Résumé: © 2017 The Authors The authors propose a novel noninvasive therapeutic approach for degenerative calcified bioprosthetic heart valves based on pulsed cavitational ultrasound (PCU) to improve the valvular function by remotely softening calcified stiff cusps. This study aims to demonstrate both in vivo, using an ovine model with implanted human calcified bioprosthesis, and in vitro that PCU can significantly improve the bioprosthesis function. A 50% decrease of the transvalvular gradient was found, demonstrating a strong improvement of the valve opening function. This new noninvasive approach has the potential to improve the outcomes of patients with severe bioprosthesis stenosis.

Résumé: © 2017 by the authors. Plane wave imaging in ShearWave Elastography (SWE) captures shear wave propagation in real-time at ultrafast frame rates. To assess the capability of this technique in accurately visualizing the underlying shear wave mechanics, this work presents a multiphysics modeling approach providing access to the true biomechanical wave propagation behind the virtual image. This methodology was applied to a pediatric ventricular model, a setting shown to induce complex shear wave propagation due to geometry. Phantom experiments are conducted in support of the simulations. The model revealed that plane wave imaging altered the visualization of the shear wave pattern in the time (broadened front and negatively biased velocity estimates) and frequency domain (shifted and/or decreased signal frequency content). Furthermore, coherent plane wave compounding (effective frame rate of 2.3 kHz) altered the visual appearance of shear wave dispersion in both the experiment and model. This mainly affected stiffness characterization based on group speed, whereas phase velocity analysis provided a more accurate and robust stiffness estimate independen t of the use of the compounding technique. This paper thus presents a versatile and flexible simulation environment to identify potential pitfalls in accurately capturing shear wave propagation in dispersive settings.