Basic Arrhythmia practice questions with answers and rationales 2026/2027
version
1. Which ECG component represents atrial depolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Answer: A. P wave
Rationale: The P wave represents electrical depolarization of the atria.
2. Which ECG component represents ventricular depolarization?
A. P wave
B. PR interval
C. QRS complex
D. T wave
Answer: C. QRS complex
Rationale: The QRS complex represents ventricular depolarization.
3. The T wave represents:
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial contraction
Answer: B. Ventricular repolarization
Rationale: The T wave represents recovery/repolarization of the ventricles.
4. A normal adult resting heart rate is generally:
A. 20–40 bpm
B. 40–59 bpm
C. 60–100 bpm
D. 110–160 bpm
Answer: C. 60–100 bpm
Rationale: A normal adult sinus rate is generally 60–100 beats/minute.
5. A heart rate below 60 beats/minute is called:
A. Tachycardia
B. Bradycardia
C. Dysrhythmia
D. Fibrillation
,Answer: B. Bradycardia
Rationale: Bradycardia refers to a heart rate below 60 bpm in adults.
6. A heart rate above 100 beats/minute is called:
A. Bradycardia
B. Tachycardia
C. Asystole
D. Block
Answer: B. Tachycardia
Rationale: Tachycardia refers to a heart rate above 100 bpm in adults.
7. Which rhythm normally originates in the sinoatrial node?
A. Sinus rhythm
B. Ventricular fibrillation
C. Junctional rhythm
D. Ventricular tachycardia
Answer: A. Sinus rhythm
Rationale: The SA node is the normal pacemaker of the heart.
8. What is the normal PR interval?
A. 0.04–0.08 seconds
B. 0.12–0.20 seconds
C. 0.22–0.30 seconds
D. 0.30–0.40 seconds
Answer: B. 0.12–0.20 seconds
Rationale: The normal PR interval is approximately 0.12–0.20 seconds.
9. A normal QRS duration is generally:
A. Less than 0.12 seconds
B. 0.20–0.30 seconds
C. 0.30–0.40 seconds
D. More than 0.40 seconds
Answer: A. Less than 0.12 seconds
Rationale: A normal ventricular conduction time produces a QRS under 0.12 seconds.
10. Which rhythm is characterized by a regular rhythm, rate 60–100, and one normal P
wave before every QRS?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular fibrillation
D. Junctional rhythm
, Answer: B. Normal sinus rhythm
Rationale: Normal sinus rhythm has regular atrial and ventricular activity with a normal P
before each QRS.
11. Sinus bradycardia is characterized by:
A. Rate below 60 with normal sinus P waves
B. Rate above 100 with no P waves
C. Wide irregular QRS complexes
D. Chaotic ventricular activity
Answer: A. Rate below 60 with normal sinus P waves
Rationale: Sinus bradycardia maintains normal sinus morphology but has a slower rate.
12. Sinus tachycardia generally has a rate:
A. Below 40 bpm
B. 40–59 bpm
C. 60–100 bpm
D. Above 100 bpm
Answer: D. Above 100 bpm
Rationale: Sinus tachycardia is sinus rhythm occurring at a rate greater than 100 bpm.
13. Which condition can cause sinus tachycardia?
A. Fever
B. Sleep
C. Hypothermia
D. Increased vagal tone
Answer: A. Fever
Rationale: Fever, pain, anxiety, dehydration, and other physiologic stresses can increase sinus
rate.
14. Which condition can cause sinus bradycardia?
A. Exercise
B. Fever
C. Increased vagal tone
D. Severe anxiety
Answer: C. Increased vagal tone
Rationale: Increased parasympathetic/vagal activity can slow the sinus rate.
15. A premature beat originating in the atria is called a:
A. PVC
B. PAC
C. PJC
D. Escape beat
version
1. Which ECG component represents atrial depolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Answer: A. P wave
Rationale: The P wave represents electrical depolarization of the atria.
2. Which ECG component represents ventricular depolarization?
A. P wave
B. PR interval
C. QRS complex
D. T wave
Answer: C. QRS complex
Rationale: The QRS complex represents ventricular depolarization.
3. The T wave represents:
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial contraction
Answer: B. Ventricular repolarization
Rationale: The T wave represents recovery/repolarization of the ventricles.
4. A normal adult resting heart rate is generally:
A. 20–40 bpm
B. 40–59 bpm
C. 60–100 bpm
D. 110–160 bpm
Answer: C. 60–100 bpm
Rationale: A normal adult sinus rate is generally 60–100 beats/minute.
5. A heart rate below 60 beats/minute is called:
A. Tachycardia
B. Bradycardia
C. Dysrhythmia
D. Fibrillation
,Answer: B. Bradycardia
Rationale: Bradycardia refers to a heart rate below 60 bpm in adults.
6. A heart rate above 100 beats/minute is called:
A. Bradycardia
B. Tachycardia
C. Asystole
D. Block
Answer: B. Tachycardia
Rationale: Tachycardia refers to a heart rate above 100 bpm in adults.
7. Which rhythm normally originates in the sinoatrial node?
A. Sinus rhythm
B. Ventricular fibrillation
C. Junctional rhythm
D. Ventricular tachycardia
Answer: A. Sinus rhythm
Rationale: The SA node is the normal pacemaker of the heart.
8. What is the normal PR interval?
A. 0.04–0.08 seconds
B. 0.12–0.20 seconds
C. 0.22–0.30 seconds
D. 0.30–0.40 seconds
Answer: B. 0.12–0.20 seconds
Rationale: The normal PR interval is approximately 0.12–0.20 seconds.
9. A normal QRS duration is generally:
A. Less than 0.12 seconds
B. 0.20–0.30 seconds
C. 0.30–0.40 seconds
D. More than 0.40 seconds
Answer: A. Less than 0.12 seconds
Rationale: A normal ventricular conduction time produces a QRS under 0.12 seconds.
10. Which rhythm is characterized by a regular rhythm, rate 60–100, and one normal P
wave before every QRS?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular fibrillation
D. Junctional rhythm
, Answer: B. Normal sinus rhythm
Rationale: Normal sinus rhythm has regular atrial and ventricular activity with a normal P
before each QRS.
11. Sinus bradycardia is characterized by:
A. Rate below 60 with normal sinus P waves
B. Rate above 100 with no P waves
C. Wide irregular QRS complexes
D. Chaotic ventricular activity
Answer: A. Rate below 60 with normal sinus P waves
Rationale: Sinus bradycardia maintains normal sinus morphology but has a slower rate.
12. Sinus tachycardia generally has a rate:
A. Below 40 bpm
B. 40–59 bpm
C. 60–100 bpm
D. Above 100 bpm
Answer: D. Above 100 bpm
Rationale: Sinus tachycardia is sinus rhythm occurring at a rate greater than 100 bpm.
13. Which condition can cause sinus tachycardia?
A. Fever
B. Sleep
C. Hypothermia
D. Increased vagal tone
Answer: A. Fever
Rationale: Fever, pain, anxiety, dehydration, and other physiologic stresses can increase sinus
rate.
14. Which condition can cause sinus bradycardia?
A. Exercise
B. Fever
C. Increased vagal tone
D. Severe anxiety
Answer: C. Increased vagal tone
Rationale: Increased parasympathetic/vagal activity can slow the sinus rate.
15. A premature beat originating in the atria is called a:
A. PVC
B. PAC
C. PJC
D. Escape beat
