Which medication is administered for bradycardia?

• A. Adenosine 6 mg IV
• B. Epinephrine 1 mg IV
• C. Calcium chloride 1 g IV
• D. Atropine 1 mg IV, repeat PRN every 3-5 minutes (max dose 3 mg)

Answer: (D)

Treating symptomatic bradycardia hinges on increasing the heart rate by reducing the dominant vagal (parasympathetic) influence on the heart. Atropine blocks muscarinic receptors, which are activated by acetylcholine to slow the heart, so blocking them lets the SA node fire faster and improves AV nodal conduction. That’s why atropine given IV is the first-line medication for symptomatic bradycardia, typically given as 0.5 mg IV every 3–5 minutes up to a total of 3 mg. The goal is to raise the heart rate and improve perfusion quickly. Other drugs shown here have different primary roles: adenosine is used to acutely terminate certain tachycardias, not to treat a slow heart rate; epinephrine and calcium have uses in cardiac arrest, severe hypotension, or specific overdoses, not routine bradycardia management. If atropine doesn’t work, pacing or infusions of dopamine or epinephrine may be considered.