Flow Characteristics in a Stented and Non-Stented Side Wall Aneurysm Model

A large number of cerebral saccular aneurysms are now being detected while still asymptomatic due to an increasing use of diagnostic techniques such as computerized tomography and magnetic resonance imaging. Current studies suggest that unruptured asymptomatic aneurysms are in various stages of development and most may progress to rupture. The geometry of the aneurysm and pulsatile flow conditions are determinant factors in aneurysm growth which frequently leads to rupture with high mortality and morbidity. This study investigates the changes of flow patterns in a model blood vessel with a side wall aneurysm before and after placement of a stent in the vessel traversing the ostium of the aneurysm. Implantation of a stent, which covers the aneurysmal ostium, alters local hemodynamics. By reestablishing physiological flow these local changes can lead to flow stasis in the aneurysm, thereby promoting thrombo-occlusion of the aneurysmal pouch. Our preliminary studies (Wakhloo et al, 1994) have shown that stents were able to permanently occlude side wall aneurysms of the canine carotid artery. Furthermore, stents induce neointimal growth and subsequent endothelialization of the stented vessel lumen. However, stent geometry among other parameters and local hemodynamics determine the long term biocompatibility of the implant (Wakhloo et al, 1995).