Atrial Flutter, Fibrillation and Low Blood Pressure

Atrial flutter and atrial fibrillation are similar disorders. Both start in the atria, the small upper chambers of the heart. Both cause the atria to beat from 250 to 300 beats per minute (the normal range is typically 60 to 100 beats per minute).

The difference between atrial fibrillation and atrial flutter is in the regularity of the heartbeat. While atrial fibrillation is characterized by a rapid, irregular heartbeat, a heart affected by atrial flutter beats regularly, although at a much faster pace than normal.

During atrial flutter high levels of electrical activity in the atria also affect the ventricles (the ventricles are the larger, lower chambers of the heart, and are responsible for pumping blood to the body). Although not every beat from the atria is passed on to the ventricles, the ventricles do beat abnormally fast at approximately 150 beats per minute.

As a result of the increased frequency of the heartbeat, atrial flutter interferes with the heart's ability to pump blood to the body effectively. This can result in hypotension (low blood pressure) and heart failure. People experiencing low blood pressure and heart failure may experience weakness and shortness of breath.

Diagnosis of atrial flutter relies heavily on EKG readings . An EKG printout of atrial flutter will display a characteristic "saw-toothed" appearance.

In addition to the possibility of experiencing low blood pressure, atrial flutter also increases the risk of developing a blood clot. People living with atrial fibrillation have a higher risk of developing a blood clot than people with atrial flutter, however both conditions can result in blood clots.

If ventricular beats exceed 220 beats per minute, atrial flutter becomes life-threatening. Electrical cardioversion with defibrillation paddles is the most commonly used emergency treatment. If such treatment is not possible, beta blockers, or other drugs, may be used. Beta blockers block the action of the atrioventricular (AV) node, a node in the heart that controls the flow of electrical impulses between the atria and the ventricles.

Resources

Beers, M.H. & Berkow, R. (ed). Atrial flutter. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S. & Longo, D. (ed). Harrison's Principles of Internal Medicine, 14th Edition. McGraw-Hill, New York, 1998.

NASPE-Heart Rhythm Society. (updated 2003). Atrial fibrillation and flutter.

National Library of Medicine. (updated 2004). Ventricular tachycardia. MedlinePlus Medical Encyclopedia.