Atrial tachycardia (AT) is a type of abnormal heart rhythm, or arrhythmia. It occurs when the electrical signal that controls the heartbeat starts from an unusual location in the upper chambers (atria) and rapidly repeats, causing the atria to beat too quickly.

What happens during atrial tachycardia?

A normal heartbeat begins with an electrical impulse from the sinus node, a single point in the heart's right atrium (right upper chamber). During atrial tachycardia, an electrical impulse outside the sinus node fires repeatedly, often due to a short circuit — a circular electrical pathway. Electricity circles the atria again and again, causing the upper chambers to contract more than 100 times per minute. (A normal heart rate is between 60 and 100 beats per minute.) The rapid heart contractions prevent the chambers from filling completely between beats.

An arrhythmia centered in the upper chambers of the heart is called a supraventricular tachycardia (SVT) — literally, fast "heartbeat above the ventricles" (lower chambers). Atrial tachycardia usually occurs for brief periods and starts and stops spontaneously. That's called paroxysmal AT. If it continues, it is called persistent AT

What are the symptoms of atrial tachycardia?

Atrial tachycardia may cause no symptoms at all or may cause any of the following:

• Palpitations (a fluttering in the chest)
• Fainting
• Chest pain
• Shortness of breath
• Fatigue
• Heart failure

What causes atrial tachycardia?

Atrial tachycardia occurs most commonly in elderly patients and those with other types of heart disease, though it occasionally appears in children, younger people and those with healthy hearts. Causes include:

• A "stretched" atrium resulting from high blood pressure (hypertension) or from cardiomyopathy
• A previous heart attack
• Excessive use of alcohol, cocaine and other stimulants
• An "irritable focus," when cells outside the sinus node start generating an electrical impulse automatically on their own

Sometimes, atrial tachycardia is idiopathic, meaning doctors can find no specific cause.

What are the complications of atrial tachycardia?

• Incessant (prolonged) atrial tachycardia may lead to cardiomyopathy (a weakening of the heart muscle) and heart failure. This type of cardiomyopathy is often reversible if the atrial tachycardia can be controlled.
• Sometimes atrial tachycardia can lead to another, more serious type of arrhythmia called atrial fibrillation.

How is atrial tachycardia diagnosed?

Atrial tachycardia can sometimes be diagnosed in your physician's office with an electrocardiogram (ECG or EKG). But when atrial tachycardia is an occasional event, an office ECG may be normal. If this is the case, your doctor may give you an ECG monitor to wear at home that will record your heart rhythm over time. These include:

• Holter monitor: a portable ECG you wear continuously for one to seven days to record your heart rhythms over time
• Event monitor: a portable ECG you wear for one or two months, which records only when triggered by an abnormal heart rhythm or when you manually activate it
• Implantable monitor: a tiny event monitor inserted under your skin, worn for several years to record events that only seldom take place

However, treatment decisions are based on a more fine-tuned study of where and how the electrical signals are produced. Your doctor may recommend an electrophysiological study of your heart, during which a narrow, flexible tube called a catheter is threaded through a vein to your heart under light sedation. Fine wires inside the catheter can help pinpoint the origin of the errant electrical signal. Electrophysiology testing is generally combined with catheter ablation — a procedure that aims to cure the arrhythmia by cauterizing its source.

How is atrial tachycardia treated?

• Treatment of any underlying conditions
• Catheter ablation to destroy specific patches of heart muscle that are incorrectly producing electrical signals; usually performed at the same time as an electrophysiological study
• Medications to control the heart rhythm including beta blockers, calcium channel blockers or antiarrhythmic medications such as flecainide, propafenone or amiodarone

For more information about arrhythmias and their tests and treatments, visit the Arrhythmias page or the Johns Hopkins Electrophysiology and Arrhythmia Service.