NCCT Electrocardiography Technician Fundamentals 1 — Questions and Answers
Question 1: The P wave on an ECG represents:
- Ventricular depolarization
- Atrial depolarization (Correct answer)
- Ventricular repolarization
- Atrial repolarization
Correct answer: Atrial depolarization
The P wave reflects the electrical depolarization of the atria, initiating atrial contraction.
Question 2: A normal PR interval duration on an adult ECG is:
- 0.06–0.10 seconds
- 0.12–0.20 seconds (Correct answer)
- 0.20–0.30 seconds
- 0.40–0.60 seconds
Correct answer: 0.12–0.20 seconds
A normal PR interval is 0.12–0.20 seconds, representing conduction from the SA node through the AV node.
Question 3: The QRS complex on an ECG represents:
- Atrial depolarization
- Ventricular repolarization
- Ventricular depolarization (Correct answer)
- SA node firing
Correct answer: Ventricular depolarization
The QRS complex represents the electrical depolarization of the ventricles, triggering ventricular contraction.
Question 4: In a standard 12-lead ECG, how many chest (precordial) leads are there?
- 4
- 6 (Correct answer)
- 8
- 10
Correct answer: 6
A 12-lead ECG includes 6 precordial (chest) leads: V1 through V6.
Question 5: Which of the following is the primary pacemaker of the heart?
- AV node
- Bundle of His
- Purkinje fibers
- SA node (Correct answer)
Correct answer: SA node
The sinoatrial (SA) node, located in the right atrium, is the heart's primary pacemaker, normally firing at 60–100 bpm.
Question 6: Artifact on an ECG tracing is most commonly caused by:
- Slow paper speed
- Patient movement or muscle tremor (Correct answer)
- Incorrect lead placement on the chest
- Low battery in the ECG machine
Correct answer: Patient movement or muscle tremor
Patient movement or muscle tremor (somatic tremor artifact) is the most common source of ECG artifact.
NCCT Electrocardiography Technician Fundamentals 1
The P wave on an ECG represents: