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Difficulty: MediumPediatric Cardiovascular Disorders

An 88-week-old female infant presents to the urgent care clinic with fussiness and refusal to feed for the past four hours. The infant is alert and responsive. Vital signs include a heart rate of 270 /min270\text{ /min}, respiratory rate of 50 /min50\text{ /min}, and blood pressure of 82/48 mmHg82/48\text{ mmHg}. Peripheral pulses are robust, capillary refill is under 2 seconds2\text{ seconds}, and extremities are warm. A 12-lead electrocardiogram shows a regular, narrow-complex tachycardia with absent P waves and constant R-R intervals. A peripheral intravenous line is already in place. Arrange the following acute management steps in the correct progressive order, from the initial non-pharmacologic approach to subsequent therapies if the arrhythmia persists.

  1. 1Apply a bag of ice-water to the infant's face for up to 15 seconds
  2. 2Administer a rapid intravenous bolus of adenosine
  3. 3Administer a slow intravenous infusion of amiodarone or procainamide
  4. 4Perform synchronized electrical cardioversion

Answer

The correct sequence for managing hemodynamically stable pediatric supraventricular tachycardia begins with vagal maneuvers, followed by intravenous adenosine, then second-line antiarrhythmics such as amiodarone, and finally synchronized cardioversion if medical therapy fails.
The algorithmic approach to pediatric supraventricular tachycardia depends entirely on hemodynamic stability. For a stable infant, the safest initial step is a vagal maneuver, specifically applying an ice-water bag to the face to elicit the dive reflex. If unsuccessful, a rapid intravenous push of adenosine is the first-line medication due to its short half-life and efficacy in terminating reentrant circuits. Refractory cases warrant second-line antiarrhythmics such as amiodarone or procainamide (usually with expert consultation). If the arrhythmia persists despite these measures, or if the patient becomes hemodynamically unstable at any point, synchronized electrical cardioversion is then indicated.

Step-by-Step Solution

1
Evaluate hemodynamic stability.
Patient is alert with normal blood pressure and perfusion, indicating stable SVT.
Stability determines whether to start with medical/non-pharmacologic therapy or proceed directly to electrical cardioversion.
2
Initiate non-pharmacologic therapy.
Apply ice-water to the face.
Elicits the vagal response (mammalian dive reflex) which can safely terminate AV node-dependent reentrant tachycardias.
3
Administer first-line medication.
Rapid IV adenosine is given.
If vagal maneuvers fail, adenosine transiently blocks the AV node to terminate the arrhythmia.
4
Administer second-line medication.
IV amiodarone or procainamide is given.
Used for SVT refractory to initial vagal and adenosine therapies.
5
Prepare for electrical therapy.
Synchronized electrical cardioversion is performed.
Indicated if the patient remains refractory to all pharmacologic interventions or clinical status deteriorates to instability.

Key Concept

Management algorithm for hemodynamically stable pediatric supraventricular tachycardia (SVT)

Alternative Method

In older, cooperative children, having the patient blow into an obstructed syringe (Valsalva maneuver) can be used instead of the ice-water application as the initial vagal maneuver.
Estimated Time:1m 30s
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Topics

Pediatric Cardiovascular Disorders

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