Gastric electrical stimulation for gastroparesis

High-energy pacing inhibits slow-wave dysrhythmias in the small intestine

The motility of the gastrointestinal tract is coordinated in part by rhythmic slow waves, and disrupted slow-wave patterns are linked to functional motility disorders. At present, there are no treatment strategies that primarily target slow-wave activity. This study assessed the use of pacing to suppress glucagon-induced slow-wave dysrhythmias in the small intestine. Slow waves in the jejunum were mapped in vivo using a high-resolution surface-contact electrode array in pigs (n = 7). Glucagon was intravenously administered to induce hyperglycemia. Slow-wave propagation patterns were categorized into antegrade, retrograde, collision, pacemaker, and uncoupled activity. Slow-wave characteristics such as period, amplitude, and speed were also quantified. Postglucagon infusion, pacing was applied at 4 mA and 8 mA and the resulting slow waves were quantified spatiotemporally. Antegrade propagation was dominant throughout all stages with a prevalence of 55 ± 38% at baseline. However, glucagon infusion resulted in a substantial and significant increase in uncoupled slow waves from 10 ± 8% to 30 ± 12% (P = 0.004) without significantly altering the prevalence of other slow-wave patterns. Slow-wave frequency, amplitude, and speed remained unchanged. Pacing, particularly at 8 mA, significantly suppressed dysrhythmic slow-wave patterns and achieved more effective spatial entrainment (85%) compared with 4 mA (46%, P = 0.039). This study defined the effect of glucagon on jejunal slow waves and identified uncoupling as a key dysrhythmia signature. Pacing effectively entrained rhythmic activity and suppressed dysrhythmias, highlighting the potential of pacing for gastrointestinal disorders associated with slow-wave abnormalities.NEW & NOTEWORTHY Glucagon was infused in pigs to induce hyperglycemia and the resulting slow-wave response in the intact jejunum was defined in high resolution for the first time. Subsequently, with pacing, the glucagon-induced dysrhythmias were suppressed and spatially entrained for the first time with a success rate of 85%. The ability to suppress slow-wave dysrhythmias through pacing is promising in treating motility disorders that are associated with intestinal dysrhythmias.

A global bibliometric and visualized analysis of the status and trends of gastroparesis research

BACKGROUND

Gastroparesis has a substantial impact on the quality of life but has limited treatment options, which makes it a public health concern. No bibliometric studies on gastroparesis have been published thus far. Thus, this article aims to summarize and analyze research hotspots to provide a reference for clinical researchers.

MATERIALS AND METHODS

Gastroparesis-related research articles were searched in the Web of Science Core Collection (WOSCC), and relevant information was extracted after screening. A total of 1033 documents were analyzed with the bibliometric method using Microsoft Excel, Citespace, and VOSviewer.

RESULTS

Overall, our search retrieved 1033 papers contributed by 966 research institutions from 53 countries. Since 1980, publications in this field have increased rapidly. United States (n = 645) and Temple University (n = 122) were the most productive country and institution, respectively. Parkman, with 96 publications, was the most prominent author.

CONCLUSIONS

Research hotspots in gastroparesis can be summarized into four domains: innovation in diagnostic modalities, change of oral therapeutic agents, choice of surgical interventions, and pathological mechanisms. Future research on gastroparesis should focus on the quality of life of patients, diagnostic techniques, pyloromyotomy, and transpyloric stent placement.

Diabetic Gastroparesis and its Emerging Therapeutic Options: A Narrative Review of the Literature

Diabetic gastroparesis (DG) is one of the many complications of diabetes mellitus (DM). Even though this condition surfaces years after uncontrolled disease, it affects the quality of life in several ways and causes significant morbidity. Common symptoms experienced by the patients include postprandial nausea, vomiting, abdominal fullness, and pain. Strict glycemic control is essential to evade the effects of DG. The purpose of this review article is to briefly study the pathophysiology, clinical features, diagnostic modalities, and the effects of DG on different aspects of life. Furthermore, it also focuses on the emerging treatment modalities for DG. Tradipitant and relamorelin are two such treatment options that are gaining noteworthy recognition and are discussed in detail in this review article. As observed through various clinical trials, these drugs help alleviate symptoms like nausea, vomiting, abdominal pain, and bloating in patients suffering from DG, thereby targeting the most common and bothersome symptoms of the disease. This leads to an improvement in the quality of life, making it a reliable treatment option for this disease. But while pharmacological intervention is vital, psychological support and lifestyle changes are equally important and are the reason why a multidisciplinary approach is required for the treatment of DG.

Optical Mapping of Virtual Electrode Polarization Pattern and Its Relationship with Pacemaker Location during Gastric Pacing. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023;2023:1-4. [PMID: 38082999 DOI: 10.1109/embc40787.2023.10340002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Gastric rhythmic contractions are regulated by bioelectrical events known as slow waves (SW). Abnormal SW activity is associated with gastric motility disorders. Gastric pacing is a potential treatment method to restore rhythmic SW activity. However, to date, the efficacy of gastric pacing is inconsistent and the underlying mechanisms of gastric pacing are poorly understood. Optical mapping is widely used in cardiac electrophysiology studies. Its immunity to pacing artifacts offers a distinct advantage over conventional electrical mapping for studying pacing. In the present study, we first found that optical mapping can image pacing-induced virtual electrode polarization patterns in the stomach (adjacent regions of depolarized and hyperpolarized tissue). Second, we found that elicited SWs usually (15 of 16) originated from the depolarized areas of the stimulated region (virtual cathodes). To our knowledge, this is the first direct observation of virtual electrode polarization patterns in the stomach. Conclusions: Optical mapping can image virtual electrode polarization patterns during gastric pacing with high spatial resolution.Clinical Relevance- Gastric pacing is a potential therapeutic method for gastric motility disorders. This study provides direct observation of virtual electrode polarization pattern during gastric pacing and improves our understanding of the mechanisms underlying gastric pacing..

Evaluation of Pacing Parameters to Induce Contractions in the Small Intestine

Postoperative ileus and chronic intestinal pseudo-obstruction are intestinal motility disorders that can compromise bowel function resulting in a significant reduction in quality of life and prolonged hospital stays. While medication and nutritional support provides relief for some patients, a significant patient population remains untreated. Therefore, alternative treatment options are required. A novel framework that enables small intestine pacing and video mapping of the contractile response was developed. Pacing pulse parameters (pulse-period: 2.7, 10 s, pulse-width: 100, 400 ms, and pulse-amplitude: 4, 6, 8 mA) were systematically varied to investigate the effect of pacing on the small intestine contractility. The contractile response was quantified by computing the strain of the intestinal diameter at the pacing site. The framework was applied in vivo on porcine jejunal loops (n=4) where segmental contractions were induced in response to pacing pulses. Strain increased with increasing pulse-amplitude and pulse-width, while pacing at a period of 2.7 s elicited higher contractile strains compared to pacing at a period of 10 s at all settings (e.g., -0.18 ± 0.06 vs 0.12 ± 0.06 at 8 mA, 400 ms). For a pulse-width of 100 ms, the contractile strain continued to increase with increasing pulse-amplitude, while the induced strain was comparable for all pulse-amplitudes when paced with high pulse-width (400 ms). Therefore, pacing is an effective tool in modulating the intensity of segmental contractions.Clinical Relevance- Different pacing parameters can define contraction intensity and frequency in the small intestine. This is of therapeutic potential for treating motility disorders such as post-operative ileus and chronic intestinal pseudo-obstruction.

Gastric Electrical Stimulation for Refractory Gastroparesis: A Promising Treatment Modality for Symptom Control and Gastric Emptying

Gastroparesis is a disorder with few available treatments and delayed stomach emptying. Gastric electrical stimulation (GES) has shown promise in treating the signs and symptoms of gastroparesis as well as gastric emptying by stimulating the stomach with high-frequency electrical impulses. In this case, a 43-year-old lady with refractory gastroparesis had a GES device laparoscopically implanted. Even though GES seems promising, more study is necessary to improve patient choice, technique, and long-term results. Patients with refractory gastroparesis who have not responded to traditional therapy should be considered for GES, with treatment decisions being made individually depending on clinical presentation and patient preferences.

Systematic review of small intestine pacing parameters for modulation of gut function

BACKGROUND AND PURPOSE

The efficacy of conventional treatments for severe and chronic functional motility disorders remains limited. High-energy pacing is a promising alternative therapy for patients that fail conventional treatment. Pacing primarily regulates gut motility by modulating rhythmic bio-electrical events called slow waves. While the efficacy of this technique has been widely investigated on the stomach, its application in the small intestine is less developed. This systematic review was undertaken to summarize the status of small intestinal pacing and evaluate its efficacy in modulating bowel function through preclinical research studies.

METHODS

The literature was searched using Scopus, PubMed, Ovid, Cochrane, CINAHL, and Google Scholar. Studies investigating electrophysiological, motility, and/or nutrient absorption responses to pacing were included. A critical review of all included studies was conducted comparing study outcomes against experimental protocols.

RESULTS

The inclusion criteria were met by 34 publications. A range of pacing parameters including amplitude, pulse width, pacing direction, and its application to broad regional small intestinal segments were identified and assessed. Out of the 34 studies surveyed, 20/23 studies successfully achieved slow-wave entrainment, 9/11 studies enhanced nutrient absorption and 21/27 studies modulated motility with pacing.

CONCLUSION

Small intestine pacing shows therapeutic potential in treating disorders such as short bowel syndrome and obesity. This systematic review proposes standardized protocols to maximize research outcomes and thereby translate to human studies for clinical validation. The use of novel techniques such as high-resolution electrical, manometric, and optical mapping in future studies will enable a mechanistic understanding of pacing.

A New Paradigm Shift in Gastroparesis Management

Gastroparesis, once regarded as a rare disease, is difficult to diagnose and challenging to treat; there were many breakthrough advances in the 2010s, shifting the paradigm of the understanding of this complex entity and its management. Similar to diabetes, its increasing prevalence reflects increased accessibility to diagnostic modalities and suggests that gastroparesis was underacknowledged in the past. Major developments in the three main aspects of the disease include the discovery of smooth muscle cells, interstitial cells of Cajal, PDGFRα+ cells syncytium, rather than interstitial cells of Cajal alone, as the main gastric pacemaker unit; the development of validated point-of-care diagnostic modalities such as a wireless motility capsule, the carbon 13-labeled breath test, and impedance planimetry; and the introduction of novel minimally invasive therapeutic options such as newer pharmacologic agents and gastric peroral endoscopic pyloromyotomy. All aspects of these advances will be discussed further in this review.

Physical organogenesis of the gut

The gut has been a central subject of organogenesis since Caspar Friedrich Wolff’s seminal 1769 work ‘De Formatione Intestinorum’. Today, we are moving from a purely genetic understanding of cell specification to a model in which genetics codes for layers of physical–mechanical and electrical properties that drive organogenesis such that organ function and morphogenesis are deeply intertwined. This Review provides an up-to-date survey of the extrinsic and intrinsic mechanical forces acting on the embryonic vertebrate gut during development and of their role in all aspects of intestinal morphogenesis: enteric nervous system formation, epithelium structuring, muscle orientation and differentiation, anisotropic growth and the development of myogenic and neurogenic motility. I outline numerous implications of this biomechanical perspective in the etiology and treatment of pathologies, such as short bowel syndrome, dysmotility, interstitial cells of Cajal-related disorders and Hirschsprung disease.

Gastroparesis: A Multidisciplinary Approach to Management

Gastroparesis is a neuromuscular disorder whose hallmark is delayed gastric emptying. It is a global challenge to the healthcare system because of poor treatment satisfaction for both the patients and clinicians, eventually leading to a reduction in the quality of life, with antecedent anxiety and depression. Although it is multifactorial in origin, diabetic, idiopathic, and drug-induced gastroparesis are the major risk factors. Disrupted interstitial cells of Cajal (ICC) and gastric dysrhythmia are pivotal to the pathogenesis, with most of the investigations targeted toward assessing gastric emptying and accommodation usually affected by distorted ICC and other neural networks. The treatment challenges can be overcome by a multidisciplinary approach involving gastroenterologists, gastrointestinal surgeons, biomedical engineers, nutritionists, psychologists, nurses, radionuclide radiologists, pharmacists, and family physicians. The exploration of the fundamental physiological processes underlying gastroparesis with the use of biomechanical materials should be given more attention by biomedical engineers to integrate innovative engineering with medicine for solving complex medical issues.

Gastric electrical stimulation improves symptoms and need for supplemental nutrition in children with severe nausea and vomiting: A ten-year experience

BACKGROUND

Gastric electrical stimulation (GES) is a promising therapy for children with severe nausea and vomiting, but information on long-term outcomes is limited. We sought to evaluate the long-term efficacy and safety of GES and to describe patient benefit and satisfaction.

METHODS

Using a prospective registry, we identified patients aged <21 years treated with GES at our institution between 2009 and 2019. Encounters were selected at baseline prior to GES and at follow-up at 1 month, 12 months, and the most recent visit. We compared symptoms, route of nutrition, and medication usage at baseline to follow-up timepoints. Factors associated with improvement were evaluated. We recorded complications and need for battery replacement. We contacted families to administer the Glasgow Children's Benefit Inventory (GCBI) and a parent satisfaction questionnaire.

KEY RESULTS

Eighty-five patients (68.2% female, median age 15.8 years) completed a trial of temporary GES due to severe nausea and vomiting. Seventy-seven (90.6%) had a positive response and underwent permanent stimulator placement. Use of tube feeding or parenteral nutrition (PN) decreased from 72.7% at baseline to 29.9% at the most recent follow-up (p < 0.001). Higher baseline vomiting severity was associated with the ability to stop supplemental nutrition by 1 month (p < 0.05). Fourteen patients (18.2%) had complications, primarily due to stimulator-associated discomfort, and 29 (37.7%) required battery replacement. Median GCBI was +52.1, indicating health-related benefit.

CONCLUSIONS AND INFERENCES

Children with severe nausea and vomiting treated with GES experienced significant and durable improvement in symptom severity and their ability to tolerate oral nutrition.

Direct optogenetic stimulation of smooth muscle cells to control gastric contractility

Rationale: Antral peristalsis is responsible for gastric emptying. Its failure is called gastroparesis and often caused by dysfunction of enteric neurons and interstitial cells of Cajal (ICC). Current treatment options, including gastric electrical stimulation, are non-satisfying and may improve symptoms but commonly fail to restore gastric emptying. Herein, we explore direct optogenetic stimulation of smooth muscle cells (SMC) via the light-gated non-selective cation channel Channelrhodopsin2 (ChR2) to control gastric motor function.

Methods: We used a transgenic mouse model expressing ChR2 in fusion with eYFP under the control of the chicken-β-actin promoter. We performed patch clamp experiments to quantify light-induced currents in isolated SMC, Ca²⁺ imaging and isometric force measurements of antral smooth muscle strips as well as pressure recordings of intact stomachs to evaluate contractile responses. Light-induced propulsion of gastric contents from the isolated stomach preparation was quantified in video recordings. We furthermore tested optogenetic stimulation in a gastroparesis model induced by neuronal- and ICC-specific damage through methylene blue photo-toxicity.

Results: In the stomachs, eYFP signals were restricted to SMC in which blue light (460 nm) induced inward currents typical for ChR2. These depolarizing currents led to contractions in antral smooth muscle strips that were stronger than those triggered by supramaximal electrical field stimulation and comparable to those evoked by global depolarization with high K⁺ concentration. In the intact stomach, panoramic illumination efficiently increased intragastric pressure achieving 239±46% (n=6) of the pressure induced by electrical field stimulation and triggered gastric transport. Within the gastroparesis model, electric field stimulation completely failed but light still efficiently generated pressure waves.

Conclusions: We demonstrate direct optogenetic stimulation of SMC to control gastric contractility. This completely new approach could allow for the restoration of motility in gastroparesis in the future.

Design and Validation of a Surface-Contact Electrode for Gastric Pacing and Concurrent Slow-Wave Mapping

OBJECTIVE

Gastric contractions are, in part, coordinated by slow-waves. Functional motility disorders are correlated with abnormal slow-wave patterns. Gastric pacing has been attempted in a limited number of studies to correct gastric dysmotility. Integrated electrode arrays capable of pacing and recording slow-wave responses are required.

METHODS

New flexible surface-contact pacing electrodes (SPE) that can be placed atraumatically to pace and simultaneously map the slow-wave activity in the surrounding area were developed. SPE were applied in pigs in-vivo for gastric pacing along with concurrent high-resolution slow wave mapping as validation. Histology was conducted to assess for tissue damage around the pacing site. SPE were compared against temporary cardiac pacing electrodes (CPE), and hook-shaped pacing electrodes (HPE), for entrainment rate, entrainment threshold, contact quality, and slow-wave propagation patterns.

RESULTS

Pacing with SPE (amplitude: 2 mA, pulse width: 100 ms) consistently achieved pacemaker initiation. Histological analysis illustrated no significant tissue damage. SPE resulted in a higher rate of entrainment (64%) than CPE (37%) and HPE (24%), with lower entrainment threshold (25% of CPE and 16% of HPE). High resolution mapping showed that there was no significant difference between the initiated slow-wave propagation speed for SPE and CPE (6.8 ± 0.1 vs 6.8 ± 0.2 mm/s, P>0.05). However, SPE had higher loss of tissue lead contact quality than CPE (42 ± 16 vs 13 ± 10% over 20 min).

CONCLUSION

Pacing with SPE induced a slow-wave pacemaker site without tissue damage.

SIGNIFICANCE

SPE offered an atraumatic pacing electrode with a significant reduction of power consumption and placement time compared to impaled electrodes.

Gastric Electrical Stimulation for Treatment of Refractory Gastroparesis: the Current Approach to Management

Purpose of Review

Gastroparesis is one of the more challenging entities in the landscape of gastroenterology, posing difficulties for both patients and physicians with regard to effective management and therapies. In this article, we reviewed various gastroparesis treatment options, with an emphasis on gastric electrical stimulation (GES).

Recent Findings

GES has demonstrated a significant reduction of cardinal symptoms in refractory gastroparetic patients, particularly nausea and vomiting, across multiple studies. However, GES has not been shown to conclusively decrease gastric emptying time in these patients. Such finding has led the investigators to analyze the impact of combining GES with pyloroplasty. While this treatment pathway is nascent, its results thus far reveal an amplified improvement of gastroparesis symptomatology in addition to significant reduction of gastric transit, compared to GES by itself.

Summary

Limited treatment choices are available for refractory gastroparesis. Combining GES with pyloroplasty holds promise but requires further assessment in large-scale trials to fully evaluate the risks and benefits.

Techniques and devices for the endoscopic treatment of gastroparesis (with video)

BACKGROUND AND AIMS

Gastroparesis is a symptomatic chronic disorder of the stomach characterized by delayed gastric emptying in the absence of mechanical obstruction. Several endoscopic treatment modalities have been described that aim to improve gastric emptying and/or symptoms associated with gastroparesis refractory to dietary and pharmacologic management.

METHODS

In this report we review devices and techniques for endoscopic treatment of gastroparesis, the evidence regarding their efficacy and safety, and the financial considerations for their use.

RESULTS

Endoscopic modalities for treatment of gastroparesis can be broadly categorized into pyloric, nonpyloric, and nutritional therapies. Pyloric therapies such as botulinum toxin injection, stent placement, pyloroplasty, and pyloromyotomy specifically focus on pylorospasm as a therapeutic target. These interventions aim to reduce the pressure gradient across the pyloric sphincter, with a resultant improvement in gastric emptying. Nonpyloric therapies, such as venting gastrostomy and gastric electrical stimulation, are intended to improve symptoms. Nutritional therapies, such as feeding tube placement, aim to provide nutritional support.

CONCLUSIONS

Several endoscopic interventions have shown utility in improving the quality of life and symptoms of select patients with refractory gastroparesis. Methods to identify which patients are best suited for a specific treatment are not well established. Endoscopic pyloromyotomy is a relatively recent development that may prove to be the preferred pyloric-directed intervention, although additional and longer-term outcomes are needed.

On a coupled electro-chemomechanical model of gastric smooth muscle contraction

The stomach is a central organ in the gastrointestinal tract that performs a variety of functions, in which the spatio-temporal organisation of active smooth muscle contraction in the stomach wall (SW) is highly regulated. In the present study, a three-dimensional model of the gastric smooth muscle contraction is presented, including the mechanical contribution of the mucosal and muscular layer of the SW. Layer-specific and direction-dependent model parameters for the active and passive stress-stretch characteristics of the SW were determined experimentally using porcine smooth muscle strips. The electrical activation of the smooth muscle cells (SMC) due to the pacemaker activity of the interstitial cells of Cajal (ICC) is modelled by using FitzHugh-Nagumo-type equations, which simulate the typical ICC and SMC slow wave behaviour. The calcium dynamic in the SMC depends on the SMC membrane potential via a gaussian function, while the chemo-mechanical coupling in the SMC is modelled via an extended Hai-Murphy model. This cascade is coupled with an additional mechano-electrical feedback-mechanism, taking into account the mechanical response of the ICC and SMC due to stretch of the SW. In this way the relaxation responses of the fundus to accommodate incoming food, as well as the typical peristaltic contraction waves in the antrum for mixing and transport of the chyme, have been well replicated in simulations performed at the whole organ level. STATEMENT OF SIGNIFICANCE: In this article, a novel three-dimensional electro-chemomechanical model of the gastric smooth muscle contraction is presented. The propagating waves of electrical membrane potential in the network ofinterstitial cells of Cajal (ICC) and smooth muscle cells (SMC) lead to a global pattern of change in the calciumdynamics inside the SMC. Taking additionally into account the mechanical response of the ICC and SMC due to stretch of the stomach wall, also referred to as mechanical feedback-mechanism, the result is a complex spatio-temporal regulation of the active contraction and relaxation of the gastric smooth muscle tissue. Being a firstapproach, in future view such a three-dimensional model can give an insight into the complexload transferring system of the stomach wall, as well as into the electro-chemomechanicalcoupling process underlying smooth muscle contraction in health and disease.

Gastric Electrical Stimulators Causing Erosion Through the Colonic Wall

Gastroparesis is a chronic motor disorder of the stomach characterized by the demonstration of delayed gastric emptying without obstruction and a grouping of symptoms including nausea, vomiting, early satiety, postprandial fullness, bloating and abdominal pain. When conservative medical management is not effective, gastric electrical stimulation is an effective alternative. Gastric electrical stimulation, in general, has had a low complication rate as of yet, with the most common being infection of the implanted device. We present a complication in which the gastric electrical stimulator electrodes eroded through the colonic wall.

Systematic review on gastric electrical stimulation in obesity treatment

Introduction: Obesity is a very common public health problem worldwide. However, there is a lack of effective therapies. Only a small portion of patients with morbid obesity are accepting bariatric surgery as the last option due to the risks associated with invasive therapy. Areas covered: In this paper, we review an emerging weight loss treatment: gastric electrical stimulation (GES). The feasibility of GES as a potential therapy for obesity is introduced. Methodologies and parameters of GES are presented. Several GES methods for treating obesity and their effects on food intake and body weight are presented. Possible mechanisms involved in the anti-obesity effect of GES are discussed. Finally, our comments on the potential of GES for obesity and expectations for future development of the GES therapy are provided. The PubMed central database was searched from inception to May 2019. The literature search used the following terms: 'Gastric electrical stimulation' combined with 'obesity' and 'Implantable gastric stimulation' and 'pharmaceutical therapy' and 'bariatric surgery'. Expert opinion: There is a potential to use GES for treating obesity. However, more efforts are needed to develop appropriate stimulation devices and to design an adequate therapy for treating obesity in humans.

Periprocedural Considerations for Patients with Gastric Electrical Stimulators

OBJECTIVES

Gastric electrical stimulation (GES) is a technology that uses neurostimulation for the modulation of gastric activity. In clinical practice, the most commonly encountered form of GES is high frequency GES. GES devices are typically used for the treatment of refractory gastroparesis, although they have also been investigated for obesity management and the treatment of refractory gastroesophageal reflux disease. Just as many patients with chronic diseases require surgery, patients with an implanted GES device may encounter the need for periprocedural care. Therefore, the purpose of this review is to address the special needs of patients with an implanted GES device.

MATERIALS AND METHODS

A systematic computerized search of the literature was performed to consolidate existing knowledge on GES management in the periprocedural setting. Duplicate results were eliminated, and results were further narrowed based on title and abstract. All articles with possible relevance were then reviewed in full. Manufacturer information including pamphlets and websites were also reviewed.

RESULTS

A total of 1201 articles were identified for initial review, and 33 met inclusion criteria.

CONCLUSIONS

Available data suggests GES is a technology with increasing prevalence. When patients with an implanted GES device present for periprocedural care, the anesthesia staff must consider the device when planning for the procedure. Topics addressed include general anesthetic considerations, nerve localization, radiation exposure, electrocautery, diathermy, emergency external defibrillation, and MRI compatibility.

Pathophysiology and management of diabetic gastroenteropathy

Polyneuropathy is a common complication to diabetes. Neuropathies within the enteric nervous system are associated with gastroenteropathy and marked symptoms that severely reduce quality of life. Symptoms are pleomorphic but include nausea, vomiting, dysphagia, dyspepsia, pain, bloating, diarrhoea, constipation and faecal incontinence. The aims of this review are fourfold. First, to provide a summary of the pathophysiology underlying diabetic gastroenteropathy. Secondly to give an overview of the diagnostic methods. Thirdly, to provide clinicians with a focussed overview of current and future methods for pharmacological and nonpharmacological treatment modalities. Pharmacological management is categorised according to symptoms arising from the upper or lower gut as well as sensory dysfunctions. Dietary management is central to improvement of symptoms and is discussed in detail, and neuromodulatory treatment modalities and other emerging management strategies for diabetic gastroenteropathy are discussed. Finally, we propose a diagnostic/investigation algorithm that can be used to support multidisciplinary management.

Outcomes of per oral endoscopic pyloromyotomy in gastroparesis worldwide

Per oral endoscopic pyloromyotomy (POP), also known as gastric per-oral endoscopic myotomy (GPOEM), is a novel procedure with promising potential for the treatment of gastroparesis. As more data emerge and the procedure is becoming more recognized in clinical practice, its safety and efficacy need to be carefully evaluated. Appropriate patient selection for favorable clinical success prediction after GPOEM also needs additional research. This review aims to systemically summarize the existing data on clinical outcomes of POP. Symptomatologic responses to the procedure, its adverse effects, procedural techniques, and predictive factors of clinical success are also discussed.

Gastric Electrical Stimulator for Treatment of Gastroparesis

Patients with gastroparesis sometimes suffer from intractable nausea and vomiting, abdominal pain, and bloating, as well as a host of other symptoms that can often be difficult to control. Initially, patients are treated conservatively; some do well with conservative management but unfortunately some do not. Over the years, studies have shown the benefits of gastric electrical stimulation, which often results in symptomatic improvement and improvement in gastric emptying times. This article discusses the history of gastric electrical stimulation and its use in clinical practice to help those suffering from gastroparesis that is refractory to conservative medical management.

Spontaneous Electrical Activity and Rhythmicity in Gastrointestinal Smooth Muscles

The gastrointestinal (GI) tract has multifold tasks of ingesting, processing, and assimilating nutrients and disposing of wastes at appropriate times. These tasks are facilitated by several stereotypical motor patterns that build upon the intrinsic rhythmicity of the smooth muscles that generate phasic contractions in many regions of the gut. Phasic contractions result from a cyclical depolarization/repolarization cycle, known as electrical slow waves, which result from intrinsic pacemaker activity. Interstitial cells of Cajal (ICC) are electrically coupled to smooth muscle cells (SMCs) and generate and propagate pacemaker activity and slow waves. The mechanism of slow waves is dependent upon specialized conductances expressed by pacemaker ICC. The primary conductances responsible for slow waves in mice are Ano1, Ca2+-activated Cl- channels (CaCCs), and CaV3.2, T-type, voltage-dependent Ca2+ channels. Release of Ca2+ from intracellular stores in ICC appears to be the initiator of pacemaker depolarizations, activation of T-type current provides voltage-dependent Ca2+ entry into ICC, as slow waves propagate through ICC networks, and Ca2+-induced Ca2+ release and activation of Ano1 in ICC amplifies slow wave depolarizations. Slow waves conduct to coupled SMCs, and depolarization elicited by these events enhances the open-probability of L-type voltage-dependent Ca2+ channels, promotes Ca2+ entry, and initiates contraction. Phasic contractions timed by the occurrence of slow waves provide the basis for motility patterns such as gastric peristalsis and segmentation. This chapter discusses the properties of ICC and proposed mechanism of electrical rhythmicity in GI muscles.

Gastric Electrical Stimulation Improves Symptoms of Diabetic Gastroparesis in Patients on Peritoneal Dialysis-2 Case Reports

Diabetic gastroparesis (DGP), a delay in gastric emptying without obstruction to outflow as a complication of diabetes, typically develops after at least 10 years of diabetes. Cardinal symptoms include nausea, vomiting, early satiety, bloating, and upper abdominal pain. The aim of DGP treatment is to alleviate the severity and frequency of symptoms, improve the level of gastric emptying, ameliorate the patient's nutritional status and to optimize glycemic control. In the treatment of chronic drug-refractory nausea and vomiting secondary to DGP, gastric electrical stimulation (GES) such as Enterra Therapy System (Medtronic Inc., Minneapolis, MN, USA) can be considered. It is well established that diabetic nephropathy is the most common cause of end-stage renal disease (ESRD) requiring renal replacement therapy. The exact prevalence of patients with severe DGP and ESRD is not known; however, finding a therapeutic approach to these patients, particularly those whose gastroparesis symptoms preclude them from undergoing kidney transplant procedure, represents a huge challenge. Our experience suggests that GES implantation can be an effective treatment modality for type 1 diabetic patients on peritoneal dialysis (PD) who are simultaneous pancreas-kidney transplantation candidates, by improving the severity and frequency of gastroparesis symptoms and eventually ensuring their optimal nutritional and fluid intake.

Current and Emerging Therapeutic Options for Gastroparesis

Gastroparesis is a complex, debilitating dysmotility disorder with challenging symptom management. A diagnosis of gastroparesis is based on objectively delayed gastric emptying in the absence of mechanical obstruction. Given the limited efficacy of treatment options and serious side effects, significant research continues for therapeutic options for gastroparesis. Promising investigational pharmacologic therapies include relamorelin, prucalopride, and aprepitant. A novel endoscopic therapy is gastric peroral endoscopic pyloromyotomy, which is associated with improved gastric emptying. This article reviews both current and emerging therapeutic options for gastroparesis, including dietary modification and pharmacologic, electrical stimulation, endoscopic, and surgical therapies. Further research and novel treatment options are needed to address the substantial morbidity of gastroparesis.

Design and application of a novel gastric pacemaker

Omnipresent bioelectrical events known as slow waves are responsible for coordinating motility in the gastrointestinal tract. Functional motility diseases, such as gastroparesis, are associated with slow wave dysrhythmias. Electrical stimulation is a potential therapy to correct abnormal slow wave patterns. We present the design and application of a new gastric pacemaker. Real-time changes to the stimulation parameters such as period, amplitude and pulse width were applied using a graphical user interface, which communicated with the microcontroller to deliver the stimulus. The new pacemaker allows the voltage, delivered current and resistance between pacing electrodes to be continuously monitored. The pacing device was applied experimentally and was able to modulate and entrain gastric slow wave activity. After the onset of pacing, the direction of slow wave propagation was altered. Furthermore, the mean velocity and amplitude of slow wave activity increased from 4.7±1.5 to 5.4±1.3 mm/s, and from 1.1±1.1 to 1.7±0.9 mV, respectively. A simplified bidomain electrical model was used to simulate the recorded stimulus artifact. The model illustrated a new approach to evaluate if the stimulus has been delivered to the gastric tissue. The new pacing device and model will be used to investigate the mechanisms that allow pacing to entrain slow wave activity.

Outcomes of surgical intervention for refractory gastroparesis: a systematic review

BACKGROUND

Gastroparesis (GP) is characterized by delayed gastric emptying with symptoms of nausea, vomiting, early satiety, postprandial fullness, and abdominal pain. Various surgical options exist to treat GP not responding to medical treatments (refractory GP), including gastric electric stimulation (GES), gastrectomy (GTx), and pyloric interventions (PI), whereas the outcomes of these procedures have been published; few comparison studies exist.

METHODS

PubMed literature review for articles from September 1988 to October 2017 was performed for prospective and retrospective analyses reporting >5 patients. Unweighted (per study) and weighted (per patient) overall improvement and improvement in symptoms of nausea, vomiting, and abdominal pain were calculated and compared for the different procedures.

RESULTS

Of 325 studies satisfying search criteria, 38 met the study criteria and were included for analysis. Total response to intervention, both weighted and unweighted, was greater with PIs compared to GES (P < 0.05). For unweighted symptom improvements, nausea improved more with PI than with GES (P < 0.05). GES improved vomiting more than epigastric pain (P < 0.05). For weighted symptom improvements, pyloric surgery and GTx improved vomiting compared to GES (P < 0.05).

CONCLUSIONS

Published outcomes of GES, pyloric surgery, and GTx for refractory GP are compared. Pyloromyotomy/pyloroplasty improves patient response greater than with GES. Weighing by number of studies, pyloric surgery improves nausea and abdominal pain greater than GES. For GES, vomiting is more likely to improve than abdominal pain. Weighing by number of patients, pyloric surgery and GTx improved vomiting compared to GES.

Outcomes of High-Frequency Gastric Electric Stimulation for the Treatment of Severe, Medically Refractory Gastroparesis in Finland

Background and Aims:

Severe, medically uncontrollable gastroparesis is a rare entity, which can be treated using a high-frequency gastric electric stimulator implanted surgically. Previous follow-ups have proven positive outcomes with gastric electric stimulator in patients with gastroparesis. The aim of this study was to evaluate the efficacy and safety of gastric electric stimulator in patients, in whom gastroparesis could not be controlled by conservative means in our country.

Materials and Methods:

This is a retrospective multi-center cohort comprising all patients who had been implanted gastric electric stimulator for severe, medically refractory gastroparesis during 2007–2015 in Finland.

Results:

Fourteen patients underwent implantation of gastric electrical stimulator without any postoperative complications. Laparoscopic approach was used in 13 patients (93%). Prior implantation, all patients needed frequent hospitalization for parenteral feeding, 13 had severe nausea, 11 had severe vomiting, 10 had notable weight loss, and 6 had frequent abdominal pain. After operation, none of the patients required parenteral feeding, 11 patients (79%) gained median of 5.1 kg in weight (P < 0.01), and symptoms were relieved markedly in 8 and partially in 3 patients (79%). Of partial responders, two continued to experience occasional vomiting and one mild nausea. Five patients needed medication for gastroparesis after the operation. One patient did not get any relief of symptoms, but gained 6 kg in weight. No major late complications occurred.

Conclusion:

Gastric electrical stimulator seems to improve the nutritional status and give clear relief of the symptoms of severe, medically uncontrollable gastroparesis. Given the low number of operations, gastric electrical stimulator seems to be underused in Finland.

Fluoroscopic gastric peroral endoscopic pyloromyotomy (G-POEM) in patients with a failed gastric electrical stimulator

Background

Gastric electrical stimulators (GESs) have been used to treat refractory gastroparesis in patients who fail initial therapies such as dietary modifications, control of psychological stressors and pharmacologic treatment. More recently, gastric peroral endoscopic pyloromyotomy (G-POEM) has emerged as a novel endoscopic technique to treat refractory gastroparesis. We present a case series of patients with refractory gastroparesis who failed treatment with an implanted GES that were safely treated with G-POEM performed under fluoroscopy as a salvage therapy.

Methods

Cases of G-POEM performed on patients with refractory gastroparesis who failed treatment with a GES were retrospectively reviewed. All G-POEM procedures were performed under fluoroscopic guidance with the GES still in place. Gastroparesis Cardinal Symptoms Index (GCSI) and gastric emptying scintigraphy were assessed before and after the procedure. Patients were followed up for up to 18 months post procedure.

Results

Five patients underwent G-POEM after failing treatment with a GES. Under fluoroscopy, the GES and their leads were visualized in different parts of the stomach. One GES lead was observed at the antrum near the myotomy site. All procedures were successfully completed without complications. Patients' GCSI decreased by an average of 62% 1 month post procedure. Patients also had notable improvements in gastric emptying 2 months post procedure.

Conclusion

In patients with refractory gastroparesis who have failed treatment with a GES, G-POEM can be safe and effective without removing the GES. To visualize the GES and avoid cutting GES leads during myotomy, the procedure should be performed under fluoroscopy.

Tailored approach to gastroparesis significantly improves symptoms

BACKGROUND

Gastroparesis is difficult to treat and many patients do not report relief of symptoms with medical therapy alone. Several operative approaches have been described. This study shows the results of our selective surgical approach for patients with gastroparesis.

MATERIALS AND METHODS

This is a retrospective study of prospective data from our electronic medical record and data symptom sheet. All patients had a pre-operative gastric emptying study showing gastroparesis, an esophagogastroduodenoscopy, and either a CT or an upper GI series with small bowel follow-through. All patients had pre- and post-operative symptom sheets where seven symptoms were scored for severity and frequency on a scale of 0-4. The scores were analyzed by a professional statistician using paired sample t test.

RESULTS

58 patients met inclusion criteria. 33 had gastric stimulator (GES), 7 pyloroplasty (PP), 16 with both gastric stimulator and pyloroplasty (GSP), and 2 sleeve gastrectomy. For patients in the GSP group, the second procedure was performed if there was inadequate improvement with the first procedure. There was no mortality. The follow-up period was 6-316 weeks (mean 66.107, SD 69.42). GES significantly improved frequency and severity for all symptoms except frequency of bloating and postprandial fullness. PP significantly improved nausea and vomiting severity, frequency of nausea, and early satiety. Symptom improvement for GSP was measured from after the first to after the second procedure. GSP significantly improved all but vomiting severity and frequency of early satiety, postprandial fullness, and epigastric pain.

CONCLUSION

All procedures significantly improved symptoms, although numbers are small in the PP group. GES demonstrates more improvement than PP, and if PP or GES does not adequately improve symptoms GSP is appropriate. In our practice, gastrectomy was reserved as a last resort.

Gut dysfunction in Parkinson's disease

Early involvement of gut is observed in Parkinson’s disease (PD) and symptoms such as constipation may precede motor symptoms. α-Synuclein pathology is extensively evident in the gut and appears to follow a rostrocaudal gradient. The gut may act as the starting point of PD pathology with spread toward the central nervous system. This spread of the synuclein pathology raises the possibility of prion-like propagation in PD pathogenesis. Recently, the role of gut microbiota in PD pathogenesis has received attention and some phenotypic correlation has also been shown. The extensive involvement of the gut in PD even in its early stages has led to the evaluation of enteric α-synuclein as a possible biomarker of early PD. The clinical manifestations of gastrointestinal dysfunction in PD include malnutrition, oral and dental disorders, sialorrhea, dysphagia, gastroparesis, constipation, and defecatory dysfunction. These conditions are quite distressing for the patients and require relevant investigations and adequate management. Treatment usually involves both pharmacological and non-pharmacological measures. One important aspect of gut dysfunction is its contribution to the clinical fluctuations in PD. Dysphagia and gastroparesis lead to inadequate absorption of oral anti-PD medications. These lead to response fluctuations, particularly delayed-on and no-on, and there is significant relationship between levodopa pharmacokinetics and gastric emptying in patients with PD. Therefore, in such cases, alternative routes of administration or drug delivery systems may be required.

Long-term outcomes of gastric electrical stimulation in children with gastroparesis

BACKGROUND

Gastric electrical stimulation (GES) has been used in adults with gastroparesis. However its use has been limited in children. We describe the largest experience with GES in children with long-term outcomes.

METHODS

Data were collected on children who underwent GES over a 10-year period. Data regarding demographics, medical history, hospital course, and outcomes were collected and analyzed. Symptom scores (validated Likert scores) were compared using a paired Student's t test.

RESULTS

Overall, 97 patients underwent GES, and a majority were teenage Caucasian girls. Ninety-six had temporary GES (tGES), and 66 had improvement in their symptoms. A total of 67 underwent permanent implantation (pGES), and there was significant reduction in all individual symptoms (p<0.001) as well as the total symptom score (TSS) (p<0.0001) at 1, 6, 12, and >12 months. Recurrence of symptoms leading to device removal occurred in 7 cases. Forty-one patients had continued improvement in symptoms for over 12 months, with a mean follow-up of 3.5 years (range 1-9 years).

CONCLUSIONS

This study represents the largest experience of systematic application of GES in children. GES is a safe and effective therapy for selected children with intractable GP with continued symptomatic improvement at 1 year and beyond.

Pyloroplasty for Refractory Gastroparesis

Gastroparesis is a chronic gastric motility disorder in which the pathophysiology mimics a post-vagotomy state. Pyloroplasty is beginning to emerge as a successful drainage procedure for refractory gastroparesis. Here we report our experience using pyloroplasty in the surgical management of diabetic and nondiabetic gastroparesis. A retrospective study was performed of 46 patients undergoing pyloroplasty for refractory gastroparesis from January 2010 through December 2013. Gastric emptying scintigraphy and the Gastroparesis Cardinal Symptom Index were assessed pre-and postoperatively. Laparoscopic pyloroplasty was performed in 42 patients, open pyloroplasty in three, and one patient was converted from laparoscopic to open pyloroplasty. Studies were repeated during the six to 12 month postoperative interval. The postoperative gastric emptying scintigraphy improved in 90 per cent of patients and normalized in 60 per cent. Postoperative T½ was significantly reduced ( P = 0.001) as was four-hour retention ( P < 0.001). The Gastroparesis Cardinal Symptom Index showed statistically significant reduction in symptom severity for all nine categories ( P < 0.0005) as well as total symptom score ( P < 0.005). No patients developed dumping syndrome. Pyloroplasty is a highly effective therapy for refractory gastroparesis, offering significant reduction in symptom severity, improvement in quality of life, and acceleration of gastric emptying.

Gastric Electrical Stimulation for Refractory Gastroparesis: Predictors of Response and Redefining a Successful Outcome

Predictors of a favorable response and measures of success with gastric electrical stimulation (GES) for gastroparesis remain elusive. Published results remain inconsistent with respect to patient perceived benefit, despite statistical improvements in objective measures of symptom severity. We performed a retrospective analysis of 56 patients with gastroparesis who underwent insertion of a gastric electrical stimulator during the study period. Data included demographics, symptoms, total symptom severity score (TSS, range 0–24, initial and most recent), and gastric emptying times. TSS were grouped into four severity categories (0–10, 11–14, 15–18, 19–24). TSS improvement was defined as movement to a lower severity category. Perception of improvement was compared with that of TSS score improvement using χ2 test. Etiology as a predictor of improvement was measured using logistic regression. Initial mean TSS was 21, and post-treatment TSS was 13.5. Improvement was significant for individual symptoms and in reduction of TSS for both diabetic/idiopathic etiologies (P ≤ 0.001). No correlation was noted between likelihood of success/failure and gastric emptying times ( P = 0.32). Thirty-eight improved (moved to lower TSS category), whereas 18 failed (remained in same category) (P ≤ 0.001), which correlated with perception of improvement. Of 18 failures, 14 (77.7%) were idiopathic. On logistic regression, diabetics were more likely than idiopathic patients to move to a lower TSS category (odds ratio 14, P = 0.003) and even more likely to improve based on patient perception (odds ratio 45, P = 0.005). GES produces far more consistent improvement in diabetics. Further study of GES in idiopathic gastroparesis is needed. Application of the proposed TSS severity categories allowed differentiation of small, statistically significant (but clinically insignificant) reductions in TSS from larger, clinically significant reductions, thereby permitting more reliable application of TSS to the evaluation of GES efficacy.

Gastric electrical stimulation for refractory gastroparesis: predictors of response and redefining a successful outcome

Predictors of a favorable response and measures of success with gastric electrical stimulation (GES) for gastroparesis remain elusive. Published results remain inconsistent with respect to patient perceived benefit, despite statistical improvements in objective measures of symptom severity. We performed a retrospective analysis of 56 patients with gastroparesis who underwent insertion of a gastric electrical stimulator during the study period. Data included demographics, symptoms, total symptom severity score (TSS, range 0-24, initial and most recent), and gastric emptying times. TSS were grouped into four severity categories (0-10, 11-14, 15-18, 19-24). TSS improvement was defined as movement to a lower severity category. Perception of improvement was compared with that of TSS score improvement using χ(2) test. Etiology as a predictor of improvement was measured using logistic regression. Initial mean TSS was 21, and post-treatment TSS was 13.5. Improvement was significant for individual symptoms and in reduction of TSS for both diabetic/idiopathic etiologies (P ≤ 0.001). No correlation was noted between likelihood of success/failure and gastric emptying times (P = 0.32). Thirty-eight improved (moved to lower TSS category), whereas 18 failed (remained in same category) (P ≤ 0.001), which correlated with perception of improvement. Of 18 failures, 14 (77.7%) were idiopathic. On logistic regression, diabetics were more likely than idiopathic patients to move to a lower TSS category (odds ratio 14, P = 0.003) and even more likely to improve based on patient perception (odds ratio 45, P = 0.005). GES produces far more consistent improvement in diabetics. Further study of GES in idiopathic gastroparesis is needed. Application of the proposed TSS severity categories allowed differentiation of small, statistically significant (but clinically insignificant) reductions in TSS from larger, clinically significant reductions, thereby permitting more reliable application of TSS to the evaluation of GES efficacy.

Surgical approaches to treatment of gastroparesis: gastric electrical stimulation, pyloroplasty, total gastrectomy and enteral feeding tubes

Gastric electrical stimulation (GES) is neurostimulation; its mechanism of action is affecting central control of nausea and vomiting and enhancing vagal function. GES is a powerful antiemetic available for patients with refractory symptoms of nausea and vomiting from gastroparesis of idiopathic and diabetic causes. GES is not indicated as a way of reducing abdominal pain in gastroparetic patients. The need for introducing a jejunal feeding tube means intensive medical therapies are failing, and is an indication for the implantation of the GES system, which should always be accompanied by a pyloroplasty to guarantee accelerated gastric emptying.

Synchronized dual pulse gastric electrical stimulation induces activation of enteric glial cells in rats with diabetic gastroparesis

Objective. The aims of this study were to investigate the effects of synchronized dual pulse gastric electrical stimulation (SGES) on gastric motility in different periods for diabetic rats and try to explore the possible mechanisms of the effects. Methods. Forty-six rats were used in the study. Gastric slow waves were recorded at baseline, 7-14-day diabetes and 56-63-day diabetes before and after stimulation and the age-matched control groups. SGES-60 mins and SGES-7 days (60 mins/day) were performed to test the effects on gastric motility and to evaluate glial marker S100B expression in stomach. Results. (1) Gastric emptying was accelerated in 7-14-day diabetes and delayed in 56-63-day diabetes. (2) The S100B expression in 56-63-day diabetes decreased and the ultrastructure changed. (3) The age-associated loss of EGC was observed in 56-63-day control group. (4) SGES was able to not only accelerate gastric emptying but also normalize gastric slow waves. (5) The S100B expression increased after SGES and the ultrastructure of EGC was partially restored. The effect of SGES-7 days was superior to SGES-60 mins. Conclusions. Delayed gastric emptying due to the growth of age may be related to the EGC inactivation. The effects of the SGES on gastric motility may be associated with EGC activation.

Advances in research of colonic electrical stimulation

In recent years great attention has been paid to the study of colonic electrical stimulation. Colonic electrical stimulation is expected to become a valuable option for treatment of gastrointestinal dysfunction. This article reviews the classification, mechanisms and clinical applications of colonic electrical stimulation.