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Dr. Alessandro Giardini
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Supraventricular tachycardia or SVT is the most common significant rhythm disturbance in children and young people. It is the sudden onset of a very fast heart rate, typically between 180 and 280 beats per minute, caused by an abnormal electrical circuit operating above the level of the ventricles. Most episodes start abruptly, stop abruptly, and leave the child feeling tired but otherwise unharmed.
The vast majority of children with SVT are entirely normal between episodes. Their hearts are structurally sound, their ECG in sinus rhythm may be completely unremarkable, and they participate in sport and school without restriction. For families who have witnessed an SVT episode, especially for the first time, the experience can be deeply frightening. Understanding what is actually happening, and when treatment really is necessary is very empowering.
Not every child with SVT needs medication. Not every child on medication needs to have an ablation. The right treatment plan depends on the type of SVT, the age of the child, the frequency and duration of episodes, and the presence or absence of any underlying heart condition.
SVT is not a single diagnosis but a family of arrhythmias. The mechanism underneath determines both the likelihood of spontaneous resolution and the best approach to treatment.
Atrioventricular re-entrant tachycardia (AVRT) is the most common type in infancy. It uses an accessory pathway, an extra electrical connection between the atria and ventricles that is not supposed to be there. Wolff-Parkinson-White syndrome (WPW) is the best-known example. A significant proportion of infants with AVRT will have no further episodes after the first year of life, as the pathway loses its ability to conduct. This spontaneous resolution makes the management of SVT in babies quite different from management in older children and teenagers.
Atrioventricular nodal re-entrant tachycardia (AVNRT) involves a re-entry circuit within the AV node itself. It is more common in older children and adolescents and is much less likely to resolve spontaneously. This is the type most often seen in teenagers who report recurrent episodes of sudden pounding heartbeat and light-headedness.
Understanding which type is present, sometimes visible on a 12-lead ECG taken at the time of the palpitation or sometimes only evident during an electrophysiology study, guides every decision that follows.
An infant who has one episode of SVT in the first weeks of life, converts easily, and then has no further episodes for months may not need any treatment beyond parental education about vagal manoeuvres and clear guidance on when to seek care. Dr Giardini's approach in this age group is to give families the tools to manage brief self-terminating episodes at home, and to set clear thresholds in terms of episode duration, symptoms, and age for seeking urgent review.
A single episode in an otherwise healthy child with no structural heart disease and a normal resting ECG may not require long-term medication, particularly if the episode terminated spontaneously or with a simple vagal manoeuvre. The decision involves balancing the risk of recurrence against the side effects and compliance burden of daily medication.
Dr Giardini recommends medication when episodes are frequent enough to affect quality of life, when they are prolonged and not reliably self-terminating, or when vagal manoeuvres consistently fail to convert the rhythm. The goal of medication is to reduce the frequency and duration of episodes, not necessarily to eliminate them entirely. Medical treatment is also required as a preventive measure when the episodes of SVT are associeted with symptoms that suggest that the heart is struggling to maintain normal circulation like in thos children who faint, those who have chest pain or those who feel tired, dizzy or out of breath during an epsiode.
Beta-blockers are the most commonly used first-line agents in children, with a well-established safety profile across age groups. Flecainide is used in older children when beta-blockers are insufficient, and digoxin has historically been used in infants, though its role has evolved over time. Starting medication in infants or very young children always involves a period of monitored observation.
Medication is a holding strategy in many cases. It buys time for the child to grow and for the family to reach a point where a definitive procedure is appropriate, or to demonstrate whether the arrhythmia will resolve spontaneously.
A cardiac ablation is the procedure that identifies and interrupts the abnormal electrical pathway or circuit responsible for SVT. This is the only treatment that offers a permanent cure. The success rates in experienced hands are excellent (around 95%), and for most children the procedure is performed as a day case under general anaesthesia.
Dr Giardini would discuss ablation when medication has failed to control episodes adequately, when the child is experiencing side effects that limit the use of medication, or when the family and child have reached a point of wanting a definitive solution rather than ongoing pharmacological management. For teenagers in particular, the prospect of taking daily medication indefinitely versus a single procedure with a high cure rate makes ablation a very reasonable first choice.
Age and size matter. Most centres do not offer ablation in young children (usually under 15 kg of weight) unless there are compelling clinical reasons. This is because the smaller vascular access and proximity of the catheter to critical structures in a young child means the risk-to-benefit ratio shifts with growth. In an infant with medically refractory SVT causing cardiac compromise, ablation can be performed earlier, but it requires significant experience.
In children with WPW, the presence of a high-risk accessory pathway on electrophysiology testing creates an additional reason to recommend ablation. A pathway capable of rapid antegrade conduction during atrial fibrillation carries a small but real risk of ventricular fibrillation and sudden death. Dr Giardini discusses this carefully with families, as it is one of the situations where ablation becomes a safety recommendation rather than purely a quality-of-life decision.
SVT in a child with an underlying structural heart condition requires a more careful and often more proactive approach. The same arrhythmia that is a nuisance in an otherwise healthy teenager can be haemodynamically destabilising in a child with a single ventricle or residual obstruction. These children are referred for specialist electrophysiology evaluation much earlier, and the threshold for intervention is lower.
Most children with SVT have entirely normal lives between episodes. There are no cardiac activity restrictions for the majority, though competitive sport in children with WPW is assessed individually depending on pathway characteristics. Dr Giardini provides each family with a written vagal manoeuvre plan, a clear escalation pathway, and a contact route for urgent questions. The anxiety around SVT, especially in the first months after diagnosis, is often as significant a burden as the rhythm itself and that deserves attention alongside the clinical management.
Possibly, if the mechanism is AVRT using an accessory pathway. A meaningful proportion of infants with this pattern have no further SVT after twelve months of age as the pathway loses its ability to conduct. However, there is also a recognised risk that SVT recurs in later childhood or adolescence even in those who appeared to have outgrown it. Dr Giardini tracks this with regular ECG review and Holter ECG monitors if required and discusses the individual risk at each appointment.
Vagal manoeuvres are techniques that stimulate the vagus nerve and can slow the AV node enough to break an SVT circuit. In young children, applying ice-cold water or a bag of ice to the face for a few seconds while the child is lying down is one commonly taught method. This is usually only done in hospital to treat SVT in newborns. In older children and teenagers, bearing down as if straining, called a Valsalva manoeuvre, is effective. Dr Giardini provides specific guidance personalised to the child's age and the type of SVT before any family is asked to manage episodes at home.
Catheter ablation is a well-established procedure with a long track record in the paediatric population. The main risks are access site bruising, a small chance of damage to the normal conduction system (particularly for pathways close to the AV node, where cryoablation is often preferred), and the general risks of any procedure under anaesthesia. Serious complications are uncommon in experienced centres. Dr Giardini would refer families to a specialist electrophysiology service for this procedure and ensures families have a full discussion of the risks and expected outcomes beforehand.
Not necessarily. Two episodes in three years in a teenager who is well between events and can be managed with vagal manoeuvres is a very different situation from weekly episodes that disrupt school, sport, and sleep. Dr Giardini's approach to infrequent episodes in older children leans toward a watch-and-plan strategy, providing rescue training and a clear ablation pathway rather than committing to daily medication for infrequent events.
In an otherwise healthy child with structurally normal heart and typical AVNRT or AVRT, the risk of cardiac arrest from SVT alone is extremely low. The situation is different in WPW, where a specific, high-risk pathway pattern carries a small but real risk. This is one reason Dr Giardini takes WPW seriously even when the child is currently well. The assessment of risk in WPW involves an electrophysiology study in some cases.
There is no strong evidence that caffeine reliably triggers SVT in most children, but some young people do notice more frequent or easier-to-trigger episodes after energy drinks, particularly those high in stimulants. Dr Giardini advises avoiding energy drinks as a reasonable precaution, less because of robust trial data and more because there is no benefit to having them and some signal in clinical experience that they can lower the triggering threshold.
Author: Dr. Alessandro Giardini, MD, PhD, Consultant Paediatric Cardiologist
Written 06/06/2026