In pediatric resuscitation, the ability to rapidly identify cardiac rhythms is not just a skill, it is a lifeline. Unlike adults, where cardiac arrest is often sudden and primary, pediatric arrest is typically the end-stage of progressive respiratory failure or shock.
Under the 2025 AHA PALS Guidelines, the emphasis has shifted toward earlier recognition of “pre-arrest” rhythms to intervene before pulselessness occurs. This guide provides a clinical breakdown of core PALS rhythms, their identifying features, and the immediate interventions required for the pediatric patient.
Why Rhythm Recognition Matters in PALS
Unlike adult cardiac arrest, which is often a sudden arrhythmic event (V-Fib), pediatric cardiac arrest is usually the end-result of progressive respiratory failure or shock. Recognizing abnormal rates and rhythms allows providers to intervene before pulselessness occurs.
The Foundation: Assessing Rate & Regularity
Experts utilize a systematic approach to every ECG strip. In pediatrics, the definition of “normal” changes as the child ages.
- Determine the Rate
A normal heart rate for a newborn is dangerously fast for a 10-year-old.
- Newborn (0–1 month): 100–180 bpm
- Infant (1–12 months): 90–160 bpm
- Toddler (1–5 years): 80–150 bpm
- School-age (6–11 years): 70–120 bpm
- Adolescent (12+ years): 60–100 bpm
- Assess Regularity and QRS Width
- Regularity: Is the R-R interval consistent?
- QRS Duration: In PALS, a Narrow QRS is ≤ 0.08 seconds. A Wide QRS is > 0.08 seconds. This distinction is critical for choosing the correct treatment algorithm.
Sinus Rhythms: The Baseline
Sinus Bradycardia
Visual Identifier: A slow, regular rhythm where every QRS is preceded by a P-wave.
- Clinical Significance: Often a sign of hypoxia or increased vagal tone.
- PALS Action: If HR is < 60 bpm with poor perfusion despite oxygen/ventilation, start CPR.
Sinus Tachycardia
Visual Identifier: A fast, regular rhythm with visible P-waves and a rate that typically varies with activity or fever.
- Differentiation: Rate is usually < 220 bpm in infants or < 180 bpm in children.
Tachyarrhythmias: Narrow vs. Wide
Supraventricular Tachycardia (SVT)
Visual Identifier: An extremely fast, perfectly regular narrow-complex tachycardia (≤ 0.08s) where P-waves are absent or “retrograde.”
- Rates: > 220 bpm (infants) or > 180 bpm (children).
- Clinical Note: Unlike Sinus Tach, SVT has an abrupt onset and a “fixed” rate.
Ventricular Tachycardia (VT)
Visual Identifier: A wide-complex tachycardia (> 0.08s) with a “bizarre” appearance.
- Torsades de Pointes: A polymorphic VT where the QRS complexes appear to “twist” around the isoelectric line.
Pulseless Arrest Rhythms
Shockable Rhythms
- Ventricular Fibrillation (VF): Chaotic, irregular quivering with no discernible waves. It looks like “static” or a “shaking worm” on the monitor.
- Pulseless VT: A wide-complex VT where the patient has no palpable pulse.
Priority: Immediate defibrillation (2 J/kg).
Non-Shockable Rhythms
- Asystole: A flat (isoelectric) line. Always verify in two leads and check the monitor gain.
- PEA (Pulseless Electrical Activity): Any organized electrical rhythm on the monitor that fails to produce a palpable pulse.
The H’s and T’s: Reversible Causes
When treating PEA or Asystole, you must address the underlying causes.
| The H’s | The T’s |
| Hypovolemia (Most common) | Toxins (Overdose) |
| Hypoxia | Tamponade (Cardiac) |
| Hydrogen Ion (Acidosis) | Tension Pneumothorax |
| Hypo / Hyperkalemia | Thrombosis (Pulmonary/Coronary) |
| Hypothermia | Trauma |
Conclusion
Mastering PALS rhythm recognition is about understanding the physiology behind the monitor. By systematically assessing rate, regularity, and QRS width, you can intervene accurately according to the latest AHA guidelines.
Confidence comes with practice. Staying current with your PALS Certification Renewal ensures that when a “code blue” is called, your rhythm interpretation skills are sharp enough to save a life.
Frequently Asked Questions (FAQ)
What is the most common pediatric arrhythmia?
Supraventricular Tachycardia (SVT) is the most common symptomatic tachycardia in children. It is characterized by a narrow QRS complex and a heart rate that lacks variability.
How do you differentiate SVT from Sinus Tachycardia on an ECG?
Look for the P-waves and rate variability. Sinus Tachycardia usually has visible P-waves and a rate that changes with stimulation. SVT has a fixed, extremely high rate (>220 bpm in infants) and typically hidden P-waves.
What is the QRS cutoff for “wide” vs “narrow” in PALS?
According to AHA PALS standards, a narrow QRS is ≤ 0.08 seconds, while a wide QRS is > 0.08 seconds. This measurement is vital for determining if a tachycardia originates above or within the ventricles.
What are the shockable rhythms in a pediatric code?
The two shockable rhythms in PALS are Ventricular Fibrillation (VF) and Pulseless Ventricular Tachycardia (pVT). Both require rapid defibrillation and high-quality CPR.