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RELIAS DYSRHYTHMIA BASIC A Complete Practice Test
2026 -2027 100 Questions with Verified Answers &
Detailed Rationales
SECTION 1: ECG FOUNDATIONS & MEASUREMENTS (Questions 1-15)
1. The electrical impulse normally originates from which structure of the
heart?
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, is the heart's
natural pacemaker. It normally discharges at 60-100 beats per minute. The AV
node delays impulses, the Bundle of His conducts impulses to the ventricles,
and Purkinje fibers are the terminal conduction pathway.
2. At what rate does the SA node normally fire in a resting adult?
A) 20-40 beats per minute
B) 40-60 beats per minute
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C) 60-100 beats per minute
D) 100-150 beats per minute
Correct Answer: C) 60-100 beats per minute**
Rationale:The SA node is the primary pacemaker with an intrinsic firing rate of
60-100 bpm. The AV junction has a backup rate of 40-60 bpm, and the
Purkinje fibers have an intrinsic rate of 20-40 bpm.
3. Which component of the ECG represents ventricular depolarization?
A) P wave
B) PR interval
C) QRS complex
D) T wave
Correct Answer: C) QRS complex
Rationale:The QRS complex represents the electrical impulse traveling
through the ventricles, causing them to contract. The P wave represents atrial
depolarization, and the T wave represents ventricular repolarization.
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4. On standard ECG paper, what is the standard speed?**
A) 15 mm/second
B) 25 mm/second
C) 50 mm/second
D) 100 mm/second
Correct Answer: B) 25 mm/second
Rationale:The standard ECG paper speed is 25 mm per second. At this speed,
each small box (1 mm) represents 0.04 seconds, and each large box (5 mm)
represents 0.20 seconds.
5. On standard ECG paper, 1 small box (1 mm) represents how many seconds?
A) 0.04 seconds
B) 0.10 seconds
C) 0.20 seconds
D) 0.50 seconds
Correct Answer: A) 0.04 seconds
Rationale:At standard speed (25 mm/sec), each small box = 0.04 sec (40 ms).
Each large box (5 small boxes) = 0.20 sec.
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6. A normal PR interval should measure:
A) 0.04-0.08 seconds
B) 0.08-0.12 seconds
C) 0.12-0.20 seconds
D) 0.20-0.30 seconds
Correct Answer: C) 0.12-0.20 seconds
**Rationale:** The normal PR interval ranges from 0.12 to 0.20 seconds (3-5
small boxes). It represents the time from the beginning of atrial depolarization
to the beginning of ventricular depolarization.
7. A normal QRS duration should measure:
A) Less than 0.04 seconds
B) Less than 0.08 seconds
C) Less than 0.12 seconds
D) Less than 0.20 seconds
*Correct Answer: C) Less than 0.12 seconds
Rationale:The normal QRS duration is less than 0.12 seconds (less than 3 small
boxes). A QRS duration of 0.12 seconds or greater indicates a bundle branch
block or ventricular origin of the rhythm.
RELIAS DYSRHYTHMIA BASIC A Complete Practice Test
2026 -2027 100 Questions with Verified Answers &
Detailed Rationales
SECTION 1: ECG FOUNDATIONS & MEASUREMENTS (Questions 1-15)
1. The electrical impulse normally originates from which structure of the
heart?
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, is the heart's
natural pacemaker. It normally discharges at 60-100 beats per minute. The AV
node delays impulses, the Bundle of His conducts impulses to the ventricles,
and Purkinje fibers are the terminal conduction pathway.
2. At what rate does the SA node normally fire in a resting adult?
A) 20-40 beats per minute
B) 40-60 beats per minute
,2
C) 60-100 beats per minute
D) 100-150 beats per minute
Correct Answer: C) 60-100 beats per minute**
Rationale:The SA node is the primary pacemaker with an intrinsic firing rate of
60-100 bpm. The AV junction has a backup rate of 40-60 bpm, and the
Purkinje fibers have an intrinsic rate of 20-40 bpm.
3. Which component of the ECG represents ventricular depolarization?
A) P wave
B) PR interval
C) QRS complex
D) T wave
Correct Answer: C) QRS complex
Rationale:The QRS complex represents the electrical impulse traveling
through the ventricles, causing them to contract. The P wave represents atrial
depolarization, and the T wave represents ventricular repolarization.
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4. On standard ECG paper, what is the standard speed?**
A) 15 mm/second
B) 25 mm/second
C) 50 mm/second
D) 100 mm/second
Correct Answer: B) 25 mm/second
Rationale:The standard ECG paper speed is 25 mm per second. At this speed,
each small box (1 mm) represents 0.04 seconds, and each large box (5 mm)
represents 0.20 seconds.
5. On standard ECG paper, 1 small box (1 mm) represents how many seconds?
A) 0.04 seconds
B) 0.10 seconds
C) 0.20 seconds
D) 0.50 seconds
Correct Answer: A) 0.04 seconds
Rationale:At standard speed (25 mm/sec), each small box = 0.04 sec (40 ms).
Each large box (5 small boxes) = 0.20 sec.
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6. A normal PR interval should measure:
A) 0.04-0.08 seconds
B) 0.08-0.12 seconds
C) 0.12-0.20 seconds
D) 0.20-0.30 seconds
Correct Answer: C) 0.12-0.20 seconds
**Rationale:** The normal PR interval ranges from 0.12 to 0.20 seconds (3-5
small boxes). It represents the time from the beginning of atrial depolarization
to the beginning of ventricular depolarization.
7. A normal QRS duration should measure:
A) Less than 0.04 seconds
B) Less than 0.08 seconds
C) Less than 0.12 seconds
D) Less than 0.20 seconds
*Correct Answer: C) Less than 0.12 seconds
Rationale:The normal QRS duration is less than 0.12 seconds (less than 3 small
boxes). A QRS duration of 0.12 seconds or greater indicates a bundle branch
block or ventricular origin of the rhythm.
