ECG in Clinical Practice Flashcards

Which lead configuration would produce a completely flat line (asystole appearance) if a limb lead becomes disconnected?

Answer: The affected lead traces flat while others remain

A disconnected limb lead causes a flat trace in the specific lead using that electrode, not true asystole.

A regular narrow-complex tachycardia at 150 bpm with no visible P waves most likely represents what?

Answer: Supraventricular tachycardia

A regular narrow-complex tachycardia around 150 bpm is typically supraventricular tachycardia.

What does the PR interval represent on an ECG?

Answer: Time from atrial depolarization to ventricular depolarization

The PR interval measures conduction from the atria through the AV node to the ventricles.

Which artifact appears as consistent, fine, fast oscillations often caused by 60 Hz electrical sources?

Answer: AC electrical interference

Uniform fast oscillations are typically AC interference from nearby electrical equipment.

A normal QRS complex duration should be less than which value?

Answer: 0.12 seconds

A normal QRS complex is less than 0.12 seconds (three small boxes).

If the limb leads on the right and left arms are reversed, what change is commonly seen?

Answer: Lead I becomes inverted

Right/left arm lead reversal typically inverts lead I and can mimic pathology.

Which of the following patients requires modified electrode placement using a right-sided ECG?

Answer: Suspected right ventricular infarction

Right-sided leads (e.g., V4R) are used to assess suspected right ventricular infarction.