Nearly 100 percent of arrhythmias, or irregular heartbeats, that occur take place in the atria, or the upper chambers of the heart. The most common ones that we hear about are atrial fibrillation and its cousin, atrial flutter. When this occurs, the heart’s electrical system misfires, causing the rapid firing of too many different impulses at once. This in turn, causes a very fast, chaotic rhythm in the atria.
In this white board session, Patrick J. Tchou, MD, Associate Section Head of the Section of Electrophysiology and Cardiac Pacing in the Department of Cardiovascular Medicine, explains how this can cause a normal heart rate of 50 to 60 beats per minute to rise as high as 300 to 400.