Effect of Stent Radial Force on Stress Pattern After Deployment: A Finite Element Study

Abstract

The present article presents a method for assessing the radial stiffness of nitinol stents. An idealized stent model was created, and its radial stiffness was calculated by means of finite element modeling. The calculations were validated against experimental measurements. The variation of radial stiffness with geometrical dimensions was calculated, and the effect of increasing radial stiffness on endovascular deployment was analyzed. Peak tensile and compressive stresses as well as stent penetration were calculated in the case of an idealized pulmonary artery model having realistic dimensions as well as stiffness. The results of stress calculations were compared with a second set of simulations, where an idealized behavior of the stent (uniform expansion to a theoretical contact diameter) was modeled. The results show how in reality nitinol stents behave in a non-ideal way, having a non-uniform expansion and exerting non-uniform pressure on the contact areas with the artery. Such non-ideality decreases though with the increase in radial stiffness. The radial force alone may be insufficient in describing the stent-artery interaction, and numerical modeling proves to be necessary for capturing such complexity.

Severe, recurrent in-stent carotid restenosis: endovascular approach, risk factors. Results from a prospective academic registry of 2637 consecutive carotid artery stenting procedures (TARGET-CAS)

“…Interestingly, lack of stent coverage of the common carotid artery was an independent restenosis risk factor [17]. Moreover, the Carotid Wallstent has the lowest radial force [16], reducing the chance of further stent expansion, and it was shown that at higher radial force, the stent has better chances of making the artery conform to its original shape [18]. Non-circular stent cross section may provoke flow disturbances, increase in shear stress and in consequence stimulate neointima proliferation.…”

Spatial Orientation and Morphology of the Pulmonary Artery: Relevance to Optimising Design and Positioning of a Continuous Pressure Monitoring Device

“…The antenna is designed to have a suitable shape and the required radiation efficiency for use in the PA and the length of the antenna from tip to tip is currently set to 37 mm. Additionally, finite element modelling (FEM) and experiments were conducted to identify arterial stress patterns and stent radial forces for different stent strut thickness [ 4 ].…”

“…Heart failure is one of the leading causes of morbidity and mortality worldwide [ 1 – 4 ]. The disease is generally progressive, with the advanced forms of the disease carrying a very poor prognosis, and importantly, it is becoming more resistant to conventional therapy [ 5 , 6 ].…”

Numerical simulation of the functionality of a stent structure for venous valve prostheses

“…Therefore, the software output radial force between ring structure and venous model was used to calculate the stent pressure as radial force divided by the relative cylinder surface area of the ring structure. The stent penetration was also calculated as difference between the diameter of the first stent vessel contact DC and the contact diameter at equilibrium DE [7].…”

“…3) is about 1.16 mm and the resulting operating point of the stent [7] defined as intersecting pressure-diameter response of the ring structure with the venous model is about 8.92 mm.…”