Fluid mechanics of human fetal right ventricles from image-based computational fluid dynamics using 4D clinical ultrasound scans.
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.
Department of Biomedical Engineering, National University of Singapore, Singapore.
Hadi
H
Wiputra
Department of Biomedical Engineering, National University of Singapore, Singapore.
Chang Quan
CQ
Lai
Department of Biomedical Engineering, National University of Singapore, Singapore.
Guat Ling
GL
Lim
Department of Biomedical Engineering, National University of Singapore, Singapore.
Joel Jia Wei
JJ
Heng
Department of Biomedical Engineering, National University of Singapore, Singapore.
Lan
L
Guo
Division of Pediatric Cardiology, Koo Teck Phuat, National University Children's Medical Institute, Singapore.|Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore; and.
Sanah Merchant
SM
Soomar
Department of Biomedical Engineering, National University of Singapore, Singapore.
Hwa Liang
HL
Leo
Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore.
Arijit
A
Biwas
Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore.
Citra Nurfarah Zaini
CN
Mattar
Department of Biomedical Engineering, National University of Singapore, Singapore; bieyapc@nus.edu.sg.
Choon Hwai
CH
Yap
D003198:Computer Simulation; D003971:Diastole; D019561:Echocardiography, Four-Dimensional; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000502:physiology; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D057446:Hydrodynamics; D007091:Image Processing, Computer-Assisted; D008962:Models, Theoretical; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D033081:Shear Strength; D013599:Systole; D016216:Ultrasonography, Prenatal
fluid mechanics; human fetus; interventricular pressure gradient; right ventricle; ventricular vortex; wall shear stress