title: Fluid mechanics of blood flow in human fetal left ventricles based on patient-specific 4D ultrasound scans.
abstract: The mechanics of intracardiac blood flow and the epigenetic influence it exerts over the heart function have been the subjects of intense research lately. Fetal intracardiac flows are especially useful for gaining insights into the development of congenital heart diseases, but have not received due attention thus far, most likely because of technical difficulties in collecting sufficient intracardiac flow data in a safe manner. Here, we circumvent such obstacles by employing 4D STIC ultrasound scans to quantify the fetal heart motion in three normal 20-week fetuses, subsequently performing 3D computational fluid dynamics simulations on the left ventricles based on these patient-specific heart movements. Analysis of the simulation results shows that there are significant differences between fetal and adult ventricular blood flows which arise because of dissimilar heart morphology, E/A ratio, diastolic-systolic duration ratio, and heart rate. The formations of ventricular vortex rings were observed for both E- and A-wave in the flow simulations. These vortices had sufficient momentum to last until the end of diastole and were responsible for generating significant wall shear stresses on the myocardial endothelium, as well as helicity in systolic outflow. Based on findings from previous studies, we hypothesized that these vortex-induced flow properties play an important role in sustaining the efficiency of diastolic filling, systolic pumping, and cardiovascular flow in normal fetal hearts.
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
authors.forename: Chang Quan
authors.initials: CQ
authors.lastname: Lai
authors.affiliation: Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore, Singapore, Singapore.
authors.forename: Guat Ling
authors.initials: GL
authors.lastname: Lim
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Jamil
authors.affiliation: Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore, Singapore, Singapore.
authors.forename: Citra Nurfarah Zaini
authors.initials: CN
authors.lastname: Mattar
authors.affiliation: Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore, Singapore, Singapore.
authors.forename: Arijit
authors.initials: A
authors.lastname: Biswas
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore. bieyapc@nus.edu.sg.
authors.forename: Choon Hwai
authors.identifier: 0000-0003-2918-3077
authors.initials: CH
authors.lastname: Yap
mesh_terms: D003198:Computer Simulation; D005318:Fetal Heart / Q000502:physiology; D005333:Fetus / Q000098:blood supply*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D011312:Pressure; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014463:Ultrasonography; D016276:Ventricular Function / Q000502:physiology*
keywords: Cardiovascular; Computational fluid dynamics simulations; Human fetal; Left ventricular fluid mechanics