Comparison of Aortic Flow Patterns Before and After Transcatheter Aortic Valve Implantation

Abstract

Little is known of the likely changes in blood flow velocity profiles and aortic wall shear stress (WSS) following transcatheter aortic valve implantation (TAVI). The objective of this study was to investigate the effects of TAVI on flow patterns in the thoracic aorta by using cardiovascular magnetic resonance imaging (CMR) and computational fluid dynamics (CFD). An elderly patient with aortic stenosis was examined using MRI pre-and post-TAVI, and CFD simulations were carried out incorporating MRI-derived patient-specific anatomy and upstream flow conditions. Pre-TAVI velocity profiles demonstrated the highly disturbed turbulent flow and jet impacting the wall of the arch owing to the partial opening of the stenosed aortic valve, with likely pathological effects. In the Post-TAVI aorta, velocity profiles were similar to those of healthy aortas with spatially more uniform WSS and lower turbulence levels, demonstrating the favourable effects of the TAVI procedure in restoring normal aortic flow. This study has shown both the effectiveness of TAVI on an individual patient and the advantage of the combined CMR and CFD method for a comprehensive patient-specific assessment of pre-and post-TAVI aortic flow patterns and WSS over CMR alone.

On the choice of outlet boundary conditions for patient-specific analysis of aortic flow using computational fluid dynamics

“…These OBCs were commonly used in previous studies (e.g. Tan et al, 2012;Cheng et al, 2016). For OBC5, zero-pressure was imposed at all the model outlets, representing the simplest outlet boundary condition.…”

Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms: The Impact of Patient-Specific Inflow Conditions and Fluid/Solid Coupling

“…While there is extensive research on coupled multidomain outflow boundary conditions that elucidate the explicit relationship between pressure and flow rate and its effect on the hemodynamics [30], literature on patient-specific inflow boundary conditions is scarce. To this end, studies by Kose et al [31], Kim et al [32], and Tan et al [33] demonstrated the use of PC-MRI-derived inlet velocity, corresponding to the patient-specific arterial geometry in rigid-wall fluid flow analyses.…”

Fluid Dynamic Characterization of Transcatheter Aortic Valves Using Particle Image Velocimetry

“…In the past few years, the role of computational modeling and simulations in design and verification of prosthetic heart valves is becoming more and more important (43). As a result, in vitro experimental testing such as the one presented in this study can be used to validate and verify the computational simulations (46)(47)(48)(49). As a result, in vitro experimental testing such as the one presented in this study can be used to validate and verify the computational simulations (46)(47)(48)(49).…”

“…The U.S. Food and Drug Administration (FDA) and EU Medical Device Regulatory System are major driving forces behind the trend (44,45). As a result, in vitro experimental testing such as the one presented in this study can be used to validate and verify the computational simulations (46)(47)(48)(49). A combined experimental and computational approach should be considered to shed light on the flow-mediated mechanisms of thrombosis in bioprosthetic aortic valves.…”