Nutritional Assessment in Patients after Gastric Electrical Stimulation (GES).

BACKGROUND: Gastric electrical stimulation (GES) is used for patients with drug-refractory gastroparesis (Gp) symptoms. Approximately two-thirds of patients with Gp symptoms are either overweight or obese. We aimed to assess symptoms and nutritional status pre-GES and post-GES placement in a large sample of drug-refractory Gp patients. METHODS: We conducted a chart review of 282 patients with drug-refractory Gp who received temporary followed by permanent GES at an academic medical center. Gastrointestinal symptoms were collected by a traditional standardized PRO (0-4, 0 being asymptomatic and 4 being worst symptoms), baseline nutritional status by BMI plus subjective global assessment (SGA score A, B, C, for mild, moderate, and severe nutritional deficits), ability to tolerate diet, enteral tube access, and parenteral therapy were assessed at baseline and after permanent GES placement. RESULTS: Comparing baseline with permanent, GES was found to significantly improve upper GI symptoms in all quartiles. Of the 282 patients with baseline body mass index (BMI) information, 112 (40%) patients were severely malnourished at baseline, of which 36 (32%) patients' nutritional status improved after GES. Among all patients, 76 (68%) patients' nutritional status remained unchanged. Many patients with high BMI were malnourished by SGA. CONCLUSION: We conclude that symptomatic patients of different BMIs showed improvement in their GI symptoms irrespective of baseline nutritional status. Severely malnourished patients were found to have an improvement in their nutritional status after GES therapy. We conclude that BMI, even if high, is not by itself a contraindication for GES therapy for symptomatic patients.

Low-Resolution Electrogastrogram at Baseline and Response to Temporary Gastric Electrical Stimulation-A Comparison of Cutaneous With Mucosal Recordings.

INTRODUCTION: Gastric electrical stimulation (GES) is a widely accepted therapy for gastroparesis symptoms, but how a brief cutaneous electrogastrogram (EGG) can be used in conjunction with GES has not been well defined. We evaluated the clinical importance of EGG, its correlation with mucosal electrograms (mEGs), gastric emptying tests (GETs), and gastrointestinal symptoms before and after temporary GES (tGES). MATERIALS AND METHODS: We studied 1345 patients; 991 had complete data. EGG measurements like frequency and amplitude were recorded at baseline and five days post-tGES using short recording periods. A total of 266 participants having additional cutaneous propagation values were separately analyzed. Patients underwent solid GET before and after tGES and self-reported symptoms using standardized traditional patient-reported outcomes (TradPRO) scores. Pearson correlations were assessed at baseline, post-stimulation, and their changes over the follow-up period. RESULTS: EGG measures correlated with symptoms and GET results. Patients with abnormal baseline cutaneous frequency had higher baseline total symptom scores (p < 0.003). Post-tGES, one-hour gastric emptying was significantly changed (p < 0.0001) and was mainly observed with abnormal baseline cutaneous frequencies (p < 0.0001). Cutaneous frequency significantly increased after tGES (p < 0.0001), correlating positively with TradPRO scores and one-hour gastric emptying. Mucosal and cutaneous measures correlated pre- and post-treatment. Of the 266 patients, 153 changed propagation states between baseline and temporary; changing states from lower at baseline to higher at temporary was more likely than vice versa. Short EGG recording times can demonstrate changes after the bioelectric therapy of GES. CONCLUSION: EGG is valuable in the diagnosis of delayed gastric emptying and comparable with mEG. It is less invasive and can identify patients who may require GES. Frequency, amplitude, their ratio (frequency-amplitude ratio), and propagation appear to be reliable measures of EGG. EGG provides cost-effective measurement of electrophysiological properties and significantly correlates with important clinical measures. Shorter EGG recording times may be adequate to see changes from bioelectric therapies. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT03876288.

Nausea and Vomiting in 2021: A Comprehensive Update.

GOAL: A comprehensive review of treatments for nausea and vomiting (N/V). BACKGROUND: N/V are common symptoms encountered in medicine. While most cases of acute N/V related to a specific cause can be straightforward to manage, other cases of acute N/V such as chemotherapy-induced N/V and especially chronic unexplained N/V can be difficult to control, leading to a significant decline in the patient's quality of life and increased cost of medical care from repeated hospitalizations. STUDY: Traditional management has relied on pharmacotherapy which may be inadequate in a certain proportion of these patients. Many of the medications used in the management of N/V have significant side effect profiles making the need for new and improved interventions of great importance. RESULTS: This review covers a broad review of the pathophysiology of N/V, pharmacotherapy, including safety concerns and controversies with established pharmaceuticals, newer immunotherapies, bioelectrical neuromodulation (including gastric electrical stimulation), behavioral and surgical therapies, and complementary medicine. CONCLUSION: On the basis of emerging understandings of the pathophysiology of N/V, improved therapies are becoming available.

Effectiveness of gastric electrical stimulation in gastroparesis: Results from a large prospectively collected database of national gastroparesis registries.

BACKGROUND: Gastric electrical stimulation (GES) for treating gastroparesis symptoms is controversial. METHODS: We studied 319 idiopathic or diabetic gastroparesis symptom patients from the Gastroparesis Clinical Research Consortium (GpCRC) observational studies: 238 without GES and 81 with GES. We assessed the effects of GES using change in GCSI total score and nausea/vomiting subscales between baseline and 48 weeks. We used propensity score methods to control for imbalances in patient characteristics between comparison groups. KEY RESULTS: GES patients were clinically worse (40% severe vs. 18% for non-GES; P < .001); worse PAGI-QOL (2.2. vs. 2.6; P = .003); and worse GCSI total scores (3.5 vs. 2.8; P < .001). We observed improvements in 48-week GCSI total scores for GES vs. non-GES: improvement by ≥ 1-point (RR = 1.63; 95% CI = (1.14, 2.33); P = .01) and change from enrollment (difference = -0.5 (-0.8, -0.3); P < .001). When adjusting for patient characteristics, symptom scores were smaller and not statistically significant: improvement by ≥ 1-point (RR = 1.29 (0.88, 1.90); P = .20) and change from the enrollment (difference = -0.3 (-0.6, 0.0); P = .07). Of the individual items, the nausea improved by ≥ 1 point (RR = 1.31 (1.03, 1.67); P = .04). Patients with GCSI score ≥ 3.0 tended to improve more than those with score < 3.0. (Adjusted P = 0.02). CONCLUSIONS AND INFERENCES: This multicenter study of gastroparesis patients found significant improvements in gastroparesis symptoms among GES patients. Accounting for imbalances in patient characteristics, only nausea remained significant. Patients with greater symptoms at baseline improved more after GES. A much larger sample of patients is needed to fully evaluate symptomatic responses and to identify patients likely to respond to GES.

Gastroparesis syndromes: Response to electrical stimulation.

BACKGROUND AND AIMS: Factors underlying gastroparesis are not well defined, nor is the mechanism of action of gastric electrical stimulation (GES). We hypothesized that GES acts via several mechanisms related to underlying disordered pathophysiology. METHODS: We studied 43 consecutive eligible patients with gastroparetic symptoms, previously evaluated by two methods in each of five core areas: inflammatory, autonomic, enteric, electrophysiologic, and hormonal; and also categorized by GI symptoms, metabolic status, illness quantification, and gastric physiology. We then studied 41 patients who underwent temporary GES for 5-7 days. Thirty-six of those patients were implanted and 30 were followed up at 6 months after permanent GES. RESULTS: In previous but separately reported work, patients had similar GI symptoms regardless of baseline gastric emptying or diabetic/idiopathic status and all patients demonstrated abnormalities in each of the five areas studied. After GES, patients showed early and late effects of electrical stimulation with changes noted in multiple areas, categorized by improvement status. CONCLUSION: Patients with symptoms of gastroparesis have multiple abnormalities, including systemic inflammation and disordered hormonal status. GES affects many of these abnormalities. We conclude electrical stimulation improves symptoms and physiology with (a) an early and sustained anti-emetic effect; (b) an early and durable gastric prokinetic effect in delayed emptying patients; (c) an early anti-arrhythmic effect that continues over time; (d) a late autonomic effect; (e) a late hormonal effect; (f) an early anti-inflammatory effect that persists; and (g) an early and sustained improvement in health-related quality of life. This study is registered with Clinicaltrials.gov under study # NCT03178370 (https://clinicaltrials.gov/ct2/show/NCT03178370).

Cajal Cell Counts are Important Predictors of Outcomes in Drug Refractory Gastroparesis Patients With Neurostimulation.

BACKGROUND AND AIMS: Cajal cells serve as the pacemaker cells of the gastrointestinal tract and regulates peristalsis. On the baisis of that fact, it has been hypothesized that a decrease in Cajal cells can lead to gastroparesis and other motility issues. Treatment with medications has a limited efficacy and most resort to gastric electrical stimulation (GES) devices for symptomatic relief. We believe that the number of Cajal cells present is directly proportional to symptomatic relief with GES. MATERIALS AND METHODS: Twenty-three (white female) subjects were recruited from the gastric motility clinic University of Mississipi for this study with the criteria of drug refractory gastropersis. Symptoms were measured using Likert scale and gastric emptying times were measured pre-GES and post-GES. Serosal electrogram measurements were recorded during surgical placement of permanent electrical stimulator under various modes. Cajal cell count scoring via immunohistochemistry were performed during the implantaion of the GES. RESULTS: The data were grouped in 2 categories based on the Cajal cells that is ≥2.00 and <2.00. Subjects with higher Cajal cells reported a statiscially improvement in gastroperesis symptoms. Significant differences were also noted in the first hour gastric emptying study. The mean group difference is 17.5 (95% confidence interval, 1.41-33.58; P=0.035). Serosal amplitude differences were noted being significantly higher in the group with ≥2 cajal cells. CONCLUSIONS: Electrograms obtained after GES demonstrates immediate improvement in gastric electrical activity and gastroparesis symptoms in patients with relatively higher Cajal cell counts when compared with patients with extensive loss of Cajal cells.

The Effect of Gastric Electrical Stimulation on Small Bowel Motility in Patients With Gastroparesis and Concomitant Pancreatic and Small Bowel Dysfunction: From Animal Model to Human Application.

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.

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.

Treating an oft-unrecognized and troublesome entity: using gastric electrical stimulation to reduce symptoms of malignancy-associated gastroparesis.

PURPOSE: Malignancy-associated gastroparesis (MAG) is a cause of morbidity in cancer patients but therapies are lacking. Gastric electrical stimulation (GES) is a novel treatment for MAG. Here, we describe 19 patients with MAG who underwent temporary GES placement. PATIENTS AND METHODS: Nineteen patients (6 males, 13 females) with various malignancies were reviewed for symptom scores and physiologic measures at baseline and after temporary GES placement. Symptoms were scored by three variables: nausea (N), vomiting (V), and GI total symptom score (TSS). Physiologic profiles were measured by solid and liquid phase gastric emptying scans (GET) at 1, 2, and 4 h and cutaneous electrogastrogram (EGG) and mucosal electrogram (EG) frequencies. Symptoms were measured for 5 days after temporary endoscopic GES placement, and measures were repeated post GES placement. RESULTS: Baseline GET results displayed delayed gastric emptying in 16 of 19 patients (mean solid retention 21.7 % at 4 h, normal <10 %; mean liquid retention 10.4 % at 4 h, normal <5 %). Cutaneous EGG (mean frequency 5.5 cpm) and EG (mean proximal frequency 5.1 cpm; mean distal frequency 5.1 cpm) showed evidence of neuromuscular dysfunction (normal 2.5-3.3 cpm). Symptom scores in N, V, and TSS showed statistically significant reduction after GES placement. CONCLUSION: A small sample of patients with MAG and receiving temporary GES experienced symptom improvement, with less change on gastric emptying time or gastric electrical amplitude or frequency. GES may provide a potential therapeutic option for symptomatic management of MAG and evaluation of these MAG patients after permanent GES placement is ongoing. Prospective studies of MAG using temporary and permanent GES may be warranted.

Acute Slow Wave Responses to High-Frequency Gastric Electrical Stimulation in Patients With Gastroparesis Defined by High-Resolution Mapping.

BACKGROUND AND AIMS: High-frequency gastric electrical stimulation (GES) has emerged as a therapy for gastroparesis, but the mechanism(s) of action remain unclear. There is a need to refine stimulation protocols for clinical benefit, but a lack of accurate techniques for assessing mechanisms in clinical trials, such as slow wave modulation, has hindered progress. We thereby aimed to assess acute slow wave responses to GES in gastroparesis patients using high-resolution (HR) (multi-electrode) mapping, across a range of stimulation doses achievable by the Enterra stimulation device (Medtronic Inc., MN, USA). MATERIALS AND METHODS: Patients with medically refractory gastroparesis (n = 8) undergoing device implantation underwent intraoperative HR mapping (256 electrodes). Baseline recordings were followed by four protocols of increasing stimulation intensity, with washout periods. Slow wave patterns, frequency, velocity, amplitude, and dysrhythmia rates were quantified by investigators blinded to stimulation settings. RESULTS: There was no difference in slow wave pattern, frequency, velocity, or amplitude between baseline, washout, and stimulation periods (all p > 0.5). Dysrhythmias included ectopic pacemakers, conduction blocks, retrograde propagation, and colliding wavefronts, and dysrhythmia rates were unchanged with stimulation off vs. on (31% vs. 36% duration dysrhythmic; p > 0.5). Symptom scores and gastric emptying were improved at 5.8 month follow-up (p < 0.05). CONCLUSIONS: High-frequency GES protocols achievable from a current commercial device did not acutely modulate slow wave activity or dysrhythmias. This study advances clinical methods for identifying and assessing therapeutic GES parameters, and can be applied in future studies on higher-energy protocols and devices.

Mini-laparotomy with Adjunctive Care versus Laparoscopy for Placement of Gastric Electrical Stimulation.

We compared outcomes for two gastric electrical stimulation placement strategies, minilaparotomy with adjunctive care (MLAC) versus laparoscopy without adjunctive care (LAPA). For electrode placement, the peritoneal cavity was accessed with either a single 2.5 to 3.0 cm midline incision (MLAC) or three trocar incisions (LAPA). For both groups, generator was placed subcutaneously over the anterior rectus sheath. For MLAC, adjunctive pain control measures were used for placement of both electrode and generator (transversus abdominus plane block). For LAPA, those that could not be completed by laparoscopy were converted to traditional open approach and kept in the analysis. MLAC (n = 128) resulted in shorter operative times than LAPA (n = 37) (median operative time: 87.5 vs 137.0 minutes, P ≤ 0.01). Hospital length of stay was also shorter for MLAC than for LAPA (median: 2.0 vs 3.0 days, P ≤ 0.01) without any increase in readmission rates to the hospital within 30 days of discharge (11.0 vs 16.2%, P = 0.39). After equalizing learning curves, these differences were even greater (median operative time: 84.5 vs 137.0 minutes, P < 0.01; median length of stay: 1.0 vs 3.0 days; P < 0.01) without increasing 30-day readmission rates (9.1 vs 16.2%, P = 0.25). For implantation of gastric electrical stimulators, minilaparotomy can result in improved outcomes when coupled with adjunctive pain control measures.

Gastric Electrical Stimulation and Sacral Electrical Stimulation: A Long-Term Follow-Up Study of Dual-Device Treatment.

AIMS: The objective of this study was to investigate sacral electrical stimulation (SES) and gastric electrical stimulation (GES) by comparing upper and lower gastrointestinal (GI) and genitourinary (GU) symptoms and quality of life, before treatment and in the long term after treatment. We hypothesized that dual-device treatment would greatly improve upper and lower gastrointestinal and genitourinary symptoms, as well as quality of life. METHODS: Fifty-four patients who underwent dual-device treatment (GES and SES) were enrolled in this study. Patients who had surpassed 24 months since the second-device insertion were included. Patients were evaluated before and after both devices were implanted and given a symptom questionnaire regarding their upper GI, lower GI, and GU symptoms and their quality of life. RESULTS: With combined treatment, a statistically significant improvement was seen in upper GI, lower GI, and GU symptoms and quality of life. However, fecal incontinence and fecal urgency improvements did not reach statistical significance, likely due to the small sample size. CONCLUSION: The implantation of two stimulators appears to be safe and effective to improve patients' quality of life for those with upper GI symptoms, bowel problems, and bladder dysfunction.

Neurostimulation of the gastrointestinal tract: review of recent developments.

OBJECTIVE: Neurostimulation is one manifestation of neuromodulation of the gastrointestinal (GI) tract. This manuscript reviews the history of neurostimulation of the GI tract with emphasis on current methods of stimulation. MATERIALS AND METHODS: A review was completed of the current research on GI neurostimulation methods with an emphasis on their clinical applications. RESULTS: Upper GI disorders can be modulated with both temporary (placed endoscopically or surgically) or permanent (placed surgically) gastric electrical stimulation (GES) devices. The current GI neurostimulation of stomach (GES) devices have been used in both children and adults, and some patients have been followed in excess of 15 years with good long-term results. Similar GES devices also have been used for a variety of lower GI disorders, including constipation and fecal incontinence, for a number of years. CONCLUSIONS: GI neurostimulation, as a type of neuromodulation, has been demonstrated to function at several locations in the GI tract for a variety of disorders. The future of neurostimulation in the GI tract will likely be influenced by a better understanding of pathophysiology as well as the development of new techniques and devices for neuromodulation.

Evaluation and treatment of gastric stimulator failure in patients with gastroparesis.

OBJECTIVE: This study evaluates treatment of gastroparesis patients refractory to gastric electrical stimulation (GES) therapy with surgical replacement of the entire GES system. SUMMARY BACKGROUND DATA: Some patients who have symptomatic improvement with GES later develop recurrent symptoms. Some patients improve by simply altering pulse parameter settings. Others continue to have symptoms with maximized pulse parameters. For these patients, we have shown that surgical implantation of a new device and leads at a different gastric location will improve symptoms of gastroparesis. METHODS: This study evaluates 15 patients with recurrent symptoms after initial GES therapy who subsequently received a second GES system. Positive response to GES replacement therapy is evaluated by symptoms scores for vomiting, nausea, epigastric pain, early satiety, and bloating using a modified Likert score system, 0 to 4. RESULTS: Total symptom scores improved for 12 of 15 patients with GES replacement surgery. Total score for the replacement group decreased from 17.3 ± 1.6 to 13.6 ± 3.7 with a difference of 3.6 (P value = .017). This score is compared with that of the control group with a preoperative symptom score of 15.8 ± 3.6 and postoperative score of 12.3 ± 3.5 with a difference of 3.5 (P value = .011). The control group showed a 20.3% decrease in mean total symptoms score, whereas the study group showed a 22.5% decrease in mean with an absolute reduction of 2.2. CONCLUSION: Reimplantation of a GES at a new gastric location should be considered a viable option for patients who have initially failed GES therapy for gastroparesis.

Clinical guideline: management of gastroparesis.

This guideline presents recommendations for the evaluation and management of patients with gastroparesis. Gastroparesis is identified in clinical practice through the recognition of the clinical symptoms and documentation of delayed gastric emptying. Symptoms from gastroparesis include nausea, vomiting, early satiety, postprandial fullness, bloating, and upper abdominal pain. Management of gastroparesis should include assessment and correction of nutritional state, relief of symptoms, improvement of gastric emptying and, in diabetics, glycemic control. Patient nutritional state should be managed by oral dietary modifications. If oral intake is not adequate, then enteral nutrition via jejunostomy tube needs to be considered. Parenteral nutrition is rarely required when hydration and nutritional state cannot be maintained. Medical treatment entails use of prokinetic and antiemetic therapies. Current approved treatment options, including metoclopramide and gastric electrical stimulation (GES, approved on a humanitarian device exemption), do not adequately address clinical need. Antiemetics have not been specifically tested in gastroparesis, but they may relieve nausea and vomiting. Other medications aimed at symptom relief include unapproved medications or off-label indications, and include domperidone, erythromycin (primarily over a short term), and centrally acting antidepressants used as symptom modulators. GES may relieve symptoms, including weekly vomiting frequency, and the need for nutritional supplementation, based on open-label studies. Second-line approaches include venting gastrostomy or feeding jejunostomy; intrapyloric botulinum toxin injection was not effective in randomized controlled trials. Most of these treatments are based on open-label treatment trials and small numbers. Partial gastrectomy and pyloroplasty should be used rarely, only in carefully selected patients. Attention should be given to the development of new effective therapies for symptomatic control.

Long-term effects of gastric stimulation on gastric electrical physiology.

INTRODUCTION: This study evaluates the modeling of gastric electrophysiology tracings during long-term gastric electrical stimulation for gastroparesis. We hypothesized that serosal electrogastrogram may change over time representing gastric remodeling from gastric stimulation. PATIENTS: Sixty-five patients with gastroparesis underwent placement of gastric stimulator for refractory symptoms. Mean age at initial stimulator placement was 44 years (range, 8-76), current mean age was 49, and the majority of the subjects were female (n = 51, 78 %). Only a minority had diabetes-induced gastroparesis (n = 16, 25 %); the remainder were either idiopathic or postsurgical. METHODS: At the time of stimulator placement, electrogastrogram was performed after the gastric leads were placed but before stimulation was begun. Patients underwent continuous stimulation until pacer batteries depleted. At the time of replacement, before the new pacemaker was attached, electrogastrogram was again performed. RESULTS: After a mean of 3.9 years of stimulation therapy, the mean of baseline frequency before stimulation therapy was 5.06 cycles/min and declined to 3.66 after replacement (p = 0.0000002). The mean amplitude was 0.33 mV before stimulation therapy and decreased to 0.31 mV (p = 0.73). The frequency/amplitude ratio was 38.4 before stimulation therapy and decreased to 21.9 (p = 0.001). CONCLUSION: Long-term gastric electrical stimulation causes improvement in basal unstimulated gastric frequency to near normal.

Development of innovative techniques for the endoscopic implantation and securing of a novel, wireless, miniature gastrostimulator (with videos).

BACKGROUND: Gastric stimulation via high-frequency, low-energy pulses can provide an effective treatment for gastric dysmotility; however, the current commercially available device requires surgical implantation for long-term stimulation and is powered by a nonrechargeable battery. OBJECTIVE: To test and describe endoscopic implantation techniques and testing of stimulation of a novel, wireless, batteryless, gastric electrical stimulation (GES) device. DESIGN: Endoscopic gastric implantation techniques were implemented, and in vivo gastric signals were recorded and measured in a non-survival swine model (n = 2; 50-kg animals). INTERVENTION: Five novel endoscopic gastric implantation techniques and stimulation of a novel, wireless, batteryless, GES device were tested on a non-survival swine model. MAIN OUTCOME MEASUREMENTS: Feasibility of 5 new endoscopic gastric implantation techniques of the novel, miniature, batteryless, wireless GES device while recording and measurement of in vivo gastric signals. RESULTS: All 5 of the novel endoscopic techniques permitted insertion and securing of the miniaturized gastrostimulator. By the help of these methods and miniaturization of the gastrostimulator, successful GES could be provided without any surgery. The metallic clip attachment was restricted to the mucosal surface, whereas the prototype tacks, prototype spring coils, percutaneous endoscopic gastrostomy wires/T-tag fasteners, and submucosal pocket endoscopic implantation methods attach the stimulator near transmurally or transmurally to the stomach. They allow more secure device attachment with optimal stimulation depth. LIMITATIONS: Non-survival pig studies. CONCLUSION: These 5 techniques have the potential to augment the utility of GES as a treatment alternative, to provide an important prototype for other dysmotility treatment paradigms, and to yield insights for new technological interfaces between non-invasiveness and surgery.

Abnormal initiation and conduction of slow-wave activity in gastroparesis, defined by high-resolution electrical mapping.

BACKGROUND & AIMS: Interstitial cells of Cajal (ICC) generate slow waves. Disrupted ICC networks and gastric dysrhythmias are each associated with gastroparesis. However, there are no data on the initiation and propagation of slow waves in gastroparesis because research tools have lacked spatial resolution. We applied high-resolution electrical mapping to quantify and classify gastroparesis slow-wave abnormalities in spatiotemporal detail. METHODS: Serosal high-resolution mapping was performed using flexible arrays (256 electrodes; 36 cm(2)) at stimulator implantation in 12 patients with diabetic or idiopathic gastroparesis. Data were analyzed by isochronal mapping, velocity and amplitude field mapping, and propagation animation. ICC numbers were determined from gastric biopsy specimens. RESULTS: Mean ICC counts were reduced in patients with gastroparesis (2.3 vs 5.4 bodies/field; P < .001). Slow-wave abnormalities were detected by high-resolution mapping in 11 of 12 patients. Several new patterns were observed and classified as abnormal initiation (10/12; stable ectopic pacemakers or diffuse focal events; median, 3.3 cycles/min; range, 2.1-5.7 cycles/min) or abnormal conduction (7/10; reduced velocities or conduction blocks; median, 2.9 cycles/min; range, 2.1-3.6 cycles/min). Circumferential conduction emerged during aberrant initiation or incomplete block and was associated with velocity elevation (7.3 vs 2.9 mm s(-1); P = .002) and increased amplitudes beyond a low base value (415 vs 170 µV; P = .002). CONCLUSIONS: High-resolution mapping revealed new categories of abnormal human slow-wave activity. Abnormalities of slow-wave initiation and conduction occur in gastroparesis, often at normal frequency, which could be missed by tests that lack spatial resolution. Irregular initiation, aberrant conduction, and low amplitude activity could contribute to the pathogenesis of gastroparesis.

An endoscopic wireless gastrostimulator (with video).

BACKGROUND: Gastric electric stimulation (GES) at a high-frequency, low-energy setting is an option for treating refractory gastroparesis. The currently available commercial stimulator, the Enterra neurostimulator (Medtronic Inc, Minneapolis, MN), however, requires surgical implantation and is powered by a nonrechargeable battery. OBJECTIVE: To develop and test a miniature wireless GES device for endoscopic implantation in an experimental model. DESIGN: In-vivo gastric signals were recorded and measured in a nonsurvival swine model (n = 2; 110-lb animals). INTERVENTION: An endoscopically placed, wireless GES device was inserted into the stomach through an overtube; the two GES electrodes were endoscopically attached to the gastric mucosa and secured with endoclips to permit stimulation. MAIN OUTCOME MEASUREMENTS: Stable electrogastrogram measures were observed during GES stimulation. RESULTS: Electrogastrogram recordings demonstrated that gastric slow waves became more regular and of constant amplitudes when stomach tissues were stimulated, in comparison with no stimulation. The frequency-to-amplitude ratio also changed significantly with stimulation. LIMITATION: Nonsurvival pig studies. CONCLUSION: Gastric electric stimulation is feasible by our endoscopically implanted, wireless GES device.

A double-masked, randomized, placebo-controlled trial of temporary endoscopic mucosal gastric electrical stimulation for gastroparesis.

BACKGROUND: Endoscopically placed, temporary gastric electrical stimulation (tGES) may relieve symptoms of gastroparesis (Gp) and predict permanent gastric electrical stimulation (GES) outcomes. OBJECTIVE: To measure effects of 72 hours of temporary GES on Gp symptoms. DESIGN, SETTING, AND PATIENTS: From 2005 to 2006, we conducted a hospital-based, randomized, placebo-controlled, crossover trial of two consecutive, 4-day sessions (session 1 and session 2), enrolling 58 patients (11 males, 47 females; mean age 46 years) with GP symptom histories of three etiologies (idiopathic, 38; diabetes mellitus, 13; postsurgical, 7). INTERVENTION: 72 continuous hours temporary GES was provided for group A during session 1, and for group B during session 2. MAIN OUTCOME MEASUREMENTS: Symptoms measured daily; gastric emptying, electrogastrography, and quality of life measured at baseline and session close. RESULTS: In session 1, vomiting decreased in both groups, but was greater with stimulation, resulting in a day 3 difference of -1.02 (95% CI, -1.62 to -0.42; P < .001). Scores did not return to baseline during washout; on day 4, the difference persisted at -1.08 (95% CI, -1.81 to -0.35; P = .005). In session 2, vomiting slightly decreased with stimulation and slightly increased without it; at day 8, the nonactivated group had nonsignificantly greater vomiting, 0.12 (-0.68 to 0.92; P = .762). An overall treatment effect of a slight, nonsignificant daily decrease in average vomiting scores, -0.12 (-0.26 to 0.03; P = .116), was observed by pooling stimulation effects across sessions. LIMITATIONS: Missing data; potential physiological imbalances between groups. CONCLUSIONS: Although overall treatment effects were not significant, differences in favor of stimulation were suggested. Barriers to observing treatment effects included a decrease in vomiting for both groups during session 1, insufficient washout, and the absence of baseline vomiting for some patients. Future studies should better define inclusion criteria, use longer washout periods, randomize by etiology and baseline physiological findings, and pursue alternative designs. ( CLINICAL TRIAL REGISTRATION NUMBER: 00432835.).