RELIAS Dysrhythmia Basic B Exam (2025/2026
Edition) Total: 245 Questions | Verified with Correct
Answers and Rationales
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 at the junction
of the superior vena cava and the right atrium, near the crista terminalis.
2. 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 onset of atrial depolarization (P
wave) to the onset of ventricular depolarization (QRS complex), including conduction
through the AV node.
3. 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. A duration greater than
0.10 seconds indicates an intraventricular conduction delay.
,4. If an R-R interval is 0.8 seconds, the heart rate is approximately:
A. 60 bpm
B. 75 bpm
C. 80 bpm
D. 100 bpm
Rationale: Heart rate is calculated by dividing 60 seconds by the R-R interval in seconds
(60 ÷ 0.8 = 75 bpm).
5. Which rhythm originates in the AV node with absent or inverted P waves?
A. Atrial flutter
B. Junctional rhythm
C. Sinus bradycardia
D. Sinus rhythm
Rationale: Junctional rhythms originate at or near the AV node. P waves may be absent,
inverted, or retrograde (occurring after the QRS complex).
6. Atrial flutter has a characteristic appearance of:
A. Irregular baseline
B. F waves or "sawtooth" pattern
C. No P waves
D. Wide QRS complexes
Rationale: Atrial flutter produces characteristic flutter (F) waves at a rate of 250-350 bpm,
creating a "sawtooth" baseline appearance.
7. Ventricular fibrillation is best described as:
A. Rapid, irregular atrial activity
B. Chaotic ventricular activity with no pulse
C. Organized ventricular depolarization
D. Atrial contraction without QRS
,Rationale: VFIB is a life-threatening rhythm characterized by chaotic, disorganized
electrical activity with no effective ventricular contraction and no pulse. It requires immediate
defibrillation.
8. In sinus bradycardia, the heart rate is:
A. < 60 bpm
B. 60–100 bpm
C. 100–150 bpm
D. > 150 bpm
Rationale: Sinus bradycardia is defined as a sinus rhythm with a heart rate less than 60
bpm. It can be normal in athletes or may indicate a pathological condition.
9. The normal P wave represents:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. AV node conduction
Rationale: The P wave represents atrial depolarization (contraction) initiated by the SA
node. It is normally upright in leads I, II, and aVF.
10. The T wave represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. AV node conduction
Rationale: The T wave represents ventricular repolarization. It is normally upright in leads
with upright QRS complexes.
11. The U wave is:
, A. A normal finding in all patients
B. A small deflection following the T wave, often seen in hypokalemia
C. A sign of myocardial infarction
D. A sign of atrial fibrillation
Rationale: The U wave is a small, low-amplitude deflection following the T wave. Prominent
U waves are associated with hypokalemia and bradycardia.
12. Which of the following is the intrinsic rate of the SA node?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The SA node has an intrinsic firing rate of 60-100 bpm. It is the dominant
pacemaker of the heart.
13. Which of the following is the intrinsic rate of the AV junction?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The AV junction has an intrinsic rate of 40-60 bpm. It serves as the secondary
pacemaker when the SA node fails.
14. Which of the following is the intrinsic rate of the Purkinje fibers?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The Purkinje fibers have an intrinsic rate of 20-40 bpm. They serve as the
tertiary pacemaker when higher pacemakers fail.
Edition) Total: 245 Questions | Verified with Correct
Answers and Rationales
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 at the junction
of the superior vena cava and the right atrium, near the crista terminalis.
2. 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 onset of atrial depolarization (P
wave) to the onset of ventricular depolarization (QRS complex), including conduction
through the AV node.
3. 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. A duration greater than
0.10 seconds indicates an intraventricular conduction delay.
,4. If an R-R interval is 0.8 seconds, the heart rate is approximately:
A. 60 bpm
B. 75 bpm
C. 80 bpm
D. 100 bpm
Rationale: Heart rate is calculated by dividing 60 seconds by the R-R interval in seconds
(60 ÷ 0.8 = 75 bpm).
5. Which rhythm originates in the AV node with absent or inverted P waves?
A. Atrial flutter
B. Junctional rhythm
C. Sinus bradycardia
D. Sinus rhythm
Rationale: Junctional rhythms originate at or near the AV node. P waves may be absent,
inverted, or retrograde (occurring after the QRS complex).
6. Atrial flutter has a characteristic appearance of:
A. Irregular baseline
B. F waves or "sawtooth" pattern
C. No P waves
D. Wide QRS complexes
Rationale: Atrial flutter produces characteristic flutter (F) waves at a rate of 250-350 bpm,
creating a "sawtooth" baseline appearance.
7. Ventricular fibrillation is best described as:
A. Rapid, irregular atrial activity
B. Chaotic ventricular activity with no pulse
C. Organized ventricular depolarization
D. Atrial contraction without QRS
,Rationale: VFIB is a life-threatening rhythm characterized by chaotic, disorganized
electrical activity with no effective ventricular contraction and no pulse. It requires immediate
defibrillation.
8. In sinus bradycardia, the heart rate is:
A. < 60 bpm
B. 60–100 bpm
C. 100–150 bpm
D. > 150 bpm
Rationale: Sinus bradycardia is defined as a sinus rhythm with a heart rate less than 60
bpm. It can be normal in athletes or may indicate a pathological condition.
9. The normal P wave represents:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. AV node conduction
Rationale: The P wave represents atrial depolarization (contraction) initiated by the SA
node. It is normally upright in leads I, II, and aVF.
10. The T wave represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. AV node conduction
Rationale: The T wave represents ventricular repolarization. It is normally upright in leads
with upright QRS complexes.
11. The U wave is:
, A. A normal finding in all patients
B. A small deflection following the T wave, often seen in hypokalemia
C. A sign of myocardial infarction
D. A sign of atrial fibrillation
Rationale: The U wave is a small, low-amplitude deflection following the T wave. Prominent
U waves are associated with hypokalemia and bradycardia.
12. Which of the following is the intrinsic rate of the SA node?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The SA node has an intrinsic firing rate of 60-100 bpm. It is the dominant
pacemaker of the heart.
13. Which of the following is the intrinsic rate of the AV junction?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The AV junction has an intrinsic rate of 40-60 bpm. It serves as the secondary
pacemaker when the SA node fails.
14. Which of the following is the intrinsic rate of the Purkinje fibers?
A. 20-40 bpm
B. 40-60 bpm
C. 60-100 bpm
D. 100-120 bpm
Rationale: The Purkinje fibers have an intrinsic rate of 20-40 bpm. They serve as the
tertiary pacemaker when higher pacemakers fail.
