Your child has been diagnosed with long QT syndrome. This condition affects the electrical system of the heart, and can lead to a dangerous heart rhythm. The QT interval is measured on an electrocardiogram (EKG or ECG), which is a recording of the electrical activity of the heart.

Some kids with long QT syndrome have no symptoms. Others may feel changes in their heartbeat or feel lightheaded (like they're going to faint) at times. To help your child stay safe and healthy, follow the cardiologist's advice about medicines, diet, and exercise.

• Give your child any prescribed medicines exactly as directed.
• Your cardiologist gave you a list of some medicines your child should not take:
  • Be sure to check the list before giving your child any medicine.
  • If you have any questions about the medicines on the list, ask your cardiologist.
• You can see a complete list of medicines to avoid at www.crediblemeds.org.
• If you're not sure if it's safe to give your child prescription or over-the-counter medicines, call your cardiologist.
• Ask your cardiologist which activities are safe for your child to do and which to avoid.
• Don't let your child do activities where fainting could be dangerous, such as swimming alone or rock climbing.
• Make sure your child eats foods that are high in potassium, such as oranges, bananas, sweet potatoes, and spinach.
• Don't give your child grapefruit or grapefruit juice.
• Have your child wear a medical ID necklace or bracelet at all times.
• Make sure your family and other caregivers are trained in CPR.
• If your child plans to do a high-exertion activity, be sure there is an automated external defibrillator (AED) nearby.

Your child:

• has vomiting for 24 hours
• has diarrhea for 48 hours
• feels lightheaded more often than usual
• faints but recovers right away

Your child:

• has a seizure
• is unconscious and can't be awakened

Tell the emergency medical team that your child has long QT syndrome. If your child can't be awakened, begin CPR and use an AED, if available.

How is long QT syndrome diagnosed? Doctors will:

• ask about a child's health history
• take a family health history
• do an EKG to check how the heart is beating
• do exercise testing (stress test)
• sometimes, do genetic testing

How is long QT syndrome treated? Many patients with LQTS take a medicine called a beta blocker. Beta blockers help the heart beat more slowly. They can sometimes cause lightheadedness or make it worse, and can make some people more tired than usual.

What causes long QT syndrome? Often, long QT syndrome is inherited, meaning parents can pass it to their children. Other times, doctors don't know why it happens. Your cardiologist may ask that other family members get genetic testing.

What happens if someone has a dangerous heart rhythm even when following the cardiologist's advice? Some kids have to get a small device called a defibrillator implanted under their skin. If a child has a dangerous heart rhythm, the device can reset the heart to a normal rhythm.

Can children with long QT play sports? Some kids can fully participate in sports, but only under the careful guidance of their cardiologist.