CPEN Cardiac Emergencies 2 — Questions and Answers
Question 1: A 4-year-old presents with sudden onset of HR 220 bpm, narrow QRS, and no P waves visible before each QRS on ECG. What is the most likely diagnosis?
- Sinus tachycardia
- Supraventricular tachycardia (SVT) (Correct answer)
- Ventricular tachycardia
- Atrial flutter
Correct answer: Supraventricular tachycardia (SVT)
SVT in children typically presents with HR >200 bpm, narrow QRS, and absent or retrograde P waves.
Question 2: Which medication is the first-line pharmacologic treatment for SVT in a hemodynamically stable pediatric patient when vagal maneuvers fail?
- Amiodarone
- Adenosine (Correct answer)
- Verapamil
- Digoxin
Correct answer: Adenosine
Adenosine is the drug of choice for SVT in stable pediatric patients, given as a rapid IV push.
Question 3: A 3-week-old infant presents with pallor, poor feeding, and HR of 280 bpm. The most appropriate immediate intervention is:
- Vagal maneuvers
- IV adenosine
- Synchronized cardioversion (Correct answer)
- Ice to the face
Correct answer: Synchronized cardioversion
A hemodynamically unstable infant with SVT requires immediate synchronized cardioversion at 0.5–1 J/kg.
Question 4: What is the recommended initial energy dose for synchronized cardioversion in a pediatric patient with unstable SVT?
- 0.5–1 J/kg (Correct answer)
- 2 J/kg
- 4 J/kg
- 10 J/kg
Correct answer: 0.5–1 J/kg
PALS guidelines recommend 0.5–1 J/kg for the initial synchronized cardioversion, increasing to 2 J/kg if needed.
Question 5: A 7-year-old with known Wolff-Parkinson-White syndrome presents in SVT. Which medication should be AVOIDED?
- Adenosine
- Amiodarone
- Verapamil (Correct answer)
- Procainamide
Correct answer: Verapamil
Verapamil is contraindicated in WPW because it can accelerate conduction through the accessory pathway, precipitating VF.
Question 6: On a 12-lead ECG, a delta wave indicates:
- Right bundle branch block
- Pre-excitation via an accessory pathway (Correct answer)
- Hypokalemia
- Prolonged QT interval
Correct answer: Pre-excitation via an accessory pathway
A delta wave (slurred upstroke of the QRS) represents ventricular pre-excitation through an accessory pathway, characteristic of WPW.
Question 7: A 10-year-old with SVT receives adenosine 0.1 mg/kg IV without conversion. What is the next appropriate step?
- Repeat adenosine at 0.2 mg/kg (Correct answer)
- Give verapamil 0.1 mg/kg IV
- Perform unsynchronized cardioversion
- Start dopamine infusion
Correct answer: Repeat adenosine at 0.2 mg/kg
If the first dose of adenosine fails, the second dose is doubled to 0.2 mg/kg (max 12 mg), still given as a rapid IV push.
CPEN Cardiac Emergencies 2
A 4-year-old presents with sudden onset of HR 220 bpm, narrow QRS, and no P waves visible before each QRS on ECG.
What is the most likely diagnosis?