Atrial fibrillation
Atrial fibrillation is a type of irregular heartbeat caused by a disturbance in the heart's electrical conduction.
Normally, an electrical impulse originates in the right atrium-more precisely, in the sinus node located there-and is transmitted to the ventricles via the heart's electrical conduction system. There, it causes the muscle to contract. The heart pumps, producing a heartbeat.
In atrial fibrillation, however, self-sustaining electrical impulses circle around in the atria and are only partly passed on to the ventricles. This causes an irregular heartbeat that is often too fast. In some cases the heartbeat can also be slow if the electrical signal is not passed to the ventricles because of a so-called "conduction block".
Because of the circulating impulses in the atrium, it cannot fill properly with blood and therefore cannot pump the required amount into the ventricles. This reduces the heart's pumping ability because less blood is ejected into the body.
When high blood pressure is present, the conduction disorder usually occurs because the heart enlarges and undergoes fibrotic (scar) changes. As a result, electrical impulses cannot always be transmitted properly and circulating impulses occur. Atrial fibrillation, in turn, promotes the progression of these changes.
Atrial fibrillation reduces the speed of blood flow in the atria. The blood then flows very slowly, particularly in the so-called atrial appendages (small pouches within the atria). Blood clots can form there and may be carried by the bloodstream to the brain, for example, where they can cause a stroke.
How do you notice atrial fibrillation?
Typical symptoms are a racing heart (palpitations), chest pain and shortness of breath when the heart is beating too fast. At a normal rate you may only notice weakness and tiredness or a general drop in performance. If the heart rate slows down because of a conduction block, dizziness and fainting are also possible.
If atrial fibrillation becomes chronic, it is also possible not to notice it at all. The body more or less gets used to it.
How is atrial fibrillation treated?
Treatment and medical follow-up are important, even though atrial fibrillation - especially at the beginning - usually goes away on its own within 48 hours at the latest.
If left untreated, however, it can recur repeatedly / increasingly often and eventually become persistent. Treatment usually starts with medication; some drugs used to treat high blood pressure also have antiarrhythmic effects. In some cases, an attempt is made to restore a normal rhythm by cardioversion. For this, the doctor delivers an external electric shock to the heart under brief general anesthesia, which often causes it to return to a normal rhythm. In severe cases of heart rhythm disorders, a pacemaker is implanted.
A more modern treatment option is catheter ablation, a small surgical procedure. Using a catheter, usually threaded from a vein in the groin into the right atrium, the abnormal conduction pathway is destroyed by heat or cold. This treatment is considered very successful for newly developed or paroxysmal atrial fibrillation. If atrial fibrillation has been present for some time, the success rate is somewhat lower.
A more modern treatment option is catheter ablation, a small surgical procedure. Using a catheter, usually threaded from a vein in the groin into the right atrium, the abnormal conduction pathway is destroyed by heat or cold. This treatment is considered very successful for newly developed or paroxysmal atrial fibrillation. If atrial fibrillation has been present for some time, the success rate is somewhat lower.
A brief look at the heart's conduction system
The heart is a unique organ. It is the only muscle able to stimulate itself in a synchronized, regular way that adapts to the body's demands. This is made possible by the heart's conduction system. The sinus node mentioned above is located in the right atrium. It is the body's natural pacemaker. It generates electrical impulses and passes them on to the other stations in the heart. Specialized heart muscle cells pick up these impulses and conduct them through both atria. The next station is the AV node (atrioventricular node), which lies between the right atrium and the right ventricle. It delays the impulse slightly so that the atria contract and push blood into the ventricles. From the AV node, the impulse is passed on to the bundle of His, from which the two bundle branches (Tawara branches) conduct it to the Purkinje fibers. This ensures that all regions of the heart are reached.
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This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 11/2025).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
