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, 312 (5), G508-G515

High-resolution Anatomic Correlation of Cyclic Motor Patterns in the Human Colon: Evidence of a Rectosigmoid Brake

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High-resolution Anatomic Correlation of Cyclic Motor Patterns in the Human Colon: Evidence of a Rectosigmoid Brake

Anthony Y Lin et al. Am J Physiol Gastrointest Liver Physiol.

Abstract

Colonic cyclic motor patterns (CMPs) have been hypothesized to act as a brake to limit rectal filling. However, the spatiotemporal profile of CMPs, including anatomic origins and distributions, remains unclear. This study characterized colonic CMPs using high-resolution (HR) manometry (72 sensors, 1-cm resolution) and their relationship with proximal antegrade propagating events. Nine healthy volunteers were recruited. Recordings were performed over 4 h, with a 700-kcal meal given after 2 h. Propagating events were visually identified and analyzed by pattern, origin, amplitude, extent of propagation, velocity, and duration. Manometric data were normalized using anatomic landmarks identified on abdominal radiographs. These were mapped over a three-dimensional anatomic model. CMPs comprised a majority of detected propagating events. Most occurred postprandially and were retrograde propagating events (84.9 ± 26.0 retrograde vs. 14.3 ± 11.8 antegrade events/2 h, P = 0.004). The dominant sites of initiation for retrograde CMPs were in the rectosigmoid region, with patterns proximally propagating by a mean distance of 12.4 ± 0.3 cm. There were significant differences in the characteristics of CMPs depending on the direction of travel and site of initiation. Association analysis showed that proximal antegrade propagating events occurred independently of CMPs. This study accurately characterized CMPs with anatomic correlation. CMPs were unlikely to be triggered by proximal antegrade propagating events in our study context. However, the distal origin and prominence of retrograde CMPs could still act as a mechanism to limit rectal filling and support the theory of a "rectosigmoid brake."NEW & NOTEWORTHY Retrograde cyclic motor patterns (CMPs) are the dominant motor patterns in a healthy prepared human colon. The major sites of initiation are in the rectosigmoid region, with retrograde propagation, supporting the idea of a "rectosigmoid brake." A significant increase in the number of CMPs is seen after a meal. In our study context, the majority of CMPs occurred independent of proximal propagating events, suggesting that CMPs are primarily controlled by external innervation.

Keywords: colonic motility; high-resolution manometry; rectosigmoid brake.

Figures

Fig. 1.
Fig. 1.
Colonic high-resolution (HR) manometry workflow. A: fiber optic HR catheter containing 72 sensors at 1-cm intervals. B: radiograph of a fiber optic HR catheter in a human colon. CE: examples of cyclic motor patterns (CMPs). Blue arrows, antegrade CMPs; red arrows, retrograde CMPs.
Fig. 2.
Fig. 2.
AD: the spatiotemporal relationship of CMPs of four subjects. Black lines represent high-amplitude propagating sequences (HAPSs). Red lines, retrograde propagating events; blue lines, antegrade propagating events. HF, hepatic flexure; SF, splenic flexure; SG, midsigmoid colon; RSJ, rectosigmoid junction.
Fig. 3.
Fig. 3.
The anatomic point of origin of CMPs. A: antegrade CMPs. B: retrograde CMPs. C and D: 3-dimensional (3-D) colon representation of A and B.
Fig. 4.
Fig. 4.
Characteristics of CMPs according to the anatomic point of origin. A: amplitude. B: extent of propagation. C: velocity. D: duration. The P values listed indicate probabilities of an association between the direction and location of CMPs.

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