An arrhythmia is a change in the rhythm of your heartbeat. The heart can beat too fast (tachycardia) or too slow (bradycardia). An arrhythmia can also mean that your heart beats irregularly (skips a beat or has an extra beat). At some time or another, most people have felt their heart race or skip a beat. These occasional changes can be brought on by strong emotions or exercise. They usually are not a cause for alarm. Arrhythmias that occur more often or cause symptoms may be more serious and need to be discussed with your doctor.

What causes an arrhythmia?
The heart has 4 chambers. The walls of the heart contract to push blood through the chambers. The contractions are controlled by an electrical signal that begins in the heart's natural "pacemaker" (the SA node). The rate of the contractions is influenced by nerve impulses and hormones in the blood. A problem here, or signals coming from elsewhere, can cause an arrhythmia.

Minor arrhythmias may be caused by excessive alcohol use, smoking, caffeine, stress or exercise. The most common cause of arrhythmias is heart disease, particularly coronary artery disease, abnormal heart valve function and heart failure. However, arrhythmias can occur for no known reason.

Is an arrhythmia serious?
In most people, arrhythmias are minor and not dangerous. A small number of people, however, have arrhythmias that are dangerous and require treatment. Arrhythmias are also more serious if you have other heart problems. In general, arrhythmias that start in the lower chambers of the heart (the ventricles) are more serious than those that start in the upper chambers (the atria). Your doctor will talk with you about the type of arrhythmia you have and whether you need treatment.

Tests available
One test that may required for diagnosis is an electrocardiogram, also called ECG or EKG. You may need to take a treadmill test while your heart is monitored, or monitor your heart while you do your daily activities. This can be done with a Holter monitor for 24 hours. Other equipment is available for use when monitoring for more 24 hours. Further testing may be necessary.

Types of arrhythmias

• Atrial fibrillation. Atrial fibrillation is the most common cardiac arrhythmia. The risk of developing atrial fibrillation increases with age — AF affects four percent of individuals in their 80s. An individual may spontaneously alternate between AF and a normal rhythm (paroxysmal atrial fibrillation) or may continue with AF as the dominant cardiac rhythm without reversion to the normal rhythm (chronic atrial fibrillation). Atrial fibrillation is often asymptomatic, but may result in symptoms of palpitations, fainting, chest pain, or even heart failure. These symptoms are especially common when atrial fibrillation results in a heart rate which is either too fast or too slow.
• Paroxysmal atrial tachycardia (PAT). The heart has episodes when it beats fast, but regularly. This type of arrhythmia may be unpleasant but is usually not dangerous. PAT is an example of an arrhythmia where the abnormality is in the electrical system of the heart, while the heart muscle and valves may be normal. PAT is susceptible to alcohol excess, stress, caffeine, an overactive thyroid or excessive thyroid hormone intake, and certain drugs.
• Ectopic beats. The heart has an extra beat. Treatment usually is not needed unless you have several extra beats in a row and/or other problems with your heart (such as heart disease or congenital heart failure).
• Ventricular tachycardia and ventricular fibrillation. The heart beats too fast and may not pump enough blood. These types of arrhythmias are very dangerous and need immediate treatment.