Fast/Slow/Arrhythmic Heart Rate on a Child

What Causes a Fast Heart Rate?

A faster than normal heart rate is called tachycardia and can be caused by several things, most of which are benign and are not caused by something wrong with the child’s heart. It can be caused when the child has a fever, when they are dehydrated, when they are anxious or if they’ve been playing a bit too hard. There are two common types of tachycardia that do mean something is wrong with the heart. They are ventricular tachycardia and supraventricular tachycardia. Ventricle tachycardia means something is wrong with the ventricles in the heart, while supra ventricular tachycardia, or SVT means that there is something wrong with the atria and the ventricles. In SVT, the child’s heartbeat can rise to over 220 beats a minute. Though this may scare parents, sometimes easing symptoms of SVT can be as simple as putting a cloth dipped in ice water on the child’s face. Other treatments are more invasive or intense, such as radiofrequency catheter ablation or cardioversion.

What Causes a Slow Heartbeat?

A slow heart rate is called bradycardia and like tachycardia it is most often benign and not caused by a problem with the child’s heart. However, a child whose heart rate is abnormally slow can be suffering from hypothermia, malnutrition or anorexia or low levels of oxygen or potassium. Their thyroid gland may also be putting out low levels of hormone. The heart rate will go back to normal once these problems are treated.
In other children, a slow heart rate means that the sinus node in their heart is firing at a slower than the usual rate. This may be completely benign and does not require treatment. On the other hand, an abnormally slow heartbeat may be caused by an AV block that blocks the transmission of electricity from one area of the heart to the other.

What is a Dangerous Heart Rate?

Medical experts don’t agree on what constitutes a dangerously fast heart rate in a child. They do agree that a child whose heart races even when they are at rest needs to be looked at by a doctor. A heart that beats too fast for too long is not only under stress but puts other organs in the body under stress as well.

What Can Cause an Arrhythmia in a Child?

There are children who are simply born with a problem with their heart that causes it to beat abnormally. Other children develop arrhythmias later on. A child who has an arrhythmia is often tired or weak, feels palpitations in their chest, is dizzy, faints and has low blood pressure. Some arrhythmias go away over time, while others need to be treated either with surgery or medications.