What is atrial fibrillation? 4, 5
The heart is divided into four sections called chambers.
Cross section of the heart showing the four chambers and heart valves
Every day, the heart beats about 100,000 times, sending 2,000 gallons of blood surging through your body. Although it’s no bigger than your fist, your heart keeps blood flowing through the 60,000 miles of blood vessels that feed your organs and tissues. The four chambers of the heart work together to pump blood around the body. The top chambers (known as the left and right atria) pull blood into the heart, and the bottom chambers (known as the left and right ventricles) push blood out to the body. Normally, the opening and closing of valves in the heart makes a distinct 'lub dub' sound, which can be heard by using a stethoscope. However, if you have a problem with your heart, additional sounds may also be heard. These are sometimes called heart murmurs and may be the result of AF.
When you have an AF episode, the top chambers contract very quickly and irregularly (very quick heartbeats are known as tachycardias; irregular heartbeats are known as arrhythmias, both can be a symptom of AF). This prevents the atria and ventricles from working together the way they should, causing some blood to pool within the atria.
The different types of atrial fibrillation 1, 2
Atrial fibrillation (AF) can be divided into distinct categories, mainly based on how long each fibrillation episode lasts. However, there is no way of telling if you will actually feel each individual attack.
Although AF is defined by how long it lasts, 1 in 3 people with AF have no symptoms while experiencing an episode. This is referred to as 'silent AF' and may result in AF not being discovered until it causes a significant health problem, such as stroke or heart failure. Diagnosing silent AF is possible, but it is often only noticed incidentally during regular physical examinations. 1, 2, 6
These are short episodes that come and go and usually stop within 48 hours, but may last for up to 7 days. Infrequent AF is sometimes called paroxysmal AF.
These are persistent episodes that last for longer than 7 days. Over time, infrequent episodes of AF will turn into long-term episodes. In other words, AF gets worse with time.