PALS Cardiac Rhythms: Complete EKG Training Guide for Pediatric Advanced Life Support

Understanding PALS cardiac rhythms is the cornerstone of every Pediatric Advanced Life Support certification course. Unlike adult cardiac emergencies, which most commonly present with ventricular fibrillation, pediatric cardiac arrests are overwhelmingly caused by respiratory failure that progresses to hypoxia-driven rhythm deterioration. This means that by the time a child reaches cardiac arrest, the rhythm you see on the monitor reflects hours of physiological stress — and your ability to identify that rhythm in seconds can be the difference between a successful resuscitation and a tragic outcome.

The PALS curriculum requires providers to recognize and act on a defined set of cardiac rhythms with speed and precision. The American Heart Association structures the entire PALS algorithm around four broad rhythm categories: rhythms requiring CPR and defibrillation, rhythms requiring CPR without defibrillation, tachyarrhythmias with a pulse, and bradyarrhythmias with a pulse. Each category triggers a completely different treatment pathway, so misidentifying even a single rhythm feature — like confusing sinus tachycardia with supraventricular tachycardia — can lead to a harmful or ineffective intervention.

EKG interpretation in pediatric patients adds complexity because normal values shift dramatically with age. A heart rate of 160 beats per minute is completely normal in a newborn but represents significant tachycardia in a 10-year-old.

The QRS duration, PR interval, and T-wave morphology all change as children grow, meaning providers must carry age-appropriate reference ranges in their memory throughout the PALS exam and in clinical practice. The written exam portion of PALS frequently presents rhythm strips alongside clinical scenarios and asks you to select the correct algorithm step — making rhythm literacy a direct factor in whether you pass or fail.

Preparation for the rhythm interpretation component of PALS requires more than memorizing a list of arrhythmia names. You need to develop a systematic approach to every strip you encounter: rate, regularity, P-wave presence and morphology, PR interval, QRS width, and relationship between P waves and QRS complexes. This six-step system — applied consistently — prevents the common error of pattern-matching to a familiar shape without confirming all diagnostic criteria. Providers who skip steps under pressure are the ones who confuse atrial flutter with atrial fibrillation, or mistake artifact for ventricular fibrillation.

This guide walks through every rhythm category tested in PALS, provides the diagnostic criteria you must know cold, and explains exactly how each rhythm maps to the AHA algorithms. You will also find study strategies, practice quiz links, and a checklist of mastery milestones to complete before your certification day. Whether you are preparing for initial certification or a two-year renewal, this resource is designed to give you the clinical confidence and exam readiness you need. Be sure to explore the full scope of pals ekg rhythms preparation resources available at PracticeTestGeeks to maximize your study efficiency.

The stakes in pediatric resuscitation are uniquely high, and the emotional weight of caring for critically ill children makes it even more important that rhythm recognition becomes automatic rather than effortful. When your hands are performing chest compressions and your team is preparing medications, your eyes need to read that monitor strip without hesitation. The training content in this article is built to move your rhythm knowledge from conscious recall to the kind of reflexive competency that PALS is designed to certify.

Begin by reading through the rhythm categories in sequence, then use the embedded practice quizzes to test yourself under timed conditions. Research consistently shows that retrieval practice — answering questions rather than re-reading notes — produces stronger long-term retention than passive review alone. Use this guide as an active learning tool, pause at each section to quiz yourself, and return to any rhythm that still feels uncertain before moving on.

Reading a pediatric EKG strip systematically is the single most important skill you will develop for the PALS exam. The six-step approach — rate, regularity, P waves, PR interval, QRS duration, and P-to-QRS relationship — prevents confirmation bias and ensures you never miss a critical feature. Begin every strip analysis by calculating the heart rate using the 6-second rhythm strip method: count the number of QRS complexes in a 6-second strip and multiply by 10. Compare that number to the age-appropriate normal range before drawing any conclusions about whether the rhythm is abnormal.

Regularity is your second checkpoint. A regular rhythm has consistent R-to-R intervals throughout the strip; an irregular rhythm shows variable spacing. Regular rhythms are more likely to be sinus, SVT, or ventricular tachycardia. Irregular rhythms suggest atrial fibrillation, atrial flutter with variable block, or multifocal atrial tachycardia. In children, atrial fibrillation is uncommon but does occur in patients with structural heart disease, and recognizing its irregularly irregular pattern is essential for correct classification and treatment selection.

P-wave analysis tells you whether atrial depolarization is occurring normally. In sinus rhythm, P waves are upright in leads I and aVF, with a consistent morphology and a predictable relationship to each QRS complex. In SVT, P waves may be absent, hidden in the T wave, or appear as retrograde inverted P waves after the QRS.

In junctional rhythms, retrograde P waves appear before or after the QRS complex and are always inverted in the inferior leads. The absence of visible P waves combined with a narrow QRS and rapid rate in a child almost always points to SVT until proven otherwise.

The PR interval reflects conduction time from the sinus node through the AV node to the ventricles. A normal PR interval in a school-age child is 0.12–0.20 seconds; values outside this range suggest first-degree AV block (prolonged) or pre-excitation syndromes like Wolff-Parkinson-White (short). Second-degree AV blocks come in two flavors: Mobitz Type I (Wenckebach), where the PR interval progressively lengthens until a QRS is dropped, and Mobitz Type II, where the PR interval is constant but QRS complexes periodically drop without warning. Type II carries a higher risk of progressing to complete heart block.

QRS duration is your window into ventricular conduction. A narrow QRS (less than 0.09 seconds in children) means that conduction is following the normal His-Purkinje pathway and the rhythm originates above or within the AV node. A wide QRS (greater than 0.09 seconds) indicates either a ventricular origin or aberrant conduction through a damaged or bypassed conduction pathway. Wide-complex tachycardias in pediatric patients are treated as ventricular tachycardia until proven otherwise, because misidentifying VT as SVT with aberrancy and giving adenosine can cause dangerous hemodynamic deterioration.

The P-to-QRS relationship is your final checkpoint and often the one that clinches the diagnosis. In normal sinus rhythm, every P wave is followed by a QRS, and every QRS is preceded by a P wave, with a constant PR interval. In third-degree (complete) heart block, P waves and QRS complexes march through the strip at completely independent rates — the atria fire at one rate while the ventricles respond to a slower escape focus. This dissociation is diagnostic and requires immediate intervention including transcutaneous pacing and cardiology consultation in any pediatric patient showing signs of hemodynamic compromise.

Artifact recognition is an often-overlooked skill that becomes critical in high-pressure resuscitation environments. Patient movement, loose electrode contact, 60-Hz electrical interference, and CPR artifact can all produce waveforms that mimic genuine arrhythmias. Before calling a rhythm as ventricular fibrillation or asystole, confirm that the patient has no pulse and that the electrodes are attached securely. Treating artifact as VF — delivering a shock to a patient in sinus rhythm — is a serious error that the PALS exam specifically tests through scenario-based questions.

Tachyarrhythmias with a pulse represent some of the most clinically nuanced scenarios in the PALS curriculum. The first decision point is always stability: does the patient show signs of cardiopulmonary compromise such as altered mental status, hypotension, respiratory distress, or signs of shock? A stable patient with SVT at a rate of 220 bpm allows time for vagal maneuvers and adenosine. An unstable patient with the same rhythm gets immediate synchronized cardioversion — there is no time for medication trials when perfusion is failing.

Sinus tachycardia is the most common tachyarrhythmia encountered in pediatric emergencies, and it is almost never treated directly as a rhythm problem. It is a physiological response to underlying illness: fever, pain, anxiety, hypovolemia, anemia, or respiratory distress. Treatment targets the underlying cause — fluid resuscitation for hypovolemia, antipyretics for fever, oxygen for hypoxia. Giving adenosine or cardioversion for sinus tachycardia not only fails to address the root problem but can cause dangerous hemodynamic deterioration by eliminating the compensatory tachycardia that is maintaining cardiac output.

Supraventricular tachycardia is the most common pathological tachyarrhythmia in children, with an incidence of approximately 1 in 250–1,000 pediatric patients. It originates from a reentrant circuit involving the AV node or an accessory pathway, producing a narrow-complex rhythm at a characteristically fixed rate. In infants, SVT commonly presents at rates of 220–300 bpm; in older children, rates are typically 150–250 bpm. The abrupt onset and termination of SVT — compared to the gradual rate changes of sinus tachycardia — is an important historical clue that caregivers can often provide when describing the episode.

Vagal maneuvers are the first-line intervention for stable SVT. In infants, the most reliable technique is application of ice water to the face for 15–30 seconds, which stimulates the diving reflex and slows AV nodal conduction. In older children, the Valsalva maneuver — bearing down against a closed glottis, or blowing into an occluded straw — can terminate SVT in up to 25% of cases.

If vagal maneuvers fail, adenosine 0.1 mg/kg IV (maximum 6 mg first dose) given as a rapid bolus followed by a rapid saline flush is the pharmacological intervention of choice, with a second dose of 0.2 mg/kg (maximum 12 mg) if the first dose fails.

Ventricular tachycardia with a pulse in children is far less common than SVT but carries higher immediate risk. It presents as a wide-complex tachycardia — QRS duration greater than 0.09 seconds — at rates typically between 120 and 250 bpm. Monomorphic VT has uniform QRS morphology, while polymorphic VT has variable morphology and is often associated with QT prolongation or electrolyte abnormalities.

Stable monomorphic VT can be treated with amiodarone 5 mg/kg IV over 20–60 minutes. Unstable VT — any VT with signs of compromised perfusion — requires immediate synchronized cardioversion at 0.5–1 J/kg, escalating to 2 J/kg if the first attempt is unsuccessful.

Wolff-Parkinson-White syndrome deserves specific attention in the PALS context because it creates a unique risk profile for SVT management. WPW involves an accessory conduction pathway that bypasses the AV node, producing the classic EKG triad of a short PR interval, a delta wave (slurred QRS upstroke), and a widened QRS complex. In sinus rhythm, WPW is recognizable on the 12-lead EKG.

During SVT in a WPW patient, AV nodal blocking agents including adenosine, verapamil, and diltiazem are relatively contraindicated because they can paradoxically accelerate conduction down the accessory pathway and precipitate ventricular fibrillation. Cardioversion is the preferred intervention for unstable SVT in known or suspected WPW.

The atrial flutter pattern — a characteristic sawtooth baseline at a rate of approximately 300 atrial beats per minute with regular or irregular ventricular response — is uncommon in structurally normal pediatric hearts but occurs in children with congenital heart disease or after cardiac surgery. Atrial flutter with 2:1 block produces a ventricular rate of approximately 150 bpm, which can be misidentified as sinus tachycardia without careful attention to the flutter waves visible between QRS complexes. The treatment depends on stability: cardioversion for hemodynamic compromise, or rate control and anticoagulation discussion for stable patients in consultation with pediatric cardiology.

Bradyarrhythmias in pediatric patients require prompt assessment to distinguish benign physiological bradycardia from hemodynamically significant rhythms demanding immediate intervention. The PALS threshold for action is a heart rate below 60 beats per minute in a child of any age who is showing signs of poor perfusion: decreased level of consciousness, weak or absent pulses, mottled skin, prolonged capillary refill, or hypotension. Sinus bradycardia in a sleeping neonate with normal perfusion is not a PALS emergency; the same rate in a two-year-old with an altered level of consciousness absolutely is.

The most common cause of bradycardia leading to cardiac arrest in children is hypoxia. Before initiating the bradycardia algorithm with medications, the first intervention is always to ensure a patent airway, provide high-flow oxygen or bag-mask ventilation, and attach the cardiac monitor. In many cases, correcting hypoxia alone will resolve the bradycardia within seconds to minutes without the need for epinephrine or atropine. This oxygen-first principle is a core teaching point of the PALS course and appears frequently in written exam scenarios designed to test whether candidates apply this principle before reaching for pharmacological solutions.

When bradycardia with cardiopulmonary compromise persists despite oxygenation and ventilation, CPR should be initiated if the heart rate is below 60 bpm with signs of poor perfusion. Epinephrine 0.01 mg/kg IV/IO (0.1 mL/kg of the 0.1 mg/mL concentration) is the primary pharmacological agent and is given every 3–5 minutes as needed.

Atropine 0.02 mg/kg IV/IO (minimum dose 0.1 mg, maximum single dose 0.5 mg in children) is indicated specifically for bradycardia caused by increased vagal tone or primary AV conduction block. A minimum dose of 0.1 mg is critical — doses below this threshold can paradoxically worsen bradycardia through a central vagal stimulation effect.

AV block in pediatric patients represents a specific category of bradyarrhythmia with distinct EKG features and management considerations. First-degree AV block is characterized by a prolonged PR interval without dropped beats and rarely causes hemodynamic compromise. Second-degree Mobitz Type I (Wenckebach) shows progressive PR prolongation until a QRS is dropped, then the cycle repeats. Second-degree Mobitz Type II has a constant PR interval with unexpected dropped QRS complexes and carries significant risk of progression to complete heart block, warranting cardiology consultation and consideration of transcutaneous pacing even if the patient is currently stable.

Complete (third-degree) heart block is the most severe AV block and represents complete dissociation between atrial and ventricular activity. The atria fire at the sinus rate while the ventricles respond to a slow escape pacemaker at rates typically between 30 and 55 bpm. The EKG shows P waves and QRS complexes marching independently through the strip with no consistent relationship.

In neonates, complete heart block is often associated with maternal anti-Ro/La antibodies from lupus or Sjögren syndrome. In older children, it may follow cardiac surgery, myocarditis, or Lyme disease. Treatment in hemodynamically compromised patients includes epinephrine infusion to accelerate the escape rate and emergency transcutaneous pacing while preparing for permanent pacemaker implantation.

Transcutaneous pacing is a PALS skill that providers should be familiar with even though it requires specialized equipment. The technique involves placing adhesive pacing pads on the chest — typically one anteriorly over the left precordium and one posteriorly below the left scapula — and connecting them to a pacing-capable defibrillator.

The pacing rate is set above the intrinsic ventricular rate (typically 80–100 bpm in children), and the energy output is increased gradually until electrical capture is confirmed by a wide-paced QRS following each pacing spike. Mechanical capture — a palpable pulse corresponding to each paced beat — must be confirmed separately, since electrical capture does not guarantee hemodynamic effectiveness.

Junctional rhythms, accelerated idioventricular rhythms, and agonal rhythms round out the bradyarrhythmia spectrum that PALS providers should recognize. A junctional rhythm at 40–60 bpm with retrograde P waves and narrow QRS complexes indicates that the AV node or bundle of His is serving as the dominant pacemaker in the absence of reliable sinus node function.

Accelerated idioventricular rhythm — a wide-complex rhythm at 60–100 bpm — is often seen in the post-resuscitation phase and is generally benign, requiring monitoring rather than immediate intervention. Agonal rhythm — a very slow, irregular, wide-complex rhythm — indicates impending cardiac arrest and requires immediate CPR and advanced resuscitation efforts.

Building lasting rhythm recognition skill requires a structured, progressive study approach that mirrors how clinical expertise actually develops. The most effective PALS candidates combine spaced repetition of rhythm strips with scenario-based practice that forces them to connect rhythm identification to algorithm activation. Begin your preparation at least three to four weeks before your scheduled course, dedicating 30–45 minutes per session to active rhythm practice rather than passive reading. The goal is to reach automatic recognition — the rhythm name comes to mind within 2–3 seconds of seeing the strip — before you arrive at the skills station.

Flashcard-based rhythm study is highly effective when cards include both EKG images and key diagnostic criteria on the front, with treatment algorithm steps on the back. This format forces you to retrieve the rhythm name and treatment pathway simultaneously, mimicking the cognitive demand of real resuscitation decision-making. Free rhythm strip libraries are widely available online, and the AHA PALS provider manual includes representative strips for each testable rhythm. Work through at least 10 strips per session and time yourself — try to identify each rhythm within 10 seconds, matching the maximum rhythm check pause allowed during CPR.

Group study with a partner or small team dramatically accelerates rhythm mastery through the teaching effect. When you explain to a colleague why a strip shows SVT rather than sinus tachycardia — citing the fixed rate, absent P waves, and abrupt onset — you consolidate your own understanding far more effectively than if you had simply reviewed the answer key. Role-playing the team leader position during practice scenarios forces you to verbalize rhythm calls and algorithm decisions under mild social pressure, which improves performance under the real pressure of the PALS certification station.

Common exam-day errors in rhythm interpretation fall into predictable patterns that you can guard against with targeted preparation. The most frequent mistake is diagnosing SVT when the correct answer is sinus tachycardia, usually because the P waves are hidden in the T waves at fast rates.

Counter this by measuring the R-to-R interval variability carefully — sinus tachycardia varies with respiration and stimulation, while SVT has a machinelike regularity. The second most common error is calling asystole when fine VF is present. Always check lead connections, switch leads, and confirm no defibrillator pads are disconnected before treating a flat line as asystole.

Post-resuscitation rhythm monitoring is a topic that receives less attention in PALS review but appears in the exam. After achieving return of spontaneous circulation (ROSC), providers must monitor for post-ROSC arrhythmias including sinus tachycardia from catecholamine surge, PVCs, short runs of VT, and bradycardia from myocardial stunning. Continuous 12-lead monitoring is recommended, and a 12-lead EKG should be obtained to evaluate for ST changes suggesting myocardial ischemia and to assess the QTc interval before starting antiarrhythmic medications. Targeted temperature management protocols may also affect rhythm findings in post-cardiac arrest patients, with bradycardia being expected and generally tolerated during therapeutic hypothermia.

The written PALS exam is a closed-book test of approximately 30 multiple-choice questions covering cardiac arrest algorithms, arrhythmia recognition, respiratory distress management, shock recognition, and pharmacology. Rhythm interpretation questions typically represent 25–35% of the exam content, making them the single highest-yield content area for study time investment.

Questions are scenario-based: you are given a clinical vignette with a described or illustrated rhythm and asked to select the next intervention. The answer choices are often designed to distinguish between nearly correct and correct responses, testing whether you know not just what to do but the precise sequence and dosing specified in the AHA guidelines.

Maintaining your PALS competency between certification cycles requires deliberate effort given the two-year gap between required renewals. Consider reviewing PALS rhythm strips quarterly, subscribing to an AHA-aligned continuing education resource, or participating in simulation-based refresher training at your institution. The AHA HeartCode PALS platform offers online rhythm practice modules that can be completed independently. Providers who arrive at renewal already confident in their rhythm skills complete the certification stations significantly faster and with fewer remediation attempts, making ongoing practice an efficient investment of time relative to the benefit of a smooth renewal experience.