Immediate Synchronized Cardioversion is Required
For a patient with SVT who has become hemodynamically unstable (BP 80/45 mmHg, decreased responsiveness), synchronized cardioversion must be performed immediately. This is a Class I, Level B-NR recommendation from the ACC/AHA/HRS guidelines 1.
Why Cardioversion is the Answer (Option B)
Synchronized cardioversion should be performed for acute treatment in hemodynamically unstable patients with SVT when vagal maneuvers or adenosine are ineffective or not feasible 1. In this clinical scenario:
- The patient has clear signs of hemodynamic instability: hypotension (80/45 mmHg) and altered mental status (decreased responsiveness) 1, 2
- These findings indicate shock and acutely altered mental status, which are explicit indications for immediate cardioversion per ACLS guidelines 1, 2
- Cardioversion achieved 100% success in restoring sinus rhythm in cohort studies of hemodynamically unstable SVT patients 1, 2
Initial Energy Settings
- Start with 50-100 J for synchronized cardioversion 2
- Provide procedural sedation if the patient remains conscious enough to perceive pain 2
Why the Other Options Are Wrong
Propranolol (Option C) - Contraindicated
Beta blockers are absolutely contraindicated in hemodynamically unstable patients 2, 3. Propranolol would:
- Worsen the existing hypotension through negative inotropic and chronotropic effects 2
- Risk precipitating cardiovascular collapse 2, 3
- Be far too slow-acting for a patient in shock 2
Pacemaker (Option A) - Wrong Indication
- Pacemakers treat bradyarrhythmias, not tachyarrhythmias [@general medical knowledge@]
- This patient has SVT (a tachycardia), not a slow rhythm requiring pacing
Radiofrequency Ablation (Option D) - Not Acute Management
- Ablation is definitive long-term therapy with 94.3-98.5% success rates 3, 4
- However, it is performed electively after the patient is stabilized, not during acute hemodynamic compromise 3
- The immediate priority is restoring hemodynamic stability, not definitive cure
Clinical Pitfall to Avoid
Do not delay cardioversion to attempt pharmacologic interventions when clear signs of instability are present 3. While adenosine may be considered first if the tachycardia is regular with narrow QRS complex 1, 2, this patient's profound hypotension (BP 80/45) and decreased responsiveness indicate that sinus rhythm must be restored immediately 1. The time required to obtain IV access, draw up adenosine, and wait for effect could worsen end-organ hypoperfusion.
The correct answer is B. Cardioversion.