In an intraoperative emergency, which drug is used to treat bradycardia by increasing heart rate?

• A. Decrease heart rate
• B. Treats bradycardia by increasing heart rate
• C. Relaxes smooth muscle
• D. Acts as a local anesthetic

Answer: (B)

Counteracting bradycardia during surgery requires a drug that raises heart rate by blocking vagal (parasympathetic) input to the heart. In practice, antimuscarinic drugs such as atropine or glycopyrrolate are used. By blocking muscarinic receptors on the SA and AV nodes, they remove the parasympathetic brake, increasing automaticity and conduction to raise the heart rate. This matches the option that describes treating bradycardia by increasing heart rate—the exact action you want in an intraoperative emergency. The other described actions do not address the slow heart rate: decreasing heart rate would worsen bradycardia, and relaxing smooth muscle or acting as a local anesthetic does not correct the low rate.