What is atrial fibrillation?
Your heart’s pumping action is controlled by tiny electrical messages produced by a part of the heart called the sinus node. The sinus node is sometimes called your heart’s ‘natural pacemaker’.
Normally, the electrical messages are sent out regularly, with each message telling your heart to contract and pump blood around your body. This is felt as a normal, regular heartbeat, or pulse.
Atrial fibrillation happens because, as well as the sinus node sending out regular electrical impulses, different places in and around the atria (the upper chambers of the heart) also produce electrical messages, in an uncoordinated way. These multiple, irregular messages make the atria quiver or twitch, which is known as fibrillation. This is felt as an irregular and sometimes fast heartbeat, or pulse.