Library · Physiology
Collateral circulation
Make it clearer
The coronary arteries, the ones that supply the heart, are not completely isolated from one another. Between them run channels called collateral vessels, which are anastomoses, that is, connections that join the territory supplied by one artery with the territory supplied by another.
When an artery becomes blocked, a pressure gradient appears, meaning a difference in pressure along those collaterals, and that difference pushes blood through them. As more blood passes through, shear stress rises, which is the friction of the flow against the wall, and that friction wakes up the endothelium, the layer of cells that lines the inside of the vessel.
What happens next is called arteriogenesis, and it should not be confused with angiogenesis. Arteriogenesis widens and remodels collaterals that were already there, like a back road that is widened when the highway closes. Angiogenesis is something else: it builds new capillaries, and it is triggered by ischemia, which is lack of blood supply.
There is an honest limit to all of this. The flow that arrives through the collaterals can be enough while the person is at rest, but in general it does not cover what the heart muscle demands during exercise.
In brief
Collateral vessels are anastomoses that connect the territory of one coronary artery with that of another.
When an artery occludes, a pressure gradient increases flow through those collaterals, and shear stress activates their endothelium.
Arteriogenesis remodels preexisting collaterals; angiogenesis creates new capillaries and is induced by ischemia.
A back road that was already there, widening when the main highway closes.
Collateral flow can be enough at rest, but generally does not cover demand during exercise.
Sources (1)
- BMC Medicine, via PubMed CentralThe collateral circulation of the heartPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated