Abnormal Heart Rhythm

Arrhythmia

Signs and Symptoms
Diagnosis
Treatment

Signs and Symptoms

An abnormal heart rhythm is a change in the speed or pattern of the heartbeat — the heart may beat too slowly, too rapidly or irregularly. When the heart beats too slowly, too little blood is pumped out to the rest of the body. When the heart beats too quickly, it cannot fill completely with blood so the body doesn't receive the blood volume it needs to function properly. Slow heart rates are called bradycardias. Fast heart rates are called tachycardias.

The "normal" number of heartbeats varies with age. The heart beats about 140 times a minute in a newborn, compared to 70 times a minute in an older child at rest. The "normal" heart rhythm also is not constant. See more information about the heart's electrical system.

A heart that beats too fast or too slow can cause:

• Palpitations, which can be skipping, fluttering or pounding in the chest
• Fatigue
• Chest pressure or pain
• Shortness of breath
• Fainting, called syncope
• Lightheadedness or dizziness

Children may not know how to describe what they're feeling. They may have trouble keeping up with other children or realize they are having "spells" and want to sit down and rest during a period of arrhythmia. Sometimes, there are no symptoms at all.

Left untreated, certain abnormal heart rhythms can be very dangerous and in some cases even fatal. On the other hand, some arrhythmias are common and not associated with any health problems, so-called benign arrhythmias. Many children go through life with mild arrhythmia that should be monitored but doesn't require treatment. One of the goals of evaluation is to sort out the serious from the benign forms of heart beat disturbances.

Conditions associated with a rapid heart beat or tachycardia include:

• Supraventricular Tachycardia — The most common abnormal tachycardia in children, supraventricular tachycardia is when an extra electrical pathway located in the heart triggers a fast heartbeat.

• Wolfe-Parkinson White Syndrome — An accessory pathway or atrial-ventricular nodal tachycardia.

• Junctional Tachycardia — This is a fast heart rate that originates within or near the junction of the heart's electrical system between the upper and lower chambers.

• Atrial Fibrillation — This is an irregular heartbeat that may be fast. This rhythm originates in the heart's upper chambers.

• Ventricular Tachycardia — This is a fast heart rate that originates in the lower chambers of the heart.

• Long QT Syndrome — This is a set of symptoms associated with a prolonged interval between certain markers on an EKG exam. QT is a measurement of the electrical recording of the heart. The symptoms are typically fainting, dizziness or even heart arrest, which may be brought on by emotional or physical stress. This condition can be fatal and appears to be genetic in origin.

Conditions associated with a slow heartbeat or bradycardia include:

• Heart Block — This condition occurs when electrical signals can't pass normally between the upper and lower chambers. The heart often has a "back-up" system for pumping blood when this occurs, but it works at a slower rate that may not be adequate.

• Sinus Node Dysfunction — This syndrome can occur when the sinus node — the heart's built-in pacemaker — doesn't work properly.

A child may have both tachycardia and bradycardia. In addition, there are post-operative arrhythmias that sometimes occur when surgery to repair a heart defect inadvertently damages the heart's electrical system, causing tachycardias or bradycardias.