An arrhythmia is any change in the regular, even rhythm of the heartbeat. If your child has an arrhythmia, his or her heart might beat too fast or too slow, or it might skip a beat or have extra beats. An arrhythmia might result from a physical condition — such as a heart defect —or in response to outside factors, such as a fever, infection, and certain medications. Even crying and playing can briefly alter a child’s heart rate.

Most arrhythmias are harmless, but some can be serious and even life-threatening. If your child’s heart beats too fast (a condition known as tachycardia), or too slow (bradycardia), it might affect the heart’s ability to pump blood efficiently to the rest of the body. Irregular blood flow can damage organs, including the kidneys, liver, heart, and brain.