What is Atrial Fibrillation?

When someone is diagnosed with Atrial Fibrillation (A-Fib) it means that their heartbeat is irregular or abnormal. Normally our heart beats at about 70 beats each minute (bpm) and these are rhythmic, like the drumbeat of a song. If you have a normal heart rhythm and you feel your own pulse, you will see that your pulse taps out a regular, predictable beat.  

When you feel your pulse, what you are feeling is the artery expanding or stretching due to the blood pumping through it. Each time the heart beats, all the arteries in the body pulsate. That is why the pulse rate is the same as the heart rate. The pulse rate is controlled by a natural pacemaker, the sinus node, which regularly sends electrical signals to keep the heart beating.

During A-Fib, the atria ‘quiver’ continuously instead of in a unified contraction. We call that quivering “fibrillating.” The atria are not strongly contracting and pumping blood, they are just fibrillating, hence the name atrial fibrillation. The ventricles wait to beat until after the atria beat, so the random fibrillation also causes them to pump at an irregular rhythm. If you feel the pulse of someone who has A-Fib, you will feel the pulse beat fast, then slow, then fast, etc.

This irregular heartbeat can lead to the heart beating too fast or too slow. The former can cause a feeling of the heart racing (palpitations) and the latter can cause dizziness or even fainting. The blood does not get strongly pumped around the body like it should. If blood stays too long in one place it can lead to a risk of blood clots which could break off and block the flow to a part of the body.