Which medications can cause bradycardia?

• A. Beta blockers
• B. Calcium channel blockers
• C. Digoxin
• D. All of the above

Answer: (D)

Medications that slow the heart rate do so by dampening the electrical activity that controls how fast the heart beats. Beta blockers reduce the heart’s rate and its conduction through the AV node by blocking sympathetic stimulation. Calcium channel blockers of the non-dihydropyridine type (like verapamil and diltiazem) slow AV nodal conduction directly, which can lower the resting heart rate. Digoxin increases vagal (parasympathetic) tone and also slows AV conduction, which can lead to bradycardia, especially if the drug level is high or in patients with renal impairment or electrolyte disturbances. Because each of these drug classes can produce a slower heart rate, they’re all potential culprits when bradycardia occurs.