantation of the permanent electrodes has been favoured as it increases treatment success rates. Long-term success rates of SNM vary significantly in the literature (50 - 80 %) due to heterogeneous patient populations as well as improved surgical approaches. With the introduction of "tined lead electrodes" (2002), tissue damage is reduced to a minimum. Technical innovation, financial feasibility (reimbursed in Germany since 2004) and wider application, especially in otherwise therapy-refractory patients or complex dysfunctions of the pelvis, have established SNM as a potent treatment option in urology.

The efferent segment in continent cutaneous urinary diversion: a comprehensive review of the literature

To critically assess the biophysical properties and current status of outlet formation in heterotopic intestinal urinary diversion. As despite three decades of clinical experience with continent cutaneous urinary diversion through bowel segments, no consensus has been reached for the optimal efferent segment although its function largely determines patient satisfaction. A comprehensive Medline literature search using the Medical Subject Headings database (search terms: continent urinary diversion followed by either efferent segment, nipple, Mitrofanoff, Yang-Monti, Benchekroun, tapered ileum, intussuscepted ileum, Kock pouch, T-valve, or Ghonheim) was conducted to identify all full-length original articles addressing the various principles and techniques of outlet formation as well as their outcomes and complications. Examined series were published in English between 1966 and 2010. All studies were systematically evaluated using a checklist (study design, number of patients, etc.) and rated according to the Oxford Centre for Evidence-Based Medicine Levels of Evidence (LoE). While there was a continuous flow of publications over the last three decades, the vast majority of studies were retrospective case series with numerous confounding factors and poorly defined, non-standardized outcomes (LoE, 3). Only a few investigations compare different efferent segments (LoE, 2a). No randomized studies exist. The major biophysical principles are based on the use of flap, nipple, and hydraulic valves. Vermiform appendix, intussuscepted ileal nipple, and the Yang-Monti tube are the most popular techniques and have well-established data on outcomes, complications, and failure rates. Artificial sphincter systems and tissue engineering have provided disappointing results thus far. Most reconstructive strategies are subject to a process of on-going improvement. The continuous quest for optimization has not led to a single universally applicable efferent segment in continent cutaneous urinary diversion. While all techniques have their unique set of advantages and disadvantages, they will always remain a compromise. Success depends on selecting the optimal strategy for individual patients. A major change in principles in the near future is unlikely.

Electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter system

This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10-10(7) Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system.

Design and simulation of advanced charge recovery piezoactuator drivers

The German Artificial Sphincter System project aims at the development of an implantable sphincter prosthesis driven by a piezoelectrically actuated micropump. The system has been designed to be fully implantable, i.e. the power supply is provided by a rechargeable lithium polymer battery. In order to provide sufficient battery duration and to limit battery dimensions, special effort has to be made to minimize power consumption of the whole system and, in particular, of the piezoactuator driver circuitry. Inductive charge recovery can be used to recover part of the charge stored within the actuator. We are going to present a simplified inductor-based circuit capable of voltage inversion across the actuator without the need of an additional negative voltage source. The dimension of the inductors required for such a concept is nevertheless significant. We therefore present a novel alternative concept, called direct switching, where the equivalent capacitance of the actuator is charged directly by a step-up converter and discharged by a step-down converter. We achieved superior performance compared to a simple inductor-based driver with the advantage of using small-size chip inductors. As a term of comparison, the performance of the aforementioned drivers is compared to a conventional driver that does not implement any charge recovery technique. With our design we have been able to achieve more than 50% reduction in power consumption compared to the simplest conventional driver. The new direct switching driver performs 15% better than an inductor-based driver. A novel, whole-system SPICE simulation is presented, where both the driving circuit and the piezoactuator are modeled making use of advanced nonlinear models. Such a simulation is a precious tool to design and optimize piezoactuator drivers.

The First Teleautomatic Low‐Voltage Prosthesis With Multiple Therapeutic Applications: A New Version of the German Artificial Sphincter System

To date, there are no artificial sphincter prostheses for urinary or fecal incontinence that may be implemented elsewhere instead, for example, in the upper gastrointestinal tract. Conventional systems are conceptually similar but are constructed specifically for distinct applications and are manual in operation. The German Artificial Sphincter System (GASS) II is the evolution of a highly integrative, modular, telemetric sphincter prosthesis with more than one application. Redesigning and integrating multilayer actuators into the pump allows us to reduce the input voltage to -10 to +20 V (V(PP) = 30 V). This provides for a flow rate of 2.23 mL/min and a counterpressure stability of 260 mbar. Furthermore, multiple applications have become feasible due to our standardized connection system, therapy-specific compression units, and application-specific software. These innovations allow us to integrate not only severe fecal and urinary incontinence, erectile dysfunction, and therapy-resistant reflux disease, but also morbid adiposity into the gamut of therapeutic GASS applications.

Manometry data support a novel concept of the lower esophageal sphincter system

Detailed understanding of the functional anatomy of the lower esophageal sphincter (LES) is germane to successful surgical treatment of esophageal disorders. However, a comprehensive concept of the structure-function relationship of the LES is currently lacking. We reviewed published anatomic evidence, medical imaging, and impedance manometry data sets and developed a novel functional concept of the LES. Morphologic evidence accumulated over the past three decades indicates that the LES is an anatomic structure that differs markedly from typical ring sphincters of the gastrointestinal tract (e.g., upper esophageal sphincter or anal sphincters). Recent impedance manometry investigations shed new light on the functional anatomy of the LES. These data corroborate a concept of this sphincter as a double-layer, twisted stretch sphincter. This sphincter requires tissue tension for optimal function. Retightening of the longitudinal stretch of the esophagus provides an effective therapy if this tension is lost, e.g., for patients with hiatal hernias. Paralysis of the muscle fibers of this sphincter system results in functional obstruction, and this explains the pathophysiology of "achalasia". Based on available data, we propose a novel concept that better explains the structure-function relationship of the LES. Improved knowledge of the biomechanical factors of esophageal disorders can be expected to advance surgical treatment for these diseases.

Performance of piezoelectric micropumps actuated by charge recovery

The German Artificial Sphincter System (GASS) aims at the development of an implantable device intended for the treatment of fecal or urinary incontinence. The core of the system is a piezoactuated silicon micropump that is able to pressurize/depressurize a cuff prosthesis. Our group has developed advanced piezoactuators and electronic driving circuits in order to reduce the power consumption of our system. In this paper we present our results regarding the performance of a charge recovery driver in comparison with a conventional driver. We have achieved a similar mechanical performance of the pump while cutting power consumption by more than 50%.