What is Atrial Fibrillation?

Atrial fibrillation (sometimes nicknamed A-fib or AF) is a rhythm disorder or arrhythmia of the heart. In fact, it is one of the most common rhythm disorders in the world.

To understand what AF is, you have to know how the healthy heart functions. The heart has four chambers: two upper chambers (atria) and two lower chambers (ventricles). The lower chambers are the large areas of the heart that do most of the pumping. The ventricles are so large that they make up the entire sound the doctor hears when he or she listens to your heart with a stethoscope.

The upper chambers are much smaller. Their role is to beat just before the ventricles beat. This allows them to pump an extra measure of blood into the already-full ventricles, so that the ventricles are filled with as much blood as possible before they pump. Doctors have nicknamed this function “atrial kick” because the atria “kick in” a little more blood right before the large chambers of your heart beat.

Atrial fibrillation occurs when the atria try to beat too fast. The atrial rate during AF can be 200, 250, even 300 beats a minute. Your normal resting heart rate should be around 70 beats a minute.

You can see what this can do to the heart by making a fist. Think of this as an atrial beat or contraction. You can probably open and close your fist once every second pretty easily; that would be comparable to a heart rate of 60 beats a minute. You can probably still do it more than once a second. But could you open and close your fist four or five times each second?

If you try, you’ll see that you move your fist but there is not enough time for it to really open and shut. Your hand moves, but it does not clearly open and close. That’s what happens when your atria start to fibrillate. In an attempt to beat three, four or even five times a second (rates of 180, 240 or 300 beats a minute), the atria no longer pump. They quiver. This means that they can no longer pump blood out efficiently.

That creates the problems with AF. First, your atria are no longer offering “atrial kick” so your ventricles are not pumping at maximum capacity. That diminishes what doctors call “cardiac output” and it can make you feel tired or short of breath when you exercise even slightly.

Second, because the atria are quivering rather than contracting, the blood in the upper chambers does not go anywhere. It tends to slosh around the atria instead of getting pumped through the heart. As this blood pools in the atria, it can start to form clots. A stroke occurs when a clot breaks free and gets lodged in the brain (a “brain attack”). People with atrial fibrillation are have a five times greater risk of having stroke than people without atrial fibrillation!

The third problem caused by atrial fibrillation often causes the most symptoms. The healthy heart is a complex system. The electrical energy that triggers an atrial contraction travels down to the ventricles to pump the blood through the body. A healthy person has a one-to-one relationship of atrial and ventricular contractions, that is, every time the atria contract, the ventricles follow suit.

During atrial fibrillation, the ventricles may struggle to keep up the atria. At slightly high atrial rates, the ventricles may indeed keep up a one-to-one relationship, but when atrial fibrillation occurs, it is likely that the ventricular rate will increase (even sharply) but that your heart will no longer be working in synchrony. The atrial rate may be 300 beats a minute, the ventricular rate may be 180 beats a minute. It is the rapid ventricular rate that can give you feelings of a pounding in the chest, a “racing heart,” or rapid heart beat.

Atrial fibrillation is actually a very complex cardiac condition. Although it is a very common arrhythmia, medical experts still are unclear on what causes it and why it develops. For many years, it was believed that atrial fibrillation was “chaotic,” almost a random but very rapid rhythm. Today we know that it is only “seemingly chaotic” but there may be more organization to the rhythm than appears.

There is not just one type of atrial fibrillation. Doctors have identified three main groups of atrial fibrillation.

1.Paroxysmal (sudden, short, stops by itself)
2.Persistent (lasts longer but responds to treatment)
3.Permanent (does not go away or respond to treatment)

Paroxysmal is a medical term for “sudden onset.” Paroxysmal atrial fibrillation starts suddenly, without warning. Typically, it lasts a short time (perhaps just minutes) and then goes away on its own. It is not unusual for people with paroxysmal AF to not know it, because there may be no symptoms.

Persistent AF is like the name sounds. AF may still occur without warning, but now it tends to last longer. It may require some sort of medical treatment (typically drugs) to control it. People with persistent atrial fibrillation will experience periods of time, even long periods, when they do not have AF. But when AF occurs, it can last until it is treated.

Permanent AF is also called chronic AF. At this point, atrial fibrillation occurs all of the time. It no longer responds to treatment.

While everyone in medicine agrees that these are the three main types of AF, it is not always clear where one ends and the next begins. Atrial fibrillation is what doctors call a progressive disorder. That means that most people start out with paroxysmal atrial fibrillation but over time it worsens to persistent AF and then permanent AF.

If your doctor tells you that you have atrial fibrillation, your treatment options will depend on what stage you’re at. For people in the earliest stage, paroxysmal AF, there are a lot of therapies on the market. In fact, many engineers and scientists are working at finding ways to treat paroxysmal atrial fibrillation.

Ablation Frontiers is unique among medical enterprises right now in that our research and development efforts are looking at ways to treat all three types of atrial fibrillation. While many companies are exploring ways to treat paroxysmal atrial fibrillation, few are interested in tackling the much more devastating (and difficult) conditions of persistent or permanent atrial fibrillation. In fact, Ablation Frontiers alone is working on therapeutic options for all three types of atrial fibrillation.

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