What is AFib?

You asked: What is AFib?

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Atrial fibrillation, or AFib as it’s known among friends, is a common for of heart disease that affects up to 1 in 3 people at some point in their lives costing the US healthcare system about $6 billion per year. Risk factors for AFib include older age, high blood pressure, diabetes, smoking, prior heart attacks, heavy alcohol use, and more. Unlike a heart attack, which is due to a blockage in the blood supply to the heart – a plumbing problem – AFib is due to a problem in the heart’s conduction system – an electrical problem.

The heart’s electrical system functions as the brains behind the operation, so to speak. The heart is a muscle that requires coordination to beat properly and send blood out to your body. Normally, the mastermind controlling this coordinated contraction is a region of the heart inside the right atrium made up of a specialized group of cells that form what’s called the sinoatrial node (SA node). Once the SA node fires, it sends out an electrical impulse through the heart’s specialized conduction system, which acts like an electrical highway making the top 2 chambers of the heart – the atria – beat before the bottom 2 chambers of the heart – the ventricles.

heart anatomy

Important to understand though is that most of the heart muscle acts as a follower. It does not exclusively take orders from the SA node. Rather, it only waits for the earliest signal to fire before it does what it’s told and contracts. In all of us, each part of our heart has its own firing rate. It just so happens that the SA node is most often the earliest. If there is another part that fires faster, this too can set off a heartbeat, which we call a premature beat. These are very common and can often be felt as palpitations, skipped beats, or extra beats. For most people, these extra beats, if they happen, will be mostly isolated and the normal rhythm – sinus rhythm – will resume thereafter.

Atrial fibrillation, on the other hand, is more of an everyone-for-him/herself type of rhythm. Unlike sinus rhythm where the SA node sequentially tells various parts of the heart to beat in order to have a coordinated contraction, the atria – top 2 chambers – go wild in an electrical cacophony! Once they start, the fun don’t stop, as it were. Instead of one leader telling the rest of the heart what to do and when, there is complete electrical chaos in the atria. Groups of cells are firing off signals all over the place without regard for any sort of team effort. The result is that not only do the atria not contract well because they are just quivering with electricity, the electrical highways that bring these signals to the ventricles – the bottom pumping chambers – are constantly bombarded with firing orders. They do the best they can, but with so many impulses to respond to, the heart rate – here defined by the number of times the ventricles contract per minute – can become very fast. When they have to pump so quickly, they can become inefficient at it, not being allowed the proper time to fill and empty as they should.

apple watch ecgWhen AFib takes over, people can have a variety of symptoms such as palpitations, heart racing, and even dizziness or passing out if the pumping function of the heart is affected. If you check your own pulse, or have a wearable such as the Apple Watch that does it for you, you can pick up on this fast, irregular heartbeat, which could be your first clue that you might have AFib. Although these symptoms may cause people to take notice, AFib can also go unnoticed by many. The reason this can be dangerous and is so important to recognize is because of the risks of having atrial fibrillation.

Two of the potential side effects of AFib are a compromise in the heart’s function from the fast, uncoordinated heart rate leading to a reduction in its pumping abilities – known as heart failure – and the formation of blood clots in the atria because of the compromise in blood flow when the atria are quivering instead of pumping. When these blood clots form and break off, they can go to various parts of the body, including the brain, and cause strokes. It is important to diagnose and treat AFib to avoid these dreaded outcomes.

 

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