Fetal and neonatal hemodynamic assessment of aortic coarctation - imaging and computational modelling

Abstract

Aortic Coarctation (AoC) is one of the most difficult cardiac defects to diagnose before birth, occurring in 5-7% of congenital heart diseases. It consists of a narrowing of the distal aortic arch causing a decrease of blood flow. Prenatal diagnosis is important to reduce mortality and morbidity, given that an intervention is required in the first days after birth to ensure survival. However, false-positive and false-negative rates in prenatal diagnosis are high and the induced hemodynamic remodelling is not fully understood. The aim of this project was to understand and predict the hemodynamic remodelling in babies with AoC by means of imaging and computational modelling. Echocardiography data from 43 patients with AoC was analysed and compared to control data to describe the hemodynamic changes from fetal to neonatal life. Furthermore, a lumped model of the fetal circulation was implemented to further understand those hemodynamic changes by performing parametric studies to evaluate effects of ventricular disproportion with different degrees of AoC. As a result, the blood flow velocities in the aortic arch from control fetuses and fetuses with AoC were indistinguishable from each other. Ventricular disproportion was demonstrated by LV and RV relative amount of flows of 34-66% and 22-78% (p < 0.001) in earlier and late gestation respectively. Moreover, a maximum of 60% of narrowing of the aortic isthmus was observed for AoC. From the parametric study we observed that when simulating AoC, the addition of ventricular disproportion was essential to obtain realistic blood flow velocities in the aortic arch.