EKG certification Certification EKG Certification General 1 — Questions and Answers
Question 1: What is the normal duration of a QRS complex in an adult?
- 0.04–0.10 seconds (Correct answer)
- 0.12–0.20 seconds
- 0.20–0.24 seconds
- 0.06–0.08 seconds
Correct answer: 0.04–0.10 seconds
A normal QRS complex measures 0.04–0.10 seconds (up to 2.5 small squares). A duration greater than 0.12 seconds suggests a bundle branch block or ventricular conduction delay.
Question 2: On a standard EKG, how fast does the paper move?
- 50 mm/sec
- 25 mm/sec (Correct answer)
- 10 mm/sec
- 100 mm/sec
Correct answer: 25 mm/sec
Standard EKG paper speed is 25 mm/sec. This means each small square (1 mm) represents 0.04 seconds, and each large square (5 mm) represents 0.20 seconds.
Question 3: Which waveform on an EKG represents atrial depolarization?
- T wave
- QRS complex
- P wave (Correct answer)
- U wave
Correct answer: P wave
The P wave represents atrial depolarization — the electrical impulse spreading through the atria from the SA node. The QRS complex represents ventricular depolarization, and the T wave represents ventricular repolarization.
Question 4: A rhythm strip shows no visible P waves and an irregularly irregular ventricular response. What is the most likely rhythm?
- Atrial flutter
- Ventricular tachycardia
- Atrial fibrillation (Correct answer)
- Junctional rhythm
Correct answer: Atrial fibrillation
Atrial fibrillation is characterized by chaotic atrial activity with no discrete P waves, a fibrillatory baseline, and an irregularly irregular ventricular response. Atrial flutter shows sawtooth flutter waves at a regular rate.
Question 5: What does the T wave on an EKG represent?
- Atrial repolarization
- Ventricular depolarization
- Ventricular repolarization (Correct answer)
- SA node firing
Correct answer: Ventricular repolarization
The T wave represents ventricular repolarization — the recovery phase of the ventricles after contraction. Atrial repolarization occurs but is hidden within the QRS complex.
Question 6: Which EKG change is a classic early sign of hyperkalemia?
- Prolonged QT interval
- Peaked, narrow T waves (Correct answer)
- Widened P wave
- ST segment depression
Correct answer: Peaked, narrow T waves
Peaked (tall, narrow, tent-shaped) T waves are typically the earliest EKG manifestation of hyperkalemia. As potassium rises further, the PR interval lengthens, QRS widens, and eventually a sine-wave pattern or cardiac arrest can occur.
EKG certification Certification EKG Certification General 1
What is the normal duration of a QRS complex in an adult?