PCT EKG Basics 2 — Questions and Answers
Question 1: Which EKG wave represents ventricular repolarization?
- P wave
- QRS complex
- T wave (Correct answer)
- U wave
Correct answer: T wave
The T wave represents ventricular repolarization, when the ventricles reset electrically after contracting.
Question 2: In a standard 12-lead EKG, how many chest (precordial) leads are included?
- 4
- 6 (Correct answer)
- 8
- 12
Correct answer: 6
A 12-lead EKG includes 6 limb leads (I, II, III, aVR, aVL, aVF) and 6 precordial leads (V1–V6).
Question 3: What does a prolonged QT interval indicate?
- Atrial enlargement
- Increased risk of dangerous ventricular arrhythmias (Correct answer)
- First-degree AV block
- Bundle branch block
Correct answer: Increased risk of dangerous ventricular arrhythmias
A prolonged QT interval indicates delayed ventricular repolarization, which increases the risk of torsades de pointes and ventricular fibrillation.
Question 4: Where is lead V1 placed on the patient's chest?
- Left 5th intercostal space, midclavicular line
- Right 4th intercostal space, sternal border (Correct answer)
- Left 4th intercostal space, sternal border
- Right 2nd intercostal space
Correct answer: Right 4th intercostal space, sternal border
V1 is placed at the 4th intercostal space along the right sternal border.
Question 5: A heart rate of 40 bpm on an EKG is classified as:
- Tachycardia
- Normal sinus rhythm
- Bradycardia (Correct answer)
- Sinus arrhythmia
Correct answer: Bradycardia
Bradycardia is defined as a heart rate below 60 bpm; 40 bpm falls well below this threshold.
Question 6: Which lead is considered the best for detecting P waves and is used as the rhythm strip?
- Lead I
- Lead aVR
- Lead II (Correct answer)
- Lead V5
Correct answer: Lead II
Lead II is parallel to the P wave axis and shows the clearest, most upright P waves, making it ideal for rhythm analysis.
Question 7: On EKG graph paper, how many seconds does one large box represent at standard paper speed?
- 0.04 seconds
- 0.10 seconds
- 0.20 seconds (Correct answer)
- 0.40 seconds
Correct answer: 0.20 seconds
At the standard paper speed of 25 mm/sec, each large box (5 mm) represents 0.20 seconds.
PCT EKG Basics 2
Which EKG wave represents ventricular repolarization?