Atrial fibrillation (AF) is an electrical rhythm disturbance of the heart affecting the atria. Abnormal electrical impulses in the atria cause the muscle to contract erratically and pump blood inefficiently. The atrial chambers are thus not able to completely empty blood into the ventricles.
Pooling of blood in the atria can cause red blood cells to stick together and form a clot. Most clots within the heart form in a portion of the left atrium known as the left atrial appendage. The most worrysome complication of atrial fibrillation is dislodgement of a clot and embolism of the clot material to one of the major organs of the body (e.g., the brain).
A clot that embolizes to the brain can interrupt blood flow to a portion of the brain, resulting in a cerebrovascular accident, more commonly known as a stroke. Most individuals with atrial fibrillation are advised by their doctors to take one of a number of medications to prevent clot formation within the heart (and therefore reduce the risk of stroke secondary to clot embolism from the heart). The most commonly used medications are warfarin and aspirin. Atrial fibrillation is the most common form of irregular heartbeat (arrhythmia). Normally, your heart's electrical system controls the rhythm at which your heart beats. See illustrations of the heart and its electrical system .
