High-Resolution Electrogastrogram: A Novel, Noninvasive Method for Determining Gastric Slow-Wave Direction and Speed

Abstract

Despite its simplicity and noninvasiveness, the use of the electrogastrogram (EGG) remains limited in clinical practice for assessing gastric disorders. Recent studies have characterized the occurrence of spatial gastric myoelectric abnormalities that are ignored by typical approaches relying on time-frequency analysis of single channels. In this paper we present the high-resolution (HR) EGG, which utilizes an array of electrodes to estimate the direction and speed of gastric slow-waves. The approach was verified on a forward electrophysiology model of the stomach, demonstrating that an accurate assessment of slow-wave propagation can be made. Furthermore, we tested the methodology on eight healthy adults and calculated propagation directions (181 ± 29 degrees) and speeds (3.7 ± 0.5 mm/s) that are consistent with serosal recordings of slow-waves described in the literature. By overcoming the limitations of current methods, HR-EGG is a fully automated tool that may unveil new classes of gastric abnormalities. This could lead to a better diagnosis of diseases and inspire novel drugs and therapies, ultimately improving clinical outcomes.

A Combined Methodology to Eliminate Artifacts in Multichannel Electrogastrogram Based on Independent Component Analysis and Ensemble Empirical Mode Decomposition

“…Still, acquiring gastric signals and identifying them in the presence of artifacts is not straightforward, like in cardiac signals, where the features are evident most of the time. The proposed work differs from the conventional methodology [1][2][3][4][5][6][7] of extracting gastric signals. Conventional acquisition of EGG 4,12-14 uses a lower sampling rate of (e.g 3-4 Hz) which partly avoids cardiac artifacts to be measured along with gastric signals.…”

“…A common reference electrode was placed on the midpoint of the vertical line joining the xiphoid and the umbilicus. 1,5 Signals measured on all the measurement channels are referenced to the common reference electrode channel. EGG measurements were performed on four subjects (all male), one of whom had a gastric disorder diagnosed based on endoscopy and biopsy for bacterial infection in the stomach.…”

“…2,3 Meanwhile, apart from measuring EGG signals using a limited number of electrodes, multichannel measurements are thought to be suitable to understand the physiology of gastric slow waves in a better way. 4,5 Many techniques have been used by researchers for the purpose of extracting surface EGG with a clinically acceptable signal-to-noise ratio. Classical Fourier domain approaches, [6][7][8][9] like bandpass filters (BPFs) and autoregressive models, have an inherent limitation on their applicability to nonstationary EGG signals whose frequency, amplitude, and phase widely vary across measurement timings and subjects.…”

“…Classical Fourier domain approaches, [6][7][8][9] like bandpass filters (BPFs) and autoregressive models, have an inherent limitation on their applicability to nonstationary EGG signals whose frequency, amplitude, and phase widely vary across measurement timings and subjects. 5 To circumvent this problem, researchers 10,11 have used wavelets to extract gastric signals amidst severe contaminations from biological artifacts and random noise. Nevertheless, the performance of wavelet denoising crucially depends on the proper selection of mother wavelet.…”

Colonic Electromechanical Abnormalities Underlying Post-operative Ileus: A Systematic and Critical Review

“…Electrogastrography has been applied in humans in HR to record gastric electrical activity from the body surface, but it is unknown if these techniques are sufficiently reliable, and whether similar techniques can be applied to non-invasively measure colonic motility. [65][66][67][68] Serosal HR electrode arrays have previously been used for short-duration intra-operative mapping of both the stomach and small intestine. 69 This technique has not yet been applied to the colon, but could aid in clarifying the relationship between electrical activity and motor patterns if applied in conjunction with HR manometry.…”