Pediatric Tachycardia and SVT (PALS)

A fast heart rate in a child is a symptom, and it has many causes. Your first call is the rhythm. Is it a fast sinus rhythm, responding to a stressor? Or is it a supraventricular tachycardia (SVT) that is not? For sinus tachycardia, you treat the cause. SVT runs on the PALS tachycardia pathway. At the bedside you judge both the same way: is the child perfusing?

Teams have to decide fast. A child in compensated shock can look well right up until the heart rate can't be sustained. A fast regular rhythm can cause collapse in minutes.

Why Kids Are Different

• Cardiac output depends on rate: a small infant heart fills poorly when it beats fast. Output can drop before the child is hypotensive.
• Normal rates are age-specific: an awake infant or toddler often runs fast at baseline. Check the rate against the age band on the vital signs page. Don't compare it to an adult number.
• Sinus tachycardia is common: fever, pain, fear, dehydration, anemia, hypoxia and sepsis all push the sinus rate up. Treat the cause first.
• Dosing is per kilogram: adenosine and cardioversion doses are weight-based. A dosing-weight error scales the dose. Use the Broselow tape or a measured weight.

Rate first. Then rhythm. Then perfusion. The SVT rate threshold, per the 2025 AHA PALS tachyarrhythmia algorithm, is about 220/min or more in infants and about 180/min or more in children. A rate under those numbers does not rule out SVT. A rate over them does not prove it. The rhythm strip and the 12-lead make the diagnosis.

Age-Specific Presentations

• Neonate: poor feeding, pallor, apnea or hypotension. The rate can be very high. The cause is often sepsis or heart disease.
• Infant: irritability, feeding failure, sweating, tachypnea. A sustained rate near the SVT range, with a poor color, is a red flag.
• Child: palpitations, chest pain, dizziness or weakness. Many children look well despite a fast rate.
• Adolescent: palpitations and presyncope. A sudden start and a sudden stop suggest reentry.

The ECG and the child in front of you sort sinus from SVT. The table shows the usual differences. If sinus tachycardia persists after you treat the cause, it needs a 12-lead ECG.

This is the pathway for a narrow-complex, regular tachycardia at SVT rates. Follow the 2025 AHA PALS tachyarrhythmia algorithm, your local protocol and medical direction.

Stable (Perfusing)

1. Assess and monitor: airway, breathing and oxygen; continuous ECG and BP; 12-lead ECG if available. Establish IV or IO access.
2. Vagal maneuver: use a protocol-approved maneuver (see Vagal Maneuvers). Do not delay the next step if the child is not cooperative.
3. Adenosine (Paramedic/RN/CCT, per local protocol): 0.1 mg/kg rapid IV/IO push, then a rapid saline flush (max 6 mg). Give at the site closest to the heart. Record a continuous rhythm strip during and after the push.
4. No conversion in 1–2 min: adenosine 0.2 mg/kg rapid IV/IO push (max 12 mg), with a rapid saline flush.
5. Still in SVT after adenosine: expert consultation (pediatric cardiology or medical direction) before any further antiarrhythmic. Do not repeat adenosine beyond the protocol.
6. If adenosine fails or the child deteriorates: synchronized cardioversion, 0.5–1 J/kg then 2 J/kg, per protocol. Amiodarone or procainamide only with expert consultation.

Unstable (Poor Perfusion)

1. Synchronized cardioversion: 0.5–1 J/kg for the first shock, then 2 J/kg if the rhythm does not convert (Paramedic/RN/CCT, per local protocol).
2. Sedation: give only if it does not delay the shock (per AHA PALS wording); do not let sedation delay cardioversion.
3. Access and drugs: establish access while preparing the shock. Adenosine may be considered only if IV/IO access is already in place and it will not delay the shock. Do not hold cardioversion for adenosine when the child is in decompensated shock.

A wide-complex tachycardia in a child is ventricular tachycardia until you prove otherwise. It could also be pre-excited AF. Treatment depends on two things: whether the rhythm is regular and monomorphic, and whether the child is perfusing.

1. Unstable: synchronized cardioversion 0.5–1 J/kg, then 2 J/kg, as for narrow-complex SVT. Call for expert help early.
2. Stable and irregular: treat it as possible pre-excited AF. Skip adenosine and AV-nodal blockers. Get expert consultation.
3. Stable, regular and monomorphic: under the PALS 2025 pathway, adenosine is allowed only with expert consultation (0.1 mg/kg, max 6 mg, then 0.2 mg/kg, max 12 mg). In pre-excited AF, adenosine can cause VF.
4. Other antiarrhythmics: PALS lists amiodarone or procainamide, only with expert consultation. Avoid combining them. Lidocaine dosing for children is specialist-directed. Treat torsades with magnesium. For doses, follow the local pediatric formulary.

The adenosine dose below is the PALS pathway dose. The FDA label for adenosine (see References) runs a different weight-based schedule. It starts at 0.05–0.1 mg/kg and steps up in increments of 0.05–0.1 mg/kg. The single-dose maximum is 0.3 mg/kg, with a 12 mg cap. Follow your protocol and medical direction.

Adenosine is high-alert. Before every push, get a second clinician to check the weight, the dose and the mL. Doses vary by protocol; follow local protocols and medical direction.

• Continuous ECG and SpO₂ during and after any adenosine dose, with a defibrillator ready.
• Reassess perfusion and mental status every 5 minutes during treatment, then every 15 minutes.
• Transfer to a pediatric ICU or pediatric cardiology when SVT recurs, the child needs more than one antiarrhythmic, or the child is unstable.

Neonates and Young Infants

• Infant SVT is common. It shows up as poor feeding or pallor. The rate can be very high, and the cause is often sepsis or congenital heart disease.
• The adenosine label gives pediatric weight-based dosing. Neonatal data are limited, so involve pediatric cardiology early.
• Use a pediatric cardioversion pad or an attenuator. Confirm the pad size against the device instructions.

Adolescents

• The adenosine label gives adult dosing at 50 kg or more. Many protocols switch at 40 kg, or at puberty. The switch is protocol-dependent, so follow your local rule.
• Adolescents with sudden tachycardia and syncope need the same wide-complex caution as younger children.

Children with Congenital Heart Disease or Pre-excitation

• Children with single-ventricle or repaired heart disease may tolerate SVT poorly. Call pediatric cardiology early.
• Pre-excitation (WPW): in pre-excited AF, avoid AV-nodal blocking drugs, and bring in expert consultation.
• A child with a central line or a tracheostomy may need a modified approach to access and sedation. See the Pediatric Vascular Access page.

Adenosine Precautions

• Asthma or bronchospasm: adenosine can cause bronchoconstriction. Avoid it unless the benefit outweighs the risk, and watch for wheeze and falling SpO₂.
• Heart transplant or denervated heart: these hearts are very sensitive to adenosine. Adults get reduced doses, and pediatric dosing is protocol-dependent.
• Methylxanthines (caffeine, theophylline): they antagonize adenosine. Larger doses may be needed, or the drug may fail.
• Dipyridamole and carbamazepine: dipyridamole potentiates adenosine, so smaller doses may work. Carbamazepine may increase heart block from other agents.
• AV block or sick sinus: contraindicated in second- or third-degree AV block, and in sick sinus syndrome or symptomatic bradycardia, unless a functioning pacemaker is present.
• Proarrhythmia: transient atrial fibrillation or other new arrhythmias can follow conversion. Keep the defibrillator ready.
• Central line: dosing through a central line has not been systematically studied. Follow protocol.

• Equipment: pre-drawn, labeled adenosine with a second syringe and a saline flush; pediatric pads or an attenuator; a length-based tape or measured weight.
• Destination: a pediatric-ready ED or a pediatric cardiology center for recurrent SVT, unstable rhythm or pre-excitation.
• Restraint: size-appropriate restraint on the stretcher, never a caregiver's lap during transport or cardioversion.
• Caregiver: ask about heart disease, prior SVT, medicines and recent ingestion; keep the caregiver present where safe.
• Infant heat loss: keep the infant warm during transport and during any sedation.
• Handoff: use IMIST-AMBO or MIST, with the rhythm strip, time of each dose and the response.