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 is about 60 to 100 beats per minute. The normal heart rate is faster in children.
In multifocal atrial tachycardia (MAT), many locations in the atria fire signals at the same time. Too many signals lead to a rapid heart rate. It most often ranges between 100 to 130 beats per minute or more in adults. The rapid heart rate causes the heart to work too hard and not move blood efficiently. If the heartbeat is very fast, there is less time for the heart chamber to fill with blood between beats. Therefore, not enough blood is pumped to the brain and the rest of the body with each contraction.
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:
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
When the heart rate is less than 100 beats per minute, the arrhythmia is called "wandering atrial pacemaker."