CET Arrhythmia Recognition & Classification 3 — Questions and Answers
Question 1: Torsades de pointes is a form of polymorphic ventricular tachycardia most commonly associated with:
- Prolonged QT interval (Correct answer)
- Shortened QT interval
- Prolonged PR interval
- Wide QRS complex
Correct answer: Prolonged QT interval
Torsades de pointes ('twisting of the points') occurs in the setting of a prolonged QT interval and is characterized by QRS complexes that twist around the isoelectric baseline.
Question 2: Which ECG finding is most characteristic of hyperkalemia contributing to a bradyarrhythmia?
- Peaked, narrow, tall T waves with widening QRS (Correct answer)
- Prolonged QT with flat T waves
- Delta waves with short PR interval
- Sawtooth baseline at 300 bpm
Correct answer: Peaked, narrow, tall T waves with widening QRS
Hyperkalemia produces peaked, tall, narrow T waves early, and progressive QRS widening, which can degrade into a sine-wave pattern and cardiac arrest.
Question 3: A patient has an irregular rhythm with no discernible P waves and a variable ventricular rate of 90–140 bpm. The most likely diagnosis is:
- Atrial fibrillation (Correct answer)
- Multifocal atrial tachycardia
- Atrial flutter with variable block
- Junctional rhythm with PVCs
Correct answer: Atrial fibrillation
Atrial fibrillation is characterized by an irregularly irregular rhythm, absence of distinct P waves, and fibrillatory baseline activity (f waves).
Question 4: Premature ventricular contractions (PVCs) are characterized on the ECG by:
- Wide QRS >0.12 s without a preceding P wave, followed by a full compensatory pause (Correct answer)
- Narrow QRS with a shortened PR interval
- Wide QRS preceded by an abnormal P wave
- Regular wide complexes at a rate of 150 bpm
Correct answer: Wide QRS >0.12 s without a preceding P wave, followed by a full compensatory pause
PVCs arise from ectopic ventricular foci, producing wide, bizarre QRS complexes without a preceding P wave, typically followed by a compensatory pause.
Question 5: The Brugada pattern on an ECG is characterized by which of the following?
- Coved ST elevation in V1–V2 with right bundle branch block pattern (Correct answer)
- Horizontal ST depression in V4–V6
- Tall R waves in V1 with left axis deviation
- Prolonged QT with U waves in V2–V3
Correct answer: Coved ST elevation in V1–V2 with right bundle branch block pattern
Brugada syndrome shows a distinctive coved-type ST elevation (>2 mm) in the right precordial leads (V1–V2) with a right bundle branch block-like pattern, predisposing to ventricular fibrillation.
Question 6: Which arrhythmia is described as three or more consecutive PVCs at a rate greater than 100 bpm lasting less than 30 seconds?
- Non-sustained ventricular tachycardia (Correct answer)
- Sustained ventricular tachycardia
- Ventricular fibrillation
- Accelerated idioventricular rhythm
Correct answer: Non-sustained ventricular tachycardia
Non-sustained VT is defined as three or more consecutive ventricular beats at ≥100 bpm that self-terminate within 30 seconds.
Question 7: In a patient with known digoxin toxicity, which ECG finding is most characteristic?
- Bidirectional ventricular tachycardia (Correct answer)
- Torsades de pointes
- Atrial flutter with 2:1 block
- Accelerated junctional rhythm only
Correct answer: Bidirectional ventricular tachycardia
Bidirectional ventricular tachycardia, where the QRS axis alternates beat to beat, is highly specific for digitalis toxicity.
CET Arrhythmia Recognition & Classification 3
Torsades de pointes is a form of polymorphic ventricular tachycardia most commonly associated with: