Abstract
This study examines how heart rate (HR) affects hemodynamics in a South African infant with Coarctation of the Aorta. Computed tomography angiography 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 HR levels. Turbulence was analyzed over time and space using turbulence-resolving and pulsatile large-eddy simulations. Specifically, a 60% reduction in HR led to a reduction in maximum velocity by 45%, and a 57% decrease in pressure drop. The reduction in turbulence-related metrics was less significant. The ratio of turbulent kinetic energy to total kinetic energy decreased by 2%, while turbulent wall shear stress decreased by 3%. These results demonstrate that HR significantly affects velocity and pressure drop, while turbulence arising from the coarctation region is relatively unaffected. 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, the results indicate that while HR modulation can influence flow dynamics, it may not significantly reduce turbulence-induced shear stresses within the coarctation zone. Therefore, further investigation is necessary to understand the potential impact of HR modulation in the management of CoA, and whether interventions targeting the anatomical correction of the coarctation may be more effective in improving hemodynamic outcomes.