Cardiovascular system Atrial fibrillation

The atrial fibrillation is one of the commonest heart arrhythmias. They occur in more than 5% of the population older than 70 years old, but can also affect youngsters. In the atrial fibrillation, there is a very fast and chaotic atrial contraction instead of a more synchronized one, causing the atria to become ineffective in helping the heart to pump blood.

The causes of the atrial fibrillation are: heart valve diseases, coronary diseases, myocardiopathy, hyperthyroidism, high pressure, alcohol abuse, among others. However, an atrial fibrillation may occur without heart disease, and then is called as isolated atrial fibrillation.

The main symptom is palpitation (feeling of heart strongly beating or in surge). Shortness of breath may also occur. The greatest risk is in the potential clot formation inside the atria and their possible embolism, causing a stroke.


The treatment varies with each case. Atrial fibrillation occurs in more than 30% of the cases in the postoperatory of a cardiac surgery and is usually transient. In other cases, the treatment will depend on the accompanying disease. There are drugs able to revert the fibrillation and other drugs to control the rate (decreasing the heart acceleration). An electrical shock (cardioversion) can be used in some cases to revert the arrhythmia. Anticoagulants are needed in patients with persistent fibrillation.


An invasive treatment may be necessary in other situations. The left atrium ablation by catheter and the AV node ablation with pacemaker implantation are exceptional procedures, as well as the surgery for atrial fibrillation. In the surgery, ablation lines are usually made inside the atrium when there is indication for surgery of the associated mitral valve, aiming to prevent the mechanism that originates the fibrillation (reentry). This procedure can be performed with several energy sources such as ultrasound, cryoablation (by cold), among others. The success chance is around 70%.

* More information on the surgical interventions such as the aforementioned Pacemaker Implantation and Mitral Valve Surgery can be found in Cardiovascular System > Procedures and Interventions.

Support notes

Heart valve diseases: The heart valves are unable to fully open (stenosis) or properly close (failure), or there is a combination of both conditions. Click here to go to the page of Valvulopathies and to know more about this subject.

Coronary diseases: Also called ischemic cardiopathy, this is the term used to define the narrowing of coronary arteries, caused by atherosclerosis. Click here to go to the page of Ischemic Cardiopathy and to know more about this subject.