born with a good Circle of Willis because what that means is that if you have one blood vessel that's blocked up that you can get help from the other blood vessels that's known as collateral circulation means one blood vessel can help out another one that's blocked up and some people can block off the whole carotid artery and not have a problem because the other vessels are helping out some people can actually block off both of their carotid arteries the biggest blood supply to the brain slowly blocks off and the other