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

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 heart beat. 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 heart beat 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 aged 50 and over. It is often seen in people with conditions that lower the amount of oxygen in the blood. These conditions include:

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

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

• Coronary heart disease
• Had surgery within the last 6 weeks
• Overdosed on the drug theophylline
• Diabetes
• Sepsis (widespread systemic infection)

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.