Analysis of the Role of Vasa Vasorum in the Oxygen Transport to the Aneurysm Wall.

The role of the vasa vasorum in the growth and rupture of intracranial aneurysms, as well as the conditions stimulating its local development along aneurysm walls are not completely clear and have not been studied on an aneurysm-specific basis. In this study, the oxygen distribution throughout the wall of an intracranial aneurysm that underwent substantial thickening and developed an extensive adventitial vasa vasorum network was numerically modeled in order to elucidate the role played by the vasa vasorum. The computational model was constructed based on high-resolution ex vivo micro computed tomography and multi-photon microscopy images of a tissue sample of the aneurysm harvested during open surgery. The mathematical model was based on the transport equation including oxygen diffusion and consumption in the tissue and diffusion across the lumen in the intimal side, and the vasa vasorum in the adventitial side. The governing equation was numerically solved with a finite volume approach on a high-resolution mesh containing approximately 48 million tetrahedra with an element size of 10 μm. The results demonstrate that the observed vasa vasorum plexus provided adequate oxygen supply to the outer layers of the thickened walls. Furthermore, the models show that without the vasa vasorum, due to consumption throughout the wall, the oxygen demand could not be met by diffusion from the luminal surface. These findings support the idea that local hypoxic conditions in regions of increased wall thickness stimulate the development of the vasa vasorum network on the adventitial surface.