During gestation, the fetus receives oxygen and nutrients from the placenta, where the fetus’ blood and the mother’s blood are separated by a porous media that allows the transit of small particles. The placenta is connected to the fetus through the umbilical cord, which contains 2 umbilical arteries and an umbilical vein. Therefore, any impairment in the placental blood circulation is extremely prejudicial to the fetus. 

Blood flow is not constant, but a series of pulses originated by each cardiac contraction that propagates as waves through the vessels. When the wave encounters a change of media (at vessel bifurcations, or when entering an organ), then it is possible that not all the wave is propagated forward, and a part of it is reflected backwards. Healthy fetuses have an optimized circulatory system, in a way that the coupling between placenta and umbilical arteries reduces the amount of wave reflection, to avoid energy loss. However, in pathologies where the placental stiffness is increased, reflecting waves are created at the interface between the placenta and umbilical arteries.

By means of ultrasound Doppler, blood velocity at different points of the umbilical artery can be obtained non-invasively. However, it is difficult to quantify the forward and backward waves since 1) we cannot simultaneously image the complete artery, and 2) we can only observe the velocity, which is the sum of the forward and backward waves can be measured.

Finite element models have been used to study the pressure and flow characteristics in different vessels, and have been successful in characterizing wave-reflection phenomena. The objective of this thesis is to develop, implement and validate a 1D finite element model to quantify the presence of wave reflection phenomena of the umbilical artery in gestations, which will help us better understand hemodynamic changes due to different pathologies.
The model will be implemented in Python using the Fenics library, and integrated with current 0D models of the fetal heart for boundary conditions. The project will be co-supervised by Gabriel Bernardino, engineering postdoctoral
researcher at the Fetal Medicine Group at BCNatal (research institution associated with Hospital Casa de la Maternitat Hospital Sant Joan de Deu) and by Inmaculada Villanueva, PhD student at Physense (UPF). The project will also count with the participation of Dr. Fatima Crispi of the Fetal Medicine Group, a gynecologist subspecialized in fetal echocardiography, who will provide data for the project; and Prof. Bart Bijnens ), from the Translational Computing in Cardiology Group at IDIBAPS (Hospital Clinic)

Supervisor: Gabriel Bernadino