Investigating the Upstream and Downstream Hemodynamic Boundary Conditions of Healthy and Growth-Restricted Rat Feto-Placental Arterial Networks.

The placenta uniquely develops to orchestrate maternal adaptations and support fetal growth and development. The expansion of the feto-placental vascular network, in part, underpins function. However it is unclear how vascular development is synergistically influenced by hemodynamics and how impairment may lead to fetal growth restriction (FGR). Here, we present a robust framework consisting of ex vivo placental casting, imaging and computational fluid dynamics of rat feto-placental networks where we investigate inlet (steady and transient) and outlet (zero-pressure, Murray's Law, asymmetric fractal trees and porous blocks) boundary conditions in a model of growth-restriction. We show that the Murray's Law flow-split boundary condition is not always appropriate and that mean steady-state inlet conditions produce comparable results to transient flow. However, we conclude that transient simulations should be adopted as they provide a larger amount of valuable data, a necessity to bridge the current knowledge gap in placental biomechanics. We also show preliminary data on changes in flow, shear stress, and flow deceleration between control and growth-restricted feto-placental networks. Our proposed framework provides a standardized approach for structural and hemodynamic analysis of feto-placental vasculature and has the potential to enhance our understanding of placental function.