Cardiac Rhythm Recognition & Interpretation Flashcards

What is the normal heart rate range for an adult in normal sinus rhythm?

Answer: 60–100 bpm

Normal sinus rhythm in adults is defined as a heart rate of 60–100 bpm with a regular rhythm and consistent P-wave morphology.

Which ECG finding is characteristic of ventricular fibrillation (VF)?

Answer: Chaotic, irregular waveforms with no identifiable QRS complexes

Ventricular fibrillation produces disorganized, chaotic electrical activity with no identifiable P waves, QRS complexes, or T waves.

What does the PR interval on a 12-lead ECG represent?

Answer: Time from onset of atrial depolarization to start of ventricular depolarization

The PR interval spans from the start of the P wave to the beginning of the QRS complex, reflecting conduction from the SA node through the AV node to the bundle of His.

A regular narrow-complex tachycardia at 180 bpm with no visible P waves is most consistent with which rhythm?

Answer: Supraventricular tachycardia (SVT)

SVT typically presents with a regular rate of 150–250 bpm, narrow QRS complexes, and P waves buried within or immediately following the QRS.

What is the normal duration of a QRS complex on ECG?

Answer: 0.06–0.10 seconds

A normal QRS duration of 0.06–0.10 seconds reflects rapid ventricular depolarization via the intact His-Purkinje system.

In atrial fibrillation, how is the ventricular response best characterized?

Answer: Irregularly irregular rhythm

Atrial fibrillation produces an irregularly irregular ventricular response because impulses conduct through the AV node randomly.

Which ECG finding defines first-degree AV block?

Answer: PR interval greater than 0.20 seconds with all P waves conducted

First-degree AV block is characterized by a PR interval exceeding 0.20 seconds (200 ms) with every P wave still successfully conducted to the ventricles.