What Causes Heart Rhythm Disturbances in Children?

Understanding what causes heart rhythm disturbance or arrhythmia in children, the most common types of arrhythmias, and when treatments such as catheter ablation may be recommended can help parents make informed decisions about their child's care.

What is arrhythmia in children?

Arrhythmia refers to an abnormal heart rhythm. This may occur when the electrical signals that coordinate the heartbeat do not function as they should.

In children, arrhythmias can cause the heart to beat:

• Too fast (tachycardia)
• Too slow (bradycardia) our
• Irregularly

The heart normally beats in a coordinated rhythm controlled by electrical impulses that travel through specialised pathways in the heart. When these electrical signals are disrupted or follow an abnormal pathway, the heart rhythm may become abnormal.

Some childhood arrhythmias occur only occasionally and do not cause significant problems. Others may lead to symptoms such as palpitations, dizziness or fainting, and may require further evaluation by a paediatric cardiologist.

What causes arrhythmia in children?

Arrhythmias in children can develop for several reasons. In many cases, the heart itself is structurally normal, and the problem lies in how electrical signals travel through the heart.

Common causes include:

• Extra electrical pathways

Some children are born with an additional electrical pathway in the heart. This extra pathway can allow electrical signals to travel in a loop, causing episodes of rapid heartbeat. This is seen in conditions such as Wolff-Parkinson-White (WPW) syndrome.

• Abnormal electrical focus

Instead of starting from the heart's natural pacemaker, electrical signals may originate from an abnormal area of the heart muscle, leading to fast or irregular rhythms.

• Congenital heart conditions

Children born with structural heart defects may be more prone to rhythm disturbances. In some cases, arrhythmias may develop after corrective heart surgery due to scar tissue affecting electrical conduction.

• Inherited electrical disorders

Certain genetic conditions can affect how electrical signals move through the heart.

• Medical conditions or triggers

Other factors may occasionally trigger arrhythmias in children, including high fever, infections affecting the heart, electrolyte imbalances, or certain medications.

What are the most common arrhythmias in children?

Several types of arrhythmias can occur in children, but some are seen more frequently than others.

• Supraventricular tachycardia (SVT)

SVT is the most common arrhythmia in children. It causes the heart to suddenly beat much faster than normal due to abnormal electrical activity in the upper chambers of the heart. Episodes may start and stop suddenly and can last from seconds to hours.

• Wolff-Parkinson-White (WPW) syndrome

WPW occurs when a child has an extra electrical pathway connecting the upper and lower chambers of the heart that is visible on the ECG. This extra pathway can allow electrical signals to travel in a circular pattern, triggering rapid heart rhythms.

• Premature heartbeats

Some children may experience premature atrial contractions (PACs) or premature ventricular contractions (PVCs). These extra beats are often benign and may not require treatment if they occur infrequently.

• Ventricular tachycardia

Ventricular tachycardia is less common in children but may be more serious, particularly when associated with underlying heart disease or inherited rhythm disorders.

When should parents be concerned about a child's heartbeat?

Children with arrhythmias may experience symptoms during episodes of abnormal rhythm.

Parents should consider seeking medical advice if their child has:

• Recurrent episodes of very fast heartbeat
• Palpitations or fluttering sensations in the chest
• Dizziness or lightheadedness
• Fainting or near-fainting episodes
• Unexplained fatigue
• Chest discomfort
• Poor feeding, irritability or lethargy in infants

Although many childhood arrhythmias are not life-threatening, persistent or severe symptoms should be evaluated by a doctor.

When is catheter ablation considered for children?

Treatment for arrhythmias in children depends on the type of rhythm disturbance, its frequency, and whether it causes symptoms.

Some arrhythmias can be managed with medication or may even resolve as a child grows older. However, in certain situations, doctors may recommend catheter ablation as a more definitive treatment.

Catheter ablation may be considered when:

• Episodes of supraventricular tachycardia occur frequently
• Symptoms significantly affect the child's quality of life
• Medications do not adequately control the arrhythmia
• Medications cause unwanted side effects
• An abnormal electrical pathway, such as WPW syndrome, is identified and the condition is potentially life-threatening
• Persistent arrhythmias place strain on the heart

For many children with specific arrhythmias, catheter ablation can offer a long-term solution by eliminating the abnormal electrical pathway responsible for rhythm disturbance.

How is catheter ablation performed in children?

Catheter ablation is a minimally invasive procedure performed by a cardiac electrophysiologist. Children are usually given general anaesthesia or deep sedation so they remain comfortable and still during the procedure.

During the procedure:

• Thin, flexible tubes called catheters are inserted through blood vessels, usually in the groin.
• These catheters are guided into the heart using X-ray and specialised mapping systems.
• An electrophysiology (EP) study is performed to map and understand the heart's electrical activity.
• Doctors identify the area responsible for the abnormal electrical signals.
• Energy, typically radiofrequency energy or cryotherapy, is delivered through the catheter to destroy the abnormal tissue causing the arrhythmia.

How effective and safe is catheter ablation for children?

The success rates for catheter ablation are high.

In common conditions such as supraventricular tachycardia, the acute success rate can be as high as 98%. The risk of serious complications is less than 6 in 1,000 patients (0.6%). The success rates and risks are comparable to adults having catheter ablation.

Pacemaker therapy for children

While catheter ablation is often used to treat fast heart rhythms, some children with slow heart rhythms may require a different approach, such as a pacemaker.

For those requiring pacing support, newer technologies such as leadless pacemakers offer an alternative to traditional systems.

Unlike conventional pacemakers that rely on wires, these devices are placed directly within the heart through the veins via a minimally invasive approach. This allows the device to be removed or replaced over time, which can be an important consideration as a child grows. Without leads, there may also be a lower risk of complications, such as infection or lead damage.

At Mount Elizabeth Hospitals, our cardiology and paediatric teams work closely to evaluate each case and recommend a personalised approach that best suits the patient's immediate needs and long-term care.

When to seek specialist advice

If your child has symptoms of a possible heart rhythm problem, early evaluation can help determine whether the condition requires monitoring, medication, or further treatment.