EKG certification Certification ECG Technician Certification Exam 1 — Questions and Answers
Question 1: An ECG strip shows a rhythm where P waves are present but bear no consistent relationship to QRS complexes, and the ventricular rate is slower than the atrial rate. What rhythm does this represent?
- Second-degree AV block, Mobitz Type II
- Third-degree (complete) AV block (Correct answer)
- Junctional tachycardia
- Accelerated idioventricular rhythm
Correct answer: Third-degree (complete) AV block
In third-degree (complete) AV block, the atria and ventricles beat independently because no impulses conduct through the AV node. P waves and QRS complexes are dissociated, and the ventricular rate is slower as it is driven by an escape pacemaker below the block.
Question 2: When applying electrodes for a 12-lead ECG, where should the V4 precordial lead be placed?
- Fourth intercostal space, right sternal border
- Fifth intercostal space, midclavicular line (Correct answer)
- Left anterior axillary line at the level of V4
- Fourth intercostal space, left sternal border
Correct answer: Fifth intercostal space, midclavicular line
V4 is placed at the fifth intercostal space in the midclavicular line. Correct precordial electrode placement is critical for accurate ECG interpretation, and V4 serves as the anatomical anchor for V5 and V6 placement.
Question 3: On a standard ECG paper running at 25 mm/second, how much time does one large (5 mm) square represent?
- 0.04 seconds
- 0.10 seconds
- 0.20 seconds (Correct answer)
- 0.40 seconds
Correct answer: 0.20 seconds
At 25 mm/second, each small 1 mm square represents 0.04 seconds and each large 5 mm square (containing 5 small squares) represents 0.20 seconds. This is foundational knowledge for measuring intervals and calculating heart rate.
Question 4: A patient's ECG shows saw-tooth flutter waves at a rate of approximately 300 bpm with a ventricular rate of 75 bpm. What is the AV conduction ratio?
- 2:1
- 3:1
- 4:1 (Correct answer)
- 6:1
Correct answer: 4:1
Atrial flutter typically produces atrial rates of 250–350 bpm. With an atrial rate of 300 and a ventricular rate of 75, the ratio is 300:75 = 4:1, meaning only every 4th flutter wave conducts to the ventricles.
Question 5: Which of the following findings on a resting 12-lead ECG is most consistent with left ventricular hypertrophy (LVH)?
- S wave in V1 plus R wave in V5 or V6 greater than 35 mm (Correct answer)
- R wave in aVR greater than 11 mm
- Q waves in leads II, III, and aVF
- Delta waves in lateral leads
Correct answer: S wave in V1 plus R wave in V5 or V6 greater than 35 mm
The Sokolow-Lyon criterion for LVH is S in V1 + R in V5 or V6 ≥ 35 mm. Increased voltage in these leads reflects the greater muscle mass of the hypertrophied left ventricle generating larger electrical forces.
Question 6: During ECG acquisition, the technician notices the baseline is wandering up and down slowly on the tracing. What is the most common cause of this artifact?
- Loose or dried electrode gel causing poor skin contact (Correct answer)
- 60 Hz electrical interference from nearby equipment
- Patient talking during the recording
- Incorrect lead placement on the limbs
Correct answer: Loose or dried electrode gel causing poor skin contact
Baseline wander is most commonly caused by poor electrode contact due to dried gel, loose leads, or inadequate skin preparation. It produces a slow undulating shift of the baseline that can obscure ST-segment analysis.
EKG certification Certification ECG Technician Certification Exam 1
An ECG strip shows a rhythm where P waves are present but bear no consistent relationship to QRS complexes, and the ventricular rate is slower than the atrial rate.
What rhythm does this represent?