Atrial fibrillation

A common complication of arterial hypertension is atrial fibrillation.

Atrial fibrillation is a type of heart rhythm disorder in which the heart's electrical conduction is disturbed.

 Normally, an electrical impulse arises in the right atrium more precisely in the sinoatrial (SA) node located there and is passed through the heart's conduction system to the ventricles. There it causes the muscle to contract. The heart pumps and a heartbeat occurs.

In atrial fibrillation, however, electrical impulses circle within the atria and only some are passed on to the ventricles. This produces an irregular heartbeat that is often fast. In some cases the heartbeat can be slow if the electrical signal is not passed to the ventricles because of a so-called "conduction block".

Because of the circling impulses in the atrium, it cannot fill properly with blood and therefore cannot pump the necessary amount of blood into the ventricles. Ultimately this reduces the heart's pumping power, since the volume of blood ejected into the body is reduced.

When high blood pressure is present, the conduction disturbance usually results from enlargement of the heart and from fibrous remodeling within the heart. As a result, electrical impulses cannot always be conducted properly and circular excitation occurs. Atrial fibrillation in turn promotes the progression of these changes.

Atrial fibrillation reduces the speed of blood flow in the atria. Especially in the so-called atrial appendages (small outpouchings within the atria), blood then flows very slowly. Blood clots can form here, which can be carried by the bloodstream, for example to the brain, and cause a stroke.

Typical symptoms are 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 reduction in performance. If the heart rate slows due to a conduction block, dizziness and fainting are also possible.

If atrial fibrillation becomes chronic, it is also possible not to feel anything at all the body more or less gets used to it.

Treatment or monitoring by a doctor is important, even though atrial fibrillation especially in the early phase usually goes away on its own within at most 48 hours.

If it is left untreated, however, it can recur more and more often and ultimately become persistent. Treatment is usually medication at first, and some medications to treat high blood pressure also have antiarrhythmic effects. In some cases restoring the normal rhythm by cardioversion is attempted. For this the doctor delivers an electric shock to the heart from the outside while the patient is under short general anesthesia; this often restores 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 advanced from the femoral vein into the right atrium, the disturbed conduction pathway is destroyed by heat or cold. This treatment method is considered very successful for newly occurring or paroxysmal atrial fibrillation. If atrial fibrillation has been present for a longer time, the success rate is somewhat lower.

The heart is a unique organ. It is the only muscle capable of stimulating itself independently, synchronously, regularly and in response to demand. For this the heart has the so-called conduction system. The previously mentioned sinoatrial node is located in the right atrium. It is the body's natural pacemaker. Electrical impulses are generated there and passed 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 can contract and push blood into the ventricles. From the AV node the impulse is passed to the bundle of His, from which the two bundle branches (Tawara branches) carry the impulse to the Purkinje fibers. This ensures that all regions of the heart are reached.

One very special feature of the conduction system is that the next downstream station can generate an impulse if the predecessor fails. If the sinoatrial node does not send out signals, the AV node can generate impulses itself but at a slower rhythm. If the AV node also stops producing impulses, the heart can still be stimulated by the bundle of His, the bundle branches (Tawara branches) and the Purkinje fibers so that it can beat at a very slow rate.

• http://www.netdoktor.de/krankheiten/herzrhythmusstoerungen/vorhofflimmern/
• https://www.kompetenznetz-vorhofflimmern.de/de
• https://herzstiftung.de/service-und-aktuelles/presse/pressemitteilungen/vorhofflimmern-katheter-ablation
  

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