Long-pulse gastric electrical stimulation at tachygastrial frequency reduces food intake by inhibiting proximal gastric tone

Objective. To investigate the effects of long pulse gastric electrical stimulation (GES) at a tachygastrial frequency on food intake, gastric tone and gastric myoelectrical activity (GMA). Material and methods. Of twelve dogs implanted with electrodes and a gastric cannula, 6 underwent truncal vagotomy. Stimulus consisted of long pulses with a frequency of 9 cycles/min. Experiment one was performed in all dogs to test for food intake with or without GES. Experiment two on six normal dogs consisted of baseline, GES and recovery periods. Gastric volume and GMA were recorded. Results. 1) GES reduced food intake in both normal (398.5±111.7 g versus 573.0±97.9 g; p<0.02) and vagotomized dogs (170.6±100.4 g versus 401.0±97.3 g; p<0.05). 2) Gastric volume was increased with stimulation from 168.4±17.7 ml to 301.1±34.1 ml (p<0.02 ANOVA) and maintained at 271.8±27.6 ml. 3) The percentages of normal slow waves before, during and after GES were 83.3±4.6%, 38.0±3.5% and 61.0±12.5%, respectively (p=0.02 ANOVA). Conclusion. Long-pulse GES at tachygastrial frequency substantially reduces food intake, and is not mediated by the vagal pathway but attributed to relaxation of the stomach and impairment of intrinsic GMA.     

Long-pulse gastric electrical stimulation at tachygastrial frequency reduces food intake by inhibiting proximal gastric tone

OBJECTIVE: To investigate the effects of long pulse gastric electrical stimulation (GES) at a tachygastrial frequency on food intake, gastric tone and gastric myoelectrical activity (GMA). MATERIAL AND METHODS: Of twelve dogs implanted with electrodes and a gastric cannula, 6 underwent truncal vagotomy. Stimulus consisted of long pulses with a frequency of 9 cycles/min. Experiment one was performed in all dogs to test for food intake with or without GES. Experiment two on six normal dogs consisted of baseline, GES and recovery periods. Gastric volume and GMA were recorded. RESULTS: 1) GES reduced food intake in both normal (398.5+/-111.7 g versus 573.0+/-97.9 g; p<0.02) and vagotomized dogs (170.6+/-100.4 g versus 401.0+/-97.3 g; p<0.05). 2) Gastric volume was increased with stimulation from 168.4+/-17.7 ml to 301.1+/-34.1 ml (p<0.02 ANOVA) and maintained at 271.8+/-27.6 ml. 3) The percentages of normal slow waves before, during and after GES were 83.3+/-4.6%, 38.0+/-3.5% and 61.0+/-12.5%, respectively (p=0.02 ANOVA). CONCLUSION: Long-pulse GES at tachygastrial frequency substantially reduces food intake, and is not mediated by the vagal pathway but attributed to relaxation of the stomach and impairment of intrinsic GMA.     

Effects of dual pulse gastric electrical stimulation on gastric tone and compliance in dogs

BackgroundGastric electrical stimulation (GES) with short pulses improves nausea and vomiting in patients with gastroparesis, whereas GES with long pulses improves gastric motility.AimsTo assess the effects of a novel method of GES using dual pulse (both short and long pulses) on gastric tone, compliance and sympathovagal activity in dogs.Materials and methodsThe study was performed in 7 dogs implanted with a gastric cannula and a pair of gastric serosal electrodes for dual pulse GES. The study was composed of a number of sessions on different days with different stimulation parameters, including variations in the number of short pulses and stimulation amplitude.Results(1) Dual pulse GES of one short pulse and one long pulse with various amplitudes inhibited gastric tone (p < 0.05) but did not alter sympathetic or vagal activity. (2) Dual pulse GES with five short pulses and one long pulse not only inhibited gastric tone, but also reduced sympathetic activity and increased vagal activity (p < 0.05). (3) Dual pulse GES with five short pulses and one long pulse significantly increased gastric compliance.ConclusionsDual pulse GES reduces gastric tone and increases gastric compliance. The variation in the number of short pulse affects the sympathetic and vagal activities, whereas, the increase in stimulation strength enhances its effects on gastric tone.     

Gastric electrical stimulation using endoscopically placed mucosal electrodes reduces food intake in humans

BACKGROUND: Implantable gastric stimulation (IGS) has been proposed for treating obesity. The aim of this study was to investigate the effects of temporary mucosal electrical stimulation on water and food intake as well as gastric emptying in healthy humans. METHODS: The study was designed to study the effects of temporary gastric electrical stimulation (GES) on symptoms, gastric accommodation, food intake, and gastric emptying. It was performed in 12 healthy volunteers on 3 consecutive days. GES was performed using mucosal electrodes endoscopically placed in the fundus. RESULTS: The amount of maximum water intake was reduced with GES (894 +/- 326 mL) compared with sham-GES (1,093 +/- 417 mL, p = 0.01). The food intake was also reduced with GES (p = 0.012). In comparison with sham stimulation, GES delayed gastric emptying during the first 45 min after the meal but not during the remaining time. GES with parameters effective in reducing water and food intake and delaying gastric emptying did not induce significant dyspeptic symptoms, compared with sham stimulation. CONCLUSIONS: GES using temporary mucosal electrodes decreases food intake as well as maximum intake of water, and has a tendency of delaying gastric emptying. It may have a potential application for the treatment of obesity.     

Gastric electrical stimulation with short pulses reduces vomiting but not dysrhythmias in dogs

BACKGROUND & AIMS: The aim of this study was to investigate the acute effects of 3 different methods of electrical stimulation in the prevention of vasopressin-induced emetic response and gastric dysrhythmias. METHODS: Seven female hound dogs chronically implanted with 4 pairs of electrodes on gastric serosa were used in a 5-session study. Saline and vasopressin were infused in sessions 1 and 2, respectively. In the other 3 sessions with vasopressin infusion, 3 different methods of electrical stimulation (short-pulse stimulation, long-pulse stimulation, and electroacupuncture) were applied. Gastric slow waves and vomiting and behaviors suggestive of nausea were recorded in each session. In a separate study, additional experiments were performed in 5 vagotomized dogs to investigate vagally mediated mechanisms. RESULTS: Vasopressin induced gastric dysrhythmias, uncoupling of slow waves, and vomiting and behaviors suggestive of nausea (P < 0.02, analysis of variance). Long-pulse stimulation, but not short-pulse stimulation or electroacupuncture, was capable of preventing vasopressin-induced gastric dysrhythmias and gastric slow wave uncoupling. Short-pulse stimulation and electroacupuncture, but not long-pulse stimulation, prevented vomiting and significantly reduced the symptom scores, which was not noted in the dogs with truncal vagotomy. CONCLUSIONS: Long-pulse stimulation normalizes vasopressin-induced slow wave abnormalities with no improvement in vomiting and behaviors suggestive of nausea. Short-pulse stimulation and electroacupuncture prevent vomiting and behaviors suggestive of nausea induced by vasopressin but have no effects on slow waves, and their effects are vagally mediated.     

Pyloric electrical stimulation reduces food intake by inhibiting gastric motility in dogs

BACKGROUND & AIMS: The pylorus plays an important role in regulating gastric emptying. The aim of this study was to investigate the therapeutic potential of pyloric electrical stimulation (PES) for obesity in dogs. METHODS: The study was composed of 3 separate experiments. The first experiment was designed to study the effects of PES with various parameters on gastric emptying and gastric slow waves in 5 sessions. The second experiment was used to test the effects of PES on antral contractions. The acute effect of PES on food intake was studied in the third experiment. RESULTS: (1) Pyloric myoelectrical recording showed dual frequencies. The lower frequency was identical to the frequency of the gastric slow waves, and the higher frequency was similar to that of the intestinal slow waves. (2) Gastric emptying was significantly delayed with PES, and the delay in gastric emptying was significantly and negatively correlated with stimulation energy ( r = -.673; P < .001). (3) PES significantly impaired the regularity and coupling of the intrinsic gastric myoelectrical activity in an energy-dependent manner. The delayed gastric emptying was significantly correlated with the impairment of the coupling of gastric myoelectrical activity ( r = .441; P < .02). (4) Antral contractions on the fed state were significantly and substantially inhibited with PES. (5) Acute PES significantly reduced food intake. CONCLUSIONS: PES reduces food intake that may be attributed to its inhibitory effects on intrinsic gastric myoelectrical activity, antral contractions, and gastric emptying.     

Gastric tone variations during gastric infusion of fiber-supplemented formulas

BACKGROUND AND AIM: Despite gastric feeding being a common method of artificial nutritional support, little is known about the effects of enteral nutrition on fundic motor function. The objective of this study was to assess variations of fundic tone and their relation to antroduodenal motility before, during and after nasogastric feeding supplemented or not with fibers. METHOD: Double-blinded studies were performed in random order with the three different diets (2100 kJ) in eight volunteers: fiber free (FF), insoluble fiber (IF) or mixed fiber (MF). Fundic tone was recorded by barostat concomitantly with antroduodenal manometry. RESULTS: Before the infusion, seven spontaneous fundic relaxations occurred during the 24 studies. Concomitantly or less than 2 min before these relaxations, phase III of the migrating motor complex (MMC) with a duodenal onset was recorded. Only the 17 studies without spontaneous fundic relaxation (4 FF, 6 MF, 7 IF) were suitable for the assessment of fundic response to infusion. Disappearance of the volume waves at the beginning and during the whole infusion was observed in 11/17 studies (FF 50%, MF 66% and IF 71%, NS), but a proximal gastric relaxation following the beginning of the infusion occurred in only three individuals, one with the FF and two with IF. When it occurred, fundic relaxation was observed within 2 min and was not different from those observed spontaneously. CONCLUSION: Gastric infusion of a polymeric diet, supplemented or not with fiber, did not promote fundic relaxation in most of the cases but often induced a disappearance of gastric volume waves.     

Gastric electrical stimulation for medically refractory gastroparesis

Background & aims:

This study investigated the efficacy of gastric electrical stimulation for the treatment of symptomatic gastroparesis unresponsive to standard medical therapy.

Methods:

Thirty-three patients with chronic gastroparesis (17 diabetic and 16 idiopathic) received continuous high-frequency/low-energy gastric electrical stimulation via electrodes in the muscle wall of the antrum connected to a neurostimulator in an abdominal wall pocket. After implantation, patients were randomized in a double-blind crossover design to stimulation ON or OFF for 1-month periods. The blind was then broken, and all patients were programmed to stimulation ON and evaluated at 6 and 12 months. Outcome measures were vomiting frequency, preference for ON or OFF, upper gastrointestinal tract symptoms, quality of life, gastric emptying, and adverse events.

Results:

In the double-blind portion of the study, self-reported vomiting frequency was significantly reduced in the ON vs. OFF period (P < 0.05) and this symptomatic improvement was consistent with the significant patient preference (P < 0.05) for the ON vs. OFF period determined before breaking the blind. In the unblinded portion of the study, vomiting frequency decreased significantly (P < 0.05) at 6 and 12 months. Scores for symptom severity and quality of life significantly improved (P < 0.05) at 6 and 12 months, whereas gastric emptying was only modestly accelerated. Five patients had their gastric electrical stimulation system explanted or revised because of infection or other complications.

Conclusions:

High-frequency/low-energy gastric electrical stimulation significantly decreased vomiting frequency and gastrointestinal symptoms and improved quality of life in patients with severe gastroparesis.     

Gastric electrical stimulation in patients with gastroparesis

Abstract As in the heart, there is a pacemaker in the human stomach and it generates myoelectrical activity with a frequency of approximately three cycles per minute. Abnormalities in gastric myoelectrical activity may result in gastric motility disorders, such as gastroparesis. Electrical stimulation of the stomach is achieved by delivering electrical currents via electrodes attached to the smooth muscle of the stomach. Recently, a number of studies on electrical stimulation of the stomach in both humans and dogs have indicated that gastric electrical stimulation with appropriate parameters is able to entrain gastric slow waves and normalize gastric dysrhythmias. This has led some investigators to use gastric electrical stimulation to treat patients with gastroparesis. Previous studies and the current state of the field in gastric electrical stimulation in treatment of gastroparesis will be discussed and summarized.     

Gastric electrical stimulation in intractable symptomatic gastroparesis

BACKGROUND: The treatment of gastroparesis remains unsatisfactory despite prokinetic and anti-emetic drugs. Gastric electrical stimulation has been proposed as a therapeutic option. We have assessed the effect of gastric electrical stimulation on symptoms, medical treatment, body weight and gastric emptying in patients with intractable symptomatic gastroparesis in a non-placebo-controlled study. METHODS: In this multicenter study, 38 highly symptomatic patients with drug-refractory gastroparesis were enrolled. Patients first received temporary electrical stimulation using percutaneous electrodes. The 33 responders to temporary stimulation then underwent surgical implantation of a permanent stimulator. Severity of vomiting and nausea was assessed before and after stimulation. Patients were reassessed 3, 6, and 12 months after permanent implantation. RESULTS: With stimulation, 35/38 patients (97%) experienced >80% reduction in vomiting and nausea. This effect persisted throughout the observation period (2.9-15.6 months, 341 patient-months). Gastric emptying did not initially change, but improved in most patients at 12 months. At 1 year, the average weight gain was 5.5% and 9/14 patients initially receiving enteral or parenteral nutrition were able to discontinue it. CONCLUSION: Electrical stimulation of the stomach has an immediate and potent anti-emetic effect. It offers a safe and effective alternative for patients with intractable symptomatic gastroparesis.     

Gastric electrical stimulation for the treatment of diabetic gastroparesis

Diabetic gastroparesis is a component of autonomic neuropathy, and is the most common manifestation of gastrointestinal neuropathy. Diabetes is responsible for about one quarter of gastroparesis. The upper gastrointestinal symptoms are often non-specific and dominated by nausea, vomiting, early satiety, fullness, bloating. We also have to look for diabetic gastroparesis in case of metabolic instability, such as postprandial hypoglycaemia. The pathophysiology of diabetic gastroparesis is complex, partly due to a vagus nerve damage, but also to changes in secretion of hormones such as motilin and ghrelin. A decrease in the stem cell factor (SCF), growth factor for cells of Cajal (gastric pacemaker), was found in subjects with diabetic gastroparesis. These abnormalities lead to an excessive relaxation in the corpus, a hypomotility of antrum, a desynchronization antrum-duodenum-pylorus, and finally an abnormal duodenal motility. The treatment of diabetic gastroparesis is based on diabetes control, and split meals by reducing the fiber content and fat from the diet. The antiemetic and prokinetic agents should be tested primarily in people with nausea and vomiting. Finally, after failure of conventional measures, the use of gastric neuromodulation is an effective alternative, with well-defined indications. Introduced in the 1970s, this technology works by applying electrical stimulation continues at the gastric antrum, particularly in patients whose gastric symptoms are refractory to other therapies. Its efficacy has been recently reported in different causes of gastroparesis, especially in diabetes. Gastric emptying based on gastric scintigraphy, gastrointestinal symptoms, biological markers of glycaemic control and quality of life are partly improved, but not normalized. Finally, a heavy nutritional care is sometimes necessary in the most severe forms. The enteral route should be preferred (nasojejunal and jejunostomy if possible efficiency). However, in case of failure especially in patients with small bowel neuropathy, the long-term parenteral nutrition is sometimes required.     

Gastric electrical stimulation in medically refractory nausea and vomiting

INTRODUCTION: High-frequency gastric electrical stimulation is a new therapeutic option to improve refractory nausea and vomiting, in gastroparetic patients. Its effects on gastric emptying are, however, inconstant and limited. Therefore, we have hypothesized that high-frequency gastric electrical stimulation could be also effective in patients suffering from refractory vomiting and nausea with normal gastric emptying, and we have compared the symptomatic efficacy of high-frequency gastric electrical stimulation between patients with delayed and normal gastric emptying. PATIENTS AND METHODS: Fifteen patients with chronic, severe and medically resistant nausea and vomiting were included in the study. Gastric emptying was delayed in eight patients (Group 1) and normal in seven patients (Group 2). At inclusion and at 6 months after the start of the stimulation, symptoms (nausea and vomiting, bloating, regurgitations, abdominal pain and appetite) and quality of life were prospectively evaluated using the Gastrointestinal Quality of Life Index score whereas gastric emptying was assessed by scintigraphy and/or octanoic acid breath test. RESULTS: Age, sex, symptoms and quality of life were not different at baseline between the two groups. At 6 months, Gastrointestinal Quality of Life Index and nausea/vomiting scores had significantly improved in both groups. Other symptoms (bloating, regurgitations, abdominal pain and appetite) had improved at 6 months in Group 1 but not in Group 2. Six months after the start of stimulation, gastric emptying was normal in 4/8 Group 1 patients and 5/7 Group 2 patients but was not significantly different from that calculated before the implantation of the stimulator. CONCLUSION: Our results suggest that high-frequency gastric electrical stimulation could be an effective therapy for treating chronic, severe vomiting and nausea whether gastric emptying is delayed or not.     

Treatment of high-frequency gastric electrical stimulation for gastroparesis

Background and Aims: The aim of this study was to assess the effects of gastric electrical stimulation (GES) on symptoms and gastric emptying in patients with gastroparesis, and the effects of GES on the three subgroups of gastroparesis. Methods: A literature search of clinical trials using high‐frequency GES to treat patients with gastroparesis from January 1995 to January 2011 was performed. Data on the total symptom severity score (TSS), nausea severity score, vomiting severity score, and gastric emptying were extracted and analyzed. The statistic effect index was weighted mean differences. Results: Ten studies (n = 601) were included in this study. In the comparison to baseline, there was significant improvement of symptoms and gastric emptying (P < 0.00001). It was noted that GES significantly improved both TSS (P < 0.00001) and gastric retention at 2 h (P = 0.003) and 4 h (P < 0.0001) in patients with diabetic gastroparesis (DG), while gastric retention at 2 h (P = 0.18) in idiopathic gastroparesis (IG) patients, and gastric retention at 4 h (P = 0.23) in postsurgical gastroparesis (PSG) patients, did not reach significance. Conclusions: Based on this meta‐analysis, the substantial and significant improvement of symptoms and gastric emptying, and the good safety we observed, indicate that high‐frequency GES is an effective and safe method for treating refractory gastroparesis. DG patients seem the most responsive to GES, both subjectively and objectively, while the IG and PSG subgroups are less responsive and need further research.