What is atrial fibrillation?
Atrial fibrillation is a heart rhythm disorder characterized by rapid and disorganized electrical activity in the atria, the upper chambers of the heart.
This chaotic activity leads to ineffective atrial contraction and a generally rapid and irregular ventricular rhythm.
Under normal circumstances, the heartbeat is initiated by the sinus node, the heart’s natural “pacemaker” located in the right atrium. The electrical impulse then spreads in an orderly fashion through the atria and to the ventricles via the atrioventricular (AV) node, ensuring coordinated and efficient contractions.
In the case of atrial fibrillation:
- The atria no longer contract in a coordinated way but rather “quiver” at a very high frequency (400 to 600 beats per minute);
- The AV node, which acts as a “filter,” allows only some of these impulses to reach the ventricles;
- The ventricles therefore beat irregularly and often rapidly, typically between 100 and 160 beats per minute at rest, whereas a normal resting heart rate is between 60 and 100 beats per minute.
- This disorganized rhythm disrupts the heart’s ability to pump effectively and can have significant consequences, particularly an increased risk of blood clots forming in the atria.
The Different Types of Atrial Fibrillation
Atrial fibrillation presents in various forms, classified based on their duration and progression:
Paroxysmal AF: Episodes that end spontaneously, usually within 48 hours, sometimes lasting up to 7 days. These episodes may be occasional or frequent;
- Persistent AF: Episodes lasting more than 7 days or requiring medical or electrical intervention to restore a normal rhythm;
- Long-standing persistent AF: Continuous AF lasting more than a year when a rhythm control strategy is considered;
- Permanent AF: AF accepted by both the patient and the physician, with no further attempts to restore sinus rhythm.
This classification is important as it influences treatment options and long-term prognosis.
