Paravalvular leakage of transcatheter aortic valve replacements depending on aortic annulus calcification

Paravalvular leakage (PVL) has a crucial impact on clinical outcomes of transcateheter aortic valve replacements (TAVR), especially the mortality increases dramatically with high-grade PVL. Furthermore, the calcification of the aortic annulus has a decisive influence on the PVL of TAVR. Therefore, we developed a technical model of a calcified aortic annulus and used it for the investigation of PVL in steady-state back-flow conditions. We investigated an Evolut PRO (Medtronic, Minneapolis, MN, USA), implanted the TAVR at different depths in the aortic annulus model ranging between 0 mm and -6 mm and characterized PVL in steady-state retrograde flow from 0 mmHg up to a maximum achievable pressure. The used test bench and detailed test method was described in previous studies. The aortic annulus model exhibits three elevations symmetrically distributed around the circumference. Depending on the degree of calcification the elevations reached 1 mm to 3 mm into the lumen. For the Evolut PRO bioprosthesis, a decreasing PVL was measured with increasing implantation depth. At an implantation depth of 0 mm (inflow of TAVR and annulus model at same height) maximum PVL was measured. Minimum PVL was measured at a height of -6 mm. Furthermore, even a small calcification of 1 mm led to a large increase in PVL. This trend continued with increasing height of the calcification. The maximum regurgitation of (2,025.21 ± 12.47) ml (n = 3 measurements) was measured at a pressure of 6 mmHg in the annulus model with 3 mm calcification. A test method to quantify PVL depending on annular calcification was successfully developed. Additionally, the influence of implantation depth on PVL was characterized. Due to the technical operating principle of the test bench, only a limited increase in pressure was possible when large PVL occurred. In this respect, the test bench must be optimized in the future.