Measurement and Analysis of In Vivo Gastroduodenal Slow Wave Patterns Using Anatomically-Specific Cradles and Electrodes

Objective: Bioelectrical 'slow waves' regulate gastrointestinal contractions. We aimed to confirm whether the pyloric sphincter demarcates slow waves in the intact stomach and duodenum. Methods: We developed and validated novel anatomically-specific electrode cradles and analysis techniques which enable high-resolution slow wave mapping across the in vivo gastroduodenal junction. Cradles housed flexible-printed-circuit and custom cradle-specific electrode arrays during acute porcine experiments (N = 9; 44.92 kg +/- 8.49 kg) and maintained electrode contact with the gastroduodenal serosa. Simultaneous gastric and duodenal slow waves were filtered independently after determining suitable organ-specific filters. Validated algorithms calculated slow wave propagation patterns and quantitative descriptions. Results: Butterworth filters, with cut-off frequencies (0.0167 - 2) Hz and (0.167 - 3.33) Hz, were optimal filters for gastric and intestinal slow wave signals, respectively. Antral slow waves had a frequency of (2.76 +/- 0.37) cpm, velocity of (4.83 +/- 0.21) mms(-1), and amplitude of (1.13 +/- 0.24) mV, before terminating at the quiescent pylorus that was (46.54 +/- 5.73) mm wide. Duodenal slow waves had a frequency of (18.13 +/- 0.56) cpm, velocity of (11.66 +/- 1.36) mms(-1), amplitude of (0.32 +/- 0.03) mV, and originated from a pacemaker region (7.24 +/- 4.70) mm distal to the quiescent zone. Conclusion: Novel engineering methods enable measurement of in vivo electrical activity across the gastroduodenal junction and provide qualitative and quantitative definitions of slow wave activity. Significance: The pylorus is a clinical target for a range of gastrointestinal motility disorders and this work may inform diagnostic and treatment practices.