Gastric Electrical Stimulation (GES) with Parameters for Morbid Obesity Elevates Lower Esophageal Sphincter (LES) Pressure in Conscious Dogs

Background: Treatment of obese patients with the implantable gastric stimulator (IGS) was reported to improve reflux symptoms, independent of weight loss. We evaluated the effect of gastric electrical stimulation on LES pressure in conscious dogs. Methods: 8 dogs were studied. GES with three sets of parameters was randomly applied via a pair of electrodes implanted in the fundus on separate days. Manometry was performed with a Dent-Sleeve catheter passed through an esophageal canula. The involvement of the cholinergic pathway was also tested. Results: 1) Stimulation with IGS parameters (40 Hz, 0.3 ms, 6 mA, 2 seconds on and 3 seconds off) induced a significant increase in LES pressure (29.9±4.8 mmHg), and remained significantly higher during the post-stimulation period (32.6±9.6 mmHg) compared to baseline (24.5±3.8 mmHg), P<0.01.2) Long pulse stimulation (10 cpm, 300 ms, 8 mA) tended to increase LES pressure from 29.6±4.4 mmHg of baseline to 31.8±4.9 mmHg with stimulation, to 32.6±4.5 mmHg after discontinuation (P=0.08); 3) Modified IGS parameters (40 Hz, 2 ms, 6 mA, 2 seconds on and 3 seconds off) did not induce a significant change in LES pressure during and after stimulation. 4) Effect of stimulation with IGS parameters on LES pressure was blocked by intravenous atropine. Conclusion: GES with IGS parameters significantly increases LES pressure in conscious dogs. This effect is mediated by the cholinergic pathway. These results suggest that GES may be able to benefit GERD patients and obese patients with GERD.