Model study of blood flow through a stent in the aorto-iliac bifurcation

Atherosclerotic ailments play a major role in industrial societies. Atherosclerotic disease causes stenotic narrowing of the arterial vessel system. These narrow passages can be widened with balloon angioplasty and stents are introduced to keep the passage open. In this study, stents designed for the aorto-iliac bifurcation are considered. Most of these stents used in peripheral arteries are self-expanding stents made from Nitinol, a thermo-reactive alloy. The insertion is done under radiographic control. However, the delicate metallic structure of the stent usually casts only a weak radiographic shadow and thus is difficult to detect. A stent with an innovative radio opaque tantalum marker (Luminexx, C.R. BARD--Angiomed, Karlsruhe), overcomes this problem. However, the markers extend into the blood flow and the question arises whether the markers may cause the generation of thrombi. In a model study in an enlarged model of the aorto-iliac bifurcation with an inserted stent the flow was visualized. The enlarged scale permits the observation and video recording of the flow in great detail. The Reynolds similarity is kept. A subsequent analysis of the flow in the vicinity of the markers shows a short residence time. These results indicate that the additional markers do not increase the risk of thrombus generation.