ACLS Tachycardia and Bradycardia Algorithms 3 — Questions and Answers
Question 1: A patient with wide-complex tachycardia at 180 bpm is stable. Adenosine is given and does not convert the rhythm. What does this suggest?
- The rhythm is SVT with aberrancy
- The rhythm is likely ventricular tachycardia (Correct answer)
- The dose was insufficient and should be repeated
- The patient needs immediate cardioversion
Correct answer: The rhythm is likely ventricular tachycardia
Failure to terminate with adenosine in a stable wide-complex tachycardia suggests the rhythm is ventricular tachycardia rather than SVT with aberrancy.
Question 2: Which rhythm does NOT require synchronized cardioversion?
- Unstable atrial fibrillation
- Unstable monomorphic VT with a pulse
- Ventricular fibrillation (Correct answer)
- Unstable SVT
Correct answer: Ventricular fibrillation
Ventricular fibrillation is a disorganized rhythm with no discernible R wave, so it requires unsynchronized defibrillation, not synchronized cardioversion.
Question 3: A patient receiving transcutaneous pacing for symptomatic bradycardia shows electrical capture but remains bradycardic and hypotensive. What is the next step?
- Increase pacer rate
- Check for mechanical capture by palpating a pulse (Correct answer)
- Switch to transvenous pacing immediately
- Administer adenosine
Correct answer: Check for mechanical capture by palpating a pulse
Electrical capture (pacing spikes with QRS complexes) must be confirmed to have mechanical capture by assessing the pulse and blood pressure.
Question 4: Which of the following best describes polymorphic VT (Torsades de Pointes) compared to monomorphic VT in ACLS management?
- Both are treated identically with amiodarone
- Torsades may require magnesium sulfate; amiodarone can worsen it (Correct answer)
- Torsades responds better to adenosine
- Monomorphic VT is always treated with defibrillation
Correct answer: Torsades may require magnesium sulfate; amiodarone can worsen it
Torsades de Pointes is treated with magnesium sulfate 1–2 g IV, while amiodarone may prolong the QT further and worsen the arrhythmia.
Question 5: In the ACLS tachycardia algorithm, what heart rate threshold generally prompts evaluation for treatment?
- Greater than 100 bpm
- Greater than 120 bpm
- Greater than 150 bpm (Correct answer)
- Greater than 180 bpm
Correct answer: Greater than 150 bpm
The ACLS tachycardia algorithm is typically initiated when heart rate exceeds 150 bpm, as rates below this rarely cause hemodynamic compromise.
Question 6: A patient with known WPW syndrome presents with atrial fibrillation at 220 bpm. Which drug is contraindicated?
- Procainamide
- Ibutilide
- Adenosine (Correct answer)
- Electrical cardioversion
Correct answer: Adenosine
Adenosine blocks the AV node but can promote conduction down the accessory pathway in WPW, potentially accelerating the ventricular rate and causing VF.
Question 7: What is the recommended initial dose of dopamine infusion for hemodynamically significant bradycardia when atropine fails?
- 1–2 mcg/kg/min
- 2–10 mcg/kg/min (Correct answer)
- 15–20 mcg/kg/min
- 0.1–0.5 mcg/kg/min
Correct answer: 2–10 mcg/kg/min
Dopamine is initiated at 2–10 mcg/kg/min as a chronotropic agent for symptomatic bradycardia refractory to atropine.
ACLS Tachycardia and Bradycardia Algorithms 3
A patient with wide-complex tachycardia at 180 bpm is stable.
Adenosine is given and does not convert the rhythm.
What does this suggest?