EKG Technician Certification Exam Prep – Real Practice Questions,
Answers & Detailed Rationales (Updated 2026) 🫀 | ECG Waveform
Interpretation, Cardiac Rhythms & Dysrhythmias, 12-Lead ECG Analysis,
Heart Blocks & Arrhythmias, Cardiac Conduction System, Rhythm & Rate
Calculations, Holter Monitoring, Stress Testing, Patient Preparation &
Clinical Cardiac Monitoring Skills
Question 1: Which chamber of the heart is primarily responsible for pumping
oxygenated blood to the systemic circulation?
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
CORRECT ANSWER: D. Left ventricle
Rationale: The left ventricle has the thickest myocardial wall and generates sufficient
pressure to pump oxygenated blood through the aortic valve into the aorta and
throughout the systemic circulation. The right ventricle pumps deoxygenated blood to
the lungs via the pulmonary artery, while the atria primarily serve as receiving
chambers.
Question 2: What is the normal duration of the PR interval on a standard EKG
tracing?
A. 0.04 to 0.08 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.36 seconds
D. 0.36 to 0.44 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The PR interval represents the time from the onset of atrial depolarization to
the onset of ventricular depolarization, reflecting conduction through the AV node. A
normal PR interval ranges from 0.12 to 0.20 seconds (3-5 small boxes on standard EKG
paper). Values outside this range may indicate conduction abnormalities.
Question 3: Which EKG lead is considered a bipolar limb lead?
A. aVR
B. aVL
C. Lead II
D. V1
CORRECT ANSWER: C. Lead II
Rationale: Leads I, II, and III are bipolar limb leads that measure electrical potential
between two specific electrodes. Lead II measures the potential difference between the
,right arm (negative) and left leg (positive). Leads aVR, aVL, and aVF are augmented
unipolar limb leads, while V1-V6 are precordial (chest) leads.
Question 4: What does the T wave represent on an EKG tracing?
A. Atrial depolarization
B. Ventricular depolarization
C. Atrial repolarization
D. Ventricular repolarization
CORRECT ANSWER: D. Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, the recovery phase of the
ventricles following contraction. Atrial repolarization occurs during the QRS complex
and is typically not visible. The P wave represents atrial depolarization, and the QRS
complex represents ventricular depolarization.
Question 5: When placing the V1 electrode, where should it be positioned on the
patient's chest?
A. Fourth intercostal space, left sternal border
B. Fourth intercostal space, right sternal border
C. Fifth intercostal space, midclavicular line
D. Fifth intercostal space, anterior axillary line
CORRECT ANSWER: B. Fourth intercostal space, right sternal border
Rationale: The V1 electrode is placed in the fourth intercostal space at the right sternal
border. Proper electrode placement is critical for accurate EKG interpretation. V2 is
placed at the fourth intercostal space, left sternal border; V4 is at the fifth intercostal
space, midclavicular line.
Question 6: Which artifact is most commonly caused by patient movement during
an EKG recording?
A. AC interference
B. Wandering baseline
C. Somatic tremor
D. Interrupted baseline
CORRECT ANSWER: C. Somatic tremor
Rationale: Somatic tremor artifact appears as irregular, jagged deflections on the EKG
tracing and is caused by patient movement, shivering, or muscle tension. AC
interference produces uniform, fine oscillations at 60 Hz; wandering baseline shows
gradual drift; interrupted baseline indicates a disconnected electrode.
Question 7: What is the standard paper speed for routine EKG recordings in the
United States?
,A. 15 mm/sec
B. 25 mm/sec
C. 50 mm/sec
D. 100 mm/sec
CORRECT ANSWER: B. 25 mm/sec
Rationale: The standard paper speed for routine EKG recordings is 25 mm/sec, where
each small box (1 mm) represents 0.04 seconds and each large box (5 mm) represents
0.20 seconds. This speed allows for accurate measurement of intervals and waveform
durations.
Question 8: Which rhythm is characterized by a heart rate less than 60 beats per
minute with a normal P wave preceding each QRS complex?
A. Sinus tachycardia
B. Sinus bradycardia
C. Junctional rhythm
D. Atrial fibrillation
CORRECT ANSWER: B. Sinus bradycardia
Rationale: Sinus bradycardia is defined as a sinus rhythm with a rate below 60 beats per
minute. It maintains normal P wave morphology, consistent PR interval, and 1:1 P:QRS
relationship. It may be normal in athletes or indicate underlying pathology such as
hypothyroidism or medication effects.
Question 9: What is the primary purpose of skin preparation before applying EKG
electrodes?
A. To reduce patient anxiety
B. To enhance electrode adhesion and signal conduction
C. To sterilize the skin for infection control
D. To mark electrode placement locations
CORRECT ANSWER: B. To enhance electrode adhesion and signal conduction
Rationale: Proper skin preparation, including cleaning with alcohol and lightly abrading
the skin, removes oils, dead skin cells, and debris. This reduces impedance, improves
electrode adhesion, and ensures optimal electrical signal transmission for accurate
EKG recordings.
Question 10: Which interval on the EKG represents the total time for ventricular
depolarization and repolarization?
A. PR interval
B. QT interval
C. ST segment
D. RR interval
, CORRECT ANSWER: B. QT interval
Rationale: The QT interval extends from the beginning of the QRS complex to the end of
the T wave, representing the total duration of ventricular electrical activity
(depolarization and repolarization). It varies with heart rate and must be corrected (QTc)
for accurate assessment; prolonged QT increases risk of torsades de pointes.
Question 11: In a normal sinus rhythm, where does the electrical impulse
originate?
A. AV node
B. Bundle of His
C. SA node
D. Purkinje fibers
CORRECT ANSWER: C. SA node
Rationale: The sinoatrial (SA) node, located in the right atrium near the superior vena
cava, is the heart's natural pacemaker. It initiates electrical impulses at a rate of 60-100
beats per minute in normal sinus rhythm, which then propagate through the atria to the
AV node.
Question 12: Which lead provides the best view of the inferior wall of the left
ventricle?
A. Lead I
B. Lead aVL
C. Lead II
D. Lead V1
CORRECT ANSWER: C. Lead II
Rationale: Leads II, III, and aVF are inferior leads that view the inferior wall of the left
ventricle. Lead II is particularly useful for rhythm analysis due to its clear P wave
visualization. Anterior walls are viewed by V1-V4; lateral walls by I, aVL, V5-V6.
Question 13: What is the normal amplitude of the P wave in limb leads?
A. Less than 0.25 mV (2.5 small boxes)
B. 0.5 to 1.0 mV
C. 1.0 to 2.0 mV
D. Greater than 2.5 mV
CORRECT ANSWER: A. Less than 0.25 mV (2.5 small boxes)
Rationale: The normal P wave amplitude in limb leads should be less than 0.25 mV (2.5
mm or 2.5 small boxes). P waves exceeding this may indicate right or left atrial
enlargement. Duration should also be less than 0.12 seconds (3 small boxes).
Question 14: Which condition is most likely to cause peaked, tented T waves on an
EKG?
Answers & Detailed Rationales (Updated 2026) 🫀 | ECG Waveform
Interpretation, Cardiac Rhythms & Dysrhythmias, 12-Lead ECG Analysis,
Heart Blocks & Arrhythmias, Cardiac Conduction System, Rhythm & Rate
Calculations, Holter Monitoring, Stress Testing, Patient Preparation &
Clinical Cardiac Monitoring Skills
Question 1: Which chamber of the heart is primarily responsible for pumping
oxygenated blood to the systemic circulation?
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
CORRECT ANSWER: D. Left ventricle
Rationale: The left ventricle has the thickest myocardial wall and generates sufficient
pressure to pump oxygenated blood through the aortic valve into the aorta and
throughout the systemic circulation. The right ventricle pumps deoxygenated blood to
the lungs via the pulmonary artery, while the atria primarily serve as receiving
chambers.
Question 2: What is the normal duration of the PR interval on a standard EKG
tracing?
A. 0.04 to 0.08 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.36 seconds
D. 0.36 to 0.44 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The PR interval represents the time from the onset of atrial depolarization to
the onset of ventricular depolarization, reflecting conduction through the AV node. A
normal PR interval ranges from 0.12 to 0.20 seconds (3-5 small boxes on standard EKG
paper). Values outside this range may indicate conduction abnormalities.
Question 3: Which EKG lead is considered a bipolar limb lead?
A. aVR
B. aVL
C. Lead II
D. V1
CORRECT ANSWER: C. Lead II
Rationale: Leads I, II, and III are bipolar limb leads that measure electrical potential
between two specific electrodes. Lead II measures the potential difference between the
,right arm (negative) and left leg (positive). Leads aVR, aVL, and aVF are augmented
unipolar limb leads, while V1-V6 are precordial (chest) leads.
Question 4: What does the T wave represent on an EKG tracing?
A. Atrial depolarization
B. Ventricular depolarization
C. Atrial repolarization
D. Ventricular repolarization
CORRECT ANSWER: D. Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, the recovery phase of the
ventricles following contraction. Atrial repolarization occurs during the QRS complex
and is typically not visible. The P wave represents atrial depolarization, and the QRS
complex represents ventricular depolarization.
Question 5: When placing the V1 electrode, where should it be positioned on the
patient's chest?
A. Fourth intercostal space, left sternal border
B. Fourth intercostal space, right sternal border
C. Fifth intercostal space, midclavicular line
D. Fifth intercostal space, anterior axillary line
CORRECT ANSWER: B. Fourth intercostal space, right sternal border
Rationale: The V1 electrode is placed in the fourth intercostal space at the right sternal
border. Proper electrode placement is critical for accurate EKG interpretation. V2 is
placed at the fourth intercostal space, left sternal border; V4 is at the fifth intercostal
space, midclavicular line.
Question 6: Which artifact is most commonly caused by patient movement during
an EKG recording?
A. AC interference
B. Wandering baseline
C. Somatic tremor
D. Interrupted baseline
CORRECT ANSWER: C. Somatic tremor
Rationale: Somatic tremor artifact appears as irregular, jagged deflections on the EKG
tracing and is caused by patient movement, shivering, or muscle tension. AC
interference produces uniform, fine oscillations at 60 Hz; wandering baseline shows
gradual drift; interrupted baseline indicates a disconnected electrode.
Question 7: What is the standard paper speed for routine EKG recordings in the
United States?
,A. 15 mm/sec
B. 25 mm/sec
C. 50 mm/sec
D. 100 mm/sec
CORRECT ANSWER: B. 25 mm/sec
Rationale: The standard paper speed for routine EKG recordings is 25 mm/sec, where
each small box (1 mm) represents 0.04 seconds and each large box (5 mm) represents
0.20 seconds. This speed allows for accurate measurement of intervals and waveform
durations.
Question 8: Which rhythm is characterized by a heart rate less than 60 beats per
minute with a normal P wave preceding each QRS complex?
A. Sinus tachycardia
B. Sinus bradycardia
C. Junctional rhythm
D. Atrial fibrillation
CORRECT ANSWER: B. Sinus bradycardia
Rationale: Sinus bradycardia is defined as a sinus rhythm with a rate below 60 beats per
minute. It maintains normal P wave morphology, consistent PR interval, and 1:1 P:QRS
relationship. It may be normal in athletes or indicate underlying pathology such as
hypothyroidism or medication effects.
Question 9: What is the primary purpose of skin preparation before applying EKG
electrodes?
A. To reduce patient anxiety
B. To enhance electrode adhesion and signal conduction
C. To sterilize the skin for infection control
D. To mark electrode placement locations
CORRECT ANSWER: B. To enhance electrode adhesion and signal conduction
Rationale: Proper skin preparation, including cleaning with alcohol and lightly abrading
the skin, removes oils, dead skin cells, and debris. This reduces impedance, improves
electrode adhesion, and ensures optimal electrical signal transmission for accurate
EKG recordings.
Question 10: Which interval on the EKG represents the total time for ventricular
depolarization and repolarization?
A. PR interval
B. QT interval
C. ST segment
D. RR interval
, CORRECT ANSWER: B. QT interval
Rationale: The QT interval extends from the beginning of the QRS complex to the end of
the T wave, representing the total duration of ventricular electrical activity
(depolarization and repolarization). It varies with heart rate and must be corrected (QTc)
for accurate assessment; prolonged QT increases risk of torsades de pointes.
Question 11: In a normal sinus rhythm, where does the electrical impulse
originate?
A. AV node
B. Bundle of His
C. SA node
D. Purkinje fibers
CORRECT ANSWER: C. SA node
Rationale: The sinoatrial (SA) node, located in the right atrium near the superior vena
cava, is the heart's natural pacemaker. It initiates electrical impulses at a rate of 60-100
beats per minute in normal sinus rhythm, which then propagate through the atria to the
AV node.
Question 12: Which lead provides the best view of the inferior wall of the left
ventricle?
A. Lead I
B. Lead aVL
C. Lead II
D. Lead V1
CORRECT ANSWER: C. Lead II
Rationale: Leads II, III, and aVF are inferior leads that view the inferior wall of the left
ventricle. Lead II is particularly useful for rhythm analysis due to its clear P wave
visualization. Anterior walls are viewed by V1-V4; lateral walls by I, aVL, V5-V6.
Question 13: What is the normal amplitude of the P wave in limb leads?
A. Less than 0.25 mV (2.5 small boxes)
B. 0.5 to 1.0 mV
C. 1.0 to 2.0 mV
D. Greater than 2.5 mV
CORRECT ANSWER: A. Less than 0.25 mV (2.5 small boxes)
Rationale: The normal P wave amplitude in limb leads should be less than 0.25 mV (2.5
mm or 2.5 small boxes). P waves exceeding this may indicate right or left atrial
enlargement. Duration should also be less than 0.12 seconds (3 small boxes).
Question 14: Which condition is most likely to cause peaked, tented T waves on an
EKG?
