What is Stroke

A stroke, otherwise known as a Cerebral Vascular Accident (CVA), occurs when a part of the brain doesn't get enough oxygenated blood, causing the brain's tissue to die rapidly.

Strokes are caused by either a blockage in a cerebral artery that delivers oxygenated blood to the brain, referred to as ischemic stroke, or a hemorrhage from an artery, referred to as hemorrhagic stroke. Because atrial fibrillation is present in 15-20% 36, 37, 38 of patients who suffer of ischemic strokes, the information provided here will focus on strokes caused by atrial thrombus (a blood clot in the atria) and arterial embolisms (thrombi that travel into the arteries). For information about other causes or risk factors for stroke, please visit the American Stroke Association website.

During atrial fibrillation (AF), the pumping mechanisms of the atria are compromised, causing blood to pool in the chambers. Oxygenated blood from the pulmonary veins tends to pool in the left atrium and can cause an atrial thrombus. If this thrombus breaks off, it becomes an arterial embolism and can be carried through the blood stream. Embolisms can cause blockages in smaller arteries, interrupting the blood supply to various parts of the brain. An ischemic stroke occurs when a blockage stops blood from flowing to part of the brain.

The nerves in our brain control every part of our body and every aspect of our behavior, from muscle movement to speech, to our ability to understand concepts and process information. Without adequate amounts of oxygen and nutrients supplied through the blood, nerve cells and brain tissue die. Unlike other cells and tissues in the body, nerve cells in the brain do not rejuvenate once they are damaged. When a brain nerve dies, the functions that are controlled by it are severely affected.

Types of Stroke

Without adequate amounts of oxygenated blood, brain tissue dies suddenly. The area of the brain that is dead is called an infarct. There are two main types of ischemic strokes that cause different levels of infarction:

Transient Ischemic Attacks (TIA's)

Sometimes referred to as mini-strokes or warning strokes, these attacks are short (less than 24 hours) and the effects are completely reversible with the patient returning to normal and complete motor functioning.

Complete Infarction (CI)

A stroke in which brain tissue dies. Rehabilitation is possible, but damage is not reversible and significant neurological problems can exist. Total recovery is unusual and can take months.