Detection of gastric slow wave propagation from the cutaneous electrogastrogram

The gastric slow wave is originated in the proximal stomach and propagates distally toward the pylorus. It determines the maximum frequency and propag ation of gastric contractions. The aim of this study was to detect the prop agation of the gastric slow wave from the surface electrogastrogram (EGG). The study was performed in 11 healthy subjects of normal weight. Gastric my oelectrical activity was recorded for 1 h in the fasting state with the use of a specially designed multichannel recording device that was composed of four identical amplifiers with cutoff frequencies of 1.8 and 16.0 cycles/m in. Four active electrodes were placed on the abdomen along the gastric axi s and were connected to a common reference electrode placed near the xiphoi d process, yielding four-channel bipolar EGG signals. Cross-covariance anal ysis was performed to compute the time lag among the four channels. There w as a time lag in EGG waveform between channels 1 and 4 (9.6 +/- 1.1 s); the average time during which the time lag was observed (greater than or equal to 3 s) was 89.9 +/- 9.0%. There was a significant difference in the time lag among different adjacent channels (P < 0.04); the time lag observed bet ween channels 3 and 4 was significantly smaller than that between channels 1 and 2 (P < 0.03). No correlation was found between the body mass index an d the time lag between channels I and 4 (r = -0.31, P = 0.3). It was conclu ded that, with a multichannel recording device with identical multiamplifie rs and an appropriate arrangement of abdominal electrodes, the propagation of the gastric slow wave could be identified from the EGG in healthy subjec ts. This method may be used to detect the coupling of the gastric slow wave noninvasively.