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Relias Dysrhythmia Basic B Exam Cardiac
Rhythm Interpretation Actual Exam 2026/2027 –
Complete Exam-Style Questions with Detailed
Rationales | Pass Guaranteed – A+ Graded
[SECTION 1: Sinus & Atrial Rhythms — Questions 1-8]
Q1: You are analyzing an ECG strip. The rhythm is irregular, corresponding with the patient's
respiration. The rate varies between 60 and 100 bpm. P waves are present, upright in Lead II, and
have a consistent morphology. The PR interval is normal. What is this rhythm?
A. Atrial Fibrillation
B. Sinus Arrhythmia
B. Sinus Arrhythmia [CORRECT]
C. Premature Atrial Complexes (PACs)
D. Sinus Tachycardia
Correct Answer: B
Rationale: Sinus arrhythmia is characterized by a variation in the R-R interval that corresponds
to the respiratory cycle; the rate typically increases during inspiration and decreases during
expiration. The key identifying features are the presence of normal, upright P waves and a
normal PR interval, distinguishing it from pathologic arrhythmias like Atrial Fibrillation (which
has no discernible P waves) or PACs (which have premature, abnormal P waves).
Q2: A patient’s ECG shows a regular rhythm at a rate of 115 bpm. The P waves are upright in
Lead II and precede every QRS complex. The PR interval is 0.16 seconds. The QRS complexes
are narrow (0.08 sec). The patient reports feeling anxious. Which rhythm is indicated?
A. Atrial Flutter
B. Sinus Tachycardia
B. Sinus Tachycardia [CORRECT]
C. Junctional Tachycardia
,2
D. Atrial Fibrillation
Correct Answer: B
Rationale: Sinus tachycardia is defined as a sinus rhythm with a rate greater than 100 bpm (up to
150-160 bpm). All other components (P wave morphology, PR interval, QRS width) are normal.
The gradual onset/offset and clinical context (anxiety) support this diagnosis over other
supraventricular tachycardias which often have abrupt onset or abnormal P waves.
Q3: An ECG strip reveals a regular rhythm except for an early beat. This early complex has a P
wave that is flattened and differs in shape from the sinus P waves. The QRS complex is narrow
(0.08 sec) and resembles the other QRS complexes. There is a brief pause following the beat.
What is this rhythm?
A. Premature Ventricular Complex (PVC)
B. Premature Junctional Complex (PJC)
C. Premature Atrial Complex (PAC) [CORRECT]
D. Atrial Escape Beat
Correct Answer: C
Rationale: A Premature Atrial Complex (PAC) is characterized by an early P wave with a
morphology different from the sinus P waves, indicating it originated from an ectopic atrial
focus. The QRS complex is usually narrow because the impulse travels through the normal
conduction pathway. The pause following a PAC is typically an incomplete compensatory pause
because the PAC often resets the sinus node.
Q4: You observe a rhythm with a ventricular rate of 150 bpm. The atrial rate appears to be 300
bpm. The baseline shows "sawtooth" waves best seen in leads II, III, and aVF. The ventricular
rhythm is regular. What is the most likely interpretation?
A. Atrial Fibrillation
B. Sinus Tachycardia
C. Atrial Flutter [CORRECT]
D. Atrial Tachycardia
, 3
Correct Answer: C
Rationale: Atrial flutter is distinguished by its characteristic "sawtooth" flutter waves (F waves)
representing an atrial rate of 250-350 bpm. The ventricular rate is often regular due to a fixed
block ratio (commonly 2:1, resulting in a ventricular rate of 150 bpm). Atrial fibrillation would
show an irregularly irregular rhythm and chaotic fibrillatory waves, not sawtooth waves.
Q5: An ECG displays an irregularly irregular ventricular rhythm. There are no discernible P
waves; instead, the baseline shows chaotic fibrillatory waves. The heart rate is 90 bpm and the
QRS complexes are narrow. Which rhythm is this?
A. Sinus Arrhythmia
B. Atrial Flutter with variable block
C. Atrial Fibrillation [CORRECT]
D. Multifocal Atrial Tachycardia
Correct Answer: C
Rationale: The hallmark of Atrial Fibrillation (AFib) is the "irregularly irregular" R-R interval
and the absence of discrete P waves, replaced by fibrillatory (f) waves. While the rate here is
controlled (<100 bpm), the irregularity and chaotic baseline distinguish it from Sinus Arrhythmia
(which has distinct P waves) or Atrial Flutter (which has organized flutter waves).
Q6: A patient with severe COPD presents with tachycardia. The ECG shows a rate of 120 bpm.
The rhythm is irregular. There are at least three different P wave morphologies visible, and the
PR intervals vary. The QRS complexes are narrow. What is this rhythm?
A. Atrial Fibrillation
B. Wandering Atrial Pacemaker
C. Multifocal Atrial Tachycardia (MAT) [CORRECT]
D. Premature Atrial Trigeminy
Correct Answer: C
Relias Dysrhythmia Basic B Exam Cardiac
Rhythm Interpretation Actual Exam 2026/2027 –
Complete Exam-Style Questions with Detailed
Rationales | Pass Guaranteed – A+ Graded
[SECTION 1: Sinus & Atrial Rhythms — Questions 1-8]
Q1: You are analyzing an ECG strip. The rhythm is irregular, corresponding with the patient's
respiration. The rate varies between 60 and 100 bpm. P waves are present, upright in Lead II, and
have a consistent morphology. The PR interval is normal. What is this rhythm?
A. Atrial Fibrillation
B. Sinus Arrhythmia
B. Sinus Arrhythmia [CORRECT]
C. Premature Atrial Complexes (PACs)
D. Sinus Tachycardia
Correct Answer: B
Rationale: Sinus arrhythmia is characterized by a variation in the R-R interval that corresponds
to the respiratory cycle; the rate typically increases during inspiration and decreases during
expiration. The key identifying features are the presence of normal, upright P waves and a
normal PR interval, distinguishing it from pathologic arrhythmias like Atrial Fibrillation (which
has no discernible P waves) or PACs (which have premature, abnormal P waves).
Q2: A patient’s ECG shows a regular rhythm at a rate of 115 bpm. The P waves are upright in
Lead II and precede every QRS complex. The PR interval is 0.16 seconds. The QRS complexes
are narrow (0.08 sec). The patient reports feeling anxious. Which rhythm is indicated?
A. Atrial Flutter
B. Sinus Tachycardia
B. Sinus Tachycardia [CORRECT]
C. Junctional Tachycardia
,2
D. Atrial Fibrillation
Correct Answer: B
Rationale: Sinus tachycardia is defined as a sinus rhythm with a rate greater than 100 bpm (up to
150-160 bpm). All other components (P wave morphology, PR interval, QRS width) are normal.
The gradual onset/offset and clinical context (anxiety) support this diagnosis over other
supraventricular tachycardias which often have abrupt onset or abnormal P waves.
Q3: An ECG strip reveals a regular rhythm except for an early beat. This early complex has a P
wave that is flattened and differs in shape from the sinus P waves. The QRS complex is narrow
(0.08 sec) and resembles the other QRS complexes. There is a brief pause following the beat.
What is this rhythm?
A. Premature Ventricular Complex (PVC)
B. Premature Junctional Complex (PJC)
C. Premature Atrial Complex (PAC) [CORRECT]
D. Atrial Escape Beat
Correct Answer: C
Rationale: A Premature Atrial Complex (PAC) is characterized by an early P wave with a
morphology different from the sinus P waves, indicating it originated from an ectopic atrial
focus. The QRS complex is usually narrow because the impulse travels through the normal
conduction pathway. The pause following a PAC is typically an incomplete compensatory pause
because the PAC often resets the sinus node.
Q4: You observe a rhythm with a ventricular rate of 150 bpm. The atrial rate appears to be 300
bpm. The baseline shows "sawtooth" waves best seen in leads II, III, and aVF. The ventricular
rhythm is regular. What is the most likely interpretation?
A. Atrial Fibrillation
B. Sinus Tachycardia
C. Atrial Flutter [CORRECT]
D. Atrial Tachycardia
, 3
Correct Answer: C
Rationale: Atrial flutter is distinguished by its characteristic "sawtooth" flutter waves (F waves)
representing an atrial rate of 250-350 bpm. The ventricular rate is often regular due to a fixed
block ratio (commonly 2:1, resulting in a ventricular rate of 150 bpm). Atrial fibrillation would
show an irregularly irregular rhythm and chaotic fibrillatory waves, not sawtooth waves.
Q5: An ECG displays an irregularly irregular ventricular rhythm. There are no discernible P
waves; instead, the baseline shows chaotic fibrillatory waves. The heart rate is 90 bpm and the
QRS complexes are narrow. Which rhythm is this?
A. Sinus Arrhythmia
B. Atrial Flutter with variable block
C. Atrial Fibrillation [CORRECT]
D. Multifocal Atrial Tachycardia
Correct Answer: C
Rationale: The hallmark of Atrial Fibrillation (AFib) is the "irregularly irregular" R-R interval
and the absence of discrete P waves, replaced by fibrillatory (f) waves. While the rate here is
controlled (<100 bpm), the irregularity and chaotic baseline distinguish it from Sinus Arrhythmia
(which has distinct P waves) or Atrial Flutter (which has organized flutter waves).
Q6: A patient with severe COPD presents with tachycardia. The ECG shows a rate of 120 bpm.
The rhythm is irregular. There are at least three different P wave morphologies visible, and the
PR intervals vary. The QRS complexes are narrow. What is this rhythm?
A. Atrial Fibrillation
B. Wandering Atrial Pacemaker
C. Multifocal Atrial Tachycardia (MAT) [CORRECT]
D. Premature Atrial Trigeminy
Correct Answer: C
