Normally, your heart beats at a rate of 60 to 100 beats per minute when you are at rest, and all of the heart chambers beat in unison. If you have AF, the electrical signals that control your heartbeat are abnormal. These signals cause the upper chambers of your heart (the atria) to beat unevenly and very quickly. In fact, the atria beat so quickly that the lower heart chambers (the ventricles) can’t quite keep up, and your heart doesn’t beat in the usual, coordinated manner.
This results in an irregular and rapid heart rate, often ranging from 100 to 180 beats per minute. When this happens, the heart cannot pump blood around the body as well as it needs to.
(Khan Academy, 2014)
Atrial fibrillation is a common problem affecting approximately 35,000 people in NZ (1% of the population). The risk of developing AF increases with age, occurring in about 5% of people older than 65 years and about 10% of people older than 80 years. Many people do not know they have it, with approximately one-third of those with AF thought to be undiagnosed.
Other things that increase your risk of AF include:
It is possible for otherwise healthy people to have AF – in fact up to one-third of people with AF have no obvious underlying cause; a condition known as lone atrial fibrillation.
Atrial fibrillation is often picked up when having a medical examination for something else.
Atrial fibrillation (AF) affects at least 5 in every 100 (5%) of people in New Zealand aged over 65 years. Having AF puts you at higher risk of some conditions compared to people without AF. For example,
Because the atria are contracting quickly and abnormally, they don’t pump blood through the heart properly. Blood can then pool in the heart and a blood clot may form. If the clot breaks loose and leaves the heart, it can travel via your blood vessels to other organs in your body. If a clot lodges in a blood vessel that supplies your brain and cuts off the blood supply, it causes a stroke.
If you have AF, you may experience palpitations (an awareness of your heart beating or pounding in your chest). Other symptoms include:
Some people have no symptoms at all, and AF is only detected after a doctor (or another healthcare worker) notices that your pulse is irregular.
Occasional missed beats or extra beats between regular beats are very common and usually nothing to worry about, but best discussed with your doctor. AF, on the other hand, has no pattern to it at all and is continuously irregular.
A quick guide from the British Heart Foundation:
Listen to these examples from the British Heart Foundation
AF is diagnosed using a simple, painless test called an electrocardiogram (ECG).
However, if you have paroxysmal (irregular bouts of) AF, your heartbeat may be normal at the time the ECG is recorded. To detect paroxysmal AF, you may need to have a Holter monitor test arranged.
The treatment for atrial fibrillation varies from person to person depending on a number of factors, including the severity of your symptoms, the cause and duration of your atrial fibrillation, and whether you have any underlying health problems. However, in general, the main aims of treatment are to:
Having AF puts you at high risk of having a stroke, and preventing blood clots is one of the most important parts of treating AF, as blood clots can cause strokes. To prevent blood clots, you may be prescribed blood-thinning medicines (anticoagulants) such as warfarin or dabigatran. Because anticoagulants stop blood clots, they may cause bleeding. Your doctor will consider your risk of bleeding and whether anticoagulants are suitable for you. Read more about anticoagulants and which anticoagulant is best for you. Aspirin is no longer recommended for preventing blood clots in people with atrial fibrillation.
You may be prescribed medicines to slow down the rate at which your ventricles are beating and help bring the heart rate to a normal level. Medicines used to control the heart rate include groups of medicines called beta blockers (for example, metoprolol, bisoprolol and carvedilol), or calcium channel blockers (diltiazem and verapamil). If your heart rate is still not settled with beta blockers and calcium channel blockers, your doctor may also add digoxin.
If you are not doing so well on rate control medications your doctor may prescribe medicines or recommend procedures to control your heart's rhythm. Medicines used to control the heart rhythm include amiodarone, sotalol, flecainide, propafenone and disopyramide. These are usually prescribed by a cardiologist.
Tests & Investigations for Heart Disease Heart Foundation (NZ)Learn about heart disease: atrial fibrillation Cardio smart (USA)Arrhythmias – Normal heartbeat animation Watch, Learn, Live: Interactive Cardiovascular Library – American Heart AssociationAtrial fibrillation – Conduction system of the heart Watch, Learn, Live: Interactive Cardiovascular Library – American Heart Association