[Show abstract][Hide abstract] ABSTRACT: To compare larger diameter corkscrew-tined leads with previously described intracardiac pacing leads for temporary gastric neurostimulation in a canine model.
Two mongrel dogs underwent gastroscopy under general anesthesia, with endoscopic placement of two cardiac leads (1 mm tine diameter, 4 mm depth) placed sequentially in 1) transverse configuration in the distal antrum mucosa; 2) longitudinal (1 cm apart) configuration in gastric corpus. Stomach was then stimulated with maximal parameters to induce neutrally mediated contraction. Procedures were then repeated with larger leads (5 mm tine diameter, 8 mm length). Gastric contractions were measured with serosal strain transducers.
Leads were placed endoscopically without difficulty. Neither lead type punctured through to the serosa of the stomach. Neither cardiac nor larger leads were capable of eliciting any gastric contractile activity with endoscopic placement either in the transverse or longitudinal orientations.
While successful on the serosal side, both the cardiac leads and the larger alternative leads failed to produce stomach contraction when implanted mucosally. This may be due to the elastic nature of the mucosa, which was observed to twist around both types of leads significantly, hindering proper penetration into the muscularis.
These results suggest that the current concept of temporary gastric electrical neurostimulation via a mucosal approach must be reevaluated, as the procedure most likely does not accurately mimic electrical stimulation in the muscularis.
[Show abstract][Hide abstract] ABSTRACT: Background Gastric electrical stimulation (GES) is an avenue for treating gastroparesis and obesity by controlling gastric motility using electrically mediated gastric contractions. Neural gastrointestinal electrical stimulation (NGES) is a GES modality capable of producing strong lumen-occluding local gastric contractions. Conversely, EnterraTM Therapy, a commercial implantable gastric electrical stimulator, has been utilized to treat symptoms of gastroparesis, but its nominal electrical parameters are not capable of generating lumen-occluding contractions. However, comparative studies between these two stimulation modalities are lacking.
Methods Strain gauge transducers 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 contractions 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 programmed at its ‘maximum’ electrical parameters but only when utilizing transverse serosal electrode implantation. Under ‘maximum’ electrical parameters Enterra was not capable of producing registerable gastric contractions with longitudinally implanted serosal electrodes. Mucosal electrode implantations did not result in GES-invoked gastric contractions in both stimulation modalities.
Conclusions & Inferences Enterra Therapy is capable of producing gastric contractions 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.
[Show abstract][Hide abstract] ABSTRACT: Neural Gastrointestinal Electrical Stimulation (NGES) is a new microprocessor-based method for invoking gastric or colonic contractions by generating multi-channel, high energy, high frequency waveforms. It has been shown that when applied to the lower stomach, NGES offers the possibility for enhancing propulsive peristalsis for the treatment of gastric motor dysfunctions, or for producing retrograde peristalsis for the treatment of obesity. When applied to the colon, NGES can be utilized either for propulsive control in severe constipation or for invoked retrograde contractility. This paper briefly discusses the implementation of an implantable neurostimulator and summarizes the performance of the NGES technique in acute tests on experimental animals and humans, and in chronic tests on animals. These experimental tests indicate that NGES is successful in accelerating gastric emptying of both liquids and solids, and in producing strong, externally-controlled, retrograde contractions.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2009; 2009:4615-8. DOI:10.1109/IEMBS.2009.5332682