Stents are mesh structured implants which are used to support the vessel wall in the
balloon expanded vessel part. Several methods were developed and applied for the
determination of mechanical properties of coronary stents, as a part of a complex pre-clinical
in vitro diagnostic system: radiopacity, flaring, metallic surface area and fatigue tests. Three
pieces of equipment were assembled for the examination of fatigue properties. The first
method simulates the bending stress in the coronary arteries; the second method simulates the
effect of the cylindrical mechanical strain which is equivalent to the systolic and diastolic
pulse in the coronary arteries; and the third method is using the energy of the ultrasound
concentrating to the stent. After fatigue tests stereomicroscopy, optical microscopy, scanning
electron microscopy were used for the determination of surface quality and condition. The
most frequent failures were scratches, pits and small shrinkage of materials originated from
the manufacturing and finishing processes. Because of fatigue tests slip lines occurred in the
critical curves, grain boundaries were outlined, the surface of the struts become rough, but
these mutations do not affect the functionality of the stents