Society: AGA

Introduction
Gastric motility is coordinated, in part, by rhythmic bioelectrical events called slow waves. Dysrhythmic slow waves with abnormal propagation patterns have been associated with a number of motility disorders, including functional dyspepsia and gastroparesis, which affect approximately 10% of the global population.

High-resolution mapping of slow waves has emerged as a promising diagnostic tool for classifying gastric electrical dysrhythmias, however, current methods for generating detailed maps of gastric electrical activity to guide targeted therapy are surgically invasive. This study aimed to validate the clinical application of a novel, minimally-invasive, endoscopic device for high-resolution mapping in humans.

Methods
A novel endoscopic mapping device was constructed that primarily comprised of a Constellation cardiac mapping catheter (60 mm diameter, 8 splines, 64 electrodes; Boston Scientific, USA), and anorectal balloon (Mui Scientific, Canada) positioned inside the mapping catheter splines (Fig. 1A).

Ethical approval and informed consent (HDEC approval #17/STH/95) was gathered from patients undergoing elective gastroscopy to participate in the study. Patients were placed in the prone position prior to device deployment to minimize potential movement. The device was then advanced into the gastric antrum, alongside a gastroscope, using an endoscopic clip to hold the tip of the device. The balloon was inflated and the stomach suctioned to maintain contact between the mucosa and electrodes (Fig. 1C). Electrical recordings were obtained for approximately 7 min, following which the device was deflated and removed. Signals measured by the novel mapping device were digitally recorded by a Biosemi ActiveTwo system (Biosemi, Amsterdam, Netherlands) at a sampling frequency of 512 Hz, prior to local storage. Data were then analyzed in custom software to detect and quantify slow wave activation patterns.

Results
Device placement and data acquisition was successful in all patients (n=13). Slow waves were recorded with frequency 2.8±0.5 cycles/min, velocity 4.3±1.4 mm/s, and amplitude 2.6±1.9 mV. These values are within an established physiological range of antral slow wave propagation, demonstrating validity of our new endoscopic device. Slow wave detection was achieved with sufficient channel coverage (>33%), allowing spatiotemporal propagation map generation (Fig. 2B), in 5 of the patients.

Conclusions
This study demonstrates the first endoscopic, minimally-invasive, high-resolution slow wave mapping in humans, using a novel device design. This device could be used to localize gastric dysrhythmias in the future as a diagnostic tool, and to guide emerging treatments. Future studies will expand the patient cohort to compare gastric slow wave activity in healthy and diseased patients.

Figure 1: (A) Recording tip of novel endoscopic device with primary components labelled (B) Device positioned in distal antrum of patient prior to inflation (C) Device inflated and ready to begin recording.

Figure 1: (A) Recording tip of novel endoscopic device with primary components labelled (B) Device positioned in distal antrum of patient prior to inflation (C) Device inflated and ready to begin recording.

Figure 2: (A) Representative electrogram from patient. Slow wave activation points are marked with red dots. The wave group highlighted in the blue band of electrogram (A), is visualized in the propagation map presented in (B). Isochrones are stepped at 0.5s intervals for propagation maps. Direction of slow wave propagation indicated with black arrow.

Figure 2: (A) Representative electrogram from patient. Slow wave activation points are marked with red dots. The wave group highlighted in the blue band of electrogram (A), is visualized in the propagation map presented in (B). Isochrones are stepped at 0.5s intervals for propagation maps. Direction of slow wave propagation indicated with black arrow.

Peter Tremain

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