Electromechanical Coupling and Anatomy of the In-Vivo Gastroduodenal Junction.

Abstract

Few biomarkers support diagnosis and treatment of disorders of gut-brain interaction (DGBI), although gastroduodenal junction (GDJ) electromechanical coupling is a target for novel interventions. Rhythmic 'slow waves', generated by interstitial cells of Cajal (ICC), and myogenic 'spikes' are bioelectrical mechanisms underpinning motility. In this study, simultaneous in-vivo high-resolution electrophysiological and impedance planimetry measurements were paired with immunohistochemistry to elucidate GDJ electromechanical coupling. Following ethical approval, the GDJ of anaesthetized pigs (N=12) was exposed. Anatomically-specific, high-resolution electrode arrays (256 electrodes) were applied to the serosa. EndoFLIP catheters (16 electrodes; Medtronic, MN, USA) were positioned luminally to estimate diameter. Post-mortem tissue samples were stained with Masson's trichrome and Ano1 to quantify musculature and ICC. Electrical mapping captured slow-waves (N=512) and spikes (N=1071). Contractions paralleled electrical patterns. Localized slow waves and spikes preceded rhythmic contractions of the antrum, and non-rhythmic contractions of the duodenum. Slow-wave and spike amplitudes were correlated in the antrum (r=0.74, p<0.001) and duodenum (r=0.42, p<0.001). Slow-wave and contractile amplitudes were correlated in the antrum (r=0.48, p<0.001) and duodenum (r=0.35, p<0.001). Distinct longitudinal and circular muscle layers of the antrum and duodenum had a total thickness of (2.8 ± 0.9) mm and (0.4 ± 0.1) mm, respectively. At the pylorus, muscle layers merged and thickened to (3.5 ± 1.6) mm. Pyloric myenteric ICC covered less area (1.5 ± 1.1 %) compared to the antrum (4.2 ± 3.0 %) and duodenum (5.3 ± 2.8 %). Further characterization of electromechanical coupling and ICC biopsies may generate DGBI biomarkers.