Stents are a wonderful creation of modern medical engineering that aid physicians and surgeons in the treatment of heart disease. Conditions, such as smoking, diabetes, and high cholesterol help promote atherosclerosis, the build up of fatty plaque within arteries, which can ultimately lead to heart attack and stroke.
We have found that more recently smart materials, such as Nitinol (Nickel Titanium Alloy), have been used by stent manufacturers in the production of stents. Nitinol exhibits both shape memory and super-elastic properties, making it perform particularly well when used for self-expanding stents. Nitinol stents are slightly larger than the size of the intended artery, and after deployment they exhibit a chronic radial force to maintain position.
With stringent requirements from regulations, manufacturers must demonstrate that they have considered risks of device failure and satisfactorily mitigated against them. Mechanical testing of stent and stent materials is performed in vitro to aide designers and researchers in gathering performance data ahead of device approval and clinical use. Although mechanical testing does not begin to simulate the complete in vivo conditions that devices undergo, it does allow experimental validation and provides more accurate data for Finite Element Analysis (FEA) and computer modeling of cardiovascular devices.
Although stents have proven to be effective and important devices for the medical device community and the general patient population, they continue to evolve. Larger and smaller stents designed for peripheral networks in distal extremities - like the superficial arteries, carotid arteries, and neural pathways - test the limits of existing materials and testing technology. Continued material evaluation, development, and delivery of new testing methods are important for the evolution and success of these devices.