RELIAS Dysrhythmia Basic B Exam (2025/2026
Edition) –Quality Questions with Verified Correct
Answers & Detailed Rationales | Comprehensive
Study Guide | Pass with Confidence
1. The SA node is located in which part of the heart?
• A) Left atrium
• B) Right atrium
• C) Left ventricle
• D) Right ventricle
Rationale: The sinoatrial (SA) node is the heart's natural pacemaker located in the
right atrium, near the superior vena cava.
2. Which structure is responsible for delaying the electrical impulse to allow
ventricular filling?
• A) SA node
• B) AV node
• C) Bundle of His
• D) Purkinje fibers
Rationale: The AV node delays the impulse by approximately 0.12–0.20 seconds,
allowing the atria to contract and fill the ventricles.
3. Which structure conducts the electrical impulse to the ventricles via the left
and right bundle branches?
• A) SA node
• B) AV node
• C) Bundle of His
• D) Purkinje fibers
,Rationale: The Bundle of His receives the impulse from the AV node and divides
into the left and right bundle branches.
4. What is the intrinsic firing rate of the SA node?
• A) 60–100 beats per minute
• B) 40–60 beats per minute
• C) 20–40 beats per minute
• D) 100–150 beats per minute
Rationale: The SA node has an intrinsic rate of 60–100 bpm, making it the
primary pacemaker.
5. What is the intrinsic firing rate of the AV node?
• A) 60–100 bpm
• B) 40–60 bpm
• C) 20–40 bpm
• D) 100–150 bpm
Rationale: The AV node has an intrinsic rate of 40–60 bpm, serving as a
secondary pacemaker.
6. What is the intrinsic firing rate of the Purkinje fibers?
• A) 60–100 bpm
• B) 40–60 bpm
• C) 20–40 bpm
• D) 100–150 bpm
Rationale: Purkinje fibers have the slowest intrinsic rate (20–40 bpm), acting as a
tertiary pacemaker.
7. The P wave on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
, • D) Ventricular repolarization
Rationale: The P wave represents atrial depolarization. Ventricular depolarization
is represented by the QRS complex.
8. The QRS complex on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
• D) Ventricular repolarization
Rationale: The QRS complex represents ventricular depolarization. The T wave
represents ventricular repolarization.
9. The T wave on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
• D) Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, which is the recovery
phase of the ventricles.
10. The normal PR interval is:
• A) 0.08–0.10 seconds
• B) 0.12–0.20 seconds
• C) 0.20–0.24 seconds
• D) 0.24–0.30 seconds
Rationale: The PR interval represents the time from the start of atrial
depolarization to the start of ventricular depolarization (AV conduction). Normal is
0.12–0.20 seconds.
11. The normal QRS duration is:
• A) 0.04–0.08 seconds
, • B) 0.06–0.10 seconds
• C) 0.10–0.12 seconds
• D) 0.12–0.16 seconds
Rationale: The QRS complex represents ventricular depolarization. Normal
duration is 0.06–0.10 seconds. Prolonged QRS indicates intraventricular
conduction delay.
12. The normal QT interval (corrected) is:
• A) < 0.30 seconds
• B) < 0.44 seconds
• C) < 0.50 seconds
• D) < 0.60 seconds
Rationale: The corrected QT interval (QTc) should be < 0.44 seconds for males
and < 0.46 seconds for females.
13. The normal P wave duration is:
• A) < 0.12 seconds
• B) 0.12–0.20 seconds
• C) 0.20–0.24 seconds
• D) 0.24–0.30 seconds
Rationale: The P wave duration is typically < 0.12 seconds. Prolonged P waves
may indicate atrial enlargement.
14. The U wave on the ECG is thought to represent:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Repolarization of the Purkinje fibers
• D) AV node delay
Rationale: The U wave is a small deflection following the T wave, thought to
represent repolarization of the Purkinje fibers.
Edition) –Quality Questions with Verified Correct
Answers & Detailed Rationales | Comprehensive
Study Guide | Pass with Confidence
1. The SA node is located in which part of the heart?
• A) Left atrium
• B) Right atrium
• C) Left ventricle
• D) Right ventricle
Rationale: The sinoatrial (SA) node is the heart's natural pacemaker located in the
right atrium, near the superior vena cava.
2. Which structure is responsible for delaying the electrical impulse to allow
ventricular filling?
• A) SA node
• B) AV node
• C) Bundle of His
• D) Purkinje fibers
Rationale: The AV node delays the impulse by approximately 0.12–0.20 seconds,
allowing the atria to contract and fill the ventricles.
3. Which structure conducts the electrical impulse to the ventricles via the left
and right bundle branches?
• A) SA node
• B) AV node
• C) Bundle of His
• D) Purkinje fibers
,Rationale: The Bundle of His receives the impulse from the AV node and divides
into the left and right bundle branches.
4. What is the intrinsic firing rate of the SA node?
• A) 60–100 beats per minute
• B) 40–60 beats per minute
• C) 20–40 beats per minute
• D) 100–150 beats per minute
Rationale: The SA node has an intrinsic rate of 60–100 bpm, making it the
primary pacemaker.
5. What is the intrinsic firing rate of the AV node?
• A) 60–100 bpm
• B) 40–60 bpm
• C) 20–40 bpm
• D) 100–150 bpm
Rationale: The AV node has an intrinsic rate of 40–60 bpm, serving as a
secondary pacemaker.
6. What is the intrinsic firing rate of the Purkinje fibers?
• A) 60–100 bpm
• B) 40–60 bpm
• C) 20–40 bpm
• D) 100–150 bpm
Rationale: Purkinje fibers have the slowest intrinsic rate (20–40 bpm), acting as a
tertiary pacemaker.
7. The P wave on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
, • D) Ventricular repolarization
Rationale: The P wave represents atrial depolarization. Ventricular depolarization
is represented by the QRS complex.
8. The QRS complex on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
• D) Ventricular repolarization
Rationale: The QRS complex represents ventricular depolarization. The T wave
represents ventricular repolarization.
9. The T wave on the ECG represents:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Atrial repolarization
• D) Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, which is the recovery
phase of the ventricles.
10. The normal PR interval is:
• A) 0.08–0.10 seconds
• B) 0.12–0.20 seconds
• C) 0.20–0.24 seconds
• D) 0.24–0.30 seconds
Rationale: The PR interval represents the time from the start of atrial
depolarization to the start of ventricular depolarization (AV conduction). Normal is
0.12–0.20 seconds.
11. The normal QRS duration is:
• A) 0.04–0.08 seconds
, • B) 0.06–0.10 seconds
• C) 0.10–0.12 seconds
• D) 0.12–0.16 seconds
Rationale: The QRS complex represents ventricular depolarization. Normal
duration is 0.06–0.10 seconds. Prolonged QRS indicates intraventricular
conduction delay.
12. The normal QT interval (corrected) is:
• A) < 0.30 seconds
• B) < 0.44 seconds
• C) < 0.50 seconds
• D) < 0.60 seconds
Rationale: The corrected QT interval (QTc) should be < 0.44 seconds for males
and < 0.46 seconds for females.
13. The normal P wave duration is:
• A) < 0.12 seconds
• B) 0.12–0.20 seconds
• C) 0.20–0.24 seconds
• D) 0.24–0.30 seconds
Rationale: The P wave duration is typically < 0.12 seconds. Prolonged P waves
may indicate atrial enlargement.
14. The U wave on the ECG is thought to represent:
• A) Atrial depolarization
• B) Ventricular depolarization
• C) Repolarization of the Purkinje fibers
• D) AV node delay
Rationale: The U wave is a small deflection following the T wave, thought to
represent repolarization of the Purkinje fibers.
