PALS Tachycardia With a Pulse 4 — Questions and Answers
Question 1: A 5-year-old with SVT remains stable. Vagal maneuvers and two doses of adenosine have failed. What is the next recommended treatment?
- Synchronized cardioversion at 1 J/kg with sedation (Correct answer)
- Defibrillation at 2 J/kg
- Adenosine 0.3 mg/kg IV
- Epinephrine infusion
Correct answer: Synchronized cardioversion at 1 J/kg with sedation
After two failed adenosine doses, synchronized cardioversion with sedation is the next step for SVT even if still stable.
Question 2: Which finding on ECG indicates that a synchronized cardioversion shock is delivered correctly?
- Shock fires on the R-wave of the QRS complex (Correct answer)
- Shock fires during the T-wave
- Shock fires at a random point in the cardiac cycle
- Shock fires only during atrial contraction
Correct answer: Shock fires on the R-wave of the QRS complex
The 'sync' mode delivers the shock on the R-wave to avoid the vulnerable T-wave period and prevent ventricular fibrillation.
Question 3: Which of the following statements about adenosine administration is CORRECT?
- It must be given as a rapid IV bolus followed immediately by a saline flush (Correct answer)
- It should be infused slowly over 5 minutes to reduce side effects
- It is effective when given via the intramuscular route
- It should not be used in children under 1 year of age
Correct answer: It must be given as a rapid IV bolus followed immediately by a saline flush
Adenosine has an extremely short half-life (~10 seconds) and must be given as a rapid bolus followed by an immediate saline flush to reach the heart.
Question 4: A 4-year-old develops a wide-complex tachycardia at 190 bpm with signs of shock. The team is uncertain if this is VT or SVT with aberrancy. What is the correct approach?
- Treat as VT; perform synchronized cardioversion immediately (Correct answer)
- Administer adenosine first to differentiate rhythm
- Obtain a 12-lead ECG before any treatment
- Observe for 10 minutes and reassess
Correct answer: Treat as VT; perform synchronized cardioversion immediately
In an unstable child with wide-complex tachycardia, treat as VT and perform synchronized cardioversion without delaying for diagnostic workup.
Question 5: Which accessory pathway conduction syndrome is most commonly associated with recurrent SVT in pediatric patients?
- Wolff-Parkinson-White (WPW) syndrome (Correct answer)
- Long QT syndrome
- Brugada syndrome
- Hypertrophic cardiomyopathy
Correct answer: Wolff-Parkinson-White (WPW) syndrome
WPW syndrome, caused by an accessory bundle (Bundle of Kent) bypassing the AV node, is the most common structural cause of SVT in children.
Question 6: When assessing a child with tachycardia and a pulse, which clinical finding most urgently indicates the need for immediate intervention regardless of rhythm analysis?
- Signs of shock such as hypotension, altered consciousness, and poor perfusion (Correct answer)
- Heart rate greater than 150 bpm in a school-age child
- Presence of fever and tachypnea
- Complaint of palpitations with normal blood pressure
Correct answer: Signs of shock such as hypotension, altered consciousness, and poor perfusion
Hemodynamic instability (shock signs) requires immediate intervention, as the child's condition may rapidly deteriorate without treatment.
Question 7: After successful cardioversion of SVT in a 2-year-old, which action is most important before leaving the bedside?
- Confirm sinus rhythm on the monitor and assess perfusion (Correct answer)
- Administer a prophylactic dose of amiodarone
- Repeat adenosine to prevent recurrence
- Remove cardiac monitoring to reduce stimulation
Correct answer: Confirm sinus rhythm on the monitor and assess perfusion
After cardioversion, immediate reassessment of rhythm and perfusion confirms successful conversion and identifies potential re-initiation of SVT.
PALS Tachycardia With a Pulse 4
A 5-year-old with SVT remains stable.
Vagal maneuvers and two doses of adenosine have failed.
What is the next recommended treatment?