Effect Of Transcatheter Heart Valve Size And Deployment Height On Coronary Flow Obstruction

Abstract

Coronary artery disease (CAD) is commonly found in patients with aortic stenosis; therefore, its prevalence is high in patients that are candidate for transcatheter aortic valve replacement (TAVR). As the TAVR procedure is expanding into younger and lower-risk population, the importance of early CAD monitoring and detection, as well as determination of potential impact of implant design or deployment strategy on CAD progression is of great importance. In this study, we investigate the effect of transcatheter heart valve (THV) size and deployment height on coronary flow obstruction during normotensive hemodynamic flow conditions. We employ unsteady, pulsatile flow, generated by a left heart model, and utilize clinically relevant geometry, pressure, and flow waveforms. Of particular interest is to understand the interaction between THV and anatomy regarding coronary flow obstruction. For a wide range of parameters, we examine two distinct THV deployment scenarios: nominal deployment – high coronary blockage (ND-HCB), and high deployment – low coronary blockage (HD-LCB). Additionally, we investigated the impact of the locations of coronary ostia and THV commissure alignment onto the risk of coronary flow obstruction. With the aid of 2D-2C particle image velocimetry (PIV), the distinctive flow patterns within the aortic sinus space are identified from the response of the flow to the presence of THV. Comparison between two THV deployment scenarios revealed that ND-HCB configurations lead to formation of stagnant flow zones, while the HD-LCB configuration provided an adequate washout of the entire coronary sinus. The optimal washout of the aortic root sinus is achieved when the distance between native leaflets and coronary ostia is maximized. Furthermore, results showed that up to 4% improvement in the coronary flow rate can be achieved if commissure alignment procedure is performed. As the coronary artery obstruction phenomenon is additive in its nature, a pre-existing stenotic condition in association with suboptimal THV deployment may lead to increased risk of full coronary blockage and immediate need for coronary intervention. In conclusion, this study using an experimental coronary assessment tool may provide potential insights to inform pre-procedural TAVR strategies in challenging patients’ anatomies, thereby maximizing the associated benefit.