In a patient with SVT or VT presenting with coma or unconsciousness, the initial rhythm-control treatment is

• A. Intravenous adenosine
• B. Lidocaine infusion
• C. Direct-current countershock
• D. Amiodarone infusion

Answer: (C)

When a tachyarrhythmia is presenting with coma or unconsciousness, the priority is to rapidly restore a perfusing rhythm. The fastest and most reliable way to do this is direct-current countershock, i.e., electrical cardioversion/defibrillation. This therapy immediately depolarizes the heart and interrupts chaotic or reentrant circuits, giving the heart a chance to resume a normal rhythm and blood flow.

Medications like adenosine are useful for certain stable, narrow-complex SVTs but are not appropriate or effective in an unconscious patient with a wide-complex tachycardia or VT/VF. Antiarrhythmics such as lidocaine or amiodarone can be considered after initial resuscitation or once a rhythm is stabilized, but they do not provide the same immediate stabilization as defibrillation in this critical setting.

In short, the first-line rhythm-control step for an unconscious patient with SVT or VT is an immediate electrical shock to reset the rhythm.