The Impact of Heart Rate Associated Turbulent Wall Shear Stress in Aortic Coarctation: An in silico, Image-based Computational Fluid Dynamics Approach

This study examines how heart rate affects hemodynamics in a South African infant with Coarctation of the Aorta. Computed tomography angiography (CT) segments aortic coarctation anatomy; Doppler echocardiography derives inlet flow waveforms. Simulations occur at 100, 120, and 160 beats per minute, representing reduced, resting, and elevated heart rate (HR) levels. Turbulence was analysed over time and space using turbulence-resolving and pulsatile large-eddy simulations. The results show that HR significantly affects velocity and pressure drop more than turbulent kinetic energy and wall shear stress, highlighting HR's crucial role in flow dynamics in the coarctation area. Lower HR does not necessarily boost hemodynamic efficiency, as the energy ratio declines from 9.5% to 7.4% with a 60% HR reduction. The balance between turbulent kinetic energy and total kinetic energy shows minimal enhancement due to the complex interplay among HR, turbulence, and geometry. This complexity prompts discussion on how HR-slowing medications, such as beta-blockers or ivabradine, could positively influence hemodynamic stresses. In particular, in the coarctation zone, increased sensitivity to shear stress at lower HR levels suggests nuanced impacts of HR-affecting drugs on hemodynamic stresses, offering new insights new insights for therapeutic management.