PCT EKG Basics 4 — Questions and Answers
Question 1: A PCT notices the EKG shows wide QRS complexes at a rate of 160 bpm with no identifiable P waves. This is most consistent with:
- Sinus tachycardia
- Atrial flutter with 2:1 block
- Ventricular tachycardia (Correct answer)
- Junctional tachycardia
Correct answer: Ventricular tachycardia
Ventricular tachycardia presents with wide QRS complexes (≥0.12 s), a rate typically 100–250 bpm, and absent or dissociated P waves.
Question 2: Which electrode is placed on the left leg (LL) when setting up a standard 12-lead EKG?
- Red electrode
- White electrode
- Green electrode (Correct answer)
- Black electrode
Correct answer: Green electrode
The green (or red in some systems) electrode is placed on the left leg; standard color coding in the US is white (RA), black (LA), green (LL), red (RL).
Question 3: A patient's EKG shows a PR interval of 0.28 seconds with each P wave followed by a QRS. This represents:
- Normal conduction
- First-degree AV block (Correct answer)
- Second-degree AV block
- Third-degree AV block
Correct answer: First-degree AV block
First-degree AV block is defined as a PR interval greater than 0.20 seconds with every P wave still followed by a QRS complex.
Question 4: What does the isoelectric (flat) baseline between EKG waves represent?
- Electrical artifact
- No net electrical activity in the heart (Correct answer)
- Atrial repolarization
- SA node firing
Correct answer: No net electrical activity in the heart
The isoelectric line indicates no net electrical activity is being detected at that moment, serving as the reference baseline.
Question 5: Coarse ventricular fibrillation on an EKG appears as:
- Regular wide QRS complexes at 180 bpm
- Absent QRS with chaotic high-amplitude waveforms (Correct answer)
- Sawtooth waves at 300 bpm
- P waves without QRS complexes
Correct answer: Absent QRS with chaotic high-amplitude waveforms
Coarse ventricular fibrillation shows chaotic, irregular, high-amplitude waveforms with no identifiable P waves, QRS complexes, or T waves.
Question 6: Which intercostal space is used for lead V4 placement?
- 3rd intercostal space
- 4th intercostal space
- 5th intercostal space (Correct answer)
- 6th intercostal space
Correct answer: 5th intercostal space
V4 is placed at the 5th intercostal space at the midclavicular line.
Question 7: In third-degree (complete) AV block, which of the following is true?
- P waves and QRS complexes occur at the same rate
- P waves and QRS complexes are completely dissociated (Correct answer)
- Every other P wave conducts to the ventricles
- QRS complexes precede P waves
Correct answer: P waves and QRS complexes are completely dissociated
In complete heart block, the atria and ventricles beat independently because no impulses conduct through the AV node; P waves and QRS complexes are dissociated.
PCT EKG Basics 4
A PCT notices the EKG shows wide QRS complexes at a rate of 160 bpm with no identifiable P waves.
This is most consistent with: