Health Encyclopedia

Multifocal atrial tachycardia

Definition

Multifocal atrial tachycardia is a rapid heart rate that occurs when too many signals (electrical impulses) are sent from the upper heart to the lower heart.

Causes, incidence, and risk factors

The human heart gives off electrical impulses, or signals, which tell it to beat. Normally, these signals begin in an area of the upper right chamber called the sinoatrial node (sinus node or SA node). This node is considered the heart's "natural pacemaker." It helps control the heartbeat. When the heart detects a signal, it contracts (or beats). The normal heart rate in adults about 60 to 100 beats per minute. The normal heart rate is faster in children.

In multifocal atrial tachycardia (MAT), multiple locations within the heart fire signals at the same time. Too many signals lead to a rapid heart rate -- anywhere from 100 to 250 beats per minute. The rapid heart rate causes the heart to work too hard. If the heartbeat is very fast, the heart has less time to fill up with blood, so it doesn't have the right amount of blood to pump to the brain and the rest of the body.

MAT is most common in people age 50 and over. It is often seen in people with conditions that lower the amount of oxygen in the blood. These conditions include:

Bacterial pneumonia
Chronic pulmonary obstructive disease (COPD)
Congestive heart failure
Lung cancer
Lung failure
Pulmonary embolism

You may be at higher risk for MAT if you have:

Coronary heart disease
Diabetes
Had surgery within the last 6 weeks
Overdosed on the drug theophylline
Sepsis

Symptoms

Chest tightness
Light-headedness
Fainting
Sensation of feeling the heart beat (palpitations)
Shortness of breath
Weight loss and failure to thrivein infants

Additional symptoms that may be associated with this disease:

Signs and tests

An examination shows a rapid heart beat of 100 to 180 beats per minute. Blood pressure is normal or low. There may be signs of poor circulation.

Tests to diagnose MAT include:

ECG
Electrophysiologic study (EPS)

Heart monitors are used to record the rapid heart beat. These include:

24-hour Holter monitor
Portable, long-term loop recorders -- allow you to start recording if symptoms occur
If the patient is in the hospital, the heart rhythm is monitored 24 hours a day.

Treatment

If you have a condition that can lead to MAT, that condition should be treated first.

Treatment for MAT includes:

Methods to improve blood oxygen levels
Magnesium given through a vein
Stopping medications, such as theophylline, which can increase the heart rate
Medicines to control the heart rate, such as such as calcium channel blockers (verapamil, diltiazem) or certain beta-blockers

Expectations (prognosis)

MAT can be controlled if the condition that causes the rapid heart beat is treated and controlled.

Complications

Cardiomyopathy
Heart failure
Reduced pumping action of the heart

Calling your health care provider

Call your health care provider if:

A rapid or irregular heartbeat is associated with other MAT symptoms
You have MAT and your symptoms get worse, do not improve with treatment, or new symptoms develop

Prevention

To reduce the risk of developing MAT, promptly treat the disorders that cause it.

References

Ferri FF. Ferri’s Clinical Advisor: Instant Diagnosis and Treatment. 8th ed. St. Louis, Mo: Mosby; 2006:540.

Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002:1080-1081.

Olgin JE, Zipes DP. In: Specific Arrhythmias: Diagnosis and Treatment. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007: chap. 35.

Review Date:5/12/2008
Reviewed By:Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School, and Private practice specializing in Cardiovascular Disease, Watertown, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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