Numerical model of a valvuloplasty balloon: in vitro validation in a rapid-prototyped phantom

Benedetta Biffi, Giorgia M. Bosi, Valentina Lintas, Rod Jones, Spyros Tzamtzis, Gaetano Burriesci, Francesco Migliavacca, Andrew M. Taylor, Silvia Schievano, Giovanni Biglino

Patient-specific simulations can provide insight into the mechanics of cardiovascular procedures. Amongst cardiovascular devices, non-compliant balloons are used in several minimally invasive procedures, such as balloon aortic valvuloplasty. Although these balloons are often included in the computer simulations of these procedures, validation of the balloon behaviour is often lacking. We therefore aim to create and validate a computational model of a valvuloplasty balloon. A finite element (FE) model of a valvuloplasty balloon (Edwards 9350BC23) was designed, including balloon geometry and material properties from tensile testing. Young's Modulus and distensibility of different rapid prototyping (RP) rubber-like materials were evaluated to identify the most suitable compound to reproduce the mechanical properties of calcified arteries in which such balloons are likely to be employed clinically. A cylindrical, simplified implantation site was 3D printed using the selected material and the balloon was inflated inside it. The FE model of balloon inflation alone and its interaction with the cylinder were validated by comparison with experimental Pressure-Volume (P-V) and diameter-Volume (d-V) curves. Root mean square errors (RMSE) of pressure and diameter were RMSE P  = 161.98 mmHg (3.8 % of the maximum pressure) and RMSE d  = 0.12 mm (<0.5 mm, within the acquisition system resolution) for the balloon alone, and RMSE P  = 94.87 mmHg (1.9 % of the maximum pressure) and RMSE d  = 0.49 mm for the balloon inflated inside the simplified implantation site, respectively. This validated computational model could be used to virtually simulate more realistic valvuloplasty interventions.