Electro-Mechanical Mapping of the Small Intestine and the Influence of High-Energy Pacing

Compromised electrical and mechanical activity in the gastrointestinal tract is associated with several motility disorders. Conventional treatment fails in a significant proportion of the patient population, and pacing is a promising alternative therapy. However, the correlation between slow waves and contractions during pacing remains unexplored. Therefore, this study simultaneously mapped contractile and slow wave responses in high-resolution during pacing to elucidate their relationship and therapeutic implications.

Electrical and contractile activity were measured simultaneously in the jejunum of seven pigs in vivo. After a baseline session, pacing was applied at 10-second intervals with a pulse amplitude of 8 mA and pulse widths of either 100 or 400 milliseconds. Slow wave and contractile responses were quantified by the propagation pattern and strain.

Pacing spatially entrained the slow wave activity, generating a radial pacemaker propagation pattern with a success of 89% at both the energy levels, and induced a localized ring contraction at the pacing site in response to each pacing pulse. Induced contractions had mean contractile strains of -0.15 ± 0.04 and -0.19 ± 0.05 when paced at 100 milliseconds and 400 milliseconds, respectively.

This study defined the spatial response of slow wave activity during pacing, while mapping contractile activity. Slow waves propagated radially in a pacemaker pattern, whereas contractions remained localized. This insight into electrophysiologic modulation during pacing warrants further investigation. These findings are significant because they correlate the electrical and mechanical responses during intestinal pacing and will help optimize pacing techniques as a novel therapy for motility disorders.