ECG ECG Rhythm Interpretation 1 — Questions and Answers
Question 1: What are the hallmark ECG findings of atrial fibrillation?
- Irregularly irregular rhythm with absent P waves and fibrillatory baseline (Correct answer)
- Regular rhythm with peaked T waves
- Wide QRS complexes with regular rhythm
- Sawtooth pattern between QRS complexes
Correct answer: Irregularly irregular rhythm with absent P waves and fibrillatory baseline
Atrial fibrillation shows an irregularly irregular ventricular rhythm (varying R-R intervals), absence of organized P waves replaced by fibrillatory baseline activity, and usually narrow QRS complexes.
Question 2: How do you differentiate between ventricular tachycardia and supraventricular tachycardia with aberrancy?
- VT shows AV dissociation, fusion/capture beats, and concordance; SVT with aberrancy usually has preceding P waves (Correct answer)
- Color of the ECG tracing
- Patient's age alone
- Heart rate alone determines the difference
Correct answer: VT shows AV dissociation, fusion/capture beats, and concordance; SVT with aberrancy usually has preceding P waves
Key VT indicators include AV dissociation, fusion/capture beats, extreme axis deviation, and QRS concordance. SVT with aberrancy typically shows preceding atrial activity and a bundle branch block pattern.
Question 3: What does ST elevation on an ECG indicate?
- Acute myocardial injury, most commonly from coronary artery occlusion causing a STEMI (Correct answer)
- Normal variant in all patients
- Chronic stable angina
- Pulmonary embolism always
Correct answer: Acute myocardial injury, most commonly from coronary artery occlusion causing a STEMI
ST elevation typically indicates acute myocardial injury from coronary artery occlusion (STEMI), though it can also occur in pericarditis, early repolarization, left ventricular aneurysm, and other conditions.
Question 4: What are the three degrees of AV heart block?
- First degree (prolonged PR), second degree (dropped beats), and third degree (complete dissociation between P waves and QRS) (Correct answer)
- Mild, moderate, and severe
- Temporary, intermittent, and permanent
- Left, right, and bilateral
Correct answer: First degree (prolonged PR), second degree (dropped beats), and third degree (complete dissociation between P waves and QRS)
First degree shows prolonged PR interval (>0.20s), second degree has intermittently dropped QRS complexes (Mobitz I with progressive PR prolongation, Mobitz II with sudden drops), and third degree shows complete AV dissociation.
Question 5: What ECG findings suggest hyperkalemia?
- Tall peaked T waves, widened QRS, flattened P waves, and potentially sine wave pattern (Correct answer)
- Short QT interval
- Prominent U waves
- Deep Q waves
Correct answer: Tall peaked T waves, widened QRS, flattened P waves, and potentially sine wave pattern
Hyperkalemia produces progressive ECG changes: peaked T waves, PR prolongation, P wave flattening, QRS widening, and eventually a sine wave pattern that can degenerate into ventricular fibrillation.
Question 6: What is the significance of a prolonged QT interval?
- It increases the risk of life-threatening ventricular arrhythmias, particularly Torsades de Pointes (Correct answer)
- It indicates excellent cardiac health
- It only occurs in athletes
- It has no clinical significance
Correct answer: It increases the risk of life-threatening ventricular arrhythmias, particularly Torsades de Pointes
Prolonged QT interval (>0.46s in men, >0.47s in women) indicates delayed ventricular repolarization, increasing vulnerability to Torsades de Pointes, a potentially fatal polymorphic ventricular tachycardia.
ECG ECG Rhythm Interpretation 1
What are the hallmark ECG findings of atrial fibrillation?