A blood vessel can become clogged in one of two main ways. The first way is due to a blood clot. When your blood vessels get damaged the blood will clot over the site of damage. This is to prevent further damage, stop any blood from leaking out of the blood vessel and to allow the tissue to heal. H0wever, sometimes if the clot becomes too big, then it will begin to close off the vessel and eventually it will close the vessel off completely stopping blood flow. Alternatively, sometimes the blood clots in a large vessel can break off and flow downstream to the smaller vessels where the clot can block the blood from getting through.
The other way blood vessels can become clogged is due to build up of fat. If the levels of fats (including cholesterol) are high in a person, they are at higher risk of developing this type of blockage. This is because there are more fats circulating around in the blood vessels, and the fats are sticky so sometimes they will stick to the blood vessel wall. Over time, as more and more fat sticks to the blood vessel walls, the vessels change and the fat deposit grows to restrict blood flow and eventually it could stop it completely.
A blockage of an artery can be a very dangerous life-threatening problem. When people have a heart attack, this is a blockage of the blood vessels in the heart. The most common form of stroke also involves the blood vessels in the brain becoming blocked. The blockage stops blood getting to that part of the brain and after about 4 minutes of getting no fresh (oxygenated) blood, the brain tissue will slowly begin to die These are both life-changing illnesses which are more common nowadays compared to 10/15 years ago, because we are getting older as a population and due to rising levels of obesity.