In Vitro Analysis of Rapid-Deployment and Transcatheter Aortic Heart Valve Prostheses—Impact on Aortic Hemodynamics

Background: Rapid-deployment aortic valve replacement (RDAVR) and transcatheter aortic valve implantation (TAVI) have become important treatment options for aortic valve (AV) disease. Preoperative prosthesis selection is, however, often based solely on annulus diameter, overlooking potential hemodynamic differences. The lack of uniform size labeling and adverse device-associated hemodynamic effects emphasize the need of a comprehensive comparison of available prostheses. This study investigated prosthetic heart valves, implanted via transcatheter or surgical rapid-deployment technique, using an in vitro mock circulation setup and advanced imaging modalities.

Methods: Aortic phantoms were designed using segmentation and CAD software, and 3D printed using a flexible material. The valves were implanted and incorporated into a flow loop simulating pulsatile cardiac output and physiological pressure values. Qualitative and quantitative analyses were preformed using 4D flow magnetic resonance imaging (MRI) and vector (V) flow ultrasound (US). Parameters assessed included flow rate, wall shear stress (WSS), pressure gradient (PG), kinetic energy loss (EL), and effective orifice area (EOA). Flow patterns within the thoracic aorta were evaluated by streamline visualization.

Results: V flow US revealed systematic differences in flow rates between RDAVR and TAVI prostheses, with the exception of the 25-mm RDAVR prosthesis, which presented significantly lower flow velocities (p < 0.0001). Localized regions of elevated WSS were heterogeneously distributed without relevant differences between the TAVI and RDAVR prostheses. The latter showed higher kinetic EL in large- compared with small-diameter models. EOA estimations from 4D flow MRI ranged from 2.02 to 2.69 cm² for RDAVR prostheses. The smaller TAVI model exhibited the smallest EOA at 1.71 cm², while the 26-mm TAVI model was comparable to larger rapid-deployment valves. PG varied strongly between models and prosthesis type, reaching as high as 22.29 mm Hg within the mid-ascending aorta for the RDAVR prosthesis with a label-size of 25 to 27 mm.

Conclusion: Despite their similarity in label sizes, the prostheses presented notable differences in hemodynamic performance, highlighting that label-size standardization based on assessment of hemodynamic parameters is essential. The herein presented methodological approach could aid in this process, potentially reducing the risk of patient–prosthesis mismatch and provide information on possible adverse hemodynamic effects.

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Artikel online veröffentlicht:
11. Februar 2025