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Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?

Dordoni E, Petrini L, Wu W, Migliavacca F, Dubini G, Pennati G - J Funct Biomater (2015)

Bottom Line: However, their effectiveness is still debated in the clinical field.However, confidence in numerical methods is only possible after verification and validation of the models used.For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan 20133, Italy. elena.dordoni@hotmail.it.

ABSTRACT
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated.

No MeSH data available.


Related in: MedlinePlus

(a) Comparison between experimental and numerical hoop force-diameter curves for Zilver™ peripheral stent. In the finite element analyses, material parameters were set using literature data (green curve) and calibrated data (blue line) obtained from an identification procedure based on experimental tests on the whole device. (b) Plot of the numerical stress-strain curves obtained from literature data (green curve) and calibrated data (blue line).
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jfb-06-00299-f011: (a) Comparison between experimental and numerical hoop force-diameter curves for Zilver™ peripheral stent. In the finite element analyses, material parameters were set using literature data (green curve) and calibrated data (blue line) obtained from an identification procedure based on experimental tests on the whole device. (b) Plot of the numerical stress-strain curves obtained from literature data (green curve) and calibrated data (blue line).

Mentions: The effectiveness of the identification procedure proposed in Section 2.3, for cases where ad hoc specimens cannot be produced, is evident in Figure 11a where the experimental hoop force-radial displacement curve of Zilver™ stent (black line) is compared with numerical results obtained using calibrated parameters (blue line) and literature data (green line) for the material constitutive model. The comparison of the corresponding stress-strain curves (Figure 11b) highlights the necessity of performing material characterization for each stent type.


Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?

Dordoni E, Petrini L, Wu W, Migliavacca F, Dubini G, Pennati G - J Funct Biomater (2015)

(a) Comparison between experimental and numerical hoop force-diameter curves for Zilver™ peripheral stent. In the finite element analyses, material parameters were set using literature data (green curve) and calibrated data (blue line) obtained from an identification procedure based on experimental tests on the whole device. (b) Plot of the numerical stress-strain curves obtained from literature data (green curve) and calibrated data (blue line).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493513&req=5

jfb-06-00299-f011: (a) Comparison between experimental and numerical hoop force-diameter curves for Zilver™ peripheral stent. In the finite element analyses, material parameters were set using literature data (green curve) and calibrated data (blue line) obtained from an identification procedure based on experimental tests on the whole device. (b) Plot of the numerical stress-strain curves obtained from literature data (green curve) and calibrated data (blue line).
Mentions: The effectiveness of the identification procedure proposed in Section 2.3, for cases where ad hoc specimens cannot be produced, is evident in Figure 11a where the experimental hoop force-radial displacement curve of Zilver™ stent (black line) is compared with numerical results obtained using calibrated parameters (blue line) and literature data (green line) for the material constitutive model. The comparison of the corresponding stress-strain curves (Figure 11b) highlights the necessity of performing material characterization for each stent type.

Bottom Line: However, their effectiveness is still debated in the clinical field.However, confidence in numerical methods is only possible after verification and validation of the models used.For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan 20133, Italy. elena.dordoni@hotmail.it.

ABSTRACT
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated.

No MeSH data available.


Related in: MedlinePlus