Relias Dysrhythmia Basic B 2026 (3 Versions
Package) | Verified Questions & Answers
with Detailed Rationales | ECG Rhythm
Interpretation Exam Prep
RELIAS DYSRHYTHMIA BASIC B 2026
ECG Rhythm Interpretation Exam Prep | 286 Verified Questions & Answers
• This material covers essential ECG rhythm interpretation concepts tested in the
Relias Dysrhythmia Basic B exam, featuring 286 verified questions with detailed
EXPERT RATIONALE to reinforce clinical understanding and boost exam
confidence.
• Study tip: Read each question carefully, attempt to answer before viewing the
correct option, then review the EXPERT RATIONALE to understand the "why"
behind each answer — this deepens retention and prepares you for real clinical
scenarios.
1. What is the normal range for a PR interval?
A. 0.06 – 0.10 seconds
B. 0.08 – 0.12 seconds
C. 0.12 – 0.20 seconds
D. 0.20 – 0.24 seconds
E. 0.24 – 0.30 seconds
Correct Answer: C. 0.12 – 0.20 seconds
EXPERT RATIONALE: The PR interval represents the time from atrial
depolarization to ventricular depolarization. A normal PR interval is 0.12 to 0.20
seconds (3–5 small squares on ECG paper). Values above 0.20 seconds suggest a
conduction delay such as first-degree AV block.
,2. What does the QRS complex represent on an ECG?
A. Atrial repolarization
B. Ventricular repolarization
C. Sinoatrial node firing
D. Ventricular depolarization
E. AV node conduction delay
Correct Answer: D. Ventricular depolarization
EXPERT RATIONALE: The QRS complex represents the electrical activation
(depolarization) of the ventricles, which triggers ventricular contraction. Normal
QRS duration is 0.06–0.10 seconds. A widened QRS suggests aberrant conduction
such as a bundle branch block.
3. What is the normal heart rate range for sinus rhythm?
A. 40 – 60 bpm
B. 60 – 80 bpm
C. 60 – 100 bpm
D. 100 – 120 bpm
E. 80 – 120 bpm
Correct Answer: C. 60 – 100 bpm
EXPERT RATIONALE: Normal sinus rhythm is defined by a heart rate between
60 and 100 beats per minute, with a regular rhythm, a P wave before every QRS,
and consistent PR intervals. Rates below 60 bpm indicate bradycardia; rates above
100 bpm indicate tachycardia.
4. Which rhythm is characterized by a rate less than 60 bpm originating from
the SA node?
,A. Sinus tachycardia
B. Junctional rhythm
C. Sinus bradycardia
D. Idioventricular rhythm
E. Atrial flutter
Correct Answer: C. Sinus bradycardia
EXPERT RATIONALE: Sinus bradycardia originates from the sinoatrial (SA) node
but at a slower-than-normal rate, below 60 bpm. P waves are present and upright,
and the PR interval is normal. It may be a normal finding in athletes or indicate
pathology in symptomatic patients.
5. What is the hallmark ECG finding in atrial fibrillation?
A. Sawtooth P waves
B. Absent P waves with irregularly irregular rhythm
C. Prolonged PR interval
D. Wide QRS complexes
E. Regular rhythm with inverted P waves
Correct Answer: B. Absent P waves with irregularly irregular rhythm
EXPERT RATIONALE: Atrial fibrillation is characterized by chaotic atrial activity,
resulting in absent distinct P waves and an irregularly irregular ventricular
response. The baseline appears as a fibrillatory (wavy) line. This is a key
distinguishing feature from atrial flutter, which has sawtooth waves.
6. Atrial flutter is best identified by which of the following ECG features?
A. Absent P waves
B. Irregularly irregular rhythm
, C. Sawtooth flutter waves at 250–350 bpm
D. Wide and bizarre QRS complexes
E. Delta waves with short PR interval
Correct Answer: C. Sawtooth flutter waves at 250–350 bpm
EXPERT RATIONALE: Atrial flutter is caused by a rapid, regular atrial circuit
producing characteristic sawtooth-shaped flutter waves, best seen in leads II, III,
and aVF, at a rate of 250–350 bpm. The ventricular rate depends on the AV node
conduction ratio (commonly 2:1, 3:1, or 4:1).
7. Which of the following best describes first-degree AV block?
A. Progressively lengthening PR interval until a QRS is dropped
B. Constant prolonged PR interval greater than 0.20 seconds
C. Complete dissociation between P waves and QRS complexes
D. Intermittent non-conducted P waves without PR lengthening
E. Absent P waves with wide QRS complexes
Correct Answer: B. Constant prolonged PR interval greater than 0.20
seconds
EXPERT RATIONALE: First-degree AV block is a conduction delay at the AV node,
resulting in a consistently prolonged PR interval exceeding 0.20 seconds. Every P
wave is still followed by a QRS complex, meaning no beats are dropped. It is
generally a benign finding but may warrant monitoring.
8. Mobitz Type I (Wenckebach) second-degree AV block is characterized by:
A. Constant PR interval with randomly dropped QRS
B. Progressive PR interval lengthening until a QRS is dropped
C. Complete AV dissociation
Package) | Verified Questions & Answers
with Detailed Rationales | ECG Rhythm
Interpretation Exam Prep
RELIAS DYSRHYTHMIA BASIC B 2026
ECG Rhythm Interpretation Exam Prep | 286 Verified Questions & Answers
• This material covers essential ECG rhythm interpretation concepts tested in the
Relias Dysrhythmia Basic B exam, featuring 286 verified questions with detailed
EXPERT RATIONALE to reinforce clinical understanding and boost exam
confidence.
• Study tip: Read each question carefully, attempt to answer before viewing the
correct option, then review the EXPERT RATIONALE to understand the "why"
behind each answer — this deepens retention and prepares you for real clinical
scenarios.
1. What is the normal range for a PR interval?
A. 0.06 – 0.10 seconds
B. 0.08 – 0.12 seconds
C. 0.12 – 0.20 seconds
D. 0.20 – 0.24 seconds
E. 0.24 – 0.30 seconds
Correct Answer: C. 0.12 – 0.20 seconds
EXPERT RATIONALE: The PR interval represents the time from atrial
depolarization to ventricular depolarization. A normal PR interval is 0.12 to 0.20
seconds (3–5 small squares on ECG paper). Values above 0.20 seconds suggest a
conduction delay such as first-degree AV block.
,2. What does the QRS complex represent on an ECG?
A. Atrial repolarization
B. Ventricular repolarization
C. Sinoatrial node firing
D. Ventricular depolarization
E. AV node conduction delay
Correct Answer: D. Ventricular depolarization
EXPERT RATIONALE: The QRS complex represents the electrical activation
(depolarization) of the ventricles, which triggers ventricular contraction. Normal
QRS duration is 0.06–0.10 seconds. A widened QRS suggests aberrant conduction
such as a bundle branch block.
3. What is the normal heart rate range for sinus rhythm?
A. 40 – 60 bpm
B. 60 – 80 bpm
C. 60 – 100 bpm
D. 100 – 120 bpm
E. 80 – 120 bpm
Correct Answer: C. 60 – 100 bpm
EXPERT RATIONALE: Normal sinus rhythm is defined by a heart rate between
60 and 100 beats per minute, with a regular rhythm, a P wave before every QRS,
and consistent PR intervals. Rates below 60 bpm indicate bradycardia; rates above
100 bpm indicate tachycardia.
4. Which rhythm is characterized by a rate less than 60 bpm originating from
the SA node?
,A. Sinus tachycardia
B. Junctional rhythm
C. Sinus bradycardia
D. Idioventricular rhythm
E. Atrial flutter
Correct Answer: C. Sinus bradycardia
EXPERT RATIONALE: Sinus bradycardia originates from the sinoatrial (SA) node
but at a slower-than-normal rate, below 60 bpm. P waves are present and upright,
and the PR interval is normal. It may be a normal finding in athletes or indicate
pathology in symptomatic patients.
5. What is the hallmark ECG finding in atrial fibrillation?
A. Sawtooth P waves
B. Absent P waves with irregularly irregular rhythm
C. Prolonged PR interval
D. Wide QRS complexes
E. Regular rhythm with inverted P waves
Correct Answer: B. Absent P waves with irregularly irregular rhythm
EXPERT RATIONALE: Atrial fibrillation is characterized by chaotic atrial activity,
resulting in absent distinct P waves and an irregularly irregular ventricular
response. The baseline appears as a fibrillatory (wavy) line. This is a key
distinguishing feature from atrial flutter, which has sawtooth waves.
6. Atrial flutter is best identified by which of the following ECG features?
A. Absent P waves
B. Irregularly irregular rhythm
, C. Sawtooth flutter waves at 250–350 bpm
D. Wide and bizarre QRS complexes
E. Delta waves with short PR interval
Correct Answer: C. Sawtooth flutter waves at 250–350 bpm
EXPERT RATIONALE: Atrial flutter is caused by a rapid, regular atrial circuit
producing characteristic sawtooth-shaped flutter waves, best seen in leads II, III,
and aVF, at a rate of 250–350 bpm. The ventricular rate depends on the AV node
conduction ratio (commonly 2:1, 3:1, or 4:1).
7. Which of the following best describes first-degree AV block?
A. Progressively lengthening PR interval until a QRS is dropped
B. Constant prolonged PR interval greater than 0.20 seconds
C. Complete dissociation between P waves and QRS complexes
D. Intermittent non-conducted P waves without PR lengthening
E. Absent P waves with wide QRS complexes
Correct Answer: B. Constant prolonged PR interval greater than 0.20
seconds
EXPERT RATIONALE: First-degree AV block is a conduction delay at the AV node,
resulting in a consistently prolonged PR interval exceeding 0.20 seconds. Every P
wave is still followed by a QRS complex, meaning no beats are dropped. It is
generally a benign finding but may warrant monitoring.
8. Mobitz Type I (Wenckebach) second-degree AV block is characterized by:
A. Constant PR interval with randomly dropped QRS
B. Progressive PR interval lengthening until a QRS is dropped
C. Complete AV dissociation
