
An arrhythmia is an irregular or abnormal heartbeat. An arrhythmia occurs when the electrical signals to the heart that coordinate its rhythm are not working properly. The term “arrhythmia” refers to any change from the normal sequence of electrical impulses, causing abnormal heart rhythms. Almost everyone's heart skips or flutters at one time or another and these mild, one-time palpitations maybe harmless. But there are about 4 million Americans who have recurrent arrhythmias, and these people should be under the care of a doctor.
The atria (the heart’s upper chambers) and ventricles (the heart’s lower chambers) work in concert, alternately contracting and relaxing to pump blood through the heart. The heart’s electrical system is the power source that generates your heartbeat. Your heartbeat is triggered by electrical impulses that travel down a special pathway through your heart. The impulse starts in a small bundle of specialized cells located in the right atrium, called the sinoatrial (SA) node. The SA node is also known as your heart’s natural pacemaker. The SA node sets the rate and rhythm of your heartbeat. Normal heart rhythm is often called normal sinus rhythm because the SA (sinus) node fires regularly.
Cardiac arrhythmias can be divided into categories based on their location and the rate of the arrhythmia: