1 research outputs found
Computational model of the fetal cardiovascular system with aortic coarctation
Tutors: Bart Bijnens, Inma Villanueva. Treball de fi de grau en BiomèdicaAortic coarctation (AoC) is a challenging congenital heart disease (CHD) to
diagnose prenatally, accounting for 6-8% of all CHDs. It involves the narrowing of a
segment of the aortic arch, typically affecting the aortic isthmus. Prenatal diagnosis of
AoC is difficult due to the presence of the fetal shunt called ductus arteriosus (DA), which
bypasses the defect in fetal circulation. During fetal life, the body adapts to coarctation
by establishing mechanisms for adequate oxygen and nutrient delivery as well as pressure
regulation to prevent adverse remodelling. However, following birth, a multitude of
hemodynamic effects can arise as a result of ductal closure. The primary indicator of AoC
is ventricular disproportion, characterized by left-to-right blood flow redistribution
resulting in an imbalance with dominant right ventricles. Nonetheless, false-positive
diagnoses can occur due to physiological right dominance in the third trimester. The lack
of clear prenatal diagnosis criteria for AoC arises from the inconsistency of associated
signs. Thus, achieving an accurate prenatal diagnosis of AoC continues to pose a
significant challenge.
Given the above, this study aimed to develop a closed 0D computational model
of the fetal cardiovascular system to improve the understanding of AoC. Particularly, it
aimed to simulate the hemodynamic changes in the fetal circulation considering different
scenarios of AoC.
To that end, we used a closed 0D model that was further extended in order to add
more detail and obtain a circuit more consistent with the real anatomical configuration of
the fetal system. Then, a thorough parametric analysis was carried out to adjust the
parameters of the extended lumped circuit and replicate the behavior of a healthy fetus
described in the literature. Finally, multiple scenarios of aortic coaction were simulated
considering different degrees of narrowing, ventricular disproportion and increment in
the radius of the DA.
The obtained results demonstrate the capacity of the extended closed 0D lumped
circuit to mimic the hemodynamic behavior of a healthy fetus. Moreover, it has been
found that, in the context of AoC, it is imperative for the body to combine the narrowing
of aortic segments and the ventricular disproportion, to ensure proper blood delivery,
regulate wall stress and wall shear stress in the upper body and most importantly, the
brain and the left ventricle. Thus, this study has identified the specific conditions under
which physiological ranges are achieved in the context of AoC. Finally, it has been
demonstrated that while DA plays a crucial role in blood flow redistribution toward the
lower body, it does not experience any increase in its radius