14 Effects of dual pulses gastric electrical stimulation on gastric tone and compliance

Abstract

Background: Gastric Electrical Stimulation (GES) has been introduced as an innovative therapy for patients with refractory gastroparesis. Studies suggest that GES with short pulses (in the order of μs) improves symptoms of nausea and vomiting for some patients with gastroparesis, whereas GES with long pulses (in the order of μs) improves gastric motility.Aims: To develop a novel method of GES: dual pulses GES and assess the effects of dual pulses GES on gastric tone and compliance.Methods: The study was performed in 7 dogs implanted with a gastric cannula and a pair of gastric serosal electrodes. Dual pulses GES was used a stimulus composed of both short and long pulses. This experiment was repeated a number of times on different days with different stimulation parameters, including a variation in the number of short pulses (1 and 5), a variation in stimulation amplitude (2 mA, 4 mA and 6 mA). The parameters soliciting the most significant effects on gastric tone and vagal activity were used in the following gastric compliance study. Gastric tone and compliance were assessed with an electrical barostat. Sympathetic and vagal activities were measured by the spectral analysis of the heart rate variability (P1 represents sympathetic activity; P2 is vagal activity; P1/P2 reflects sympathovagal balance).Results: 1) Dual pulses GES with one short pulse and various amplitudes significantly elevated gastric volume: from 108.44 ± 4.49 ml at baseline to 139.14 ± 11.73 ml at 2 mA (p < 0.05); from 108.97 ± 6.09 ml at baseline to 155.4 ± 17.49 ml at 4 mA (p < 0.05); from 115.39 ± 13.21 ml at baseline to 223.66 ± 34.89 ml at 6 mA (p < 0.05); whereas vagal and sympathetic activity was not altered. 2) Dual pulse GES with 5‐short pulses significantly inhibited sympathetic activity and excited vagal activity. P1 reduced from 0.42 ± 0.02 to 0.32 ± 0.02 (p < 0.05); P1/P2 from 0.72 ± 0.05 to 0.48 ± 0.04, whereas P2 markedly increased from 0.58 ± 0.02 to 0.68 ± 0.02 (p < 0.05). 3) During dual pulse GES with 5‐short pulses, half‐maximal volume on the pressure–volume curve (P1/2) significantly reduced from 11.8 ± 1.1 mmHg to 8.6 ± 0.6 mmHg, (p < 0.05).Conclusions: Dual pulses GES reduces gastric tone and increases gastric compliance. The variation in the number of short pulse affects the vagal and sympathetic activities. Whereas, the increase in stimulation strength enhances its effects on gastric tone.