CPEN Cardiac Emergencies 3

Question 1

A 6-year-old presents with syncope during exercise and ECG shows a QTc of 520 ms. Which condition does this suggest?

Accepted Answer

Long QT syndrome

Answer

A QTc >460 ms in children (>480 ms in adults) indicates long QT syndrome, which predisposes to polymorphic VT (torsades de pointes).

Question 2

A 13-year-old athlete collapses during a game and is found to be in ventricular fibrillation. After one defibrillation attempt, CPR is resumed. What is the next pharmacologic intervention per PALS?

Accepted Answer

Epinephrine 0.01 mg/kg IV

Answer

Epinephrine is given every 3–5 minutes during pulseless arrest, starting after the first rhythm check shows persistent shockable or non-shockable rhythm.

Question 3

Torsades de pointes is best treated with:

Accepted Answer

Magnesium sulfate IV

Answer

IV magnesium sulfate (25–50 mg/kg) is the treatment of choice for torsades de pointes, shortening the QT and stabilizing the membrane.

Question 4

Which electrolyte abnormality is MOST likely to precipitate ventricular arrhythmias in a pediatric patient?

Accepted Answer

Hypokalemia

Answer

Hypokalemia prolongs the QT interval and increases myocardial excitability, predisposing to ventricular arrhythmias including torsades de pointes.

Question 5

A 2-month-old infant has a resting heart rate of 58 bpm with a wide QRS and no relationship between P waves and QRS complexes. This ECG finding is consistent with:

Accepted Answer

Complete (third-degree) AV block

Answer

Complete AV block shows atrioventricular dissociation: P waves and QRS complexes fire independently with no consistent relationship.

CPEN - Certified Pediatric Emergency Nurse Practice Test

CPEN - Certified Pediatric Emergency Nurse Practice Test

CPEN Cardiac Emergencies 3