Childhood arrhythmias: treatment and monitoring

Childhood arrhythmias are disturbances in the formation or conduction of electrical impulses in a child's heart. They can be asymptomatic and benign (for example, rare extrasystoles), or they can manifest as palpitations, weakness, fainting, and even lead to life-threatening conditions. Unlike in adults, the range of causes in children is broader: from congenital anomalies of the conduction system and ion channels to the consequences of congenital heart defects and previous surgeries. The approach to assessment and treatment takes into account age-related heart rate norms, body weight, and pharmacokinetic characteristics. [1]

Modern pediatric electrophysiology is based on three principles: 1) accurate phenotyping of the arrhythmia (what is the mechanism? Where is the substrate? Is there structural pathology?); 2) priority of safety and evidence (pediatric doses, age references); 3) teamwork of a pediatrician, cardiologist, electrophysiologist and, if necessary, a geneticist and cardiac surgeon. This is reflected in the PACES/HRS consensus statements, reviews on pediatric electrophysiology and AHA/ACC/ESC guidelines for individual arrhythmias. [2]

In recent years, treatment strategies have shifted toward catheter ablation (for symptomatic reciprocating supraventricular tachycardia, pre-excitation syndromes, and some ventricular arrhythmias) and "smart" pharmacotherapy, taking into account age, weight, and comorbidities. For hereditary arrhythmias (long QT, catecholaminergic polymorphic VT), the emphasis is on preventing sudden death—beta-blockers, avoidance of triggers, selective ablation of triggers, and, when indicated, implantable cardioverter-defibrillators. [3]

The key to a good prognosis is early recognition of dangerous signs (syncopia on exertion, family cases of sudden death, congenital syndromes) and the correct choice of tactics: not to “treat the ECG,” but to reduce the risk and return the child to normal activity with a minimal burden of therapy on quality of life. [4]

Epidemiology

The most common arrhythmias in children are supraventricular tachycardias (SVT), primarily atrioventricular reciprocating tachycardias (AVRT) via an accessory pathway and atrioventricular nodal reciprocating tachycardias (AVNRT). The incidence of SVT episodes in childhood is estimated at approximately 1-3 cases per 1000 children; in infants, prolonged paroxysms with signs of heart failure are possible if recognized late. Life-threatening ventricular tachyarrhythmias and primary electrical diseases are significantly less common but account for the majority of the risk of sudden death in young people. [5]

The use of catheter ablations in children is increasing, driven by the proven efficacy and safety of these technologies: large series demonstrate high rates of long-term cure for spondyloarthritis and Wolff-Parkinson-White syndrome (WPW) with a low rate of serious complications in centers with pediatric experience. This is reflected in the PACES/HRS consensus statement on ablation (0-18 years) and practical algorithms for WPW in children. [6]

Ventricular extrasystoles and idiopathic ventricular tachycardias (e.g., from the right ventricular outflow tract) in healthy children often have a benign course, but require risk stratification (burden of extrasystoles, stress responses, echocardiography/MRI data). A systematic approach is described in modern reviews; pediatric data are still limited, and some decisions are extrapolated from the adult ESC guidelines on ventricular arrhythmias and prevention of sudden death (2022). [7]

Pure atrial fibrillation in children is rare and is often secondary (valvular defects, postoperative conditions, cardiomyopathy, hyperthyroidism). Treatment follows the general principles of the ACC/AHA/HRS with cautious anticoagulation according to scales adapted to pediatrics and early elimination of the underlying cause. [8]

Reasons

The causes of arrhythmia in children are divided into structural (congenital heart defects, postoperative scars, cardiomyopathy, myocarditis) and electrical (channelopathies - long/short QT, Brugada syndrome, catecholaminergic polymorphic VT; accessory conduction pathway in WPW). In infants, transient features of autonomic regulation and conduction play a significant role, while in adolescents, hormonal and autonomic changes play a significant role. [9]

Medications and metabolic factors (macrolides, antifungals, stimulants, electrolyte imbalances, thyrotoxicosis) can trigger both supraventricular and ventricular arrhythmias. In adolescents, common triggers include caffeine in energy drinks, dehydration, sleep deprivation, and stress. Correcting these factors often reduces the frequency of attacks. [10]

Following correction of complex congenital defects (Fontan procedure, tetralogy of Fallot, etc.), an arrhythmogenic substrate develops: scarring, dilation, and pressure/volume overload. Here, the role of routine monitoring increases, and the strategy is a combination of ablation, hemodynamic correction, and, if necessary, devices. [11]

Finally, some children have a hereditary predisposition: family cases of sudden death, syncope, unclear seizures - a reason for an in-depth assessment and, if indicated, genetic testing followed by family screening. [12]

Risk factors

Red flags: syncope with exertion or in water, nocturnal/unprompted syncope, family history of sudden death at a young age, known channelopathies/cardiomyopathies, congenital heart defects after surgery. The presence of any of these signs requires expedited referral to a pediatric cardiologist/arrhythmologist. [13]

Modifiable risk factors include electrolyte imbalances (potassium/magnesium deficiency), hyperthyroidism, fever (especially in Brugada syndrome), medications that prolong the QT interval, and stimulants. In adolescents, sleep patterns, caffeine/energy drink consumption, and dehydration during exercise are all modifiable. [14]

In children with congenital defects and after cardiac surgery, the risk includes atrial/ventricular dilation, residual defects, and elevated chamber pressure, which increases myocardial arrhythmogenicity. Such patients are monitored using specialized programs with periodic Holter/stress testing. [15]

In hereditary arrhythmias, triggers include emotional stress, intense exercise, cold, fever, and certain medications - family education and "precaution" cards are essential (which medications to avoid, how to respond to symptoms). [16]

Pathogenesis

Most childhood SVTs are re-entrant tachycardias (closed circuit): atrioventricular nodal re-entry or circuit involving the accessory pathway (WPW). Infants have a high proportion of automatic tachycardias (ectopic atrial tachycardia), which are maintained by increased automaticity of the lesion. [17]

Ventricular arrhythmias in children are often idiopathic (from the right ventricular outflow tract, fascicular VT) and are caused by local abnormal automaticity/calcium metabolism triggers; in patients with structural diseases, reentry substrates are located along scars. Channelopathies lead to disruption of ionic currents (sodium, potassium, calcium), which prolongs or shortens repolarization and increases the risk of polymorphic VT/ventricular fibrillation. [18]

Autonomic imbalance (high sympathetic/vagal tone) explains the variability in frequency and the triggering of attacks by stress, lack of sleep, and dehydration. In young children, the immaturity of the conduction system and variable refractoriness make episodes more frequent, but some are "outgrown." [19]

In patients after surgery and with cardiomyopathy, scar-remodeled channels, volume/pressure overload and atrial/right ventricular stretching play a key role, which forms persistent re-entry circuits and maintains arrhythmia. [20]

Symptoms

Symptoms depend on age and the type of arrhythmia. Infants with SVT often "don't complain," but present as poor feeders, pale, sweaty, and with rapid breathing; prolonged paroxysms lead to heart failure and hepatomegaly. Preschoolers and schoolchildren typically experience sudden palpitations, weakness, a "lump in the throat," and sometimes chest pain, dizziness, or syncope. [21]

Ventricular arrhythmias manifest as chest thumps, sudden dizziness, and blurred vision, especially during stress or emotional events; with channelopathies, syncope may be the first and only symptom. Any fainting during physical exertion is a red flag. [22]

Between attacks, the child may feel normal, so symptom diaries, knowledge of triggers, and availability of portable ECG recording (e.g., in adolescents, cardiac recorders/wearable devices with single-lead ECG; clinical confirmation is essential) are important. [23]

A separate group is postoperative children and patients with congenital defects: they are alarmed by “new” fatigue, a drop in tolerance to stress, increased respiratory rate, edema, and a night cough - this could be either arrhythmia or its hemodynamic consequences. [24]

Forms and stages

Large groups: supraventricular arrhythmias (AV nodal reentry, AV reciprocal via accessory pathway, atrial tachycardia, atrial flutter/fibrillation) and ventricular arrhythmias (idiopathic PVCs/VT, arrhythmias associated with cardiomyopathy/myocarditis, channelopathies). Bradyarrhythmias (sinus bradycardia, AV blocks) and disorders of sinus node automaticity are considered separately. [25]

In children, paroxysmal (sudden onset/end, normal rhythm between attacks) and persistent forms (lasting >30 seconds or requiring termination), as well as recurrent and monomorphic/polymorphic (for VT) are often distinguished. The emergency management and choice of long-term therapy depend on this. [26]

Channelopathies and ventricular arrhythmias are stratified by risk of events: international guidelines offer algorithms that consider symptoms, family history, QT interval, exercise/provocative testing data, and response to therapy. Decisions (e.g., regarding ICD placement) are always individualized within pediatric multidisciplinary teams. [27]

For children with WPW pattern without symptoms, risk assessment algorithms are used - invasive electrophysiological study (EPS) when indicated, especially in athletes/adolescents, discussion of prophylactic ablation in case of high risk of rapid conduction along an accessory pathway. [28]

Table 1. Common childhood arrhythmias: “signals” and basic tactics

Arrhythmia	What is the child/parents complaining about?	First steps
AV reciprocal/AV nodal ventricular tachycardia	Sudden "fast heartbeat", weakness, paleness	ECG recording, training in vagal maneuvers, treatment plan, discussion of ablation in case of recurrence
Ectopic atrial tachycardia	Fatigue, tachycardia "almost constantly"	ECG/Holter, Echo, pharmacotherapy, ablation discussion
Idiopathic PVCs/VT	"Shocks", discomfort, sometimes syncope	ECG, Holter, stress, Echo/MRI; in case of symptoms/high burden - ablation
Channelopathies (long QT, CPVT)	Syncope/seizures, emotional/stressful events	Urgent referral to an arrhythmologist; beta blockers, avoid triggers; ICD risk stratification [29]

Complications and consequences

Frequent paroxysms of SVT lead to tachycardiomyopathy (a decrease in ejection fraction due to a prolonged high heart rate), growth retardation in infants, and decreased school performance in children. Early recognition and treatment of the arrhythmia (medications or ablation) are usually completely reversible and prevent structural changes in the heart. [30]

Ventricular arrhythmias and channelopathies carry a risk of syncope and sudden cardiac death, especially under stress; timely diagnosis and prevention (beta-blockers, trigger ablation, ICD in some cases) significantly reduce the risk. Family information and screening of relatives are mandatory. [31]

After cardiac surgery, arrhythmias worsen hemodynamics and prognosis, increasing the need for repeat hospitalizations. A comprehensive approach (hemodynamic correction, substrate ablation, and device removal) reduces the burden on the child and family. [32]

Psychological consequences (anxiety in anticipation of an attack, restrictions in sports) require support: correct explanations, individual permission to participate in physical education, an action plan for symptoms return the child to normal activity. [33]

Diagnostics

If arrhythmia is suspected in a child, the doctor prescribes the following types of tests:

• 12-lead ECG (attack/interictal), Holter monitoring 24-72 hours, long-term event recorders as indicated.
• Echocardiography (structure, function, defects), if necessary - cardiac MRI (scars/myocarditis/cardiomyopathy).
• Exercise testing (in adolescents) to induce arrhythmia and assess the QT/QE response; electrolytes, thyroid hormones, and inflammatory markers if myocarditis is suspected.
• Genetic testing - in family cases of sudden death, suspected channelopathy/cardiomyopathy (after consultation with a geneticist).

How an episode is recorded: Parents are taught how to quickly record an ECG (at the clinic/emergency room) or use portable single-channel devices for adolescents (diagnosis confirmation is only after a doctor's interpretation). For frequent but brief attacks, a long-term skin recorder is useful. [34]

Supraventricular tachycardia on the ECG: narrow QRS complexes, regular rhythm of 180-250/min (higher in infants), retrograde P-waves; in WPW - signs of delta wave between attacks. Ventricular arrhythmias - wide complexes, AV dissociation/capture; in idiopathic VT from the outflow tract - typical left bundle branch block and inferior axis. Echo/MRI help to exclude structural causes. [35]

Additional instrumental diagnostics:

• Electrophysiological study (EPS) - in children with recurrent/symptomatic SVT, high-risk WPW, persistent VT: allows substrate mapping and ablation in the same session.
• Transesophageal electrophysiological study (TES) - for provoking and diagnosing NVT in children without vascular access.
• Provocation tests (epinephrine/load) for suspected LQTS/CPVT are performed in specialized centers.
• Family screening (ECG/Echo ± genetics) for hereditary forms. [36]

If a child presents with sudden "palpitations with dizziness," the first step is to rule out SVT: an ECG is recorded, vagal maneuvers are tried (in trained adolescents), and hemodynamics are assessed. If instability is present, electrical impulse therapy is administered; if stability is present, adenosine is administered in a hospital setting, followed by stratification and discussion of ablation. For syncope with exercise, the route is expedited: ECG, echocardiography, exercise/MRI as indicated, and prompt consultation with an arrhythmologist. [37]

Table 2. What is “looked for” during the initial assessment of arrhythmias in children

Block	Question	Why is it important?
Anamnesis	Fainting, stress/emotions, family sudden death	Red flags of channelopathies/VT
ECG/Holter	Arrhythmia type, conduction, QT	Determines tactics and risk
Echo/MRI	Defects, cardiomyopathy, scars	Structural substrate/exclusion of myocarditis
Laboratory	Electrolytes, TSH/T4	Rule out reversible causes
Plans	Diary/wearable ECG, training	Increases the chance of catching a paroxysm [38]

Differential diagnosis

What are childhood arrhythmias confused with?

• Neurogenic/vasovagal syncope: fainting in the heat/in a stuffy room, precursors - nausea, sweating; ECG is normal.
• Panic attacks/anxiety: Feeling of heart palpitations, but ECG is normal during symptoms; long-term recording helps.
• Sinus tachycardia in fever/anemia/thyrotoxicosis: explainable cause, gradual onset/end.
• Epilepsy: When experiencing “seizures,” always consider cardiogenic syncope and record an ECG/Holter.

How to distinguish in practice:

• An ECG "during" symptoms (or a wearable recorder) is the best way.
• Orthostatic tests, carotid sinus massage (in adolescents, in hospital) - as indicated.
• Stress test - if the events are related to sports/emotions.
• Targeted screening of families if hereditary forms are suspected. [39]

Table 3. NVT versus “harmless” increase in heart rate

Sign	NJT	Sinus tachycardia
Start/End	Suddenly/with a 'click'	Gradually
Frequency	Very high (often >180-200/min)	Below, changes with breathing/posture
Provocation	Often for no apparent reason	Fever, dehydration, stress
Response to vagal maneuvers/adenosine	Stops/diagnoses	Slows down, but does not "stop" [40]

Treatment

1) Emergency care for tachycardia. In case of hemodynamic instability – electrical impulse therapy (cardioversion) according to pediatric protocols. In case of stable narrow tachycardia – vagal maneuvers (in adolescents – a modified Valsalva maneuver under control), then adenosine bolus with monitoring (diagnoses and treats SVT). If SVT recurs – temporary pharmacotherapy (beta-blockers/antiarrhythmics) until the question of ablation is decided. [41]

2) Long-term strategy for NVT and WPW. In frequently recurring/symptomatic forms, preference is given to catheter ablation as a first-line method in older children and adolescents; in infants, a “bridge” of drug therapy followed by ablation is possible if the problem persists. The current PACES/HRS consensus (children 0-18 years old, including those with congenital defects) confirms the high efficacy and safety of the procedure in experienced centers. [42]

3) Ventricular arrhythmias. For idiopathic symptomatic PVCs/VT with high burden, ablation is the preferred option; for channelopathies, beta-blockers in adequate doses, avoidance of triggers; for CPVT, emphasis on strict beta-blockade ± flecainide, consideration of ablation of triggers; for high-risk patients, ICD in a multidisciplinary team. The ESC-2022 Guideline on Ventricular Arrhythmias sets the basic principles of risk stratification. [43]

4) Atrial fibrillation/flutter in children. Treatment of underlying causes (thyrotoxicosis, inflammation, defect), rate/rhythm control using adapted regimens, cautious anticoagulation taking into account age and risk of bleeding. The decision on ablation is made by the pediatric atrial fibrillation team. The new ACC/AHA/ACCP/HRS (2023) AF guidelines are important as a framework but require pediatric adaptation. [44]

5) Drug therapy: what's changing. The current AHA guideline (2024) for the pharmacotherapy of arrhythmias in the fetus/child/adolescent has systematized doses and indications (beta-blockers, flecainide/propafenone, sotalol, amiodarone, etc.) with an emphasis on safety and monitoring. The choice of drug and form (liquid/tablet) depends on age and weight, and dose adjustments are based on clinical findings and ECG/Holter monitoring. [45]

Table 4. When to consider catheter ablation in a child (simplified)

Situation	Explanation
Frequent/symptomatic SVT, not controlled by medications	Improves quality of life, prevents tachycardiomyopathy
WPW with high risk of rapid conduction	Prevention of fatal events, especially in athletes
Idiopathic symptomatic PVCs/VT with high burden	Cure, reduce the risk of cardiomyopathy
Postoperative arrhythmias on a scar substrate	Combination with hemodynamic correction/devices [46]

Table 5. Medicines for childhood arrhythmias: safety guidelines

Class	Usage	Comments
Beta blockers	NVT, channelopathies, CPVT	Drug of choice for LQTS/CPVT; doses by weight
Flecainide/propafenone	Ectopic atrial tachycardia, SVT	Requires exclusion of structural pathology, QRS/QT monitoring
Sotalol	NJT/JT	QT monitoring, caution in case of electrolyte disturbances
Amiodarone	Reserve for severe/refractory	Long-term side effects, organ function monitoring required [47]

Prevention

Primary prevention includes educating families and adolescents on symptoms and triggers, cardiac screening at visits (family history of sudden death, syncope on exertion), appropriate treatment of fever/dehydration, and caution with QT-prolonging drugs. The updated AAP policy emphasizes the importance of universal screening for sudden death risk factors in all children, not just athletes. [48]

Secondary prevention – personalized plans: an "action map" for an attack of SVT (vagal maneuvers for adolescents, when and where to seek help), family reminders for channelopathies (list of prohibited medications, tactics for fever/stress), regular Holter/exercise monitoring according to plan, early discussion of ablation in case of relapses. In families with hereditary arrhythmias – screening of relatives. [49]

Forecast

Most children with SVT and idiopathic ventricular arrhythmias, with proper management and, if necessary, ablation, have an excellent prognosis: children return to normal physical activity, and the risk of life-threatening events is minimal. Even in infants with prolonged episodes of tachycardia, recovery of left ventricular function after rhythm control is a rule. [50]

The prognosis for hereditary and "structural" arrhythmias depends on timely risk stratification and adherence to therapy. Modern approaches (genetically informed prophylaxis, beta-blockers, trigger ablation, and devices) significantly reduce the risk of sudden death and improve quality of life; the key is monitoring in specialized pediatric centers. [51]

Table 6. Red flags in a child with heart palpitations

Signal	What to do
Fainting/pre-fainting on exertion or in water	Urgently consult a pediatric cardiologist-arrhythmologist; ECG, echo, stress/MRI as indicated
Familial sudden death <40 years	ECG/Echo screening + genetic consultation
Prolonged bouts of tachycardia in an infant	Hospitalization, hemodynamic monitoring, drug therapy, ablation plan
At night, he loses consciousness without warning.	Exclude channelopathies/VT; accelerated diagnostics [52]

FAQ

• Is it possible to outgrow arrhythmia?

Yes, some childhood arrhythmias (rare extrasystoles, some forms of SVT in infants) become less common with age. However, symptomatic/common forms require evaluation and, often, active treatment—waiting until they "outgrow it" is risky. [53]

• Is catheter ablation safe in childhood?

In specialized centers, yes: high efficiency and low risk of serious complications. Ablation is the method of choice for recurrent ventricular tachycardia/WPW and some ventricular arrhythmias. The decision is made by the pediatric EP team, taking into account age, weight, and anatomy. [54]

• Should sports be restricted?

More often than not, no. After verification of a harmless arrhythmia and/or its treatment, children engage in physical activity on a general basis. In cases of hereditary syndromes and structural diseases, restrictions are individualized and prescribed by an arrhythmologist. [55]

• What are the dangers of energy drinks and some medications?

Caffeine, stimulants, and drugs that prolong QT can trigger seizures. Always check with your doctor about the "prohibited list," especially for channelopathies. If in doubt, show your doctor any new prescriptions or dietary supplements. [56]