Manometric artefacts suggesting compression of the duodenum by the superior mesenteric artery in healthy humans.
Multi-channel manometry offers the opportunity to study intestinal motor activity with high spatiotemporal resolution. We report tonic and phasic intraluminal pressure changes in the mid-portion of the horizontal part of the duodenum. In 10 healthy volunteers, we recorded 2 h of interdigestive duodenal motility using a water-perfused catheter. The assembly incorporated 12 duodenal sideholes at 1.5-cm intervals (D1-D12). Measurement of the antral and duodenal transmucosal potential difference (TMPD) was used to maintain a correct position of the catheter. The incidence of pressure waves (PWs) increased gradually from proximal (D1) to distal (D12) (P < 0.0001), while the mean amplitude of PWs decreased (P < 0.0001). In eight of 10 subjects, the signals recorded from D9 showed tonic pressure elevations with superimposed phasic pressure changes at heart-rate frequency, comprising 13.8% of total recording time. In the other two subjects, this phenomenon occurred in D8 (9.9% of time). D10 showed a lower incidence of PWs compared with neighbouring sideholes (D6-D9/D11-D12) (P < 0.035), with normal amplitudes. Fluoroscopy was performed in three subjects and showed that D9 was located at the midline. In healthy subjects manometric signals recorded from the horizontal part of the duodenum showed localized artefacts, presumably caused by compression by the superior mesenteric artery. In addition, a 'silent' region was present just distal to this site, the origin of which is uncertain.