Manufacturing 3D aortic root models for in vitro assessment of calcific aortic valve stenosis

Calcific aortic stenosis (AS) is marked by leaflet stiffening and narrowing of the aortic valve (AV) orifice. Severe AS is clinically defined by mean transvalvular pressure drop (ΔP) ≥ 40 mmHg and aortic valve area (AVA) ≤ 1.0 cm². Aortic root (AR) phantoms were developed to mimic the hemodynamic features of calcific AS.

A parametric AR geometry was reconstructed from computed tomography angiography of patients with AV stenosis. Phantoms were fabricated via silicone casting over 3D-printed molds, varying two parameters: calcium phosphate content (50 vs. 100 mg) and AV free-margin incision (50 vs. 100%). Phantoms were tested in a pulsatile mock loop to measure ΔP, regurgitation, and AVA. Unconfined compression tests were performed on cylindrical silicone-calcium specimens.

All phantoms maintained structural integrity and consistently reproduced moderate-to-severe AS hemodynamic conditions: ΔP ranged between 22 and 49 mmHg, while maximum AVA decreased from 1.14 to 0.49 cm². All configurations achieved complete diastolic coaptation. In a generalized linear mixed-effects model, both calcium burden and, more prominently, free-margin incision significantly influenced AS severity. Inter-phantom variability was negligible, and repeated measurements within the same phantom reported low residual variability. Compressive stiffness of the silicone-calcium composite (0.3-2 MPa) well aligned with ex vivo calcified leaflet tissue.

The proposed modeling strategy and AR phantoms reliably replicate calcific AS hemodynamics. With further refinement and validation, this experimental framework could support fair and reproducible hemodynamic comparisons under controlled experimental conditions across the wide spectrum of AS phenotypes.