4.1 Pediatric Dysrhythmias

4.1 Pediatric Dysrhythmias

Dysrhythmia management in the pediatric intensive care unit (PICU) differs from adult critical care in physiology, etiology, and first actions. Infants and children have higher resting heart rates, limited stroke-volume reserve, and a profound dependence on heart rate to maintain cardiac output. A rhythm disturbance that an adult might tolerate for minutes can produce rapid hypotension, lactic acidosis, and cardiac arrest in a neonate or infant. The CCRN Pediatric exam expects you to recognize common tachyarrhythmias and bradyarrhythmias, prioritize perfusion and airway, and execute synchronized cardioversion or defibrillation safely.

Pediatric Advanced Life Support (PALS) frameworks organize care around rapid circulation assessment, pulse presence, QRS width, and hemodynamic stability. This study guide uses those clinical priorities as teaching anchors. It does not reproduce proprietary algorithm flowcharts, exact boxed sequences, or copyrighted decision trees. Focus on bedside reasoning: Is there a pulse? Is the child compensating? Is the QRS narrow or wide? What reversible cause (especially hypoxia) must be fixed first?

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Hemodynamic Stability: The First Branch Point

Before naming the rhythm, decide whether the child is stable or unstable. Instability means the dysrhythmia is causing inadequate tissue perfusion. Classic pediatric warning signs include:

• Hypotension for age or a falling trend from the child’s baseline
• Acutely altered mentation, lethargy, or poor responsiveness
• Cool mottled extremities, delayed capillary refill, weak central pulses
• Respiratory distress or pulmonary edema from elevated left-sided filling pressures
• Chest pain or signs of myocardial ischemia in older children (less common, still important)

If the child is unstable with a pulse, synchronized cardioversion is usually preferred for organized tachyarrhythmias. If the child is pulseless with a shockable rhythm (pulseless VT or VF), defibrillation is paired with uninterrupted high-quality CPR. If the child is bradycardic and poorly perfused, support oxygenation and ventilation first—especially in infants, where hypoxia is the dominant trigger.

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Supraventricular Tachycardia (SVT)

SVT is the most common pathologic tachyarrhythmia in infants and young children. Mechanisms often involve reentry through the AV node or an accessory pathway. On the monitor, SVT usually appears as a narrow-complex, regular tachycardia with abrupt onset and offset. P waves may be absent, buried, or retrograde. Infants frequently present with rates around 220–300 bpm; older children may present in the 180–220 bpm range.

Differentiate from sinus tachycardia. Sinus tachycardia usually has a visible P wave of normal morphology, varies slightly with activity or fever, and rarely reaches extreme infant SVT rates without an obvious stressor. In the PICU, sinus tachycardia is treated by addressing fever, pain, anemia, hypovolemia, sepsis, or agitation—not by shocking a compensatory rhythm.

Nursing priorities for SVT

1. Ensure airway and oxygen while obtaining a rapid focused assessment and continuous ECG.
2. If unstable (poor perfusion attributable to the rate): prepare for synchronized cardioversion. Sedate if the child is conscious and time allows, but do not delay cardioversion for prolonged medication setups when perfusion is collapsing.
3. If stable: attempt brief vagal maneuvers appropriate to age (for example, ice to the face in infants using institutionally approved technique; older children may attempt Valsalva-type maneuvers). Have IV access and adenosine ready.
4. Adenosine is given as a rapid IV push followed immediately by a saline flush through a proximal line, with continuous ECG recording because termination is often transient and diagnostic. Anticipate brief asystole or pause after administration—warn the family and team, and stay prepared to support the airway.
5. Recheck perfusion after every intervention. Recurrent SVT may require cardiology consultation, maintenance antiarrhythmics, or electrophysiology evaluation, especially if accessory-pathway mediated.

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Ventricular Tachycardia (VT)

VT is less common than SVT in pediatrics but carries high risk, particularly in children with cardiomyopathy, channelopathy, myocarditis, electrolyte imbalance, or postoperative ventricular scars. VT is typically a wide-complex tachycardia. Always evaluate for a pulse.

• VT with a pulse and instability: synchronized cardioversion is the priority electrical therapy.
• Pulseless VT: treat as cardiac arrest with CPR and defibrillation.
• Stable VT with a pulse is uncommon in true PICU crises; when it occurs, expert consultation and antiarrhythmic selection (commonly amiodarone or lidocaine per current pediatric resuscitation guidance and institutional protocol) proceed under continuous monitoring.

Do not assume every wide-complex rhythm is VT—SVT with aberrancy can widen the QRS—but in an unstable child, treat the rhythm as VT and restore perfusion first. Hyperkalemia, hypocalcemia, and drug toxicity (for example, sodium-channel blockade) should be considered as reversible contributors.

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Bradycardia

In pediatric patients, bradycardia is frequently a preterminal sign of hypoxia, hypoventilation, or profound shock. Absolute rate cutoffs vary by age, but clinical context matters more than a single number. A neonate at 80 bpm with poor color and weak pulses is a crisis; an athletic adolescent at 48 bpm who is alert and normotensive may be expected.

PICU priority sequence for symptomatic bradycardia

1. Open and support the airway; provide oxygen and effective ventilation.
2. Assess pulse quality and begin chest compressions if heart rate remains critically low with poor perfusion despite oxygenation (commonly taught threshold near <60 bpm with signs of poor perfusion in infants/children during resuscitation).
3. Identify and treat reversible causes: hypoxia, hypothermia, increased intracranial pressure, medication effects (beta-blockers, digoxin, calcium-channel blockers), and electrolyte disturbances.
4. Pharmacologic chronotropy (epinephrine is often first-line in pediatric bradycardia with poor perfusion; atropine may be considered for increased vagal tone or AV block per current guidance) is secondary to airway and oxygenation when hypoxia is driving the rate.

This hypoxia-first framing is a high-yield CCRN Pediatric distinction from adult ACLS habits that default more quickly to atropine-centric pathways.

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Postoperative Heart Block

After congenital heart surgery—especially procedures near the AV node or His bundle (AV septal/AV canal defects, perimembranous VSD closure, tetralogy of Fallot repair, some aortic/mitral valve or subaortic work)—new conduction block is a known complication. Temporary epicardial pacing wires are often left in place for this reason.

Nursing vigilance includes:

• Continuous ECG surveillance for progressive PR prolongation, second-degree block, or sudden complete (third-degree) block
• Correlation of escape rate with blood pressure, lactate, and mixed/central venous saturation
• Confirmation that temporary pacing cables, connectors, and the external pacemaker are present, labeled, and function-checked
• Avoiding inadvertent wire dislodgement during turning, chest physiotherapy, or transfer
• Prompt notification of the surgical and cardiology teams when new high-grade block appears

Complete heart block may present with a slow wide escape rhythm and hypotension. Capture with temporary pacing can be immediately life-saving while longer-term recovery versus permanent pacemaker need is assessed over subsequent days.

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Cardioversion and Defibrillation: Nursing Essentials

Bedside nursing actions

• Expose the chest; dry wet skin; remove transdermal patches from pad sites.
• Select pediatric or adult pads based on size/weight; place anterolateral or anteroposterior per device guidance, avoiding overlapping pads and keeping clear of wires when possible.
• Announce “charging” and “clear”; visually confirm no contact with the bed, fluids, or team members.
• For synchronized cardioversion, verify the monitor is actually in sync mode and sensing R waves correctly—failure to sync can deliver a shock on the T wave and induce VF.
• After any shock, immediately reassess pulse, rhythm, and perfusion; resume CPR without delay if pulseless.
• Document energy, number of shocks, rhythm before/after, and clinical response.

In the PICU, many children already have arterial lines, central lines, and vasoactive infusions. Protect lines during pad placement, and have resuscitation medications drawn and labeled. Family presence, when supported by unit practice, should be accompanied by a staff member who can explain that brief pauses or muscle contractions with shocks are expected.

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Putting It Together for the Exam

Expect scenario items that mix congenital heart anatomy, postoperative day, and a monitor strip description. Your mental checklist should be: pulse → perfusion → QRS width → reversible causes (especially hypoxia) → electrical therapy readiness. SVT that suddenly collapses perfusion needs synchronized cardioversion, not prolonged diagnostic delay. Bradycardia with desaturation needs ventilation first. New postoperative AV block needs pacing readiness. Those priorities—more than memorizing a flowchart drawing—are what keep children alive and what the CCRN Pediatric exam rewards.