Arrhythmia

Arrhythmias are caused by a problem with the electrical system in the heart.

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

For example, supraventricular tachycardia (SVT) is the most common cause of a fast heartbeat. It is usually not life threatening. In contrast, long QT syndrome is a genetic condition linked 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. This may cause very rapid heartbeats or a heartbeat that is too slow for the child’s level of activity.

• 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. All 4 chambers need to work in time with each other for the heart to pump well.
• The sinus node, at the top of the right atrium, is the “pacemaker” of the heart. It works to control the heart rate. It 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 made in water when you throw in a pebble. It makes the atria squeeze, or beat.
• Next, the signal moves into the junction between the upper and the lower chambers. This spot is known as the atrioventricular node (AV node). The AV node delays the signal slightly and then passes it on to the 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 should start in the sinus node and follow the same path.

To learn about the electrical signals in your child’s heart, the doctor will use an electrocardiogram. If an abnormal heartbeat does not happen during this test, we may ask your child to wear a monitor at home.

Learn more about what to expect with an ECG.

Wearing a monitor at home may help doctors diagnose an abnormal heart rhythm that did not happen during your child’s ECG. It can also help us learn more about an abnormal rhythm that the ECG did detect.

The type of monitor depends on your child’s symptoms and age.

• For daily symptoms, children typically use a device called a Holter monitor. It can record the heart’s activity for 24 hours.
• For less frequent symptoms, children may use an event monitor. You or your child can start it when your child feels a problem with their heart rhythm.

Learn about what to expect with a Holter monitor or event monitor.

Our doctors use electrophysiology studies to find the cause of an arrhythmia and, in many cases, cure it.

During an EP study, a heart doctor (cardiologist) guides small plastic tubes (catheters) to the heart through the blood vessels of the leg to read the heart’s electrical signals. An EP study is most often used to find the cause of an abnormal heart rhythm. It is sometimes used to tell if a child needs a pacemaker or defibrillator.

If the cause of an arrhythmia is found during an EP study, the doctor may use a form of transcatheter ablation to correct the problem.

Other common tests for arrhythmia include:

• Echocardiogram
• Exercise testing
• Chest X-ray or MRI (magnetic resonance imaging) of the heart
• Blood tests

This means checking your child’s condition over time without treatment. The doctor looks for signs that the arrhythmia might be getting worse or could start to affect your child’s health.

These may be used to correct your child’s heart rate or make an irregular heartbeat steady. The option to use medicine depends on the reason for your child’s arrhythmia and whether doctors can cure it with a procedure like transcatheter ablation.

Just a few decades ago, many children needed heart surgery for arrhythmias that were difficult to treat. Now, doctors can correct many of these arrhythmias with transcatheter ablations.

• During a transcatheter ablation, the doctor guides a small tube (catheter) through the blood vessels of the leg up to the abnormal area in the heart.
• Then, the doctor destroys the small piece of tissue that is causing the problem. They either burn (cauterize) the tissue (radiofrequency ablation) or freeze the tissue (cryoablation).
• The method used depends on the location of the tissue within the heart and how close it is to the heart’s normal electrical system.

Read more about cardiac catheterization procedures.

Children with certain heart conditions may need a pacemaker or defibrillator to restore and control the rhythm of their heart. Pacemakers are small electronic devices that help control the speed and pattern of the heartbeat. They check the heart rhythm and send an electrical impulse to the heart when it beats too slowly or in an irregular way.

A defibrillator is similar to a pacemaker. It checks the heart at all times for life-threatening rhythm problems such as ventricular tachycardia or ventricular fibrillation. These arrhythmias can lead to sudden cardiac arrest (the heart stops beating) and death if not treated. When the defibrillator finds 1 of these rhythm problems, it sends an electrical shock to the heart to bring it back to a normal rhythm.

Read more about pacemakers and defibrillators.

• The Heart Center team includes more than 40 pediatric cardiologists who diagnose and treat every kind of heart problem. We have treated many children with heart rhythm problems — from simple to complex.
• Experienced doctors in our Arrythmia Program offer the full range of treatment options, like medicines, transcatheter ablation and pacemaker and defibrillator
• Seattle Children’s was the first hospital in the Pacific Northwest to establish a program to offer pediatric electrophysiology and pacing services. At our Electrophysiology Clinic, we diagnose new patients, assess patients with known heart conditions and check patients who have pacemakers and defibrillators.
• Our program has 4 pediatric electrophysiologists, which is uncommon among children’s hospitals. There are only about 200 of these specialists in the United States.
• We perform specialized procedures called electrophysiology studies and transcatheter ablation in our state-of-the-art cardiac catheterization labs. We use the most current technology, such as cryoablation, a method that makes procedures even safer for our patients.
• We also have a pediatric cardiac anesthesia team to make sure that your child is comfortable and safe during arrhythmia procedures.

• Seattle Children’s cardiologists see babies, children and teens with arrhythmias. We have experience diagnosing and treating this condition in kids of all ages.
• Your child’s treatment plan is custom-made. Doctors in the Arrythmia Program and Electrophysiology Clinic will review your child’s symptoms, health history and test results to create a plan of care just for your child. We closely check your child’s needs to make sure they get the care that is right for them as they grow.
• If your child was born with a heart condition, we have a special Adult Congenital Heart Disease Program to meet their long-term healthcare needs. This program, shared with the University of Washington, transitions your child to adult care when they are ready.

• Whatever types of care your child needs, we will help your family through this experience. We will discuss your child’s condition and treatment options in ways you understand and involve you in every decision.
• Our Child Life specialists know how to help children understand their illnesses and treatments in ways that make sense for their age.
• Seattle Children’s has many resources, from financial to spiritual, to support your child and your family and make the journey as smooth as possible.
• Many children and families travel to Seattle Children’s for care. We help you coordinate travel and housing so you can stay focused on your child.
• Read more about the supportive care we offer.

• Seattle Children’s doctors are studying technologies to refine arrhythmia care and get the best possible outcomes for children. These include using virtual reality to see a child’s heart in 3 dimensions and robotic arms to move treatment tools with great precision.
• Dr. Stephen Seslar is an international leader in developing a patient registry so doctors everywhere can pool data about arrhythmia care. The registry allows doctors to learn more about the best ways to care for children who have an electrophysiology study or transcatheter ablation.
• Research by Dr. Jack Salerno has helped doctors tell which children with arrhythmia are at risk for sudden cardiac arrest (the heart suddenly stops beating) and how they can safely take part in sports. This work has allowed more children to return to activities that matter to them.