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Background: The TANTALUS System is an investigational device that consists of an implantable pulse generator connected to gastric electrodes. The system is designed to automatically detect when eating starts and only then deliver sessions of gastric electrical stimulation (GES) with electrical pulses that are synchronized to the intrinsic antral slow waves. We report the effect of this type of GES on weight loss and glucose control in overweight/obese subjects with type 2 diabetes mellitus (T2DM). This study was conducted under a Food and Drug Administration/Institutional Review Board-approved investigational device exemption., Method: Fourteen obese T2DM subjects on oral antidiabetes medication were enrolled and implanted laparoscopically with the TANTALUS System (body mass index 39 +/- 1 kg/m(2), hemoglobin A1c [HbA1c] 8.5 +/- 0.2%).Gastric electrical stimulation was initiated four weeks after implantation. Weight, HbA1c, fasting blood glucose, blood pressure, and lipid levels were assessed during the study period., Results: Eleven subjects reached the 6-month treatment period endpoint. Gastric electrical stimulation was well tolerated by all subjects. In those patients completing 6 months of therapy, HbA1c was reduced significantly from 8.5 +/- 0.7% to 7.6 +/- 1%, p < .01. Weight was also significantly reduced from 107.7 +/- 21.1 to 102.4 +/- 20.5 kg, p < .01. The improvement in glucose control did not correlate with weight loss (R(2) = 0.05, p = .44). A significant improvement was noted in blood pressure, triglycerides, and cholesterol (low-density lipoprotein only)., Conclusions: Short-term therapy with the TANTALUS System improves glucose control, induces weight loss, and improves blood pressure and lipids in obese T2DM subjects on oral antidiabetes therapy., (Copyright 2009 Diabetes Technology Society.)

Background: Recently, gastric electrical stimulation (GES) has been used to treat gastroparesis. This study analyzes a cohort of gastroparetic patients after GES., Study Design: All patients undergoing GES from October 2003 to July 2007 were included. Pre- and postoperative assessments were performed for frequency and severity of gastrointestinal symptoms and gastric retention. The values were compared using a paired t-test for patients at 6 and 12 months. Statistical significance was defined as p < 0.05., Results: Fifty gastroparetic patients were enrolled (20 diabetic, 25 idiopathic, 2 postsurgical, and 3 connective tissue disorder patients). All patients underwent laparoscopic implantation with GES (Medtronic, Inc). Median followup was 28 months (range 3 to 51 months). Thirty-five patients were available for followup at 6 months, and 30 patients were available at 12 months. The total symptom severity score (19.05+/-8.04) decreased significantly at 6 months (12.92+/-7.41, p < 0.001) and 12 months (14.05+/-8.28, p < 0.01). Similarly, total frequency score (20.39+/-8.08) decreased significantly at 6 months (15.01+/-7.37, p < 0.01) and 12 months (15.71+/-7.40, p < 0.05). At 12 months (n=27), gastric retention at 2 hours was decreased significantly from 66% +/- 21% to 50% +/- 22% (p < 0.04) and normalized in 11 of 27 patients. The severity of symptoms was reduced in all patients with normal gastric retention postoperatively. Finally, gastric retention at 4 hours was reduced by 14%, but the difference was not significant., Conclusions: Gastroparetic symptoms at 6 months were improved and sustained at 12 months after GES. Gastric emptying at 2 hours was reduced significantly after GES. Longterm followup of this cohort is required to confirm the short-term effects of GES.

This study determined the effect of low-frequency and high-frequency gastric electrical stimulation (GES) on canine lower esophageal sphincter (LES) pressure and also evaluated the effect of such stimulation on neurohumoral factors that modulate LES pressure. Eight dogs were fitted with stimulation wires along the greater curvature of the stomach. A sleeve device measured LES pressure before, during, and after GES, and regulatory peptides were measured during fasting and after a meal. A consistent and significant rise in LES pressure was observed during GES, and it was sustained after GES was discontinued. Plasma concentration and area under the curve of pancreatic polypeptide, motilin, gastrin and neurotensin were not affected by GES. We conclude that acute low- and high-frequency GES significantly increases LES pressure. This effect may not be modulated by efferent vagal activity or release of regulatory peptides.

Objective: It has been reported that electrical stimulation at the distal stomach can disrupt intrinsic gastric electrical activity and delay gastric emptying. Gastric dysrhythmia and impaired gastric emptying are associated with upper gastrointestinal symptoms and weight loss. The purpose of this study was to evaluate the effect of low-frequency/long-pulse gastric electrical stimulation (GES), at proximal and distal stomach, on canine gastric emptying, food intake, and body weight., Research Methods and Procedures: Eight dogs were surgically implanted with four pairs of electrodes along the greater curvature and a gastric tube at the dependent part of the stomach. Liquid gastric emptying at baseline, during proximal and distal GES at 6 cycles per minute, was assessed first by a dye dilution technique. Proximal and distal GES were then randomly delivered during feeding for 10 consecutive days, and food intake and body weight were recorded daily., Results: There was no significant difference in gastric emptying parameters among the various sessions. The mean daily food consumption was significantly reduced during both sessions of GES, resulting in significant immediate weight loss. Percentage weight loss was comparable between both sessions of GES., Discussion: Short-term GES significantly reduced canine food intake and weight. This effect may not be related to changes in gastric emptying. GES may have a potential role in the treatment of obesity.

Gastric electrical stimulation (GES) was shown to improve symptoms in patients with gastroparesis. However, the underlying mechanisms remain unclear. This study assessed the influence of various patterns of GES on fasting and postprandial gastric acid secretion and 24-hr gastric pH. Eight healthy dogs were studied and we found that in the fasting state, low-frequency, long-pulse (6/12-cpm, 375-msec, 4-mA) GES at the proximal stomach significantly inhibited the secretion of gastric juice (P < 0.05). No such effect was observed during GES (6/12 cpm) at the distal stomach. In the postprandial period, low-frequency, long-pulse GES at both proximal and distal sites and at both frequencies did not significantly affect gastric acid secretion. High-frequency, short-pulse GES, investigated for obesity (21 Hz, 8 mA, and 250 microsec, with 2 secs on, 3 sec off), at the proximal and distal stomach did not significantly affect the 24-hr gastric pH profile. In conclusion, GES with various stimulation parameters, and at various sites, has little effect on gastric acid secretion. The clinical effects induced by GES at these parameters may not be related to their effect on gastric acid homeostasis. [ABSTRACT FROM AUTHOR]

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

Gastric electrical stimulation can provide symptomatic relief for patients with refractory gastroparesis. Traditionally, these wires are placed through a midline laparotomy. This paper describes and illustrates, in detail, the laparoscopic technique for successful implantation. Thirty-one consecutive patients from October 2003 to March 2005 underwent laparoscopic insertion of gastric stimulating wires for gastroparesis. Twenty-six patients were female. Four laparoscopic ports were used to insert a pair of electrodes. Anterior, cephalad retraction of the gastric wall is critical for accurate seromuscular placement of gastric leads. Intraoperative endoscopy was used to verify the seromuscular placement of the leads. Both leads were secured to a subcutaneous generator and electrical parameters were immediately established in the operating room. Patient demographics, operative details, and postoperative morbidities were recorded. All procedures were completed laparoscopically. The mean operative time was 114.4 ± 20.9 minutes (range, 95–140). No perioperative mortality occurred. Two patients developed cellulitis at the generator site postoperatively and oral antibiotics were prescribed for one week postoperatively. No hardware was removed. Two patients had their generators repositioned due to pain at the pocket site. Gastric electrical stimulation is a novel treatment modality for patients with refractory gastroparesis and can be accomplished safely via laparoscopy. Laparoscopic insertion is successful even in patients with prior surgery and intact gastrointestinal tubes. Long-term follow-up and the current prospective multicenter trial continue to assess the efficacy of this treatment modality. [ABSTRACT FROM AUTHOR]

This study determined the most efficient parameters of low-frequency/long-pulse gastric electrical stimulation (GES) required to entrain gastric slow waves and also evaluated the effect of entrainment and high-frequency, short-pulse GES on gastric electrical activity (GEA). Nine dogs were fitted with stimulation wires along the greater curvature. Entrainment was observed in six or seven animals, with long-pulse GES at six cycles per minute (cpm), at various combinations of current and pulse width and was directly related to the energy delivered. Entrainment was observed in four to seven animals, with GES at 12 cpm, and the maximal driven frequency was 6 cpm. Entrainment did not significantly increase the dominant power of GEA. High-frequency, shortpulse GES, using pulse trains of 14 Hz, 5 mA, and 330 µs, with 0.1 s on and 5 s off, and pulse trains of 40 Hz, 10 mA, and 330 µs, with 2 s on 3 s off, did not affect variables of GEA. We conclude that acute low-frequency GES but not highfrequency, short-pulse GES can entrain slow waves; the power of slow waves is not affected by either type of stimulation. [ABSTRACT FROM AUTHOR]

Currently, electrical stimulation is utilized to treat morbid obesity,gastroparesis,and diaphragmatic paralysis. Although this technology is in its infancy, numerous case reports and small series appear throughout the literature. Furthermore, electrical stimulation is not relegated to only academic centers and tertiary referral centers. As these technologies continue to evolve and alter the treatment of several different pathophysiologic processes, the general surgeon needs to understand the technical aspects of these devices and their potential complications. This paper presents the management of a gastroparetic patient with chronic abdominal pain following the successful placement of gastric pacing wires. A 45-year-old female with idiopathic gastroparesis underwent laparoscopic placement of gastric pacing wires without complications. Four months postoperatively, she presented with chronic left upper quadrant abdominal pain. Her nausea and vomiting had dissipated and she was tolerating a regular diet. Abdominal and pelvic computed tomography (CT) was normal except for the presence of a generator and pacing wires. Ultimately, she required a diagnostic laparoscopy and an upper endoscopy. The upper endoscopy was normal. The diagnostic laparoscopy showed a wide adhesive band from the seromuscular tunnel of the pacing wires to the abdominal wall in the left upper quadrant. The band was lysed and an omental patch was sutured over the insertion site of the wires. On postoperative day 1, the patient was pain-free and discharged home on a regular diet. This case presents an unusual complication of electrical pacing wires. This patient experienced somatic pain due to an adhesive band from her pacing wires to the abdominal wall. Based on the findings of this case, an omental patch was placed on top of the seromuscular electrode tunnel in order to prevent adhesions and potentially persistent abdominal wall pain. [ABSTRACT FROM AUTHOR]