StomachSim: An in-silico simulator of gastric biomechanics with application to pyloroplasty

Abstract

Aim: We have developed StomachSim, an in-silico simulator that is designed to simulate the biomechanics and fluid mechanics of a wide range of gastric conditions as well as gastric surgical procedures. Here we demonstrate its use in quantifying the effects of motility disorders and pyloroplasty on the hydrolysis and emptying of a liquid meal inside the stomach. Methods: A physiologically realistic model of the stomach, including the antral motility, is synthesized based on in-vivo imaging, and the mixing and gastric emptying are simulated using computational fluid dynamics (CFD). The enzymatic biochemistry for protein hydrolysis is also implemented by incorporating the secretion of a proteolytic enzyme from the proximal stomach walls and the subsequent enzymatic reaction with the protein dissolved in the liquid meal. Using this model, we measured the effect of stomach motility and the diameter of the pyloric orifice on the retropulsive and pyloric jets, the rate of hydrolysis in different regions, and the emptying of gastric contents. Results: This study presents a proof-of-concept for the application of StomachSim in gastric disorders and surgeries. The emptying rate of our model for the healthy case agreed with the in-vivo measurements of similar caloric density liquid meals. A stomach with a 50% lower motility amplitude had a 35% lower net emptying rate and a 41% lower emptying rate of the hydrolyzed protein. Furthermore, the emptying rate showed a non-linear variation with respect to the motility of the stomach. For a simulated pyloroplasty procedure where the pyloric orifice diameter is doubled and the orifice stays open permanently, the emptying rate of the lower motility case doubled over its original value. Conclusion: StomachSim offers a novel and potentially effective modality for examining the effect of gastric conditions and gastric surgical procedures on gastric function. Our simulations show that gastroparesis and pyloroplasty not only affect the emptying rate but also alter the mixing of contents thereby changing the rate of hydrolysis. The model helped quantify the changes in the flow of contents in the antro-duodenal region for varying degrees of gastroparesis and pyloroplasty. The authors acknowledge support from NSF award CBET 2019405 and NIH award 1R21GM139073-01. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.