A stroke occurs when the blood supply, and therefore the oxygen supply, to the brain is interrupted, resulting in the death of brain cells. There are two main types of stroke: A hemorrhagic stroke occurs when blood vessels in or near the brain leak or rupture resulting in less blood reaching the brain cells. An ischemic stroke occurs when the blood flow to the brain is blocked. The American Heart Association reports that 87 percent of all strokes are ischemic strokes. There are several conditions that can cause an ischemic stroke.
Atherosclerosis
Atherosclerosis is a condition in which plaque, a substance made of fat, cholesterol, calcium and other minerals, builds-up in the arteries. Plaque deposits on the walls of blood vessels where there is damaged caused by disease or injury, such as from high blood pressure. As the area of plaque grows, it makes the blood vessel become more and more narrow, therefore blocking the flow of blood. When this process occurs in the carotid arteries, the arteries that run through the neck and lead to the brain, a stroke can occur.
Atherosclerosis may also lead to a stroke by contributing to the formation of blood clots. When the plaque binds to the wall of the artery instead of blocking the artery, the growth may occur into the wall. In this case, the blood vessel will not become blocked. As it grows, the plaque area can rupture and expose its material to the bloodstream, which can trigger the formation of blood clots, as described by the Merck Manual. If the blood clot forms in the carotid artery, it can block the artery and result in an ischemic stroke.
Heart Related Problems
An ischemic stroke can also be caused by a heart-related condition. When the heart beats too fast or in an irregular pattern, it is known as arrhythmia. A specific type of arrhythmia, atrial fibrillation, is a heart disorder that affects approximately 2.2 million Americans, according to the American Heart Association. A heart in atrial fibrillation beats so quickly that it is not able to pump all the blood out of the atrial chambers of the heart, which can result in the formation of a blood clot. This clot can then be pumped through the arteries and become lodged in the artery leading to the brain, resulting in a stroke.
Blood Disorders
Various blood disorders can cause an ischemic stroke. Polycythemia is a blood disorder that occurs when the bone marrow produces too many red blood cells. This increase in red cells causes the blood to become thick, which can decrease the rate at which it flows. The increased thickness, along with the decreased flow rate, can cause blood clots to form that can lead to an ischemic stroke.
Antiphospholipid syndrome (APS), another blood disorder, is an autoimmune disease that is caused by the cells of the immune system recognizing normal components of the blood as foreign substances. The immune cells then make antibodies against these blood proteins, which can trigger the formation of blood clots. The Antiphospholipid Antibody Syndrome Foundation of American reports that approximately one-third of strokes that occur in those under the age of 50 are due to APS.
About this Author
Stephanie Chandler is a freelance writer whose master’s degree in biomedical science and over 15 years’ experience in the scientific and pharmaceutical professions provide her with the knowledge to contribute to health topics. Chandler has been writing for corporations and small businesses since 1991. In addition to writing scientific papers and procedures, her articles are published on Overstock.com, Helium.com and other websites.
