How Does Carotid Artery Disease Happen?

Like the arteries that supply blood to the heart -- the coronary arteries -- the carotid arteries can also develop atherosclerosis or “hardening of the arteries” on the inside of the vessels.

Over time, the buildup of fatty substances and cholesterol narrows the carotid arteries. This decreases blood flow to the brain and increases the risk of a stroke.

A stroke -- sometimes called a “brain attack” -- is similar to a heart attack. It occurs when blood flow is cut off from part of the brain. If the lack of blood flow lasts for more than 3 to 6 hours, the damage is usually permanent. A stroke can occur if:

1. the artery becomes extremely narrowed
2. there's a rupture in an artery to the brain that has atherosclerosis
3. a piece of plaque breaks off and travels to the smaller arteries of the brain
4. a blood clot forms and obstructs a blood vessel

Strokes can occur as a result of other conditions besides carotid artery disease. For example, sudden bleeding in the brain, called intracerebral hemorrhage, can cause a stroke. Other possible causes include:

1. sudden bleeding in the spinal fluid space -- subarachnoid hemorrhage
2. atrial fibrillation
3. cardiomyopathy
4. blockage of tiny arteries inside the brain