A 55-year-old woman has a 12-lead ECG showing: regular wide-complex tachycardia at 175/min, AV dissociation, capture beats, and fusion beats. Blood pressure is 90/60 mmHg. What is the most accurate diagnosis and appropriate immediate management?

• A SVT with aberrant conduction; treat with adenosine IV
• B Pre-excited atrial fibrillation (WPW); treat with amiodarone
• C Torsades de pointes; give IV magnesium sulfate
• D Ventricular tachycardia (VT); perform immediate synchronized DC cardioversion ✓

Explanation

AV dissociation with capture beats and fusion beats are pathognomonic of ventricular tachycardia (VT). These findings cannot occur in SVT with aberrancy. With hemodynamic compromise (BP 90/60), immediate synchronized DC cardioversion is the treatment of choice regardless of tachycardia morphology. Adenosine is contraindicated in VT (ineffective and potentially dangerous). Brugada criteria, Vereckei algorithm, or Berlin criteria can differentiate wide-complex tachycardias when AV dissociation is not clearly visible.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.