Certified EKG Technician (CET) Mock Examination
– Comprehensive ECG/EKG Practice Questions
with Rationales
1. When performing a standard 12-lead EKG, where should the technician place the V4
electrode?
A. Fourth intercostal space, right sternal border
B. Fourth intercostal space, left sternal border
C. Fifth intercostal space, midclavicular line
D. Fifth intercostal space, anterior axillary line
Correct Answer: C
Explanation: The V4 electrode is correctly placed at the fifth intercostal space at the
midclavicular line. This position is critical because it captures the electrical activity at the
apex of the heart. Technicians must avoid placing electrodes directly on bone or over
breast tissue, as this can impede signal quality or lead to inaccurate readings.
2. An EKG technician notices a ‘sawtooth’ pattern in the baseline between QRS complexes.
This is characteristic of which rhythm?
A. Atrial Fibrillation
B. Atrial Flutter
C. Ventricular Tachycardia
,D. Junctional Rhythm
Correct Answer: B
Explanation: Atrial Flutter is defined by rapid, regular atrial depolarizations that create a
characteristic ‘sawtooth’ or ‘F-wave’ pattern. This occurs when an electrical circuit travels
in a loop within the atrium, usually at a rate of 250-350 beats per minute. Recognizing this
pattern is vital for stroke prevention, and candidates should avoid confusing it with the
chaotic, irregular baseline of atrial fibrillation.
3. A patient is experiencing a somatic tremor artifact during an EKG. Which action should the
technician take to resolve this?
A. Check the lead wires for cracks or breaks
B. Move the patient’s limbs away from the trunk
C. Provide a blanket if the patient is shivering
D. Unplug nearby electrical equipment
Correct Answer: C
Explanation: Somatic tremor artifacts are caused by involuntary muscle movement, such
as shivering or Parkinsonian tremors. Providing a blanket to a cold patient reduces muscle
tension and eliminates the artifact, leading to a clearer tracing. Technicians should not
confuse this with AC interference, which requires moving electrical cables or equipment.
, 4. Which of the following heart rates is calculated using the 1500 method if there are 20 small
boxes between two R waves?
A. 60 bpm
B. 150 bpm
C. 100 bpm
D. 75 bpm
Correct Answer: D
Explanation: The 1500 method is the most precise way to calculate heart rate for regular
rhythms by dividing 1500 by the number of small boxes between R waves (1500/20 = 75).
This measurement reflects the standard paper speed of 25 mm/s, where 1500 small boxes
equal one minute. A common error is using this method for irregular rhythms, where the 6-
second strip method is more appropriate.
5. When placing electrodes on a patient with a left-side mastectomy, the technician should:
A. Place electrodes as close to the standard positions as possible without touching scar
tissue
B. Place the electrodes on the right side of the chest instead
C. Omit the V1 through V6 leads
D. Place electrodes on the back of the patient
Correct Answer: A
– Comprehensive ECG/EKG Practice Questions
with Rationales
1. When performing a standard 12-lead EKG, where should the technician place the V4
electrode?
A. Fourth intercostal space, right sternal border
B. Fourth intercostal space, left sternal border
C. Fifth intercostal space, midclavicular line
D. Fifth intercostal space, anterior axillary line
Correct Answer: C
Explanation: The V4 electrode is correctly placed at the fifth intercostal space at the
midclavicular line. This position is critical because it captures the electrical activity at the
apex of the heart. Technicians must avoid placing electrodes directly on bone or over
breast tissue, as this can impede signal quality or lead to inaccurate readings.
2. An EKG technician notices a ‘sawtooth’ pattern in the baseline between QRS complexes.
This is characteristic of which rhythm?
A. Atrial Fibrillation
B. Atrial Flutter
C. Ventricular Tachycardia
,D. Junctional Rhythm
Correct Answer: B
Explanation: Atrial Flutter is defined by rapid, regular atrial depolarizations that create a
characteristic ‘sawtooth’ or ‘F-wave’ pattern. This occurs when an electrical circuit travels
in a loop within the atrium, usually at a rate of 250-350 beats per minute. Recognizing this
pattern is vital for stroke prevention, and candidates should avoid confusing it with the
chaotic, irregular baseline of atrial fibrillation.
3. A patient is experiencing a somatic tremor artifact during an EKG. Which action should the
technician take to resolve this?
A. Check the lead wires for cracks or breaks
B. Move the patient’s limbs away from the trunk
C. Provide a blanket if the patient is shivering
D. Unplug nearby electrical equipment
Correct Answer: C
Explanation: Somatic tremor artifacts are caused by involuntary muscle movement, such
as shivering or Parkinsonian tremors. Providing a blanket to a cold patient reduces muscle
tension and eliminates the artifact, leading to a clearer tracing. Technicians should not
confuse this with AC interference, which requires moving electrical cables or equipment.
, 4. Which of the following heart rates is calculated using the 1500 method if there are 20 small
boxes between two R waves?
A. 60 bpm
B. 150 bpm
C. 100 bpm
D. 75 bpm
Correct Answer: D
Explanation: The 1500 method is the most precise way to calculate heart rate for regular
rhythms by dividing 1500 by the number of small boxes between R waves (1500/20 = 75).
This measurement reflects the standard paper speed of 25 mm/s, where 1500 small boxes
equal one minute. A common error is using this method for irregular rhythms, where the 6-
second strip method is more appropriate.
5. When placing electrodes on a patient with a left-side mastectomy, the technician should:
A. Place electrodes as close to the standard positions as possible without touching scar
tissue
B. Place the electrodes on the right side of the chest instead
C. Omit the V1 through V6 leads
D. Place electrodes on the back of the patient
Correct Answer: A
