How does the heart normally pump blood to the body?
I like to think of the heart as a set of instruments following an internal metronome that keeps the beat. That metronome is an internal set of electrical wiring that helps keep the heart beating regularly to the right tune and determines how fast or slow it should be beating. Blood flows from the body and lungs through veins into the two atria at the top of the heart. When these top compartments are filled, the metronome ticks off a beat and tells the atria to push that blood down into the two lower compartments, called the ventricles. Once the ventricles are filled with this blood, the metronome ticks off again and tells these two lower chambers to push blood out to the rest of the body through the arteries. The timing of the top and bottom metronome keeps the song of the heartbeat playing in synchrony.
How does the heartbeat change in AF?
AF is a disease of the top part of this metronome. Rather than tapping out a regular beat for the atria to follow, the heart’s metronome loses its ability to keep time. It often sends signals that tell the atria to beat too quickly or too slowly and may space out those beats in strange ways. Without the right timing, the atria end up pumping far too fast or drop to beats that are far too slow. They also fall out of sync with the ventricles, which causes them to sometimes try to push blood into the heart’s lower chambers when they’re not ready for it or to pause for too long when pumping is needed. This disruption in the timing of the heart’s instruments destroys the finely tuned song of the heartbeat, causing the walls of the atria to jump irregularly in a pattern called fibrillation.
How does AF cause disease?
This irregular beat means that blood sits in the atrial chambers for longer than it should. When blood sits in one place for too long, it can start to clot. Those clots can get pumped out of the heart by accident and can lodge in blood vessels, blocking blood flow to areas of the body that rely on that flow for oxygen. When this happens in the brain, it’s called a stroke. That clot blocks off the supply of essential oxygen to brain tissue and causes it to die. This is one of the main reasons why AF is such a dangerous disease.
Who’s at risk?
The major risk factor for AF is age. It’s estimated that one in every four people over 40 will end up with AF at some point in their life, but it’s not until age 60 that risk really starts to climb. On top of that, people with high blood pressure, diabetes, and different forms of heart disease also seem to have a higher risk of developing AF.
How do I know if I have AF?
AF can show up as a variety of symptoms all related to problems with the heartbeat. Palpitations are a very common symptom to look out for and show up as a feeling that your heart is beating abnormally fast. In addition to palpitations, individuals with AF can have trouble breathing, episodes of tiredness or weakness, episodes of sudden dizziness, and chest pain. You can also have episodes of fainting. Your heartbeat can also give itself away. A simple test you can do at home is to feel your pulse for a full minute and see if the beat is regular. If it’s not, you should see your doctor.
Fortunately, AF is a treatable disease and we have a variety of medications that help to bring some control back to the heart’s metronome. On top of controlling the rate and rhythm of the heart, we can also use blood thinners to prevent those dangerous clots from forming. Most of the danger of AF comes from not knowing about it. If you’ve had regular episodes of palpitations, fatigue, weakness, trouble breathing, chest pain, dizziness, fainting, or if you think your heartbeat is irregular, make an appointment to see a doctor as soon as possible.