The heart is made up of four chambers, two upper “atria” and two lower “ventricles”. The heart beats in a rhythmic pattern due to the triggering of electrical impulses generated in a bunch of nerve cells called sinoatrial (SA) node located in the atrium. These impulses travel to the atrioventricular (AV) node located in the ventricle. An irregular and frequently rapid heart rate is called atrial fibrillation. It occurs due to chaotic electrical signals in the atria, so they quiver. Thus impulses are bombarded to the ventricles and they also may start to beat rapidly, a sign that differentiates atrial fibrillation from flutter. As a result, the heart rhythm becomes fast and irregular. In atrial fibrillation, the heart beat may range from 100 to 175 beats a minute as compared to the normal 60 to 100 beats a minute.