Practice Questions
1. What does the “P wave” on an ECG represent?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Cardiac relaxation
Correct Answer: B. Atrial depolarization
Rationale:
The P wave represents the electrical impulse moving through the atria, causing atrial
contraction. It is the first wave seen in a normal cardiac cycle.
2. Which ECG rhythm is characterized by an irregularly irregular rhythm with no visible
P waves?
A. Sinus bradycardia
B. Atrial flutter
C. Atrial fibrillation
D. Ventricular tachycardia
Correct Answer: C. Atrial fibrillation
,Rationale:
Atrial fibrillation produces chaotic atrial activity, resulting in absent P waves and an irregular
ventricular response.
3. A normal adult heart rate ranges between:
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–140 bpm
Correct Answer: C. 60–100 bpm
Rationale:
A normal resting heart rate for adults is typically 60–100 beats per minute.
4. Which ECG component represents ventricular depolarization?
A. P wave
B. PR interval
C. QRS complex
D. T wave
Correct Answer: C. QRS complex
,Rationale:
The QRS complex reflects electrical activation of the ventricles leading to ventricular
contraction.
5. Sinus bradycardia is defined as a heart rate less than:
A. 40 bpm
B. 50 bpm
C. 60 bpm
D. 100 bpm
Correct Answer: C. 60 bpm
Rationale:
Sinus bradycardia occurs when the sinoatrial node fires at a rate below 60 bpm.
6. Which electrolyte imbalance commonly causes peaked T waves?
A. Hypokalemia
B. Hyperkalemia
C. Hyocalcemia
D. Hypernatremia
, Correct Answer: B. Hyperkalemia
Rationale:
Elevated potassium levels affect cardiac conduction and often produce tall, peaked T waves
on ECG.
7. What is the paper speed commonly used during a standard ECG recording?
A. 10 mm/sec
B. 15 mm/sec
C. 25 mm/sec
D. 50 mm/sec
Correct Answer: C. 25 mm/sec
Rationale:
Standard ECG recordings are usually obtained at 25 mm/sec for accurate rhythm
interpretation.
8. The PR interval measures:
A. Atrial recovery
B. Ventricular contraction time
C. Time from atrial to ventricular depolarization