Carotid artery disease occurs when fatty deposits (plaques) clog the blood vessels that deliver blood to your brain and head (carotid arteries). The blockage increases your risk of stroke, a medical emergency that occurs when the blood supply to the brain is interrupted or seriously reduced. Stroke deprives your brain of oxygen. Within minutes, brain cells begin to die. Stroke is the fourth most common cause of death and the leading cause of permanent disability in the U.S. Carotid artery disease develops slowly. The first sign that you have the condition may be a stroke or transient ischemic attack (TIA). TIA is a temporary shortage of blood flow to your brain.