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Difficulty: MediumCardiovascular System

While working in the urgent care clinic, a physician evaluates a 3232-year-old female patient complaining of a racing heartbeat that started abruptly while she was reading a book. She reports no chest discomfort, dyspnea, or lightheadedness. Her blood pressure is 122/78122/78 mmHg, and her radial pulse is rapid and weak. A 1212-lead electrocardiogram is obtained and displays a perfectly regular tachycardia at 175175 beats per minute with narrow QRS complexes and no discernible P waves.

Assuming she remains hemodynamically stable but the arrhythmia does not resolve with initial interventions, arrange the following management steps in the standard chronological sequence for this condition, concluding with definitive long-term therapy.

  1. 1Instruct the patient to perform a Valsalva maneuver
  2. 2Administer a rapid intravenous bolus of adenosine
  3. 3Administer an intravenous infusion of diltiazem
  4. 4Perform synchronized direct-current cardioversion
  5. 5Refer for an electrophysiology study and catheter ablation

Answer

The correct chronological sequence is: 1) Valsalva maneuver, 2) Intravenous adenosine, 3) Intravenous diltiazem, 4) Synchronized direct-current cardioversion, and 5) Electrophysiology study and catheter ablation.
The standard stepwise management of hemodynamically stable paroxysmal supraventricular tachycardia (PSVT) prioritizes the least invasive and most transient therapies first. Since the patient is stable, vagal maneuvers (e.g., Valsalva maneuver, carotid sinus massage) are the initial non-pharmacologic intervention. If these maneuvers fail, intravenous adenosine is administered due to its rapid onset and short half-life, effectively interrupting the AV nodal reentrant circuit. For cases refractory to adenosine, a longer-acting intravenous AV nodal blocker, such as diltiazem or metoprolol, is indicated. If all pharmacological options fail to terminate the tachycardia in the acute setting, synchronized direct-current cardioversion is utilized. Finally, the definitive long-term treatment to prevent recurrences is an electrophysiology study followed by radiofrequency catheter ablation of the accessory pathway or ectopic focus.

Step-by-Step Solution

1
Assess the patient's hemodynamic status.
The patient has a normal blood pressure and is well-perfused, categorizing her condition as hemodynamically stable.
Hemodynamic stability dictates whether immediate electrical cardioversion or a step-wise pharmacological approach should be utilized.
2
Attempt non-pharmacological interventions.
A Valsalva maneuver is performed to increase vagal tone.
Vagal maneuvers are the initial, non-invasive first-line therapy and can successfully terminate atrioventricular nodal reentrant tachycardias.
3
Administer first-line short-acting pharmacological therapy.
Intravenous adenosine is given via rapid bolus.
Adenosine causes a transient block at the AV node, effectively interrupting the reentrant circuit in most patients without causing prolonged hypotension.
4
Administer second-line pharmacological therapy if the rhythm persists.
Intravenous diltiazem is administered.
Longer-acting AV nodal blocking agents are indicated when adenosine fails to terminate the arrhythmia.
5
Perform electrical cardioversion if pharmacological therapy is exhausted.
Synchronized direct-current cardioversion is applied.
Cardioversion is required for stable patients who remain refractory to all medical interventions in the acute emergency setting.
6
Plan for definitive outpatient treatment.
The patient is referred for an electrophysiology study and ablation.
Radiofrequency catheter ablation targets the anatomical basis of the reentrant circuit, serving as the definitive long-term treatment.

Key Concept

Stepwise escalation protocol for hemodynamically stable paroxysmal supraventricular tachycardia (PSVT).
Estimated Time:1m 0s
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Topics

Cardiovascular System

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