ECG ECG Interpretation 2 — Questions and Answers
Question 1: Which ECG finding is characteristic of atrial fibrillation?
- Irregularly irregular rhythm with no P waves (Correct answer)
- Regular rhythm with tall P waves
- Wide QRS complexes only
- Saw-tooth pattern
Correct answer: Irregularly irregular rhythm with no P waves
Atrial fibrillation shows an irregularly irregular ventricular rhythm with fibrillatory baseline waves replacing organized P waves.
Question 2: A prolonged QT interval increases the risk of:
- Torsades de pointes (Correct answer)
- Atrial flutter
- First-degree heart block
- Pericarditis
Correct answer: Torsades de pointes
Prolonged QT interval can lead to torsades de pointes, a dangerous polymorphic ventricular tachycardia that can degenerate into ventricular fibrillation.
Question 3: Which lead is best for identifying atrial activity?
- Lead V1 (Correct answer)
- Lead I
- Lead aVL
- Lead V6
Correct answer: Lead V1
Lead V1, positioned over the right sternal border, is closest to the atria and provides the best visualization of P waves and atrial activity.
Question 4: What ECG change is seen with hyperkalemia?
- Peaked T waves (Correct answer)
- Inverted P waves only
- Short QT interval
- Delta waves
Correct answer: Peaked T waves
Elevated potassium levels cause tall, peaked T waves as one of the earliest ECG manifestations, progressing to widened QRS and sine wave pattern if severe.
Question 5: What does sinus rhythm mean on an ECG?
- The heart rhythm originates from the SA node (Correct answer)
- The heart is beating irregularly
- There is a conduction block
- The ventricles are pacing the heart
Correct answer: The heart rhythm originates from the SA node
Sinus rhythm means the electrical impulse originates from the sinoatrial node, the heart's natural pacemaker, producing a normal, regular rhythm with consistent P waves before each QRS.
Question 6: What is the normal duration of the QRS complex?
- 0.06 to 0.10 seconds (Correct answer)
- 0.12 to 0.20 seconds
- 0.20 to 0.30 seconds
- 0.01 to 0.04 seconds
Correct answer: 0.06 to 0.10 seconds
A normal QRS complex lasts 0.06-0.10 seconds (1.5-2.5 small boxes). A QRS wider than 0.12 seconds suggests a bundle branch block or ventricular origin.
ECG ECG Interpretation 2
Which ECG finding is characteristic of atrial fibrillation?