About Atrial Fibrillation (AF)
To understand atrial fibrillation, it’s important to understand the normal heartbeat, as well as Atrial Flutter, which is a related rhythm disturbance.
Normal Sinus Rhythm
Normally, the upper chambers (atria) beat first, pushing blood into and “priming” the lower chambers (ventricles). The ventricles, which are thick and muscular and provide essentially all of the pumping action of the heart, then beat to push the blood to the body. The blue dots in the image to the right denotes the upper chambers beating about once per second.
Atrial Flutter is a common rhythm disturbance that is similar to AF in that it feels about the same to patients, and has the same consequences including stroke. Unlike AF, however, it is not irregular and chaotic; instead, it is a regular short circuit loop, usually in the right atrium. The blue dots in the image to the right show that the upper chambers are beating much faster, about four times per second.
It’s important to distinguish atrial flutter from AF because they are managed differently; unlike AF, atrial flutter is usually very easily and permanently eliminated by catheter ablation, with a very low incidence of complications.
During AF, the atria don’t actually pump blood at all, and so don’t “prime” the ventricles. Instead, the atria “quiver” extremely rapidly and irregularly (denoted by the continuous blue line in the image to the right), causing the ventricles to beat rapidly and irregularly too, often about twice normal. The lack of “priming” and the rapid and irregular beating makes the heart pump less effectively.
Are there different kinds of AF?
Yes, it appears that there are several kinds. We often think of AF as a problem common to older patients with longstanding heart problems such as previous heart attack, leaky valves, and so forth. Sometimes, however, AF is seen in patients with an otherwise normal heart, and this is likely to be a very different kind of AF. In addition, AF is often divided into paroxysmal (comes and goes), persistent (stays until treated with a shock or a medicine), and permanent or chronic (no therapy seems to prevent it) types. These distinctions are made because the implications of these different kinds of AF, as well as the best way to manage AF, depend on type.