Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve

Abstract

Background Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.Results An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.ConclusionsWe have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12938-017-0314-2) contains supplementary material, which is available to authorized users.

Use of Computational Fluid Dynamics to Analyze Blood Flow, Hemolysis and Sublethal Damage to Red Blood Cells in a Bileaflet Artificial Heart Valve

“…The hemolysis predictions were lower than others in the literature [26,27] and support the view that current artificial heart valves do not cause a significant amount of hemolysis when functioning properly. Adapting the method to subhemolytic injury to cells could provide further improvement in the design of valve prostheses.…”

“…Failure of a suture with the valve pulling away from the surrounding tissue, dehiscence, is yet another problem [22] leading to hemolysis. While clinical studies show a prevalence of subclinical hemolysis (with a low incidence of hemolytic anemia or clinically severe hemolysis) in valve replacement patients [23][24][25], current in-vitro and CFD research into hemolysis damage are still measuring and predicting damage to RBCs from notable amounts of hemolysis caused by artificial heart valves [26][27][28][29].…”

Hemodynamic Performance of Dysfunctional Prosthetic Heart Valve with the Concomitant Presence of Subaortic Stenosis: In Silico Study

“…Using cardiac simulators, a set of in vitro studies investigated blood flow behavior downstream of BMHV in terms of level of turbulence, shear stress, and coherent structure. Clinically related echo Doppler parameters, such as EOA and Transvalvular pressure gradient, were also explored [33][34][35][36].…”

Transient Study of Flow and Cavitation Inside a Bileaflet Mechanical Heart Valve

“…In in vitro models, the blood flow is modulated by a self-regulating device mimicking the physiological mechanism; the whole device is based on the contraction and relaxation of the heart muscle during the cardiac cycle [15]. Studies about in vitro models show that they are suitable to provide the simultaneous measurement of all different quantities of interest for hemodynamics performance and the analysis of their mutual interactions [16].Different from native heart valve, the BMHV has greater resistance to flow of the blood during diastolic phase, and therefore greatly increases the flow velocity into the coronary artery. In addition, it changes the distribution of wall shear stress and increases the risk of coronary artery disease [17].…”

“…In in vitro models, the blood flow is modulated by a self-regulating device mimicking the physiological mechanism; the whole device is based on the contraction and relaxation of the heart muscle during the cardiac cycle [15]. Studies about in vitro models show that they are suitable to provide the simultaneous measurement of all different quantities of interest for hemodynamics performance and the analysis of their mutual interactions [16].…”