Age-dependent changes in oxygen tension, radiation dose and sensitivity within normal and diseased coronary arteries-Part B: modeling oxygen diffusion into vessel walls.

PURPOSE: The aim is to assess the change with age and disease of the oxygen concentration within the coronary artery walls.
MATERIALS AND METHODS: In an accompanying paper, Part A, the age-dependent morphology and composition for the wall layers of normal and diseased coronary arteries were developed from published data. In this paper, Part B, the oxygen concentration in the coronary artery walls was evaluated taking account the diffusion of oxygen from blood and the solubility of oxygen in tissues. Part C evaluates the oxygen effect and its biological implications for different radiations.
RESULTS: Diseased arteries exhibited a relatively moderate increase in the solubility of oxygen (<or=59%) in arteries with 88% luminal narrowing, as the high solubility in fat was partially offset by the lower solubility in calcium deposits. The oxygen partial pressure across the arterial wall was modeled and the avascular regions of arteries with >or=38% stenosis had anoxic areas.
CONCLUSION: Based on simulation results from the one-dimensional diffusion model, extensive hypoxic areas were determined for atherosclerotic arteries in this analysis of oxygen levels in coronary arteries modelling for the first time the effects of age and disease and associated changes in oxygen solubility due to the presence of lipids and calcium.