Figure 1: Gastric tissue patch with rhythmic peristaltic contraction waves (left) and dysrhythmic contraction waves (right). The colorbar applies to both graphs. Reprinted from [1], licensed under CC BY 4.0.
Functional dyspepsia, gastroesophageal reflux disease (GERD) and obesity are widespread health problems in industrialized countries whose treatment causes a large financial burden on healthcare systems. They have in common that they are closely linked to the biomechanics of the stomach. For example, the current golden standard in the treatment of obesity is bariatric surgery, where the gastric geometry, and thereby gastric mechanics, is irreversibly altered.
The biomechanics of the stomach are driven by an involved interplay of several physical phenomena: the complex gastric electrophysiological system generates the periodic electrical signal that drives the mechanical contraction waves of the gastric wall, which in turn serves the mixing and grinding of the fluid content of the stomach. Currently, the details of the complex interactions between these phenomena remain largely unknown. In order to enable the detailed study of the integrated behaviour of gastric electrophysiology, solid mechanics of the gastric wall and fluid mechanics of digesta, we develop a coupled multiphysics model of the human stomach.
Figure 2: Schematic representation of the multiphysics coupling between the various physical fields of a gastric electromechanics model.
Our model will allow unprecedented, detailed studies of gastric digestion in health and disease (see Figure 3). Furthermore, it will open new research opportunities in various other fields such as food design, pharmaceutical science or computer-aided medicine.
Figure 3: Idealized cylindrical stomach model with physiological peristaltic contraction waves (top) and dysrhythmic, spiral contractions (bottom). The left column shows the diffusive spreading the electrical signal (normalized transmembrane potential) driving mechanical contractions. The right column shows the resulting mechanical deformation (displacement magnitude).
References:
[1]: Brandstaeter S, Gizzi A, Fuchs SL, Gebauer AM, Aydin RC, Cyron CJ. (2018) Computational model of gastric motility with active-strain electromechanics. Z Angew Math Mech. 98(12). 2177-2197. (DOI: 10.1002/zamm.201800166).
[2]: Brandstaedter S, Fuchs SL, Aydin RC, Cyron CJ (2019) Mechanics of the stomach: a Review of an Emerging Field of Biomechanics, GAMM-Mitteilungen: e201900001