In vitro hemodynamic investigation of the embryonic aortic arch at late gestation

Abstract

This study focuses on the dynamic flow through the fetal aortic arch driven by the concurrent action of right and left ventricles. We created a parametric pulsatile computational fluid dynamics (CFD) model of the fetal aortic junction with physiologic vessel geometries. To gain a better biophysical understanding an in vitro experimental fetal flow loop for flow visualization was constructed for identical CFD conditions. CFD and in vitro experimental results were comparable.Swirling flow during the acceleration phase of the cardiac cycle and unidirectional flow following mid-deceleration phase were observed in pulmonary arteries (PA), head-neck vessels, and descending aorta. Right-to-left (oxygenated) blood flowed through the ductus arteriosus (DA) posterior relative to the antegrade left ventricular outflow tract (LVOT) stream and resembled jet flow. LVOT and right ventricular outflow tract flow mixing had not completed until ~3.5 descending aorta diameters downstream of the DA insertion into the aortic arch. Normal arch model flow patterns were then compared to flow patterns of four common congenital heart malformations that include aortic arch anomalies. Weak oscillatory reversing flow through the DA junction was observed only for the Tetralogy of Fallot configuration. Pulmonary Atresia and Hypoplastic Left Heart Syndrome configurations demonstrated complex, abnormal flow patterns in the PAs and head-neck vessels. Aortic Coarctation resulted in large scale recirculating flow in the aortic arch proximal to the DA. Intravascular flow patterns spatially correlated with abnormal vascular structures consistent with the paradigm that abnormal intravascular flow patterns associated with congenital heart disease influence vascular growth and function.

Congenital heart malformations induced by hemodynamic altering surgical interventions

“…The fifth arch pair have been have been termed to describe arteries that are only temporarily present in early development of the chick embryo, and are not considered a major PAA (Hiruma and Hirakow, 1995). Proper arch formation depends on programmed processes but is also regulated by blood flow conditions (Keller et al, 2007; Pekkan et al, 2008; Kowalski et al, 2013). …”

Preterm birth with antenatal corticosteroid administration has injurious and persistent effects on the structure and composition of the aorta and pulmonary artery

“…Second, in the pulmonary artery, as a result of the substantial rise in blood flow and the reduction in luminal pressure following preterm birth, we propose that there will be persistent changes in the morphometry and composition of the arterial wall, but these will differ from the changes in the aorta. We examined the proximal ascending aorta and pulmonary artery because these areas experience the highest blood flow velocity, shear stress, and dynamic pressures (22,23). Our objective was to determine and compare the effects of preterm birth, accompanied by antenatal corticosteroid exposure, on the structure and composition of the walls of the aorta and pulmonary artery.…”

Aortic Arch Morphogenesis and Flow Modeling in the Chick Embryo

“…Mesh generation was performed using Gambit (ANSYS Inc). A pulsatile 2 nd Order CFD solver (Fluent 6.3.26, ANSYS Inc.) originally developed for complex subject-specific anatomical flows was utilized [29,38]. This experimentally validated model incorporated an implicit pressure based numerical method, high-order discretization schemes, and a robust pressure-correction algorithm to sequentially solve the pressure continuity and the linearized momentum equations assuming i kg/m 3 × 10 -3 Pa).…”

“…Relevant to patients with congenital heart disease, a patient specific neonatal aortic arch configuration [28] and an in vitro experimental and computational study of normal and abnormal embryonic aortic arch hemodynamics at late gestation [29] was published by our group. Compared to the mature systemic aortic arch, the late fetal arch configuration displays relatively complex flow and shear patterns due to the parallel pulmonary and systemic artery flows, and the ductus arteriosus.…”