A Numerical Analysis of Pressure Pulsation Characteristics Induced by Unsteady Blood Flow in a Bileaflet Mechanical Heart Valve

Abstract

The leaflet vibration phenomenon in bileaflet mechanical heart valves (BMHVs) can cause complications such as hemolysis, leaflet damage, and valve fracture. One of the main reasons for leaflet vibration is the unsteady blood flow pressure pulsation induced by turbulent flow instabilities. In this study, we performed numerical simulations of unsteady flow through a BMHV and observed pressure pulsation characteristics under different flow rates and leaflet fully opening angle conditions. The pressure pulsation coefficient and the low-Reynolds k-ω model in CFD (Computational Fluid Dynamics) software were employed to solve these problems. Results showed that the level of pressure pulsation was highly influenced by velocity distribution, and that the higher coefficient of pressure pulsation was associated with the lower flow velocity along the main flow direction. The influence of pressure pulsation near the trailing edges was much larger than the data obtained near the leading edges of the leaflets. In addition, considering the level of pressure pulsation and the flow uniformity, the recommended setting of leaflet fully opening angle was about 80°.

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

“…BMHV has been chosen in this study since it is the most frequently implanted prosthetic heart valve. The current study focused on the forward macro-scale flow characteristics downstream of BMHV, and therefore the microcirculation of hinge housing was not simulated, and the forward flow during the valve fully open period (From 45 to 250 ms) was investigated [ 27 , 38 ]. However, despite omitting the opening and closing phases of the BMHV in the simulation, good agreement was found between numerical simulations and in vitro studies in terms of velocity profiles and magnitudes, recirculation zones, vortex shedding mechanism and echo Doppler parameters [ 21 , 39 , 40 ].…”

“…Various numerical studies of BMHVs focused on normally functioning as well as dysfunctional BMHVs, with an emphasis on the velocity field, vortex dynamics, turbulence characteristics, leaflets dynamics, and the hinge mechanism and its relationship with platelet activation and/or hemolysis. Some of these studies did not consider the opening and closing phases of BMHV (fixed leaflets), and simulated the flow for the fully open position with different inlet flow conditions, which ranged from steady state flow conditions [ 21 , 22 , 23 ] to unsteady state (pulsatile) flow conditions [ 24 , 25 , 26 , 27 ]. Moreover, the mobility of BMHV leaflets was simulated using Fluid Solid Interaction (FSI) methods.…”

3D numerical investigation of energy transfer and loss of cavitation flow in perforated plates

“…The mesh independence check result of the single-stage model is listed in Table 1. The flow rate, pressure drop and maximum vapor volume fraction were used to check the mesh independence (Xu et al, 2019). The result shows that as the number of cells exceeds 701127, the variation of flow rate and maximum vapor volume fraction can be ignored.…”

Special Issue: Smart Flow Control in Micro Scale

“…Besides, bileaflet mechanical heart valves (BMHVs) are widely used as the alternatives of diseased heart valves. Xu et al [20] performed simulations of unsteady flow in a BMHV and pressure pulsation characteristics under different flow rates and leaflet fully opening angle conditions were investigated. The work provides a good reference for the alleviation of leaflet vibration phenomenon in BMHVs.…”