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Difficulty: MediumCardiovascular System

A 3434-year-old female arrives at the emergency department reporting a sudden onset of a racing heartbeat that began while she was sitting at her desk. She feels anxious but denies chest discomfort, dyspnea, or lightheadedness. Her blood pressure is 122/78122/78 mm Hg, heart rate is 178178/min, and oxygen saturation is 99%99\% on room air. An electrocardiogram demonstrates a regular, narrow-complex tachycardia with no discernible P waves. Assuming each successive step fails to terminate the arrhythmia, arrange the following therapeutic interventions in the correct chronological order recommended by current advanced cardiovascular life support (ACLS) guidelines for a hemodynamically stable patient.

  1. 1Instruct the patient to perform a vagal maneuver (e.g., Valsalva)
  2. 2Administer a rapid intravenous bolus of adenosine
  3. 3Administer an intravenous non-dihydropyridine calcium channel blocker
  4. 4Perform synchronized direct current cardioversion

Answer

The correct sequence of interventions is: 1) Vagal maneuvers, 2) Intravenous adenosine, 3) Intravenous non-dihydropyridine calcium channel blocker, and 4) Synchronized direct current cardioversion.
The clinical scenario describes a patient with stable paroxysmal supraventricular tachycardia (PSVT). According to ACLS guidelines, the sequential management of hemodynamically stable, regular, narrow-complex tachycardia begins with non-pharmacologic vagal maneuvers. If unsuccessful, a short-acting AV nodal blocker (adenosine) is administered as a rapid bolus. If the arrhythmia persists after adenosine, longer-acting agents such as non-dihydropyridine calcium channel blockers (e.g., diltiazem) or beta-blockers are indicated. Synchronized cardioversion is reserved for patients who are initially unstable, become unstable during treatment, or fail maximal medical therapy.

Step-by-Step Solution

1
Assess the patient's hemodynamic stability.
The patient is hemodynamically stable (blood pressure is normal, no altered mental status, no ischemic chest pain).
Stability determines whether immediate synchronized cardioversion or a step-wise trial of medical therapy is indicated.
2
Initiate non-pharmacologic therapy.
Perform a vagal maneuver.
Vagal maneuvers are a non-invasive first step that can terminate the arrhythmia by transiently slowing AV node conduction.
3
Administer first-line pharmacologic therapy.
Give a rapid intravenous bolus of adenosine.
Adenosine is the drug of choice for regular, narrow-complex tachycardias due to its rapid onset and short duration of action.
4
Administer second-line pharmacologic therapy.
Give an intravenous calcium channel blocker or beta-blocker.
If adenosine fails, longer-acting agents like diltiazem are utilized for ongoing rate and rhythm control.
5
Consider electrical therapy as a last resort.
Perform synchronized direct current cardioversion.
Cardioversion is required if the rhythm is refractory to all medical therapies or if the patient suddenly develops hemodynamic instability.

Key Concept

The standard step-wise management of a hemodynamically stable, regular, narrow-complex tachycardia involves vagal maneuvers, followed by adenosine, then longer-acting AV nodal blockers (like diltiazem), and finally synchronized cardioversion if medical therapy fails.
Estimated Time:1m 30s
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Topics

Cardiovascular System

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