0.6-1.9% of US children were born with congenital heart malformations. Clinical and animal studies suggests 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 4D ultrasound scans of three 20 weeks old normal human foetuses, 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. And diastolic wall shear stresses were found to be around 1Pa, which could elevate to 2-4Pa 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 approximately 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 vortices 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.
- Human Fetus
- Right Ventricle
- Fluid Mechanics
- Ventricular Vortex
- Interventricular Pressure Gradient
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology