Atrial fibrillation is the uncontrolled twitching of the upper chambers of the heart (atria). This is a relatively common heart rhythm disorder that can inherited from parents, as in the case of familial atrial fibrillation. Usually, the heart beats at a very purposeful beat, with electrical signals keeping the rhythm of contractions, or pumps, at a regular rhythm. When the electrical signals to the atria conflict with each other, they cause quivering, or fibrillations. Someone with atrial fibrillation may feel dizziness, chest pain, and fast heart rate. The major serious complication of this disorder is that it can cause a blood clot to form in the heart which may then go to the brain causing a stroke. Because of this blood thinners are often prescribed to prevent clots. Medications and the implantation of electrical devices can restore regular heart rate in someone who has atrial fibrillation.