The coronary collateral circulation revisited

The coronary collateral circulation constitutes a vascular network that forms bridges between adjacent arteries. In response to obstructive coronary artery disease (CAD) due to atherosclerotic plaque progression, these bridging vessels enlarge by a complex interplay of physical forces along with molecular and cellular players. This process of vascular enlargement is known as arteriogenesis. The progression of vessel stenosis exerts a pressure gradient on the downstream vasculature, leading to increased shear stress. Collateral vessel growth and maturation is then dominated by monocyte infiltration. Expansion of these bridging vessels into large calibre collateral arteries allows blood flow to bypass the site of obstruction, thereby maintaining perfusion to the surrounding tissue. Many clinical studies have implicated a functional significance of collateral arteries in relation to preserving left ventricular function, reducing infarct size and lowering future adverse cardiac events. …