What Can Be Measured from Surface Electrogastrography (Computer Simulations)

Abstract

The aims of this study were to investigate thedetectability of the propagation of the gastric slowwave from the cutaneous electrogastrogram (EGG) and thepatterns of the EGG when the gastric slow waves are uncoupled. A mathematical model wasestablished based on the volume conductor theory tosimulate the transfer of the serosal gastric slow wavefrom the stomach to the abdominal surface. A number of computer simulations were conducted using themodel, and the periodic cross-correlation function wasused to estimate the phase shift between the fourchannels. It was found that the propagation of the gastric slow wave was detectable from themultichannel EGG signals. The detectability of thepropagation was, however, associated with a number offactors, such as the thickness of the abdominal wall and the propagation velocity of the serosal slowwave. The amplitude of the EGG was found to beassociated with the coupling/uncoupling and propagationvelocity of the gastric slow wave. The amplitude of the EGG increased when the propagation velocity ofthe gastric slow wave increased. The amplitude of theEGG was substantially decreased when the gastric slowwaves were uncoupled. The uncoupling of the gastric slow wave at a frequency of 3 cpm produceddysrhythmias in the EGG, including tachygastria,bradygastria, and arrhythmia. The power spectra ofsimulated different positional EGG signals showedsimilar patterns when the gastric slow wave was coupled anddifferent and unpredictable patterns when the gastricslow wave was uncoupled. In conclusion, multichannel EGGrecordings may be necessary to obtain more information on gastric slow waves from the abdominalelectrodes. The propagation and coupling or uncouplingof the gastric slow wave may be detected frommultichannel EGG recordings.