Innate collateral vessels in the absence of ischemia undergo shear stress similar to normal arterial segments of the same diameter (1079.12)

Abstract

Some species, including humans, have structural collateral vessels, CV, that can further develop in the presence of coronary stenosis by increasing pressure difference across them. Question is how CV's are maintained in the absence of ischemia.The coronary network of 6 healthy canine hearts was reconstructed in 3D from images obtained with an imaging cryomicrotome after filling with fluorescent replica material (resolution 0.020 mm). CV's were automatically detected. The full coronary network was reconstructed. For all segments, including CV's, diameter and perfused tissue mass, PTM, was derived and shear stress, SS, calculated.Innate collateral connections ranged from 286 to 1015 µm in diameter and were distributed over the myocardial wall with some higher density at the subendocardium: density 2.5 ‐ 5.0 per gram tissue. Highly correlating fractal relations were found between PTM and diameter for normal tree segments and for CV's which fully overlapped. SS in the CV's was equal to neighboring tree segments of similar diameter.Results indicate that collateral segments have the same function in distributing blood, and do so at the same SS, as normal tree segments. Hence, functionally CV's are not different from normal vascular segments and are therefore maintained. CV's form substrate for collateral growth in ischemia.Grant Funding Source: FP7‐ICT‐2007‐224495: euHeart