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Oxygen deficiency, known as hypoxia, in arterial walls has been linked to increased intimal hyperplasia, which is the main adverse biological process causing in-stent restenosis. Stent implantation can have significant effects on the oxygen transport into the arterial wall. Helical flow has been theorised to improve the local haemodynamics and the oxygen transport within stented arteries. In this study an advanced oxygen transport model was developed to assess different stent designs. This advanced oxygen transport model incorporates both the free and bound oxygen contained in blood and includes a shear-dependent dispersion coefficient for red blood cells. In two test cases undertaken the results predicted by the advanced oxygen transport model were compared those predicted by simpler models, and in vivo measurements. Two other test cases analysed the predicted oxygen transport in three different stent designs, and the effects of helical flow on the haemodynamics and oxygen transport in stented coronary arteries.
The advanced model showed good agreement with experimental measurements within the mass-transfer boundary layer and at the luminal surface; however, more work is needed for predicting the oxygen transport within the arterial wall. Simplifying the oxygen transport model within the blood produces significant errors in predicting the oxygen transport in arteries. It was found that different stent designs can produce significantly different amounts of hypoxic regions within the stented region. Additionally, helical flow increases the amount of oxygen transferred into the arterial wall, but only in a helical ribbon through the stented region that also experiences high wall shear stress spatial gradients.
Murphy, E. (2017) Oxygen Transport in Carotid and Stented Coronary Arteries. Doctoral thesis 2017.