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Difficulty: EasyCardiovascular System

A 72-year-old woman is brought to the emergency department due to severe dizziness, confusion, and near-syncope. Her heart rate is 32/min, and blood pressure is 75/40 mm Hg. The 12-lead electrocardiogram reveals third-degree atrioventricular block. Arrange the following interventions in the optimal chronological sequence for managing this patient's symptomatic bradycardia, from initial emergency stabilization to definitive treatment.

  1. 1Administer intravenous atropine
  2. 2Initiate transcutaneous pacing
  3. 3Insert a temporary transvenous pacemaker
  4. 4Implant a permanent pacemaker

Answer

The correct sequence for managing unstable symptomatic bradycardia is to first administer intravenous atropine, then initiate transcutaneous pacing, followed by the insertion of a temporary transvenous pacemaker, and finally the implantation of a permanent pacemaker.
According to the Advanced Cardiac Life Support (ACLS) bradycardia algorithm, the management of a hemodynamically unstable patient with a bradyarrhythmia dictates a specific stepwise approach. Initial emergency management begins with intravenous atropine to rapidly increase the heart rate. Because atropine is often ineffective for high-degree blocks (like third-degree atrioventricular block), the immediate next step to prevent cardiovascular collapse is noninvasive transcutaneous pacing. Once the patient is stabilized noninvasively, a temporary transvenous pacemaker is inserted to provide reliable pacing that is better tolerated. Finally, after ruling out any reversible causes, a permanent pacemaker is implanted as the definitive long-term therapy.

Step-by-Step Solution

1
Identify the clinical emergency and the need for immediate intervention
The patient is identified as having symptomatic bradycardia with severe hemodynamic instability (hypotension, altered mental status) due to third-degree atrioventricular block.
Hemodynamic instability dictates immediate progression through the Advanced Cardiac Life Support (ACLS) bradycardia algorithm.
2
Provide initial pharmacologic therapy
Intravenous atropine is administered.
Atropine is the fastest first-line treatment to attempt vagal blockade, although it may be ineffective in infra-Hisian blocks.
3
Establish noninvasive electrical support
Transcutaneous pacing is initiated.
Required when atropine fails or is unlikely to be effective, providing immediate mechanical stabilization and preventing cardiovascular collapse.
4
Transition to invasive bridging therapy
A temporary transvenous pacemaker is inserted.
Transcutaneous pacing is painful and unreliable for prolonged use; a transvenous wire securely manages the rhythm until a permanent device can be placed.
5
Provide definitive, long-term treatment
A permanent pacemaker is implanted.
Irreversible third-degree atrioventricular block requires a permanent device to ensure adequate cardiac output and prevent sudden cardiac death.

Key Concept

Stepwise management algorithm for hemodynamically unstable symptomatic bradycardia
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Topics

Cardiovascular System

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