ACLS Bradycardia 4 — Questions and Answers
Question 1: A patient with an inferior STEMI develops bradycardia. What is the most likely underlying conduction abnormality?
- Left bundle branch block
- AV block at the level of the AV node (Correct answer)
- Infranodal (His-Purkinje) block
- Sinoatrial exit block
Correct answer: AV block at the level of the AV node
Inferior MI commonly causes AV nodal ischemia (right coronary artery supplies the AV node in most people), leading to nodal-level AV block.
Question 2: During transcutaneous pacing, the patient is conscious and experiencing significant discomfort. What should the provider do?
- Discontinue pacing immediately
- Increase the pacing rate to reduce discomfort
- Administer IV analgesia and sedation (Correct answer)
- Switch immediately to defibrillation
Correct answer: Administer IV analgesia and sedation
Analgesics and sedatives should be administered to manage pain and anxiety during transcutaneous pacing in conscious patients.
Question 3: Which ECG feature distinguishes a junctional escape rhythm from a ventricular escape rhythm in complete heart block?
- Rate of the escape rhythm
- Presence of P waves
- Width of the QRS complex (Correct answer)
- Regularity of the R-R interval
Correct answer: Width of the QRS complex
Junctional escape beats produce narrow QRS complexes (≤0.12 sec), while ventricular escape beats produce wide QRS complexes (>0.12 sec).
Question 4: A patient with symptomatic bradycardia has a known transplanted heart. Why might atropine be ineffective?
- Transplanted hearts have faster baseline rates
- The donor heart is denervated and lacks vagal innervation (Correct answer)
- Atropine is contraindicated in transplanted hearts due to toxicity
- Transplanted hearts respond only to calcium channel blockers
Correct answer: The donor heart is denervated and lacks vagal innervation
The transplanted heart is denervated and does not respond to atropine because there is no vagal innervation to block.
Question 5: What pacing rate is typically used as an initial setting when starting transcutaneous pacing for bradycardia?
- 40 bpm
- 60–80 bpm (Correct answer)
- 100–120 bpm
- 150 bpm
Correct answer: 60–80 bpm
An initial pacing rate of 60–80 bpm is typically selected to achieve hemodynamic stability in bradycardic patients.
Question 6: Which of the following is TRUE about Wenckebach (Mobitz type I) second-degree AV block?
- It requires immediate transcutaneous pacing in all cases
- It typically occurs at the level of the His-Purkinje system
- It often resolves without treatment and rarely progresses to complete block (Correct answer)
- It produces wide QRS complexes
Correct answer: It often resolves without treatment and rarely progresses to complete block
Wenckebach block is usually benign, occurs at the AV node, and rarely progresses to complete heart block.
Question 7: When using the ACLS Bradycardia Algorithm, which finding would prompt IMMEDIATE intervention rather than watchful waiting?
- Heart rate of 52 bpm in a sleeping athlete
- Heart rate of 48 bpm with acute altered mental status (Correct answer)
- Heart rate of 55 bpm in an asymptomatic patient on beta-blockers
- Heart rate of 50 bpm with a blood pressure of 118/78 mmHg
Correct answer: Heart rate of 48 bpm with acute altered mental status
Altered mental status is a sign of inadequate perfusion from bradycardia and requires immediate ACLS intervention.
ACLS Bradycardia 4
A patient with an inferior STEMI develops bradycardia.
What is the most likely underlying conduction abnormality?