Heart and Blood Conditions


  • Schedule an appointment +

    • For appointments in Seattle, Bellevue, Everett, Federal Way, Olympia, Tri-Cities and Wenatchee, call 206-987-2515.
    • For appointments in Tacoma and Silverdale, call 253-272-1812.
    • For appointments in Alaska, call 907-339-1945.
    • How to schedule

    If this is a medical emergency, call 911.

  • Find a doctor +

  • Locations +

    • Seattle Children's Main Campus: 206-987-2515
    • Bellevue Clinic and Surgery Center: 425-454-4644
    • Everett: 425-304-6080
    • South Clinic in Federal Way: 253-838-5878
    • Olympia: 360-459-5009
    • South Sound Cardiology Clinics: 253-272-1812
    • Tri-Cities (Richland): 509-946-0976
    • Wenatchee: 509-662-9266
    • Pediatric Cardiology of Alaska: 907-339-1945
    • Seattle Children's doctors provide many cardiac services at regional sites throughout the Pacific Northwest. See our complete list of Heart Center locations.

  • Refer a patient +

    • If you are a provider, fax a New Appointment Request Form (NARF) (PDF) (DOC) to 206-985-3121 or 866-985-3121 (toll-free).
    • No pre-referral work-up is required for most conditions. If you have already done testing such as an EKG, Holter monitor or echocardiogram, please fax this information as well as relevant clinic notes and the NARF to 206-985-3121 or 866-985-3121 (toll-free).
    • Your patient will be seen as quickly as possible by the provider who is the best match for managing the current problem.
    • View our complete Heart Center Referral Information (PDF).

What is arrhythmia?

Arrhythmia (pronounced a-RITH-me-ah) is an abnormal heart rhythm. Typically, this means a child’s heart is beating too fast or too slow for the activity they are doing. In some children, an abnormal heartbeat may have serious consequences. But in many cases, symptoms may be bothersome but not a cause for concern.

Arrhythmias are caused by a problem with the electrical system in the heart. This can lead to a heartbeat that’s too fast (tachycardia, pronounced tack-ih-CARD-ee-ah) or too slow (bradycardia, pronounced brad-ih-CARD-ee-ah).

How the healthy heart works

  • The heart has 4 chambers that work like a pump. The atria are the 2 top chambers. They receive blood from the lungs and the rest of the body. The ventricles are the 2 bottom chambers. They pump blood out to the lungs and the rest of the body. It is important for all 4 chambers of the heart to work in sequence with one another to create an effective pump.
  • The sinus node is known as the “pacemaker” of the heart. It works to control the normal heart rate. It’s located at the top of the right atrium. The sinus node makes the heart beat slower during times of rest or sleep and beat faster with exercise or when you are scared or excited.
  • Each heartbeat begins with an electrical wave (signal) that passes from the sinus node through the upper chambers of the heart. This signal travels much like the ripples created in water when a pebble is thrown in. This electrical signal makes the chambers (atria) contract, or squeeze, making them beat.
  • Next, the electrical signal moves into the junction between the upper and the lower chambers. This junction is known as the atrioventricular node (AV node). The AV node delays the signal slightly and then passes it on to the lower chambers (ventricles), making them beat.
  • After the ventricles beat, the heartbeat cycle is complete. There should be no way for the electrical signal to travel backwards up to the atria. Rather, the next heartbeat starts in the sinus node and follows the same path.

Arrhythmia in Children

There are many kinds of arrhythmia that affect the chambers of the heart in different ways. Some are harmless, and some are serious. Children with signs or symptoms of arrhythmia should be evaluated by a heart doctor (cardiologist).

Sometimes arrhythmias are present at birth (congenital), and others are acquired, such as after an infection of the heart or heart surgery.

For example, supraventricular tachycardia (SVT) is the most common cause of a fast heartbeat and is usually not life threatening. In contrast, long Q-T syndrome (LQTS) is a genetic condition associated with life-threatening arrhythmias that may be triggered by exercise or by being startled or frightened.

In other cases, such as after heart surgery, the heart’s normal electrical system may become scarred and not function normally. It may cause very rapid heartbeats or a heartbeat that’s too slow for the child’s level of activity.

Arrhythmia at Seattle Children’s

We have extensive experience providing treatments for children with arrhythmias through our Arrhythmia Program. We have the full range of treatment options, including:

We have state-of-the-art facilities to maximize safety, including low- or no-radiation procedures. A pediatric cardiac anesthesia team makes sure that your child is comfortable and safe during arrhythmia procedures.

When you come to Seattle Children’s, a team of people will take care of your child. Along with your child’s heart doctor (cardiologist), you are connected with newborn specialists (neonatologists), 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.

Seattle Children’s has been treating children since 1907. Our team members are trained in their fields and 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.

Contact Us

Contact the Heart Center at 206-987-2015 for a cardiac referral, a second opinion or more information.