Finite element analysis of cutting balloon expansion in a calcified artery model of circular angle 180°: Effects of balloon-to-diameter ratio and number of blades facing calcification on potential calcification fracturing and perforation reduction

Abstract

Calcified artery lesions cause stent under-expansion and increase the risk of in-stent restenosis and stent thrombosis. Cutting balloons facilitate the fracturing of calcification prior to stent implantation, although vessel dissection and perforation are potential issues. In clinical practice, calcifications having maximum calcium angles ≤ 180° are rarely fractured during conventional balloon angioplasty. We hypothesize that the lesion/device diameter ratio and the number of blades facing a non-circular calcified lesion may be crucial for fracturing the calcification while avoiding vessel injury. The geometries of the cutting balloons were constructed and their finite-element models were generated by folding and wrapping the balloon model. Numerical simulations were performed for balloons with five different diameters and two types of blade directions in a 180° calcification model. The calcification expansion ability was distinctly higher when two blades faced the calcification than when one blade did. Moreover, when two blades faced the calcification model, larger maximum principal stresses were generated in the calcification even when using undersized balloons with diameters reduced by 0.25 or 0.5 mm from the reference diameter, when compared with the case where one blade faced the calcified model and a balloon of diameter equal to the reference diameter was used. When two blades faced the calcification, smaller stresses were generated in the artery adjacent to the calcification; further, the maximum stress generated in the artery model adjacent to the calcification under the rated pressure of 12 atm when employing undersized balloons was smaller than that when only one blade faced the calcification and when lesion-identical balloon diameters were used under a nominal pressure of 6 atm. Our study suggested that undersized balloons of diameters 0.25 or 0.5 mm less than the reference diameter might be effective in not only expanding the calcified lesion but also reducing the risk of dissection.

A study of balloon type on calcified coronary lesion predilation: A finite element analysis

“…In our experiments, only one blade of the cutting balloon faced the 180°c alcified plaque causing a single fracture there. In combination with the experimental results of Zhu et al, 15 more fractures are likely to result when two blades face the calcified plaque. Calcification at 270°is most easily preconditioned, with a cutting balloon causing two fractures in the calcific plaque at 1.2 MPa, an ordinary balloon producing three fractures at 1.0 MPa of pressure, and an AngioSculpt balloon producing the same three fractures at 0.8 MPa.…”

“…In our experiments, only one blade of the cutting balloon faced the 180° calcified plaque causing a single fracture there. In combination with the experimental results of Zhu et al, 15 more fractures are likely to result when two blades face the calcified plaque.…”

“…For the cutting balloon (Figure 2), the method of Zhu et al 15 was used to build a three-pleated cutting balloon model with an initial diameter of 1.42 mm, a blade height of 0.127 mm, a blade base height of 0.064 mm and a width of 0.344 mm. The blade and base were selected as C3D8R in Abaqus for grid division, generating 6400 cells and 14,460 nodes.…”

“…Young's modulus and Poisson's ratio of all the above models are shown in Table 2, and all attributes refer to previous studies. 15,20,21 Simulation process…”

“…They showed that the maximum principal stress generated by the cutting balloon blade was higher with greater thickening of calcification. Zhu et al 15 established a three-dimensional model of 180° calcified lesions, analyzed the stress applied to the lesion, and found that better results were obtained with a cutting balloon with two blades directly opposed to the calcification. Endovascular imaging studies 16 have shown that fracture of calcified plaque is required to prevent incomplete stent expansion, and suboptimal clinical outcomes, but the aforementioned studies were analyzed only using maximum principal stress at the plaque, ignoring the core issue of calcified plaque fracture.…”