What is Atrial Fibrillation and Stroke? Atrial fibrillation (AF) is defined as the rapid, irregular beating of the left atrium (upper chamber) of the heart. These rapid contractions of the heart are weaker than normal contractions, results in slow flow of blood in the atrium The blood pools and becomes sluggish and can result in the formation of blood clots. When a clot leaves the heart and travels to the brain, it can cause a stroke by blocking the flow of blood through cerebral arteries. Some people with AF have no symptoms, but others will experience a fluttering feeling in the area of the chest above the heart, chest pain, light headedness or fainting, shortness of breath, and fatigue. What Causes Atrial Fibrillation? Atrial fibrillation can affect the structure of the heart that is why atrial fibrillation is most common in older adults. Hypertension when untreated force the heart muscle to work overtime in order to maintain normal blood flow through the body. This extra work makes the heart muscle increase in size, known as cardiomegaly. As the size of the heart increases, its muscle becomes stiff, and atrial fibrillation increases. Other disorders that can lead to atrial fibrillation include 1)Heart valvular disorder (such as rheumatic heart disease), 2) Inflammation of pericardium (pericarditis) 3) Fluid around the heart (pericardial effusions), 4) Prior heart attacks, and 5) Diseases of the electrical conduction system of the heart overproduction of thyroid hormones by the thyroid gland (hyperthyroidism) can lead to atrial fibrillation, as several lung diseases and infections, such as pneumonia. Atrial fibrillation can also be caused by emotional or physical stress, alcohol, nicotine, caffeine . Why Atrial Fibrillation Cause Strokes? Depend upon the age of a person, and the specific cause of chronic atrial fibrillation, the incidence of stroke in people with this disorder can range from 5 to 17 times higher than that of people without atrial fibrillation. Most commonly, atrial fibrillation causes cardio embolic strokes -- those caused by a clot that escapes from the heart and blocks a blood vessel in the brain. Blood clots are known to form when blood remains clot for prolonged periods of time, or as a result of turbulent blood flow, both of which are likely to occur disorganized heart beat of atrial fibrillation.