Which cardiac finding would raise concern for digoxin toxicity?

• A. Tachycardia with a regular rhythm
• B. Bradycardia with an irregular rhythm
• C. Normal sinus rhythm with rate 90
• D. Bradycardia with a regular rhythm

Answer: (B)

The main concept is recognizing how digoxin toxicity affects cardiac rhythm. Digoxin slows conduction through the AV node and can increase automaticity, so toxicity often disrupts rhythm, leading to bradycardia combined with irregular beats or blocks. An irregular rhythm with bradycardia signals a disturbed conduction system due to toxic effects, which is more concerning than a regular rhythm, even if slow. Regular tachycardia or a normal sinus rhythm around 90 is not as worrisome for toxicity. Therefore, bradycardia with an irregular rhythm best indicates digoxin toxicity.