Arterial network adaptation and endothelial shear stress: A tale of 3D imaging and hemodynamic modeling

The structure of the cardiovascular system reflects its function to distribute oxygen, nutrients and humoral factors throughout the body with large arteries for blood transit that branch into smaller and smaller vessels. Reduced blood flow due to the presence of a stenosis in the large arteries not only affects the local blood flow and pressure but indirectly also the small vessels downstream. For comprehension of the network adaptation in cardiovascular disease, it is thus essential considering all scales.
In this thesis, the imaging cryomicrotome, a technology to image arterial beds of entire organs with high detail, was refined for assessment of natural bypasses, the so called collateral vessels. The pertinence of this method for studying network adaptation was demonstrated in an occlusive model and in a human heart, which could be reconstructed in 3D out of hundred thousands of arteries and small arterioles.
In addition, two methods for simpler blood flow modeling were evaluated. With these methods, deviations in cardiovascular disease can be assessed more readily in large clinical trials.
Altogether, the approaches presented in this thesis provide a promising start for a better understanding of vascular adaptation in health and disease, extending the current ‘single vessel knowledge’ to network adaptation, and generating new hypotheses on the underlying biology that could be experimentally tested. Such knowledge can serve in addition as input for modeling technologies that are currently developed for patient-specific diagnosis of coronary disease.