ABSTRACT
Objective After the implantation, coronary stent was expected at least to keep integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions, and the fatigue property of the stent should be evaluated. Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria, meanwhile, the accelerated fatigue experiment was also performed . Results It could be concluded that the dangerous points were located in the lateral inner surface of stent curvature. Conclusion The results proved that the fatigue property could be simulated through the finite element analysis, which can provide the theoretical guidance for the stent design.
ABSTRACT
Objective After the implantation,coronary stent is expected at least to keep its integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions,so the fatigue property of the stent should be evaluated.Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria,meanwhile,the accelerated fatigue experiment was also performed.Results It can be concluded that the dangerous points are all but located in the lateral inner surface of stent curvature.Conclusions The results prove that the fatigue property can be simulated through the finite element analysis,which can provide the theoretical guidance for the stent design.
ABSTRACT
Objective After the implantation,coronary stent is expected at least to keep its integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions,so the fatigue property of the stent should be evaluated.Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria,meanwhile,the accelerated fatigue experiment was also performed.Results It can be concluded that the dangerous points are all but located in the lateral inner surface of stent curvature.Conclusions The results prove that the fatigue property can be simulated through the finite element analysis,which can provide the theoretical guidance for the stent design.
ABSTRACT
This essay is to make brief comments on the Nitinol vascular stents fatigue lifetime requirements, finite element analysis and fatigue lifetime tests etc.
Subject(s)
Alloys , Blood Vessel Prosthesis , Finite Element Analysis , Materials Testing , StentsABSTRACT
With the development of cerebral interventional medical devices, Nitinol alloy has been widely used in clinical fields as a good biomaterial. This essay is to make brief comments on Nitinol alloy's present development, its material characteristics, medical basic researches, and applications in cerebral interventional devices.
Subject(s)
Humans , Alloys , Biocompatible Materials , Cerebral Revascularization , StentsABSTRACT
Objective To investigate the flexibility of both the covered stents specially designed for use in intracranial vasculature and the delivering system in passing through the bone tube and the physiological curves of the cranial internal carotid artery(CICA)to reach the targeted area,the performance (adherence)of the covered stents in occluding vascular wall diseases and the impact on the vascular branches of the covered segment.Methods The covered stents specially designed for use in intracranial vaseulature were used to treat 13 patients with CICA diseases using endovascular techniques.There were 4 huge pseudoaneurysms,4 giant aneurysms,3 small wide-necked aneurysms,1 giant pseudoaneurysm with concurrent internal carotid cavernous fistula(CCF),and 1 CCF.Prior to the detachment of the covered stents,balloon occlusion test(BOT)of the internal carotid artery on the diseased side and whole-brain digital subtraction angiography(DSA)were performed in all the patients.Three to 16 months following procedure,DSA and clinical follow-ups were performed.Results Thirteen patients all tolerated the BOT well with the DSA demonstrating well-opened anterior and posterior communicating arteries.The covered stents and the delivering systems all successfully passed CICA to reach the targeted diseased area,with the diseased segments of the internal carotid artery including C3—C4 in 4 cases,C4—C5 in 4 and C6—C7 in 5.Immediately following the detachment of the covered stents,DSA demonstrated that 7 aneurysms were completely occluded,4 aneurysms had slight endoleak,and 1 CCF had markedly-decreased blood flow through the fistula.In the patient with concurrent pseudoaneurysm and CCF,the pseudoaneurysm disappeared and the blood flow through the fistula was markedly-reduced immediately following the stenting procedure.Apart from one patient with aneurysmal subarachnoid hemorrhage who died due to extensive vascular spasm on the 9th day following the stenting procedure,all the other 12 patients had unobstructed stented vessels on the follow-up DSA images,with 2 demonstrating slight stenosis.In the 6 patients with post-procedure endoleak,DSA showed that the endoleak in 4 patients had disappeared,one endoleak disappeared following the second stenting,and one CCF remained low-flow fistula.There was no sequela related to the occlusion of branches in the covered arterial segment.Conclusion The covered stents specially designed for use in the intracranial vasculature and the delivering system are both flexible enough to pass the tortuous CICA to reach the intracranial diseased artery,and are effective in managing CICA diseases.Further follow-up is still needed to determine the long-term effect of the covered stents,and the adherence of the covered stents needs further investigation.