Question:medium
Which one of the following ECG findings represents a manifestation of digitalis toxicity?
Which one of the following ECG findings represents a manifestation of digitalis toxicity?
Show Hint
Digitalis toxicity does two opposite things to the atrium and the AV node at the same time - think about what rhythm that combination creates.
Updated On: Jul 16, 2026
- ST segment depression
- Atrial tachycardia with variable block
- Atrial flutter
- Shortening of PR interval
Show Solution
The Correct Option is B
Solution and Explanation
This question checks whether you can separate the routine digitalis ECG effect from a genuine toxicity arrhythmia.
- ST segment depression: this is the expected therapeutic 'digitalis effect' at normal doses, not proof of toxicity.
- Atrial tachycardia with variable block: toxic digoxin levels raise atrial automaticity while also depressing AV conduction, so a fast atrial focus fires but only some beats reach the ventricles - this dual signature is the classic toxicity arrhythmia.
- Atrial flutter: a nonspecific arrhythmia with many causes, not a specific fingerprint of digitalis toxicity.
- Shortening of PR interval: digitalis toxicity slows AV nodal conduction and prolongs the PR interval, so a shortened PR points elsewhere entirely (such as pre-excitation).
Correct answer: Atrial tachycardia with variable block.
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