Comparative gastric motility study of Enterra TM Therapy and neural gastric electrical stimulation in an acute canine model A. ARRIAGADA, * A. S. JURKOV, * E. NESHEV,  G. MUENCH, à M. P. MINTCHEV, *,  & C. N. ANDREWS  *Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB, Canada  Division of Gastroenterology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada àFaculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada Abstract Background Gastric electrical stimulation (GES) is an avenue for treating gastroparesis and obesity by con- trolling gastric motility using electrically mediated gastric contractions. Neural gastrointestinal electrical stimulation (NGES) is a GES modality capable of pro- ducing strong lumen-occluding local gastric contrac- tions. Conversely, Enterra TM Therapy, a commercial implantable gastric electrical stimulator, has been utilized to treat symptoms of gastroparesis, but its nominal electrical parameters are not capable of gen- erating lumen-occluding contractions. However, com- parative studies between these two stimulation modalities are lacking. Methods Strain gauge trans- ducers complemented by endoscopic monitoring have been utilized to register gastric contractions invoked with NGES and Enterra neurostimulators in four acute dogs. Mucosal and serosal electrode implantations, ‘nominal’ and ‘maximum’ electrical parameters, and longitudinal and transverse electrode placements have been tested with each neurostimulator type. Key Results Strong lumen-occluding, circumferential con- tractions were induced with a wide variety of NGES parameters utilizing both transverse and longitudinal electrode configurations from the serosal side of the stomach. Similarly, local gastric contractions were observed with the Enterra neurostimulator pro- grammed at its ‘maximum’ electrical parameters but only when utilizing transverse serosal electrode implantation. Under ‘maximum’ electrical parameters Enterra was not capable of producing registerable gas- tric contractions with longitudinally implanted serosal electrodes. Mucosal electrode implantations did not result in GES-invoked gastric contractions in both stimulation modalities. Conclusions & Inferences En- terra Therapy is capable of producing gastric contrac- tions under ‘maximum’ parameters and transverse electrode configuration. Neural gastrointestinal electrical stimulation produces stronger, lumen- occluding contractions under a wider range of electrode configurations and parameters. Keywords electrical stimulation, Enterra, gastric motility, gastroparesis, gastric electrical stimulation, neural gastrointestinal electrical stimulation, obesity. Abbreviations: GES, Gastric Electrical Stimulation; NGES, Neural Gastrointestinal Electrical Stimulation. INTRODUCTION Gastroparesis, obesity, and gastric electrical stimulation (GES) Gastroparesis is a stomach disorder in which emptying of content is abnormally delayed. 1 Associated symp- toms may include nausea, discomfort, fullness, early satiety, and bloating. 1,2 Among the available approaches to treat this disease, gastric electrical stimulation (GES) has been proposed as a promising alternative to treat the symptoms and effects of gastroparesis. Three separate GES modalities have been proposed, each utilizing electrical pulses aimed at achieving three distinct results: (i) slow wave entrainment, 2 (ii) low-energy, high-frequency stimula- tion (12 cycles-per-minute trains of 0.1 s duration, Address for Correspondence Dr. Martin P. Mintchev, Department of Electrical and Computer Engineering, University of Calgary, 2500 University Drive, NW, Calgary, AB, Canada T2N1N4. Tel: 403 220 5309; fax: 403 282 6855; e-mail: mintchev@ucalgary.ca Received: 23 September 2010 Accepted for publication: 29 October 2010 Neurogastroenterol Motil (2011) 23, 271–e122 doi: 10.1111/j.1365-2982.2010.01636.x Ó 2010 Blackwell Publishing Ltd 271