Computational model of the fetal heart with Coarctation of the Aorta

Abstract

It is thought that altered intrauterine hemodynamics may lead to congenital heart defects, such as aortic arch abnormalities. Coarctation of the aorta (CoA) is one of the most difficult cardiac defects to diagnose before birth, because of the patency of the ductus arteriosus (DA). It consists of a narrowing in the aortic isthmus (AoI) causing a decrease of blood flow. Prenatal diagnosis is important to reduce mortality and morbidity. Nonetheless, prenatal diagnosis has a high rate of false-positive and false-negatives and local hemodynamics in the CoA is not fully understood. The aim of this project was to improve our understanding of the underlying cause of CoA using computational fluid dynamics (CFD) tools. We have implemented a computational model with an idealized geometry of the fetal aorta to investigate the relationship between flow unbalance and wall shear stress (WSS) at the isthmus-ductus. An imbalanced flow was imposed in the ascending aorta (AscAo) and ductus to study if a progressive aortic flow reduction suggests the “flowdependency” of the fetal aortic arch development. As a result, when aortic flow diminished from 50% to 10% progressively, velocity and WSS decreased in the aortic arch and increased in the distal arch. A redistribution of flow could be observed in the model and a “zero flow zone” could be noticed between the brachiocephalic artery and left carotid when the flow decreased to from 50% to 10%. Additionally, another “zero flow zone” could be observed in the AoI when the aortic flow decreased from 50% to 30%.