August 2, 2015

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Atrial Fibrillation (AFib)

Heart rate during AFib

In a heart that is beating normally, the rate of ventricular contraction is the same as the rate of atrial contraction. In atrial fibrillation, however, the rate of ventricular contraction is less than the rate of atrial contraction. The rate of ventricular contraction in atrial fibrillation is determined by the speed of transmission of the atrial electrical discharges through the AV node. In people with a normal AV node, the rate of ventricular contraction in untreated AFib usually ranges from 80 to 180 beats/minute; the higher the transmission, the higher the heart rate.

Some older people have slow transmission through the AV node due to disease within the AV node. When these people develop AFib, their heart rates remain normal or slower than normal. As disease in the AV node advances, these people can even develop an excessively slow heart rate and require a permanent pacemaker to increase the rate of ventricular contractions. Continue Reading

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Reviewed on 5/27/2015
Atrial Fibrillation Quiz