A Model of Electromechanical Coupling in the Small Intestine - Multiscale Computer Modeling in Biomechanics and Biomedical Engineering - page 198

Fig. 9 Cross-sectional
diagram of intestine
illustrating variables used for
intraluminal pressure
calculation in Eq. ( 28 ): r i and
r o are the internal and
external radii respectively, r
is the radial coordinate
corresponding to the location
of this stress value, and p i and
p o are the internal and
external pressures
respectively

P o

σ
h

P i

R i

R o

To make the output of the simulation consistent with measurements obtained
from manometry, particularly high-resolution manometry [ 18 ], we calculated
pressures at points spaced approximately 10 mm apart in the longitudinal direction
on the inner surface of the intestinal model. Figure 10 demonstrates a sample of
the pressure traces obtained from the axial locations marked in Fig. 7 a. The top-
most trace corresponds to the point at the most left-most location of the geometric
model and the bottom trace to the most right-most location of the geometric
model. We found that pressure varied depending on location within each element,
as seen in the different shapes of the pressure transients in each plot in Fig. 10 . The
transient peaks in pressure correlated with periods of contractile activity. The
maximum intraluminal pressure calculated was 148 Pa.

5 Perspectives

This chapter presents a preliminary framework for an electromechanically coupled
simulation of the rat small intestine using multi-scale modeling. In this chapter, we
have highlighted several features and limitations of the methods and models used.
We have also proposed potential extensions that may be added to the modeling
framework as we continue to learn more about the electromechanical dynamics in
the small intestine. Due to the modular nature of this simulation framework, the
model may be readily updated in the future when more specific information on
intestinal motility has been understood. This is a first step toward creating a fully
coupled model that can be applied in the clinical setting as the link between
minimally-invasive electrical measurements and pressure recordings, in order to
improve diagnosis and treatment of intestinal motility disorders.