Implantable neural electrical stimulator for external control of gastrointestinal motility (original) (raw)
Related papers
Parametric Study of Neural Gastric Electrical Stimulation in Acute Canine Models
IEEE Transactions on Biomedical Engineering, 2000
Manipulation of gastric motility by gastric electrical stimulation (GES) has been suggested as a minimally invasive alternative treatment of gastric motility disorders and obesity. However, only neural GES (NGES) has been successful in invoking gastric contractions. Nevertheless, the relationship between these contractions and the controlling NGES parameters has not been quantified. We aimed at determining the relationship between the electrical energy delivered to the tissue as a function of NGES parameters, and the strength and duration of the resulting invoked gastric contractions. Five healthy mongrel dogs underwent subserosal prepyloric implantation of two NGES electrode pairs. Gastric motility was captured by a force transducer implanted in the vicinity of the distal pair of stimulating electrodes. Custom-designed implantable stimulator delivered NGES with 8-16 V (peak-to-peak) amplitudes, and 60-100% duty cycles. Normalized motility index (MI) was utilized to quantify the contractions recorded from the force transducer. The MI increased with increasing voltage amplitudes. However, it remained remarkably constant across all duty cycles when voltage was held constant. Calculated motility generation efficiency indices (MGEI) indicated that highest energy efficiency for invoked motility was achieved at the lowest duty cycle. The parametric data obtained in the present study can be utilized to optimize the power efficiency of implantable gastric neurostimulators.
Implantable, Transcutaneously Powered Neurostimulator System to Restore Gastrointestinal Motility
2005 3rd IEEE/EMBS Special Topic Conference on Microtechnology in Medicine and Biology, 2005
This neurostimulator design addresses a deficiency in a promising new method for imposing a pre-designed and electrically-invoked motility patterns in the gastrointestinal (GI) tract. Sequential Neural Gastrointestinal Stimulation (SNGES) has been shown to be effective in artificially restoring the motility of the stomach and the colon. However, the availability of an implantable device to implement this innovative stimulation protocol has been lacking. The work presented in this paper was aimed at designing a transcutaneously powered implantable device to facilitate SNGES testing. Discrete electrical components and a Complex Programmable Logic Device (CPLD) were used to rapidly prototype the neurostimulator. Transcutaneous Energy Transfer (TET) powered the device to eliminate the need for an implantable battery. This research resulted in the design, implementation, and testing of an innovative transcutaneously powered device that is small and safe enough to be chronically implanted in experimental animals or humans. The device conforms to the stimulation algorithm used in the SNGES method for restoring GI motility. A detailed design procedure addresses key issues such as charge balance, tissue heating, and biocompatibility. This design procedure lays the foundation for the future architecture of a mixed-signal ASIC based neurostimulator that would lead to further minimization of power consumption and size.
Gastroenterology, 2000
See editorial on page 433. Background & Aims: Gastric electrical stimulation has been attempted for years without much success. The aim of this study was to determine if movement of solid gastric content could be achieved using microprocessor-controlled sequential electrical stimulation. Methods: The study was performed on 9 anesthetized dogs. The dogs underwent laparotomy, pyloroplasty, and implantation of 4-6 sets of bipolar stainless-steel wire electrodes. Each set consisted of 2-6 electrodes (10 ؋ 0.25 mm, 3 cm apart) implanted circumferentially. The stomach was filled with solid food mixed with plastic pellets, and the process of gastric emptying was monitored. Artificial contractions were produced using microprocessor-controlled phase-locked bipolar trains of 50-Hz rectangular voltage with flexible amplitudes. Results: Using the above stimulating parameters, we were able to produce circumferential gastric contractions that were artificially propagated distally by embedding and phase-locking the stimulating voltage. The number of expelled pellets after the stimulation sessions was significantly higher than the number of pellets emptied during the nonstimulation sessions (P F 0.01). Conclusions: Microprocessor-controlled electrical stimulation produced artificial peristalsis and markedly accelerated the movement of solid gastric content.
Neuromodulation: Technology at the Neural Interface, 2018
Background/Aims: Patients with gastroparesis often have biliary/pancreatic and small bowel symptoms but the effects of gastric electrical stimulation on small bowel electrical activity of the mid-gut have not been studied. Animal model aim: Establish gastric and upper small bowel/biliary slow wave activity relationships with electrical stimulation. Human study aim: Demonstrate improvement in symptoms associated with proximal small bowel dysmotility in gastric stimulated patients. Materials and Methods: Animal model: In vivo evoked responses of duodenal and Sphincter of Oddi measures recorded during gastric electrical stimulation in a nonsurvival swine model (N = 3). High-resolution electrical slow wave mapping of frequency, amplitude, and their ratio, for duodenal and Sphincter of Oddi electrical activity were recorded. Human study: Patients (N = 8) underwent temporary gastric stimulation with small bowel electrodes. Subjective and objective data was collected before and after temporary gastric stimulation. Symptom scores, gastric emptying times, and mucosal electrograms via low-resolution mapping were recorded. Results: Animal gastric stimulation resulted in some changes in electrical activity parameters, especially with the highest energies delivered but the changes were not statistically significant. Human study revealed improvement in symptom and illness severity scores, and changes in small bowel mucosal slow wave activity. Conclusions: Gastric electrical stimulation in an animal model seems to show nonsignificant effects small bowel slow wave activity and myoelectric signaling, suggesting the existence of intrinsic neural connections. Human data shows more significance, with possible potential for therapeutic use of electrical stimulation in patients with gastroparesis and pancreato-biliary and small bowel symptoms of the mid-gut. This study was limited by the nonsurvival pig model, small sample size, and open label human study.
Voluntary control of an ileal pouch by coordinated electrical stimulation
Diseases of the Colon & Rectum, 1988
Ileal reservoirs were constructed in four dogs under general anesthesia and stimulated by means of a constant current generator that produced pulse trains at frequencies between 6 Hz and 1.67 kHz. Stimulation at 6 Hz with 50 ms pulses between amplitudes of 15 and 25 mA uniformly produced pouch contraction and reservoir emptying. Stimulation at other frequencies did not cause pouch emptying although pressure increases were sometimes observed. Such electrical stimulation may be useful for voluntary control of intestinal reservoirs when used as replacement for urinary bladder or colon. The mechanism by which the intestinal contraction is produced appears to be different than that produced by slow wave pacing.
AJP: Regulatory, Integrative and Comparative Physiology, 2007
The aim of this study was to determine the effects and mechanism of synchronized gastric electrical stimulation (SGES) on gastric contractions and gastric emptying. The first experiment was designed to study the effects of SGES on antral contractions in four randomized sessions. Sessions 1 (control) and 2 (atropine) were performed in the fasting state, composed of three 30-min periods (baseline, stimulation, and recovery). Sessions 3 (control) and 4 (SGES performed during 2nd 20-min period) were performed in the fed state, consisting of two 20-min periods; glucagon was injected after the first 20-min recording. The second experiment was designed to study the effect of SGES on gastric emptying and consisted of two sessions (control and SGES). SGES was delivered with train duration of 0.5–0.8s, pulse frequency of 40 Hz, width of 2 ms, and amplitude of 4 mA. We found that 1) SGES induced gastric antral contractions in the fasting state. The motility index was 1.3 ± 0.5 at baseline and ...
Alimentary Pharmacology & Therapeutics, 2009
Background-Application of electrical stimulation to the gut, primarily the stomach, has rapidly advanced in the last two decades, from mostly animal studies to the clinical arena. Most studies focused on the use of electrical stimulation for gastroparesis, the only approved indication for such intervention. Aim-to review the physiologic basis of gastric electrical activity and the technical aspects and clinical outcome of gastric electrical stimulation (GES) for gastroparesis. Methods-PubMed search from 1966-2009, using gastroparesis and GES as search terms. Areas in focus were systematically reviewed. Results-The literature consists of open label studies, mostly from single centers published in the last decade. Improvement in symptoms, quality of life and nutritional status was reported by most studies. Physiologically, stimulation parameters approved in clinical practice do not regulate gastric slow wave activity, and have inconsistent effect on gastric emptying. The mechanism of action of GES is not fully known, but data support modulation of gastric biomechanical activity and afferent neural mechanisms.
Neurogastroenterology and Motility, 2006
Neural gastrointestinal electrical stimulation (NGES) induces sequential contractions and enhances emptying in acute canine gastric and colonic models. This study was set to determine (i) the effect of NGES in a chronic canine model of delayed colonic transit and (ii) possible mechanism of action. Four pairs of electrodes were implanted in the distal colon of nine mongrel dogs. Delayed colonic transit was induced by diphenoxylate/atropine and alosetron. Transit was fluoroscopically determined by the rate of evacuation of radiopaque markers, and was tested twice in each dog, in random order, on and off stimulation. Two stimulation sequences, separated by 1 min, were delivered twice a day via exteriorized electrodes. Colonic manometry during stimulation was performed before and after intravenous (i.v.) injection of 1 mg of atropine. Complete evacuation of all markers was significantly shortened by NGES, from 4 days to 2 days, interquartile range 3-4 days vs 2-3 days, respectively, P ¼ 0.016. NGES induced strong sequential contractions that were significantly diminished by atropine: 190.0 ± 14.0 mmHg vs 48.7 ± 19.4 mmHg, respectively (P < 0.001). NGES induces strong sequential colonic contractions and significantly accelerates movement of content in a canine model of delayed colonic transit. The effect is atropine sensitive. Colonic motor response to NGES. Recording obtained during colonic manometry. NGES evoked strong, longlasting sequential contractions. The effect of NGES was significantly diminished by atropine injection as shown in the second half of the graph.
Gastric Electrical-Stimulation Effects on Canine Gastric Emptying, Food Intake, and Body Weight
Obesity, 2003
Objective: It has been reported that electrical stimulation at the distal stomach can disrupt intrinsic gastric electrical activity and delay gastric emptying. Gastric dysrhythmia and impaired gastric emptying are associated with upper gastrointestinal symptoms and weight loss. The purpose of this study was to evaluate the effect of low-frequency/longpulse gastric electrical stimulation (GES), at proximal and distal stomach, on canine gastric emptying, food intake, and body weight. Research Methods and Procedures: Eight dogs were surgically implanted with four pairs of electrodes along the greater curvature and a gastric tube at the dependent part of the stomach. Liquid gastric emptying at baseline, during proximal and distal GES at 6 cycles per minute, was assessed first by a dye dilution technique. Proximal and distal GES were then randomly delivered during feeding for 10 consecutive days, and food intake and body weight were recorded daily. Results: There was no significant difference in gastric emptying parameters among the various sessions. The mean daily food consumption was significantly reduced during both sessions of GES, resulting in significant immediate weight loss. Percentage weight loss was comparable between both sessions of GES. Discussion: Short-term GES significantly reduced canine food intake and weight. This effect may not be related to changes in gastric emptying. GES may have a potential role in the treatment of obesity.
Gastric Applications of Electrical Field Stimulation
Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, 2009
Advances in clinical applications of electricity have been vast since the launch of Hayman's first cardiac pacemaker more than 70 years ago. Gastric electrical stimulation devices have been recently licensed for treatment of gastroparesis and preliminary studies examining their potential for use in refractory obesity yield promising results.