Coupled oxygen transport analysis in the avascular wall of a post-angioplasty coronary artery stenosis

Abstract

The coupled oxygen transport in the avascular wall of a coronary artery stenosis is studied by numerically solving the convection–diffusion equations. Geometry, replicating residual stenosis after percutaneous transluminal coronary angioplasty (PTCA), is used for the analysis. Important physiological aspects, such as oxygen consumption in the wall, oxygen carried by the hemoglobin, non-Newtonian viscosity of the blood, and supply of oxygen from the vasa vasorum are included. Mean blood flow rate in the lumen is varied from basal to hyperemic conditions. The results show that the P_O2 in the medial region of the arterial wall is ∼10 mmHg. The oxygen flux to the wall increases in the flow acceleration region, whereas it decreases at the flow reattachment zone. Near the location of flow separation there is a small rise and a sharp fall in the oxygen flux. The minimum P_O2 in the avascular wall, P_O2, min, at the point of flow reattachment reduces to ∼6 mmHg for a 300 micron wall thickness. For a thinner wall of 200 micron, the P_O2, min at the location of flow reattachment increases to 6 times that of a 300 micron wall. The P_O2, min in the wall decreases by 60% when volumetric oxygen consumption is increased by 30% for the same avascular wall thickness.