Heart and Blood Conditions

Long QT Syndrome

What Is Long QT Syndrome?

Long QT syndrome (LQTS) is a rare disorder of the heart's electrical rhythm that usually affects children or young adults. It can be present at birth but may not be detected until later in life.

There are four chambers in the heart - the top two are the  atria , and the lower two are the  ventricles . The heart uses a complex electrical system to make the muscle walls of the atria and ventricles pump blood.

The heartbeat is the squeezing and relaxing of the muscle walls at the right times in the right order. The heartbeat starts in the right atrium when a group of cells called the sinus node sends an electrical signal. This is the heart's pacemaker.

The signal travels on nerve-like fibers from the atria to the ventricles and cause the muscle to squeeze. The muscle then relaxes to be ready for the next beat. In children with LQTS, one part of the heartbeat cycle is longer than normal.

Children with LQTS can suddenly develop a fast heartbeat that keeps their heart from contracting the way it should. This can be more common if they are doing a strenuous activity or are emotionally excited or startled.

The arrhythmia can prevent the body and brain from getting as much oxygen-rich (red) blood as normal. If someone's brain doesn't get enough oxygen, they can faint and could die without warning.

Long QT Syndrome in Children

Some children are born with LQTS because one or both of their parents passed down a gene that causes the condition. Parents may not know they have the gene and LQTS themselves because some people with LQTS have no symptoms.

There are several types of inherited LQTS. All affect the electrical signals that to travel through the muscle cells in the heart. Certain medicines can bring out the symptoms of LQTS.

About one in every 7,000 people has LQTS.

Long QT Syndrome at Seattle Children's

Our heart team has treated many children with LQTS. We have extensive experience with the treatment these patients may require.

When you come to Children's, a team of people will take care of your child. Along with your child's cardiologist, you are connected with heart rhythm specialists, nurses, child life specialists, social workers and others, if their expertise is needed. We work together to meet all of your child's health needs and help your family through this experience.

Since 1907, Children's has been treating children only. Our team members are trained in their fields and also in meeting the unique needs of children. For example, the doctors who give your child anesthesia are board certified in pediatric anesthesiology. This means they have extra years of training in how to take care of kids. Our child life specialists know how to help children understand their illnesses and treatments in ways that make sense for their age. Our expertise in pediatrics truly makes a difference for our patients and families.