ABSTRACT
Atrial fibrillation is a disorder of the heart's rhythm that makes it beat faster than it should and causing it to pump poorly. The condition sometimes produces a backup of fluid in the lungs which we call heart failure. This abnormal rhythm creates a risk of stroke because when the heart is not pumping correctly blood pools inside it, can clot and pieces of the clot can break off, travel to the brain and block the small arteries there. To prevent stroke, we often put people with atrial fibrillation on a medicine called warfarin, an anticoagulant. While warfarin prevents stroke, thereby saving a person's life, it can also be life-threatening because its correct use is very exacting. To regulate warfarin dosage, people have to get their blood-clotting capacity tested often, daily at first, then weekly or biweekly.
