Mechanical Properties of Selfexpandable Stents

The stents or stentgrafts (covered stents) are the medical instruments used in invasive radiology for miniinvasive treatment of stenosis and aneurisms especially in the blood circulation system. We measured and compared the mechanical parameters of different selfexpandable Nitinol stents, which differed in the geometry (radius and length), in the type of construction (number of branches and rising of winding) and in the diameter of the used wire. The results of measurements confirmed the theoretical assumptions that just the diameter of the Nitinol wire significantly influences the rigidity and the level of compressibility of the stent as well. The compromise must be found between the required rigidity of the stent and the minimal size of the delivery system. The exact description of the relation between the mechanical properties and geometry and construction of the stents enables us to design the stent to fit the patient's needs. The results of measurement are also necessary for the design and identification of the parameters of the models of the stents