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Cardiovascular Institute

What is Atrial Fibrillation?



Normal Sinus Rhythm


Tachycardia


Atrial fibrillation (Afib or AF) is one of the most common heart rhythm disorders. It is caused by a problem in the electrical conduction system of the heart. Normally, electrical impulses begin in the upper chambers of the heart (the atria) and then are conducted through ‘wiring” into the main pumping muscles (the ventricles). The electrical impulse originates in the sinoatrial node (SA) of the right atrium, which travels through the atrioventricular (AV) node into the ventricle to trigger a coordinated contraction of all the heart chambers. This is commonly referred to as normal sinus rhythm (NSR).

For patients with atrial fibrillation, the electrical impulse begins in multiple regions. This creates chaotic electrical impulses that cause the “atria to fibrillate.” Typically, this will produce fast, irregular heart rates and beats (tachycardia). Afib can be diagnosed using an electrocardiogram (EKG). It demonstrates the chaotic activity of afib when compared with normal sinus rhythm.

What are the symptoms of AF?

  • Fatigue
  • Sensation of irregular or fast heartbeat
  • Lightheadedness
  • Exercise intolerance
  • Vague chest discomfort
  • Heart failure
  • Depression or anxiety

Some people may not have any symptoms at all. In fact, many episodes of afib remain undetected and may only be an incidental finding in up 30 to 45% of patients who had an electrocardiogram for unrelated reasons.
 

Normal Sinus Rhythm

Atrial Fibrillation

Classification of Atrial Fibrillation

If you are diagnosed with atrial fibrillation, your doctor may classify you as either paroxysmal, persistent, or permanent, based upon the American Heart Association Guidelines.

Paroxysmal Atrial Fibrillation

Intermittent periods of atrial fibrillation that usually terminate spontaneously and return to normal sinus rhythm. This type of AF can be difficult to diagnose because afib has to occur for an EKG heart monitor to document the occurrence. For this type of AF, ~ 90% of irregular electrical impulses are thought to initiate in the pulmonary veins, making surgical PV isolation the most effective treatment option available.

Persistent Atrial Fibrillation

Patients are in consistent AF and require an intervention, (i.e., cardioversion) to be converted into normal sinus rhythm. Persistent AF usually means that there is a self-sustaining mechanism for irregular electrical impulses within the heart structure.

Permanent Atrial Fibrillation

The atrial fibrillation cannot be successfully cardioverted to maintain normal sinus rhythm. Like Persistent AF, there is a self-sustaining mechanism for irregular electrical impulses within the heart structure. This type of afib does not respond well to medical therapy. Surgery has been one of the only viable options for treatment of Permanent AF.

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