Question

David has an ultrasound of his common carotid arteries, which shows that his right common carotid artery is nearly 90 percent blocked. He wonders how the right side of his brain is getting enough blood if this artery is so occluded. What do you tell him?

Answer 1

There is an arrangement of vascular channels in the head of the human body. These channels are interconnected in a circulatory anastomosis (i.e. it is a connection between arteries and veins or between an artery and a vein). This channel supplies blood to the brain and the structures that are near to it. The circular interconnection of arteries and veins is known as Circle of Wills (CW or CoW), also known as loop of Willis.

In the cerebral circulation, the Circle of Willis creates a redundancy for collateral circulation (alternate circulation of blood through smaller veins). Thus, the presence of this (CoW) network helps in the supply of oxygenated blood to the brain and its neighboring structures if one of the main vessels that supplies blood is blocked or narrowed.

Hence, in case of David, I would inform him about this interconnection of the vascular channels, i.e., the Circle of Willis, and how it helps in maintaining the supply of oxygenated blood to the right side of his brain though his right common carotid artery is 90 percent blocked.