Atrial fibrillation

Atrial fibrillation is one of the most common types of rhythm problem. It is an irregular heart rhythm that is too fast but can be controlled to a normal rate. The atriums (the upper chambers of the heart) move rapidly (300 to 600 times a minute) in response to electrical impulses. Only some of these electrical impulses pass to the ventricles (lower chambers of the heart), causing them to beat irregularly at various rates. The four chambers of the heart are not beating in time, so the strength and timing of the heartbeat becomes irregular, causing less blood to be pumped out by the heart.

Atrial fibrillation can sometimes arise with no obvious cause. However, it can result from conditions that cause the upper chambers of the heart to dilate abnormally, including:

Myocardial infarction (heart attack)
Coronary artery disease
Hypertension (high blood pressure); and
Disease of the heart valves.

Atrial fibrillation can arise in the first few days after heart surgery, especially valve surgery, as the paths the electrical impulses travel down can be temporarily 'upset' by the operation. In this case, the artrial fibrillation is quickly identified and can sometimes be corrected while you are in hospital.

It can also arise in people who do not have heart disease but who:

Have hyperthyroidism (an overactive thyroid gland)
Have low potassium levels in the blood; or
Drink too much alcohol.