Blood flow through the embryonic heart outflow tract during cardiac looping in HH13–HH18 chicken embryos

Abstract

Blood flow is inherently linked to embryonic cardiac development, as haemodynamic forces exerted by flow stimulate mechanotransduction mechanisms that modulate cardiac growth and remodelling. This study evaluated blood flow in the embryonic heart outflow tract (OFT) during normal development at each stage between HH13 and HH18 in chicken embryos, in order to characterize changes in haemodynamic conditions during critical cardiac looping transformations. Two-dimensional optical coherence tomography was used to simultaneously acquire both structural and Doppler flow images, in order to extract blood flow velocity and structural information and estimate haemodynamic measures. From HH13 to HH18, peak blood flow rate increased by 2.4-fold and stroke volume increased by 2.1-fold. Wall shear rate (WSR) and lumen diameter data suggest that changes in blood flow during HH13-HH18 may induce a shear-mediated vasodilation response in the OFT. Embryo-specific four-dimensional computational fluid dynamics modelling at HH13 and HH18 complemented experimental observations and indicated heterogeneous WSR distributions over the OFT. Characterizing changes in haemodynamics during cardiac looping will help us better understand the way normal blood flow impacts proper cardiac development.

Four‐dimensional live imaging of hemodynamics in mammalian embryonic heart with Doppler optical coherence tomography

“…The results of peak blood flow velocity in the embryonic heart are comparable with the range of hemodynamic measurements in the mouse embryos from other developmental stages measured in utero using Doppler ultrasonic imaging . Also, our measured velocity values are comparable to those from the chick embryonic heart obtained with OCT . These data suggest the feasibility of our approach to perform quantitative 2D spatially‐resolved measurements of the absolute blood flow velocity inside the mouse embryonic heart.…”

Pulling on my heartstrings

“…With the advent of new imaging modalities, as well as the use of models that allow in-vivo assessment of mechanical forces, is it possible to link the two. These techniques range from in-vivo confocal microscopy [32,42], micro-computed tomography [43], high-frequency ultrasound, and optical coherence tomography [44,45]. Detailed analysis of cardiac flow has revealed that despite the existence of unidirectional flow through the developing blood vessels, flow in the embryonic heart is bidirectional, which exposes the heart to unique spatial shear stress [46].…”

Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography

“…Embryology is a major research area where OCT shows great promise as a high-resolution unlabeled imaging tool [31][32][33]. With the primary focus on the cardiovascular development and abnormalities, OCT has been reported able to reveal detailed structures of the embryonic heart comparable to histology [34][35][36], to capture four-dimensional dynamic cardiac activities [37][38][39], to quantify biomechanics of the heart tube [40][41][42], to assess cardiac hemodynamics [43][44][45], to characterize novel mutant heart phenotypes [46][47][48], and to investigate cardiac responses to physical and chemical manipulations [49][50][51][52]. Focusing on the mouse model, our group has combined OCT with live embryo culture to establish a number of structural and functional imaging methods [39,45,48,[53][54][55], suggesting an important role of OCT for in vivo analysis of the mammalian embryo.…”