Abstract
BackgroundThere are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure) mainly due to the highly unspecific nature of the disease.Understanding how perfusion is affected during ischemic conditions can be a useful clinical tool which can help clinicians during the diagnosis process. As a first step towards this final goal, a computational model of the gastrointestinal system has been developed and used to simulate realistic blood flow during normal conditions.MethodsAn anatomically and biophysically based model of the major mesenteric arteries has been developed to be used to simulate normal blood flows. The computational mesh used for the simulations has been generated using data from the Visible Human project. The 3D Navier-Stokes equations that govern flow within this mesh have been simplified to an efficient 1D scheme. This scheme, together with a constitutive pressure-radius relationship, has been solved numerically for pressure, vessel radius and velocity for the entire mesenteric arterial network.ResultsThe computational model developed shows close agreement with physiologically realistic geometries other researchers have recorded in vivo. Using this model as a framework, results were analyzed for the four distinct phases of the cardiac cycle – diastole, isovolumic contraction, ejection and isovolumic relaxation. Profiles showing the temporally varying pressure and velocity for a periodic input varying between 10.2 kPa (77 mmHg) and 14.6 kPa (110 mmHg) at the abdominal aorta are presented. An analytical solution has been developed to model blood flow in tapering vessels and when compared with the numerical solution, showed excellent agreement.ConclusionAn anatomically and physiologically realistic computational model of the major mesenteric arteries has been developed for the gastrointestinal system. Using this model, blood flow has been simulated which show physiologically realistic flow profiles.
Highlights
There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram
An anatomically and physiologically realistic computational model of the major mesenteric arteries has been developed for the gastrointestinal system
We believe that such a model could have clinical applications with relation to mesenteric ischemia, a complex vascular problem that arises due to a narrowing or blockage of blood vessels that supply oxygenated blood to the small and large intestines, for which accurate diagnosis is often delayed
Summary
There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. The purpose of our current research is to develop an extensible anatomically and biophysically based computational model of the mesenteric arterial system, which is the main blood supply to the human intestine, and to use this model to carefully examine intestinal blood flow We believe that such a model could have clinical applications with relation to mesenteric ischemia, a complex vascular problem that arises due to a narrowing or blockage of blood vessels that supply oxygenated blood to the small and large intestines, for which accurate diagnosis is often delayed. It allows an establishment of a database of normal range of mesenteric circulation that can be used to investigate deviations from normality This could help in the early diagnosis of mesenteric ischemia in order to prevent secondary diseases such as ischemic colitis, gangrene and perforation of the bowel. Numerical simulations could be used as a tool when using shape optimization theory in the development of prosthetic devices or vascular grafts, designing new prototypes, providing specific design indications for the realization of various surgical procedures and developing training beds for new vascular surgeons [5]
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