Gastric electrical stimulation significantly increases canine lower esophageal sphincter pressure

Implants with Sensing Capabilities

Because of the aging human population and increased numbers of surgical procedures being performed, there is a growing number of biomedical devices being implanted each year. Although the benefits of implants are significant, there are risks to having foreign materials in the body that may lead to complications that may remain undetectable until a time at which the damage done becomes irreversible. To address this challenge, advances in implantable sensors may enable early detection of even minor changes in the implants or the surrounding tissues and provide early cues for intervention. Therefore, integrating sensors with implants will enable real-time monitoring and lead to improvements in implant function. Sensor integration has been mostly applied to cardiovascular, neural, and orthopedic implants, and advances in combined implant-sensor devices have been significant, yet there are needs still to be addressed. Sensor-integrating implants are still in their infancy; however, some have already made it to the clinic. With an interdisciplinary approach, these sensor-integrating devices will become more efficient, providing clear paths to clinical translation in the future.

A 32-Channel Wireless Configurable System for Electrical Stimulation of the Stomach

We have designed and developed a configurable system that can generate and deliver a variety of electrical pulses suitable for gastrointestinal studies. The system is composed of a front-end unit, and a back-end unit that is connected to a computer. The front-end unit contains a stimulating module with 32 channels configured to generate two different current pulses, simultaneously. Commercial off-the-shelf components were used to develop front- and back-end units. A graphical user interface was designed in LabVIEW that allows configuration of the stimulation pulses through the back-end unit in real-time. The system was successfully validated on bench top. The bench-top studies showed the capability of the system to deliver bipolar, monopolar and unbalanced electrical pulses to a maximum load of 1.5 kΩ, at amplitudes up to ±10 mA with resolution of 10 μA, and pulse widths varying between 80 μs to 60 s with the resolution of 80 μs. This study reports the first multi-channel bipolar stimulator that is designed for gastrointestinal studies, and can be configured wirelessly. The system can be used for treating functional gastrointestinal disorders in future.

Treatment of poststroke constipation with moxibustion: A case report

RATIONALE

Moxibustion, an important therapeutic measure of TCM, can stimulate acupoints to unblock the meridians and collaterals, regulate the function of qi and blood, support health, and expel pathogens. So it could be an effective and safe for the treatment of constipation and improvement of the quality of life in poststroke patients with constipation.

PATIENT CONCERNS

He has a history of constipation, with the defecation of hard, bound stool every 2 to 3 days with the help of glycerin enema.

DIAGNOSES

Constipation for >6 months; Cerebral infarction for 9 months; Type 2 diabetes for 3 years. Hypertension for approximately 1 month.

INTERVENTIONS

From the fifth day after admission, 5 rounds of moxibustion with moxa cones were administered at the bilateral ST25 and CV6 acupoints.

OUTCOMES

The patient successfully defecated within 1hour. Subsequently, the patient could maintain daily unobstructed defecation with a normal total stool weight and moderate hardness.

LESSONS

Moxibustion is effective and safe for the treatment of constipation and improvement of the quality of life in post-stroke patients with constipation.

A Wireless Implant for Gastrointestinal Motility Disorders

Implantable functional electrical stimulation (IFES) has demonstrated its effectiveness as an alternative treatment option for diseases incurable pharmaceutically (e.g., retinal prosthesis, cochlear implant, spinal cord implant for pain relief). However, the development of IFES for gastrointestinal (GI) tract modulation is still limited due to the poorly understood GI neural network (gut⁻brain axis) and the fundamental difference among activating/monitoring smooth muscles, skeletal muscles and neurons. This inevitably imposes different design specifications for GI implants. This paper thus addresses the design requirements for an implant to treat GI dysmotility and presents a miniaturized wireless implant capable of modulating and recording GI motility. This implant incorporates a custom-made system-on-a-chip (SoC) and a heterogeneous system-in-a-package (SiP) for device miniaturization and integration. An in vivo experiment using both rodent and porcine models is further conducted to validate the effectiveness of the implant.

Electrical therapies for gastrointestinal motility disorders

Gastrointestinal (GI) motility disorders are common in clinical settings, including esophageal motility disorders, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, chronic intestinal pseudo-obstruction, post-operative ileus, irritable bowel syndrome, diarrhea and constipation. While a number of drugs have been developed for treating GI motility disorders, few are currently available. Emerging electrical stimulation methods may provide new treatment options for these GI motility disorders. Areas covered: This review gives an overview of electrical therapies that have been, and are being developed for GI motility disorders, including gastroesophageal reflux, functional dyspepsia, gastroparesis, intestinal motility disorders and constipation. Various methods of gastrointestinal electrical stimulation are introduced. A few methods of nerve stimulation have also been described, including spinal cord stimulation and sacral nerve stimulation. Potentials of electrical therapies for obesity are also discussed. PubMed was searched using keywords and their combinations: electrical stimulation, spinal cord stimulation, sacral nerve stimulation, gastrointestinal motility and functional gastrointestinal diseases. Expert commentary: Electrical stimulation is an area of great interest and has potential for treating GI motility disorders. However, further development in technologies (devices suitable for GI stimulation) and extensive clinical research are needed to advance the field and bring electrical therapies to bedside.

Antipsychotic drug-like facilitation of latent inhibition by a brain-penetrating neurotensin-1 receptor agonist

Latent inhibition (LI) is a measure of cognitive gating and refers to reduced conditioned learning when there is pre-exposure to the conditioned stimulus (CS) before it is paired with the unconditioned stimulus (US). Dysregulation of LI is associated with some neuropsychiatric disorders, including schizophrenia, and the ability to facilitate LI in rodents is a reasonably good predictive test for antipsychotic drugs. Converging evidence supports neurotensin-1 receptor (NTS1) agonists as novel drugs for schizophrenia. Therefore, we investigated the ability of a brain-penetrating, selective NTS1 agonist, PD149163, to facilitate LI in heterozygous Brattleboro rats, a strain that exhibits naturally low LI. Conditioned taste aversion to flavored water (FW; 0.1% saccharin) was induced by pairing it with malaise-inducing injections of lithium chloride (LiCl). Prior to LiCl-FW pairing, rats received subcutaneous injections of saline, or PD149163 (100 µg/kg or 200 µg/kg). Half the rats in each drug group had been allowed to drink FW the day before the LiCl-FW pairing (pre-exposed rats). Two days after pairing, the amount of FW each rat consumed was recorded. LI, defined as significantly greater FW drinking in the pre-exposed group compared with the non pre-exposed group, was exhibited only among rats that received 200 µg/kg of PD149163. These results further support NTS1 agonists as potentially novel drugs for the treatment of schizophrenia.

Gastric electrical stimulation for obesity

Obesity is a growing health problem worldwide with a major impact on health and healthcare expenditures. Medical therapy in the form of diet and pharmacotherapy has limited effect on weight. Standard bariatric surgery is effective but is associated with morbidity and mortality, creating an unmet need for alternative therapies. One such therapy, the application of electrical stimulation to the stomach, has been studied extensively for the last two decades. Though pulse parameters differ between the various techniques used, the rationale behind this assumes that application of electrical current can interfere with gastric motor function or modulate afferent signaling to the brain or both. Initial studies led by industry failed to show an effect on body weight. However, more recently, there has been a renewed interest in this therapeutic modality with a number of concepts being evaluated in large human trials. If successful, this minimally invasive and low-risk intervention would be an important addition to the existing menu of therapies for obesity.

Follow-up after gastric electrical stimulation for gastroparesis

BACKGROUND

Gastric electrical stimulation (GES) is used to treat medically refractory gastroparesis. However, there are few large series with outcomes beyond 12 months. This study reports surgical outcomes of GES for patients up to 8 years receiving treatment from a single institution.

STUDY DESIGN

A prospective database was reviewed from 2003 to 2013 for patients undergoing GES. Baseline patient characteristics were recorded, including age, sex, cause of gastroparesis, gastric emptying, and Hgb A1C. Outcomes variables included nutrition supplementation, additional operations, 30-day morbidity, and mortality. Pre- and postoperative pain and function scores are analyzed over time using generalized estimating equations. Patient outcomes in terms of reoperation rates and types of operations are also reviewed.

RESULTS

Seventy-nine patients underwent GES with a mean ± SD age of 43 ± 11 years and a BMI of 27 ± 8 kg/m(2). Symptom scores were available for 60 patients: 60 patients at baseline, 52 patients at 1 year, 14 patients during years 2 to 3, and 18 patients during years 4 to 8. Symptom scores decreased considerably in all categories. At 1-year follow-up, 44% and 31% of patients had at least a 25% reduction in symptom distress for functional and pain symptoms, respectively. Preoperatively, 9 patients required nutrition supplementation. After implantation, 34 (43%) patients underwent additional operations, with a mean of 2.15 operations per patient. Generator-related causes were the most common indication for reoperation, including battery exchanges and relocation. Other operations included 8 gastrectomies and 7 median arcuate ligament releases. Postoperatively, 4 patients required supplemental nutrition. There were no 30-day mortalities, but 11 patients died during the study period.

CONCLUSIONS

Gastric electrical stimulation was significantly associated with reductions in both functional and pain-related symptoms of gastroparesis. Patients who undergo GES have a high likelihood of additional surgery.

Progress in understanding the role of neuromodulation in the pathogenesis of functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) are a group of common digestive diseases whose pathogenesis is closely related to the abnormal brain-gut axis. Disturbances of the neuromodulatory processes in the brain-gut axis generate functional digestive disorders mainly centered on the pain, bloating symptoms and motility diseases. This article reviews neuromodulatory mechanism aspects of the brain-gut axis and discusses the clinical prospects for the neuromodulatory interventional treatment of FGIDs.

Moxibustion in combination with point injection increases motilin levels in patients with slow transit constipation

AIM: To investigate the therapeutic effect of moxibustion in combination with point injection against slow transit constipation and to explore possible mechanisms involved.

METHODS: Fifty-six patients with slow transit constipation were randomly and equally divided into test group and Western medicine group. Twenty-eight normal volunteers were included in a normal control group. The Western medicine group was given mosapride 10 mg tid for 20 d, while the test group underwent bilateral injection of 2 mL Astragalus Injection into Zusanli point, once a week for three weeks, and moxibustion for 20 min at Tianshu point, once daily for 20 d. Fasted and postprandial motilin (MLT) levels were measured at baseline and after treatment. The positive rate of colonic transit test and treatment response were compared among the three groups.

RESULTS: After treatment, fasted and postprandial MLT levels increased in the test group and Western medicine group. Mean MLT level in the test group differed significantly between before and after treatment (346.59 ± 9.90 vs 248.11 ± 12.16, P < 0.05). After treatment, the positive rate of the colonic transit test decreased significantly (30.36% vs 100%; 52.34% vs 100%, both P < 0.05) and efficacy score increased significantly (19.63 vs 8.42; 17.75 vs 8.83, both P < 0.05) in the test group and Western medicine group. Efficacy score was significant in the Western medicine group between before treatment and the follow-up period (17.72 vs 8.42, P < 0.05).

CONCLUSION: Moxibustion in combination with point injection exerts a significant therapeutic effect against slow transit constipation possibly by accelerating MLT secretion.

Neuromodulatory processes of the brain-gut axis

Brain-gut axis represents a complex reflex circuit that integrates the communication between cortex and the digestive system. Disturbances of the neuromodulatory processes in the brain-gut axis generate functional digestive disorders mainly centered on the pain symptoms and motility disorders. This article reviews structural and patho-physiological aspects of the brain-gut axis and explains how the neuromodulatory interventions currently used in order to treat GI conditions related to the brain-gut axis disturbances. The neuromodulation can be realized by pharmacological targeting mainly receptors in the periphery or using electrical stimulation applied at different levels of the nervous system or directly in the muscular layers of the bowels resulting in modulation of the digestive system activity. The efficacy of the methods using electrostimulation is dependent on the parameters of the physical system used: amplitude, frequency, burst time of the electrical current and also the positioning of the electrodes. While pharmacological interventions are largely used at the moment, neuromodulatory interventions involving electrical stimulation showed clinical efficacy in research trials and have promise.

Effect of electrical stimulation of the LES on LES pressure in a canine model

Gastric electrical stimulation modulates lower esophageal sphincter pressure (LESP). High-frequency neural stimulation (NES) can induce gut smooth muscle contractions. To determine whether lower esophageal sphincter (LES) electrical stimulation (ES) can affect LESP, bipolar electrodes were implanted in the LES of four dogs. Esophageal manometry during sham or ES was performed randomly on separate days. Four stimuli were used: 1) low-frequency: 350-ms pulses at 6 cycles/min; 2) high-frequency-1: 1-ms pulses at 50 Hz; 3) high-frequency-2: 1-ms pulses at 20 Hz; and 4) NES: 20-ms bipolar pulses at 50 Hz. Recordings were obtained postprandially. Tests consisted of three 20-min periods: baseline, stimulation/sham, and poststimulation. The effect of NES was tested under anesthesia and following IV administration of l-NAME and atropine. Area under the curve (AUC) and LESP were compared among the three periods, by ANOVA and t-test, P < 0.05. Data are shown as means +/- SD. We found that low-frequency stimulation caused a sustained increase in LESP: 32.1 +/- 12.9 (prestimulation) vs. 43.2 +/- 18.0 (stimulation) vs. 50.1 +/- 23.8 (poststimulation), P < 0.05. AUC significantly increased during and after stimulation. There were no significant changes with other types of ES. With NES, LESP initially rose and then decreased below baseline (LES relaxation). During NES, N(G)-nitro-l-arginine methyl ester increased both resting LESP and the initial rise in LESP and markedly diminished the relaxation. Atropine lowered resting LESP and abolished the initial rise in LESP. In conclusion, low frequency ES of the LES increases LESP in conscious dogs. NES has dual effect on LESP: an initial stimulation, cholinergically mediated, followed by relaxation mediated by nitric oxide.

Gastric electrical stimulation for gastroparesis

BACKGROUND

Recently, gastric electrical stimulation (GES) has been used to treat gastroparesis. This study analyzes a cohort of gastroparetic patients after GES.

STUDY DESIGN

All patients undergoing GES from October 2003 to July 2007 were included. Pre- and postoperative assessments were performed for frequency and severity of gastrointestinal symptoms and gastric retention. The values were compared using a paired t-test for patients at 6 and 12 months. Statistical significance was defined as p < 0.05.

RESULTS

Fifty gastroparetic patients were enrolled (20 diabetic, 25 idiopathic, 2 postsurgical, and 3 connective tissue disorder patients). All patients underwent laparoscopic implantation with GES (Medtronic, Inc). Median followup was 28 months (range 3 to 51 months). Thirty-five patients were available for followup at 6 months, and 30 patients were available at 12 months. The total symptom severity score (19.05+/-8.04) decreased significantly at 6 months (12.92+/-7.41, p < 0.001) and 12 months (14.05+/-8.28, p < 0.01). Similarly, total frequency score (20.39+/-8.08) decreased significantly at 6 months (15.01+/-7.37, p < 0.01) and 12 months (15.71+/-7.40, p < 0.05). At 12 months (n=27), gastric retention at 2 hours was decreased significantly from 66% +/- 21% to 50% +/- 22% (p < 0.04) and normalized in 11 of 27 patients. The severity of symptoms was reduced in all patients with normal gastric retention postoperatively. Finally, gastric retention at 4 hours was reduced by 14%, but the difference was not significant.

CONCLUSIONS

Gastroparetic symptoms at 6 months were improved and sustained at 12 months after GES. Gastric emptying at 2 hours was reduced significantly after GES. Longterm followup of this cohort is required to confirm the short-term effects of GES.

Systematic review: applications and future of gastric electrical stimulation

BACKGROUND

Over the past 20 years, gastric electrical stimulation has received increasing attention among researchers and clinicians.

AIM

To give a systematic review on the effects, mechanisms and applications of gastric electrical stimulation.

METHODS

Medline was used to identify the articles to be included in this review. Key words used for the search included gastric electrical stimulation, gastric pacing, electrical stimulation, stomach, gastrointestinal motility, central nervous system, gastroparesis, nausea and vomiting; obesity and weight loss. Combinational uses of these keywords were made to identify relevant articles. Most of the articles included in this review ranged from 1985 to 2006.

RESULTS

Based on the general search, the review was structured as follows: (i) peripheral and central effects and mechanisms of gastric electrical stimulation; (ii) clinical applications of gastric electrical stimulation for gastroparesis and obesity and (iii) future development of gastric electrical stimulation.

CONCLUSIONS

Great progress has been made during the past decades. Gastric electrical stimulation has been shown to be effective in normalizing gastric dysrhythmia, accelerating gastric emptying and improving nausea and vomiting. Implantable device has been made available for treating gastroparesis as well as obesity. However, development of a new device and controlled clinical studies are required to further prove clinical efficacy of gastric electrical stimulation.