Volume 28, Issue 5 (September 2000)
Cyclic Loading and Creep of Intracranial Aneurysm Clips
Intracranial aneurysm clips are used to clamp closed a portion of a blood vessel in order to prevent the rupture of cerebrovascular aneurysms. After implantation, the clips are subjected to stress, produced by the clamped tissue, in a corrosive environment. Aneurysm clips can fail by fracture or by loosening and slippage, and a failure can result in death if the aneurysm ruptures. Previous research has shown that the force required to open an aneurysm clip may decrease with repeated openings. The influence of repeated loadings on the ultimate survivability of the clip is not known. Factors such as creep and stress relaxation, which may cause a clip to loosen or slip after implantation, have not been studied. Standard test methods do not address these performance characteristics. The objective of this research is to develop test methods to investigate the cyclic load-displacement and creep behavior of intracranial aneurysm clips in both air and a simulated physiologic environment. Results of testing aneurysm clips with three spring geometries are given.