Relias Dysrhythmia Basic Test | Relias Learning |
Academic Year 2026/2027 | Comprehensive
Competency
SECTION I — ECG FUNDAMENTALS & CARDIAC CONDUCTION (Questions 1–15)
Question 1
Which structure normally functions as the primary pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B. SA node
Rationale: The sinoatrial (SA) node, located in the right atrium, has the fastest
intrinsic firing rate (60–100 bpm) and normally initiates the electrical impulse that
produces sinus rhythm. The AV node has a backup rate of 40–60 bpm, and the
Purkinje fibers fire at 20–40 bpm.
Question 2
Which ECG component represents atrial depolarization?
A. P wave
B. QRS complex
C. T wave
D. ST segment
Correct Answer: A. P wave
Rationale: The P wave represents electrical depolarization of the atria.
Ventricular depolarization is represented by the QRS complex, and ventricular
repolarization is represented primarily by the T wave.
,Question 3
The normal PR interval is generally:
A. 0.04–0.08 second
B. 0.12–0.20 second
C. 0.24–0.32 second
D. 0.36–0.44 second
Correct Answer: B. 0.12–0.20 second
Rationale: A normal PR interval is approximately 0.12–0.20 second (3–5 small
boxes). It represents conduction from the onset of atrial depolarization to the
onset of ventricular depolarization. Values above 0.20 second indicate first-
degree AV block.
Question 4
On standard ECG paper, one small box represents how much time?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 1.00 second
Correct Answer: A. 0.04 seconds
Rationale: At the standard paper speed of 25 mm/sec, each small box (1 mm)
represents 0.04 seconds. Each large box (5 small boxes) represents 0.20 seconds.
Question 5
What is the normal duration of the QRS complex?
A. Less than 0.04 seconds
B. Less than 0.12 seconds
C. Less than 0.20 seconds
D. Greater than 0.20 seconds
Correct Answer: B. Less than 0.12 seconds
, Rationale: A narrow QRS complex (<0.12 sec) indicates that the electrical
impulse traveled through the ventricles via the normal conduction pathway. A
QRS ≥0.12 seconds suggests a ventricular origin or bundle branch block.
Question 6
Which ECG wave represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Correct Answer: C. T wave
Rationale: The T wave represents the electrical recovery (repolarization) of
the ventricles. The P wave represents atrial depolarization, and the QRS complex
represents ventricular depolarization.
Question 7
What is the normal intrinsic firing rate of the AV junction?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–150 bpm
Correct Answer: B. 40–60 bpm
Rationale: The AV junction has an intrinsic backup rate of 40–60 bpm. The SA
node fires at 60–100 bpm, and the Purkinje fibers fire at 20–40 bpm.
Question 8
On ECG paper, one large box represents:
A. 0.04 seconds
B. 0.10 seconds
, C. 0.20 seconds
D. 0.40 seconds
Correct Answer: C. 0.20 seconds
Rationale: Since one small box is 0.04 seconds, five small boxes (one large
box) equal 0.20 seconds. This is the standard measurement used for rapid rate
estimation.
Question 9
Which method is correct for calculating heart rate for a regular rhythm?
A. Count the number of QRS complexes in 6 seconds and multiply by 10
B. Divide 300 by the number of large boxes between R waves
C. Count the number of P waves in 3 seconds and multiply by 20
D. Divide 1500 by the number of small boxes between R waves
Correct Answer: B. Divide 300 by the number of large boxes between R
waves
Rationale: The 300 method divides 300 by the number of large boxes
between R waves. For irregular rhythms, the 6-second method (count QRS
complexes in 6 seconds × 10) is preferred. The 1500 method (divide 1500 by small
boxes) also works but is less commonly used for rapid estimation.
Question 10
Which lead is most commonly used for continuous cardiac monitoring in a
hospital setting?
A. Lead I
B. Lead II
C. Lead aVF
D. Lead V1
Correct Answer: B. Lead II
Academic Year 2026/2027 | Comprehensive
Competency
SECTION I — ECG FUNDAMENTALS & CARDIAC CONDUCTION (Questions 1–15)
Question 1
Which structure normally functions as the primary pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B. SA node
Rationale: The sinoatrial (SA) node, located in the right atrium, has the fastest
intrinsic firing rate (60–100 bpm) and normally initiates the electrical impulse that
produces sinus rhythm. The AV node has a backup rate of 40–60 bpm, and the
Purkinje fibers fire at 20–40 bpm.
Question 2
Which ECG component represents atrial depolarization?
A. P wave
B. QRS complex
C. T wave
D. ST segment
Correct Answer: A. P wave
Rationale: The P wave represents electrical depolarization of the atria.
Ventricular depolarization is represented by the QRS complex, and ventricular
repolarization is represented primarily by the T wave.
,Question 3
The normal PR interval is generally:
A. 0.04–0.08 second
B. 0.12–0.20 second
C. 0.24–0.32 second
D. 0.36–0.44 second
Correct Answer: B. 0.12–0.20 second
Rationale: A normal PR interval is approximately 0.12–0.20 second (3–5 small
boxes). It represents conduction from the onset of atrial depolarization to the
onset of ventricular depolarization. Values above 0.20 second indicate first-
degree AV block.
Question 4
On standard ECG paper, one small box represents how much time?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 1.00 second
Correct Answer: A. 0.04 seconds
Rationale: At the standard paper speed of 25 mm/sec, each small box (1 mm)
represents 0.04 seconds. Each large box (5 small boxes) represents 0.20 seconds.
Question 5
What is the normal duration of the QRS complex?
A. Less than 0.04 seconds
B. Less than 0.12 seconds
C. Less than 0.20 seconds
D. Greater than 0.20 seconds
Correct Answer: B. Less than 0.12 seconds
, Rationale: A narrow QRS complex (<0.12 sec) indicates that the electrical
impulse traveled through the ventricles via the normal conduction pathway. A
QRS ≥0.12 seconds suggests a ventricular origin or bundle branch block.
Question 6
Which ECG wave represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
Correct Answer: C. T wave
Rationale: The T wave represents the electrical recovery (repolarization) of
the ventricles. The P wave represents atrial depolarization, and the QRS complex
represents ventricular depolarization.
Question 7
What is the normal intrinsic firing rate of the AV junction?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–150 bpm
Correct Answer: B. 40–60 bpm
Rationale: The AV junction has an intrinsic backup rate of 40–60 bpm. The SA
node fires at 60–100 bpm, and the Purkinje fibers fire at 20–40 bpm.
Question 8
On ECG paper, one large box represents:
A. 0.04 seconds
B. 0.10 seconds
, C. 0.20 seconds
D. 0.40 seconds
Correct Answer: C. 0.20 seconds
Rationale: Since one small box is 0.04 seconds, five small boxes (one large
box) equal 0.20 seconds. This is the standard measurement used for rapid rate
estimation.
Question 9
Which method is correct for calculating heart rate for a regular rhythm?
A. Count the number of QRS complexes in 6 seconds and multiply by 10
B. Divide 300 by the number of large boxes between R waves
C. Count the number of P waves in 3 seconds and multiply by 20
D. Divide 1500 by the number of small boxes between R waves
Correct Answer: B. Divide 300 by the number of large boxes between R
waves
Rationale: The 300 method divides 300 by the number of large boxes
between R waves. For irregular rhythms, the 6-second method (count QRS
complexes in 6 seconds × 10) is preferred. The 1500 method (divide 1500 by small
boxes) also works but is less commonly used for rapid estimation.
Question 10
Which lead is most commonly used for continuous cardiac monitoring in a
hospital setting?
A. Lead I
B. Lead II
C. Lead aVF
D. Lead V1
Correct Answer: B. Lead II
