Understanding Pediatric Arrhythmias: From SVT to Bradycardia—Symptoms, Diagnosis, and Management

Pediatric arrhythmias cover a range of abnormal heart rhythms in children, from common supraventricular tachycardia (SVT) to serious ventricular arrhythmias and inherited channelopathies. Early recognition of symptoms—such as rapid heartbeats, feeding difficulties, fainting episodes, or unexplained fatigue—paired with timely testing (ECG, Holter monitoring, and echocardiography) allows clinicians to distinguish benign from dangerous rhythms. Management spans simple vagal maneuvers and medications for stable SVT, to synchronized cardioversion, antiarrhythmic drugs, catheter ablation, or device implantation for more severe cases. With structured long-term follow-up by a pediatric electrophysiologist, most children go on to lead active, healthy lives.

1. Introduction

An arrhythmia arises when the heart’s electrical system malfunctions, causing the heartbeat to be too fast, too slow, or irregular. In children, these rhythm disturbances can occur in hearts that are otherwise structurally normal or alongside congenital heart defects. While some arrhythmias are harmless and resolve on their own, others can compromise cardiac output, leading to dizziness, fainting, or, in rare cases, sudden cardiac arrest. Understanding the types, signs, and treatments is key to ensuring prompt, effective care and preventing long-term complications.

2. Common Types of Pediatric Arrhythmias

2.1 Supraventricular Tachycardia (SVT)

• Mechanism: Rapid heart rate originating above the ventricles, often due to an extra electrical pathway.

• Presentation: Sudden onset of rapid, regular heartbeats (180–220 bpm in older children; >220 bpm in infants), irritability, sweating, or feeding refusal in infants.

• Prognosis: Most children respond well to initial therapies and may outgrow the condition by adolescence.

2.2 Ventricular Tachycardia (VT)

• Mechanism: Fast rhythm arising from the ventricles, sometimes linked to structural anomalies.

• Presentation: Wide-complex rapid heartbeat, poor perfusion, dizziness, or syncope.

• Risk: Potential to degenerate into ventricular fibrillation; requires prompt intervention.

2.3 Bradyarrhythmias

• Sinus Bradycardia: Heart rate below age-appropriate norms; often benign but may indicate sinus node issues.

• Atrioventricular (AV) Block:

  • First-degree: Prolonged PR interval without dropped beats.

  • Second-degree: Occasional dropped beats (Mobitz I or II).

  • Third-degree: Complete dissociation of atrial and ventricular activity—typically requires pacemaker placement.

2.4 Inherited Channelopathies

• Examples: Long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic VT.

• Characteristic: Genetic defects in ion channels leading to life-threatening arrhythmias despite a structurally normal heart.

• Management: Lifelong surveillance, lifestyle adjustments, medications, and often an implantable defibrillator.

3. Clinical Recognition

Parents and clinicians should watch for:

• Palpitations or Fluttering Sensations: Especially in older children who can describe the feeling.

• Feeding Difficulties and Poor Weight Gain: Infants may stop nursing or tire quickly during SVT episodes.

• Syncope or Near-Syncope: Fainting spells suggest inadequate cerebral perfusion, warranting urgent evaluation.

• Exercise Intolerance and Fatigue: May indicate ongoing tachycardia or bradycardia.

• Pallor, Sweating, or Cyanosis: Signs of hemodynamic compromise during an arrhythmic event.

4. Diagnostic Workup

1. Electrocardiogram (ECG): The first, essential test to characterize rhythm, intervals, and conduction pathways.

2. Holter or Event Monitor: Ambulatory recording for 24 – 48 hours (or longer) to capture intermittent arrhythmias and correlate them with symptoms.

3. Echocardiography: Ultrasound evaluation to detect underlying structural heart disease that may predispose to arrhythmias.

4. Electrophysiology Study (EPS): Invasive testing to pinpoint the origin and mechanism of complex or recurrent arrhythmias, often guiding ablation.

5. Genetic Testing: Recommended when inherited channelopathies are suspected, enabling family screening and tailored therapy.

5. Treatment Strategies

5.1 Acute Management

• Vagal Maneuvers: For stable SVT—diving reflex (ice to the face) in infants, Valsalva maneuver in older children.

• Adenosine: Rapid IV bolus for temporary AV nodal block in SVT.

• Synchronized Cardioversion: Electrical shock (0.5 – 1 J/kg) for unstable tachyarrhythmias.

• Pharmacologic Support: Epinephrine or atropine for bradycardia with poor perfusion; external or transvenous pacing if medications fail.

5.2 Long-Term Management

• Antiarrhythmic Medications: Beta-blockers, sotalol, or amiodarone based on arrhythmia type and severity.

• Catheter Ablation: High-success procedure (> 90 %) for SVT pathways or focal tachycardias, offering potential cure.

• Device Implantation:

  • Pacemakers for symptomatic AV block or severe bradycardia.

  • Implantable Defibrillators (ICDs) for survivors of ventricular fibrillation or high-risk channelopathies.

6. Follow-Up and Prognosis

Children treated for arrhythmias require ongoing care to:

• Monitor growth-related changes in device settings or medication dosing.

• Assess for recurrence of arrhythmia or new conduction issues.

• Adjust lifestyle recommendations, including safe exercise guidelines.

• Provide education and psychosocial support for both child and family.

Most children with SVT achieve long-term freedom from arrhythmia, especially after ablation. Those with inherited channelopathies often need lifelong management but can lead full lives with appropriate precautions and therapy.

7. Conclusion

Pediatric arrhythmias, though varied in presentation and risk, can be effectively diagnosed and treated when recognized early. A multidisciplinary approach—combining prompt acute care, individualized long-term strategies, and dedicated follow-up—ensures that children with rhythm disturbances enjoy optimal health and activity levels.

About Dr. Neeraj Jain

Dr. Neeraj Jain is a leading paediatric cardiologist specializing in the diagnosis and management of heart rhythm disorders and congenital heart disease in children.

Website: https://www.cardiopaediatrician.com/Contact Email: info@cardiopaediatrician.comPhone: 07424794298

Hospital Affiliations:

• The Holly Private HospitalHigh Road, Buckhurst Hill, Essex, IG9 5HXTel: 020 8505 3311

• The Spire London East HospitalRoding Lane South, Redbridge, Essex, IG4 5PZTel: 020 8551 1100

• Spire Hartswood HospitalEagle Way, Great Warley, Brentwood, CM13 3LETel: 01277 232525