The effect on gastric tone of gastric electrical stimulation with trains of short pulses varies with sites and stimulation conditions.

BACKGROUND

Gastric electrical stimulation (GES) can improve symptoms in patients with gastroparesis and induce weight loss in obese subjects.

AIMS: To evaluate the effect on gastric tone of GES under different conditions at different sites of the stomach.

METHODS

Eleven dogs were implanted with a gastric cannula and two pairs of stimulation electrodes (in the middle of the lesser curvature and of the greater curvature, 10 cm from the pylorus). Gastric tone was assessed with a barostat. GES was applied using: (1) Enterra conditions (14 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); (2) modified Enterra conditions (40 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); and (3) implantable gastric stimulation (IGS) conditions (40 Hz, 5 mA, 0.3 ms, 2 s on, 3 s off). Six sessions were performed randomly with each animal on six separate days.

RESULTS

(1) At the lesser curvature, GES with modified Enterra conditions significantly elevated gastric volume from 96.9 +/- 8.3 ml at baseline to 133.9 +/- 11.7 ml (P = 0.015) and a similar effect was observed with IGS (91.3 +/- 7.1 ml vs. 186.3 +/- 27.1 ml, P = 0.013). GES with Enterra conditions had no such an effect. (2) At the greater curvature, GES with Enterra conditions significantly increased gastric volume from basal 94.1 +/- 4.4 ml to 122.1 +/- 11.3 ml (P = 0.032); modified Enterra conditions had the opposite effect (96.5 +/- 9.0 ml vs. 77.4 +/- 11.7 ml, P = 0.025) and no significant effect was observed with IGS conditions.

CONCLUSION

The effects of GES on gastric tone vary with the conditions and sites of stimulation. These findings may help to explain the distinct effects of GES therapy in patients with gastroparesis and obesity.