Atrial fibrillation (AF) is caused by disruption of the normal functioning of the electrical system in the two upper chambers of the heart (atria). In AF, the atria are stimulated to contract very irregularly and rapidly. The atria essentially fibrillate instead of contracting.
Symptoms include rapid, fluttering, too slow, or irregular pulse, palpitations, fatigue, tightness in the chest, shortness of breath, fainting, dizziness, and light-headiness. It is uncommon in younger people unless you have certain heart conditions. Causes and risk factors might be high blood pressure and some heart or lung conditions.
Less common causes are hyperthyroidism, pericarditis, viral infection, excessive alcohol or caffeine consumption, certain medications, and stress. Genetic variants are known to contribute to the risk of AF. Up to a third of patients with AF have a family history of the disease. The disorder is usually controllable with treatment.