For a patient with a hemodynamically unstable tachyarrhythmia, what is the immediate intervention?

• A. Synchronized cardioversion
• B. Vagal maneuvers
• C. Defibrillation (unsynchronized)
• D. Immediate beta-blocker infusion

Answer: (A)

When a tachyarrhythmia causes hemodynamic instability, the immediate goal is to restore stable cardiac output as quickly as possible. Synchronized cardioversion delivers a timed electric shock that interrupts the abnormal rhythm while aiming to preserve a normal rhythm, with the shock synchronized to the R wave to avoid inducing ventricular fibrillation. This rapid, controlled reset is the most effective way to quickly improve perfusion in a patient who is unstable.

Vagal maneuvers rely on a stable rhythm and slow conduction, so they’re too slow and unreliable when instability is present. Defibrillation (unsynchronized) is used for pulseless VT or VF; in a patient with a pulse, an unsynchronized shock can be dangerous and is not appropriate. Immediate beta-blocker infusion would not provide rapid rhythm control and could worsen hypotension, making the situation worse rather than improving it.

So, the best immediate intervention is synchronized cardioversion to promptly restore a stable rhythm and improve perfusion.