Atrial fibrillation, or AF for short, is a common disease in cardiology, so what is the essence of AF, what is its pathogenesis, and what are the dangers of AF? Here we briefly popularize it. The heart has two atria and two ventricles. The left and right atria are composed of cardiomyocytes responsible for contraction and cardiomyocytes that can initiate electrical excitation by their own depolarization and have an autonomous rhythm. Under normal conditions, the cardiomyocytes in the atria, led by the sinus node, contract neatly and simultaneously to pump blood to the ventricles and then to the whole body to maintain our life activities. Atrial fibrillation, on the other hand, is essentially an arrhythmia in which the cardiomyocytes contract asynchronously, each doing their own thing, contracting at different times, and without cohesion, they are unable to contract at the same time; the heart muscle is busy, but working separately, resulting in ineffective atrial contractions and an unworkable heart. There are several classifications of atrial fibrillation: 1. Atrial fibrillation that lasts less than 7 days and automatically returns to sinus rhythm after 7 days or recovers within 7 days with intervention therapy is paroxysmal; 2. Over 7 days, it is persistent atrial fibrillation; 3. Then someone with atrial fibrillation for more than 12 months, i.e., 1 year, is called long-term persistent atrial fibrillation. When the patient and the doctor no longer make further attempts to restore sinus rhythm in patients with atrial fibrillation, i.e., when the fact of atrial fibrillation has been psychologically accepted, it can be called permanent atrial fibrillation. What are the dangers of atrial fibrillation? 1. First of all, atrial fibrillation is the atrial cells do not work unitedly anymore, then the function of the heart as a pumping organ will be affected, and the ejection fraction of the heart decreases, affecting the blood supply to all organs of the body. Over time, heart failure will develop. Secondly, atrial fibrillation will seriously affect the hemodynamics of the heart, and will form turbulence, and this turbulence will impact the inner wall of the atria, causing endothelial damage, and will also form thrombus, and once this wall thrombus is dislodged, it is a time bomb, and it will suffer wherever it goes. If the embolus enters the brain, it will form cerebral thrombus, causing cerebral embolism, and the risk of stroke in atrial fibrillation patients is five times higher than normal; if the embolus enters the lower limbs, it will lead to lower limb artery occlusion syndrome, and if the embolus is not treated in time, it will lead to gangrene of the lower limbs in serious cases. Therefore, patients with atrial fibrillation should undergo anticoagulation and antiplatelet therapy in addition to resuscitation therapy to reduce thrombosis. Having atrial fibrillation is not scary, as long as you actively treat it and prevent its complications, you can still live a normal life. In addition, the medication of atrial fibrillation should be guided by a doctor with professional knowledge, and it is also necessary to go to a regular hospital for systematic treatment in the Department of Cardiovascular and Cerebrovascular Medicine.