Calcium channel blockers are indicated to treat which dysrhythmia?

• A. Ventricular tachycardia
• B. Sinus bradycardia
• C. Second-degree AV block
• D. Atrial fibrillation

Answer: (D)

Calcium channel blockers are used to slow conduction through the AV node to control ventricular rate in atrial fibrillation with rapid ventricular response. In AF with RVR, the ventricles respond to impulses passing through the AV node, so reducing AV nodal conduction lowers the heart rate and improves hemodynamics. By blocking L-type calcium channels in the AV node, these meds slow the ventricular response without reliably converting AF to sinus rhythm. They’re particularly useful when beta-blockers aren’t suitable. They wouldn’t treat ventricular tachycardia, which originates in the ventricles and needs different antiarrhythmics or electrical therapy. They would also worsen sinus bradycardia or AV block by further slowing conduction, so they’re not indicated in those conditions. In short, they aid rate control in AF, not rhythm termination.