4D shear stress maps of the developing heart using Doppler optical coherence tomography

Accurate imaging and measurement of hemodynamic forces is vital for investigating how physical forces acting on the embryonic heart are transduced and influence developmental pathways. Of particular importance is blood flow-induced shear stress, which influences gene expression by endothelial cells and potentially leads to congenital heart defects through abnormal heart looping, septation, and valvulogenesis. However no imaging tool has been available to measure shear stress on the endocardium volumetrically and dynamically. Using 4D structural and Doppler OCT imaging, we are able to accurately measure the blood flow in the heart tube in vivo and to map endocardial shear stress throughout the heart cycle under physiological conditions for the first time. These measurements of the shear stress patterns will enable precise titration of experimental perturbations and accurate correlation of shear with the expression of molecules critical to heart development.