ECG Online Electrocardiogram 3 — Questions and Answers
Question 1: The QRS complex on an ECG primarily represents:
- Atrial repolarization
- Ventricular depolarization (Correct answer)
- SA node firing
- Atrial depolarization
Correct answer: Ventricular depolarization
The QRS complex reflects depolarization of the ventricles.
Question 2: Which electrode color is standard for the right arm in the AHA labeling system?
- Black
- Green
- White (Correct answer)
- Red
Correct answer: White
Under AHA labeling, the right arm electrode is white.
Question 3: The natural pacemaker of the heart is the:
- AV node
- SA node (Correct answer)
- Purkinje fibers
- Bundle of His
Correct answer: SA node
The sinoatrial (SA) node initiates each normal heartbeat.
Question 4: Muscle tremor (somatic) artifact appears on an ECG as:
- A perfectly flat line
- Irregular, jagged, rapid spikes (Correct answer)
- A slow smooth wave
- Missing QRS complexes
Correct answer: Irregular, jagged, rapid spikes
Muscle tremor produces irregular, jagged spikes across the baseline.
Question 5: How many seconds does one large box on standard ECG paper represent?
- 0.04 sec
- 0.20 sec (Correct answer)
- 1.0 sec
- 0.10 sec
Correct answer: 0.20 sec
One large box equals 0.20 seconds at 25 mm/sec.
Question 6: Before applying chest electrodes, the technician should:
- Apply lotion to the skin
- Clean and prep the skin site (Correct answer)
- Leave skin oily for adhesion
- Place electrodes over bone only
Correct answer: Clean and prep the skin site
Skin should be cleaned and prepped to ensure good electrode contact.
Question 7: The T wave on an ECG represents:
- Ventricular repolarization (Correct answer)
- Atrial depolarization
- Ventricular depolarization
- SA node discharge
Correct answer: Ventricular repolarization
The T wave reflects repolarization (recovery) of the ventricles.
ECG Online Electrocardiogram 3
The QRS complex on an ECG primarily represents: