Contraction-related frequency harmonics in human electrogastrography

Electrogastrography (EGG), the cutaneous recording of the myoelectrical activity of the stomach using surface electrodes, is attractive due to its noninvasiveness. Despite many attempts made over the decades, analysis of surface EGG has not led to identification of contraction-related electrical response activity of the stomach that would help the clinician to diagnose motility disorders of the stomach. In this study, the authors propose a feasible method to detect the gastric contraction by frequency-domain signal analysis of the surface EGG signal, in which a high cutoff frequency was set 8 Hz to prevent loss of information. The powers of dominant frequency and its harmonics were compared with gastric contraction parameters such as the spike wave from serosal recording in dog or the antropyloric pressure in human. As the results, increase of the power of the second harmonic of the dominant frequency was highly correlated with the gastric contraction without significant effect of after-meal gastric distension causing the power of the dominant frequency to increase. The feasibility of this method was established through computer simulation, animal experiments and clinical trials