ORIGINAL Dysrhythmia Interpretation Practice
Test – 2026 Edition
Comprehensive Educational Study Questions
SECTION 1: BASIC ECG CONCEPTS AND WAVEFORMS
Question 1
What does the P wave represent on an ECG?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct ANSWER: B
Rationale:
A. Ventricular depolarization - INCORRECT. Ventricular depolarization is represented by the QRS
complex, not the P wave. The QRS complex shows the electrical impulse spreading through the
ventricles.
B. Atrial depolarization - CORRECT. The P wave represents atrial depolarization, which is the electrical
activity that causes the atria to contract.
www.utmb.edu
It is the first deflection seen in the cardiac cycle and indicates that the impulse originated from the SA
node and spread through the atria.
C. Ventricular repolarization - INCORRECT. Ventricular repolarization is represented by the T wave, not
the P wave. The T wave shows when the ventricles are resetting electrically after contraction.
D. Atrial repolarization - INCORRECT. Atrial repolarization typically occurs during the QRS complex and is
usually not visible as a separate wave on the ECG because it is masked by the larger QRS complex.
Question 2
What is the normal duration of the PR interval?
,A. 0.04-0.08 seconds
B. 0.12-0.20 seconds
C. 0.20-0.30 seconds
D. 0.30-0.40 seconds
Correct ANSWER: B
Rationale:
A. 0.04-0.08 seconds - INCORRECT. This duration is too short and would represent the normal duration
of the QRS complex, not the PR interval. The QRS complex normally measures 0.04-0.10 seconds.
B. 0.12-0.20 seconds - CORRECT. The normal PR interval measures 0.12-0.20 seconds (3-5 small boxes on
ECG paper).
ecgweekly.com
The PR interval represents the time from the beginning of atrial depolarization to the beginning of
ventricular depolarization, including the delay at the AV node.
C. 0.20-0.30 seconds - INCORRECT. A PR interval of 0.20 seconds or greater indicates first-degree AV
block. This is prolonged and not within normal limits.
D. 0.30-0.40 seconds - INCORRECT. This is significantly prolonged and would indicate severe conduction
delay, possibly marked first-degree AV block or other conduction abnormalities.
Question 3
Which wave on the ECG represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Correct ANSWER: C
Rationale:
A. P wave - INCORRECT. The P wave represents atrial depolarization, not ventricular repolarization.
B. QRS complex - INCORRECT. The QRS complex represents ventricular depolarization (activation), not
repolarization.
ecgwaves.com
C. T wave - CORRECT. The T wave represents ventricular repolarization, which is when the ventricles
reset electrically after contraction.
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The normal T wave is usually in the same direction as the QRS complex and is slightly asymmetric with a
steeper downward slope.
D. U wave - INCORRECT. The U wave, when present, is thought to represent repolarization of the
Purkinje fibers or papillary muscles, not ventricular repolarization. It is not always visible on a normal
ECG.
Question 4
What is the normal heart rate range for adults?
A. 40-60 beats per minute
B. 60-100 beats per minute
C. 100-120 beats per minute
D. 120-160 beats per minute
Correct ANSWER: B
Rationale:
A. 40-60 beats per minute - INCORRECT. This range is below normal and would be considered
bradycardia. A heart rate below 60 bpm is classified as bradycardia.
B. 60-100 beats per minute - CORRECT. The normal average resting heart rate for adults is 60-100 beats
per minute.
www.heart.org
This is the standard reference range used in clinical practice.
C. 100-120 beats per minute - INCORRECT. A heart rate over 100 bpm is considered tachycardia. This
range would be classified as mild to moderate tachycardia.
D. 120-160 beats per minute - INCORRECT. This range represents significant tachycardia and is well
above the normal resting heart rate for adults.
Question 5
What does the QRS complex represent?
A. Atrial depolarization
B. Atrial repolarization
C. Ventricular depolarization
D. Ventricular repolarization
Correct ANSWER: C
, Rationale:
A. Atrial depolarization - INCORRECT. Atrial depolarization is represented by the P wave, not the QRS
complex.
B. Atrial repolarization - INCORRECT. Atrial repolarization is usually hidden within the QRS complex and
not visible as a separate wave.
C. Ventricular depolarization - CORRECT. The QRS complex represents ventricular depolarization
(activation), which is the electrical impulse spreading through the ventricles causing them to contract.
ecgwaves.com
D. Ventricular repolarization - INCORRECT. Ventricular repolarization is represented by the T wave, not
the QRS complex.
Question 6
What is the normal duration of the QRS complex?
A. Less than 0.12 seconds
B. 0.12-0.20 seconds
C. 0.20-0.30 seconds
D. 0.30-0.40 seconds
Correct ANSWER: A
Rationale:
A. Less than 0.12 seconds - CORRECT. The normal QRS complex duration is less than 0.12 seconds (less
than 3 small boxes), typically 0.04-0.10 seconds. A QRS complex greater than 0.12 seconds indicates a
bundle branch block or ventricular rhythm.
B. 0.12-0.20 seconds - INCORRECT. This is the normal range for the PR interval, not the QRS complex. A
QRS of this duration would be abnormally wide.
C. 0.20-0.30 seconds - INCORRECT. This duration is significantly prolonged and would indicate a severe
conduction abnormality or ventricular rhythm.
D. 0.30-0.40 seconds - INCORRECT. This is extremely prolonged and would be seen in severe conduction
abnormalities or wide complex ventricular rhythms.
Question 7
On standard ECG paper, how much time does one small box represent?
A. 0.02 seconds
B. 0.04 seconds
C. 0.08 seconds
Test – 2026 Edition
Comprehensive Educational Study Questions
SECTION 1: BASIC ECG CONCEPTS AND WAVEFORMS
Question 1
What does the P wave represent on an ECG?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct ANSWER: B
Rationale:
A. Ventricular depolarization - INCORRECT. Ventricular depolarization is represented by the QRS
complex, not the P wave. The QRS complex shows the electrical impulse spreading through the
ventricles.
B. Atrial depolarization - CORRECT. The P wave represents atrial depolarization, which is the electrical
activity that causes the atria to contract.
www.utmb.edu
It is the first deflection seen in the cardiac cycle and indicates that the impulse originated from the SA
node and spread through the atria.
C. Ventricular repolarization - INCORRECT. Ventricular repolarization is represented by the T wave, not
the P wave. The T wave shows when the ventricles are resetting electrically after contraction.
D. Atrial repolarization - INCORRECT. Atrial repolarization typically occurs during the QRS complex and is
usually not visible as a separate wave on the ECG because it is masked by the larger QRS complex.
Question 2
What is the normal duration of the PR interval?
,A. 0.04-0.08 seconds
B. 0.12-0.20 seconds
C. 0.20-0.30 seconds
D. 0.30-0.40 seconds
Correct ANSWER: B
Rationale:
A. 0.04-0.08 seconds - INCORRECT. This duration is too short and would represent the normal duration
of the QRS complex, not the PR interval. The QRS complex normally measures 0.04-0.10 seconds.
B. 0.12-0.20 seconds - CORRECT. The normal PR interval measures 0.12-0.20 seconds (3-5 small boxes on
ECG paper).
ecgweekly.com
The PR interval represents the time from the beginning of atrial depolarization to the beginning of
ventricular depolarization, including the delay at the AV node.
C. 0.20-0.30 seconds - INCORRECT. A PR interval of 0.20 seconds or greater indicates first-degree AV
block. This is prolonged and not within normal limits.
D. 0.30-0.40 seconds - INCORRECT. This is significantly prolonged and would indicate severe conduction
delay, possibly marked first-degree AV block or other conduction abnormalities.
Question 3
Which wave on the ECG represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Correct ANSWER: C
Rationale:
A. P wave - INCORRECT. The P wave represents atrial depolarization, not ventricular repolarization.
B. QRS complex - INCORRECT. The QRS complex represents ventricular depolarization (activation), not
repolarization.
ecgwaves.com
C. T wave - CORRECT. The T wave represents ventricular repolarization, which is when the ventricles
reset electrically after contraction.
,myhealth.alberta.ca
The normal T wave is usually in the same direction as the QRS complex and is slightly asymmetric with a
steeper downward slope.
D. U wave - INCORRECT. The U wave, when present, is thought to represent repolarization of the
Purkinje fibers or papillary muscles, not ventricular repolarization. It is not always visible on a normal
ECG.
Question 4
What is the normal heart rate range for adults?
A. 40-60 beats per minute
B. 60-100 beats per minute
C. 100-120 beats per minute
D. 120-160 beats per minute
Correct ANSWER: B
Rationale:
A. 40-60 beats per minute - INCORRECT. This range is below normal and would be considered
bradycardia. A heart rate below 60 bpm is classified as bradycardia.
B. 60-100 beats per minute - CORRECT. The normal average resting heart rate for adults is 60-100 beats
per minute.
www.heart.org
This is the standard reference range used in clinical practice.
C. 100-120 beats per minute - INCORRECT. A heart rate over 100 bpm is considered tachycardia. This
range would be classified as mild to moderate tachycardia.
D. 120-160 beats per minute - INCORRECT. This range represents significant tachycardia and is well
above the normal resting heart rate for adults.
Question 5
What does the QRS complex represent?
A. Atrial depolarization
B. Atrial repolarization
C. Ventricular depolarization
D. Ventricular repolarization
Correct ANSWER: C
, Rationale:
A. Atrial depolarization - INCORRECT. Atrial depolarization is represented by the P wave, not the QRS
complex.
B. Atrial repolarization - INCORRECT. Atrial repolarization is usually hidden within the QRS complex and
not visible as a separate wave.
C. Ventricular depolarization - CORRECT. The QRS complex represents ventricular depolarization
(activation), which is the electrical impulse spreading through the ventricles causing them to contract.
ecgwaves.com
D. Ventricular repolarization - INCORRECT. Ventricular repolarization is represented by the T wave, not
the QRS complex.
Question 6
What is the normal duration of the QRS complex?
A. Less than 0.12 seconds
B. 0.12-0.20 seconds
C. 0.20-0.30 seconds
D. 0.30-0.40 seconds
Correct ANSWER: A
Rationale:
A. Less than 0.12 seconds - CORRECT. The normal QRS complex duration is less than 0.12 seconds (less
than 3 small boxes), typically 0.04-0.10 seconds. A QRS complex greater than 0.12 seconds indicates a
bundle branch block or ventricular rhythm.
B. 0.12-0.20 seconds - INCORRECT. This is the normal range for the PR interval, not the QRS complex. A
QRS of this duration would be abnormally wide.
C. 0.20-0.30 seconds - INCORRECT. This duration is significantly prolonged and would indicate a severe
conduction abnormality or ventricular rhythm.
D. 0.30-0.40 seconds - INCORRECT. This is extremely prolonged and would be seen in severe conduction
abnormalities or wide complex ventricular rhythms.
Question 7
On standard ECG paper, how much time does one small box represent?
A. 0.02 seconds
B. 0.04 seconds
C. 0.08 seconds
