Introduction to Atrial Fibrillation

Mechanisms of Atrial Fibrillation

Several mechanisms have been proposed to explain the disorganized electrical activity that precedes atrial fibrillation. These mechanisms include:

• Atrial fibrillation occurs when a single electrical wave, known as the "mother" wave, is fractionated into multiple "daughter" wavelets resulting in a short refractory period and slow conduction which then precipitates atrial fibrillation.

• Atrial fibrillation can occur as a result of a single, rapidly-firing focus of electrical impulses within the atria. These electrical impulses can be discharged either continuously or in intermittent, short bursts.

• In some cases, atrial fibrillation can occur as a result of ectopic (premature) beats that arise from the ostium (opening) of the pulmonary vein in the left atrium.

Irrespective of the specific mechanism involved, atrial fibrillation reduces the efficiency of contraction of the heart leading to pooling of blood within the heart's chambers and the formation of blood clots that can lead to stroke and other potentially serious complications.