Influence of Tricuspid Bioprosthetic Mitral Valve Orientation Regarding the Flow Field Inside the Left Ventricle: In Vitro Hydrodynamic Characterization Based on 2D PIV Measurements

Abstract

The flow patterns of a prosthetic heart valve in the aortic or mitral position can change according to its type and orientation. This work describes the use of 2D particle image velocimetry (PIV) applied to the in vitro flow fields characterization inside the upper part of a left ventricular model at various heart rates and as a function of two orientations of stented tricuspid mitral bioprostheses. In the ventricular model, each mitral bioprosthesis (27 and 31 mm diameter) was installed in two orientations, rotated by 180°, while the aortic bileaflet mechanical valve (27 mm diameter) remained in a fixed orientation. The results (N = 50) showed changes in the intraventricular flow fields according to the mitral bioprostheses positioning. Also, changes in the aortic upstream velocity profiles were noticed as a function of mitral orientations.

In Vitro Hydrodynamic Evaluation of a Scaffold for Heart Valve Tissue Engineering

“…Through the bileaflet aortic prosthesis, the velocities at peak of systole (according to Fig. A) were up to 0.7 m/s, as occurred in a previous work .…”

“…B, higher magnitude of velocity vectors occurs for regions in dark gray color, up to 0.6 m/s. Comparatively, when a tricuspid bioprosthesis of 31 mm was used for the same ventricular states, velocities were slightly lower, up to 0.5 m/s, with a aperture area of 2.02 cm 2 . Therefore, a smaller area must have occurred for the scaffold.…”

“…The scaffold and an aortic bileaflet mechanical valve (CarboMedics Inc., Austin, TX, USA, diameter of 27 mm) were used in the left ventricular model (LVM) of the Escola Politécnica of the University of São Paulo. The instrumentation, control and data acquisition system of the LVM were described previously . The blood analogue fluid was conceived as a liquid solution based on 37% by volume of glycerol in water at 21 ± 0.5°C, allowing the dynamic viscosity of 4.0 mPa s and, also, the refractive index matching necessary for using the PIV technique.…”

“…The final interrogation area was 32 × 32 pixels, with high accuracy subpixel refinement. In order to eliminate bad vectors, local neighborhood size of 3 × 3 pixels was used (moving average with 3 iterations and acceptance factor of 0.1) .…”

Model-based management of cardiovascular failure: Where medicine and control systems converge

“…However, the means to make best use of these measurements is lacking. The following recommendations might therefore be made from a control systems perspective, defining questions or needs the field can contribute to answering: devices [88,[165][166][167][168] or prosthetic heart valves [169,170] in an automated care framework.…”