Conditions

Atrial fibrillation

Atrial Fibrillation — Dr Agueznai, Cardiologist in Casablanca

Atrial fibrillation is the most common heart rhythm disorder (so much so that doctors sometimes simply say "arrhythmia" when referring to atrial fibrillation).
The frequency of atrial fibrillation increases with age: it rises twentyfold between the ages of 40 and 80. Ten per cent of people over 80 have it (compared with 1% of people under 60).

What is atrial fibrillation?

Atrial fibrillation results in a marked acceleration of the contraction rate of the atria: from 300 to 500 beats per minute. Only some of these beats are transmitted to the ventricles, which beat at a rate of between 40 and 200 beats per minute, often irregularly. When the tachycardia also affects the ventricles, it is referred to as rapid atrial fibrillation (complete tachyarrhythmia due to atrial fibrillation). Atrial fibrillation may be occasional ("lone", usually before the age of 60) or recurrent. It may last from a few hours to less than a week ("paroxysmal fibrillation"), a few weeks ("persistent") or a few months or even several years ("permanent"). Ventricular fibrillation Ventricular fibrillation is characterised by abnormally fast and chaotic contractions of the ventricles. They lose their effectiveness and blood circulation is virtually no longer maintained. Ventricular fibrillation is a medical emergency. Without prompt treatment (known as "defibrillation" or "cardioversion"), the person loses consciousness and quickly dies. In addition to medicines that strengthen and regulate the heart, treatment of ventricular fibrillation includes anticoagulants (to prevent blood clots forming in the chambers of the heart) and sometimes the implantation of an automatic implantable defibrillator, which will automatically resynchronise the heart in the event of a ventricular arrhythmia.

The causes of atrial fibrillation are varied and are often linked to wear of the tissues that conduct the electrical impulse through the heart. For example: problems with the mitral valve (between the left atrium and left ventricle) that cause excess pressure in the left atrium; high blood pressure; hyperthyroidism; other heart diseases or heart failure; abuse of stimulants; genetic diseases. Endurance athletes sometimes suffer from atrial fibrillation when their training programme is too intense.

The main complication of atrial fibrillation is embolism. Because atrial fibrillation reduces the effectiveness of the atria, it can cause blood to stagnate ("stasis") in them. This encourages blood clots to form in the atria, and these clots can be carried into the arteries and block the smallest of them, for example in the brain (stroke) or in the retina. In France, atrial fibrillation is estimated to be responsible for a quarter of the 130,000 strokes diagnosed each year. Atrial fibrillation can also lead to potentially fatal ventricular fibrillation. Treatment of atrial fibrillation is based on anticoagulant medicines to prevent clots from forming and antiarrhythmic medicines that slow down and regulate the heart rhythm.

This information is provided for guidance only and does not replace a medical consultation.