Key result
Computational fluid dynamics of normal 20-week fetal right ventricles showed peak systolic pressure gradients of 0.2-0.9 mmHg and diastolic vortex rings that did not alter systolic ejection work.
Computational fluid dynamics of normal fetal right ventricles reveals that diastolic vortexes determine wall shear stress patterns but do not significantly influence systolic ejection work, providing a baseline for studying congenital heart malformations.
Characterizes normal fetal RV flow dynamics via CFD; leaves open hemodynamic contributions to malformations pending abnormal-case comparisons.
There are 0.6-1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2-0.9 mmHg during systole, and 0.1-0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2-4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts.
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Wiputra et al. (2016) studied Normal human fetuses (n=3). Computational fluid dynamics simulations was evaluated on Flow and energy dynamics. Computational fluid dynamics of normal 20-week fetal right ventricles showed peak systolic pressure gradients of 0.2-0.9 mmHg and diastolic vortex rings that did not alter systolic ejection work.