Relias Dysrhythmia Basic Test and Answers 2026/2027 (Basic A
Dysrhythmia) - 100 Questions
This exam rigorously assesses mastery of sinus rhythm interpretation, including normal sinus rhythm, sinus
bradycardia, sinus tachycardia, sinus arrhythmia, and sinus arrest/pause. Questions require multi-step analysis of
ECG criteria, clinical implications, and differential diagnosis. It contains 100 multiple-choice questions, each
with four distractors and a fully worked rationale that explains why the keyed answer is correct. Content is
organized into 8 focused sections: Sinus Rhythms, Atrial Rhythms, Junctional Rhythms, Ventricular Rhythms, AV
Blocks, Pacemaker Rhythms, Electrolyte and Drug Effects on ECG, Interpretation of Rate, Rhythm, P Wave, PR
Interval, QRS Complex. Targeted learning outcomes include: Accurately identify and differentiate all sinus
rhythms using rate, regularity, P-wave morphology, and PR interval.; Apply physiologic and pathophysiologic
principles to explain rate and rhythm variations.; Integrate ECG findings with clinical context to guide
appropriate management decisions.. Every item has been reviewed for clinical accuracy, current guidelines, and
clarity so that students can study with confidence and self-correct as they work through the bank. Use it as a
high-yield review immediately before the exam, or as a structured practice tool during the unit - the rationales
double as concise teaching notes. The recommended writing time is 2 hours, with a passing score of 85%. Aligned
with Designed to meet ACC/AHA/HRS clinical competency standards for healthcare professionals. standards and
reflects the question style commonly seen on accredited program examinations. Students consistently achieving
Section 1: Sinus Rhythms (Questions 1-13)
1 A patient's ECG shows a regular rhythm at 38 bpm, each QRS preceded by a
normal P wave, PR interval 0.16 s, QRS duration 0.08 s. What is the most
likely diagnosis?
A) Sinus bradycardia with first-degree AV block
B) Junctional bradycardia
C) Sinus bradycardia
D) Sinoatrial exit block
Answer: C
Rationale: The rate is <60 bpm with normal P waves and PR interval,
confirming sinus bradycardia. First-degree AV block requires PR >0.20 s.
Junctional bradycardia lacks P waves. SA exit block would show dropped P
waves.
2 Which mechanism most likely underlies the gradual increase in heart rate
from 70 to 110 bpm over 30 seconds during inspiration, with gradual
decrease on expiration, in a healthy individual?
A) Increased vagal tone during inspiration
B) Decreased sympathetic outflow during expiration
C) Stretch of the SA node during inspiration
D) Baroreceptor-mediated reflex
,Answer: B
Rationale: Sinus arrhythmia is due to respiratory variation in vagal tone. During
inspiration, vagal tone decreases (not increases), allowing heart rate to rise.
Stretch of SA node is not a primary mechanism. Baroreceptors respond to
blood pressure changes, not directly to respiration.
3 An ECG shows a regular rhythm at 140 bpm, P waves upright in lead II, PR
interval 0.12 s, QRS 0.08 s. The patient is febrile (39°C) and hypotensive.
Which of the following best explains the rate?
A) Increased automaticity of the AV junction
B) Enhanced sympathetic stimulation of the SA node
C) Reentrant tachycardia involving the AV node
D) Accelerated idioventricular rhythm
Answer: B
Rationale: The ECG criteria indicate sinus tachycardia (rate >100, normal P
waves, normal intervals). Fever and hypotension cause increased sympathetic
drive and decreased vagal tone, accelerating SA node firing. AV junctional
tachycardia would have absent or retrograde P waves. Reentrant SVT often has
P waves hidden or abnormal. Idioventricular rhythm is wide QRS.
4 A rhythm strip shows a pause of 2.8 seconds with no P wave or QRS
complex. The underlying rhythm is 72 bpm with normal sinus P waves.
What is the most likely cause?
A) Second-degree AV block type I
B) Sinoatrial arrest
C) Sinoatrial exit block
D) Ventricular pause due to concealed conduction
Answer: B
Rationale: A pause without any P wave indicates that the SA node failed to fire
(sinus arrest). In SA exit block, the SA node fires but the impulse is blocked,
so you would see a pause that is a multiple of the P-P interval. AV block would
still show P waves during the pause.
5 Which of the following is true regarding the effect of carotid sinus massage
on sinus tachycardia versus sinus node reentrant tachycardia?
A) Both typically terminate abruptly
,B) Sinus tachycardia gradually slows, while sinus node reentrant tachycardia
may terminate abruptly
C) Sinus tachycardia is unaffected, while sinus node reentrant tachycardia
slows gradually
D) Both show no response
Answer: B
Rationale: Carotid sinus massage increases vagal tone. Sinus tachycardia
responds with gradual slowing due to SA node suppression. Sinus node
reentrant tachycardia, a reentrant rhythm, may terminate abruptly if the circuit
is interrupted. Both can be affected, but the response pattern differs.
6 A patient with a history of heart transplant presents with a heart rate of 95
bpm, regular, P waves present but with variable morphology. Which rhythm
is most likely?
A) Wandering atrial pacemaker
B) Sinus rhythm with multifocal atrial tachycardia
C) Denervated sinus rhythm
D) Atrial fibrillation with slow ventricular response
Answer: C
Rationale: In heart transplant, the donor SA node is denervated, leading to a
higher resting rate (90-100 bpm) and blunted response to autonomic stimuli.
Variable P wave morphology can occur due to two atrial foci (native and
donor). Wandering atrial pacemaker is not specific to transplant. MAT requires
at least three P wave morphologies and rate >100.
7 Which finding would most reliably distinguish sinus bradycardia from
junctional bradycardia?
A) Rate less than 40 bpm
B) Presence of P waves before each QRS
C) QRS duration less than 0.12 s
D) Regularity of the rhythm
Answer: B
Rationale: Sinus bradycardia has P waves preceding each QRS with normal
axis. Junctional bradycardia typically has no P waves or inverted P waves after
QRS. Rate alone cannot distinguish (both can be slow). QRS is narrow in both.
Both are regular.
, 8 A 12-lead ECG shows a rhythm of 52 bpm, P waves upright in II, III, aVF,
PR interval 0.14 s, QRS 0.10 s. There is a 0.12 s pause every 8 beats. What is
the rhythm?
A) Sinus bradycardia with nonconducted PAC
B) Sinus arrhythmia
C) Sinus bradycardia with first-degree AV block
D) Sinoatrial exit block (type I)
Answer: A
Rationale: The pause is shorter than two P-P intervals, suggesting a blocked
premature atrial complex (PAC) that resets the sinus node. Sinus arrhythmia
would show gradual variation with respiration. First-degree AV block requires
PR >0.20 s. SA exit block type I would show progressive shortening of P-P
intervals before the pause.
9 Which of the following is a characteristic of inappropriate sinus tachycardia?
A) Heart rate >100 bpm at rest with exaggerated response to minimal
exertion
B) Episodic tachycardia with sudden onset and termination
C) P waves that are negative in leads II, III, aVF
D) Rate typically 150-250 bpm
Answer: A
Rationale: Inappropriate sinus tachycardia is defined by a resting heart rate
>100 bpm or an exaggerated heart rate response to exercise/stress, with normal
P wave axis. It is non-paroxysmal (not sudden onset/termination). Negative P
waves suggest ectopic atrial rhythm. Rates of 150-250 are typical of AVNRT or
atrial flutter.
10 A patient has a rhythm strip showing a pause of 1.6 seconds. The P-P
interval of the underlying rhythm is 0.8 seconds. What is the most likely
rhythm?
A) Sinus arrest
B) Sinoatrial exit block (type II)
C) Sinus arrhythmia
D) Second-degree AV block type I
Answer: B
Dysrhythmia) - 100 Questions
This exam rigorously assesses mastery of sinus rhythm interpretation, including normal sinus rhythm, sinus
bradycardia, sinus tachycardia, sinus arrhythmia, and sinus arrest/pause. Questions require multi-step analysis of
ECG criteria, clinical implications, and differential diagnosis. It contains 100 multiple-choice questions, each
with four distractors and a fully worked rationale that explains why the keyed answer is correct. Content is
organized into 8 focused sections: Sinus Rhythms, Atrial Rhythms, Junctional Rhythms, Ventricular Rhythms, AV
Blocks, Pacemaker Rhythms, Electrolyte and Drug Effects on ECG, Interpretation of Rate, Rhythm, P Wave, PR
Interval, QRS Complex. Targeted learning outcomes include: Accurately identify and differentiate all sinus
rhythms using rate, regularity, P-wave morphology, and PR interval.; Apply physiologic and pathophysiologic
principles to explain rate and rhythm variations.; Integrate ECG findings with clinical context to guide
appropriate management decisions.. Every item has been reviewed for clinical accuracy, current guidelines, and
clarity so that students can study with confidence and self-correct as they work through the bank. Use it as a
high-yield review immediately before the exam, or as a structured practice tool during the unit - the rationales
double as concise teaching notes. The recommended writing time is 2 hours, with a passing score of 85%. Aligned
with Designed to meet ACC/AHA/HRS clinical competency standards for healthcare professionals. standards and
reflects the question style commonly seen on accredited program examinations. Students consistently achieving
Section 1: Sinus Rhythms (Questions 1-13)
1 A patient's ECG shows a regular rhythm at 38 bpm, each QRS preceded by a
normal P wave, PR interval 0.16 s, QRS duration 0.08 s. What is the most
likely diagnosis?
A) Sinus bradycardia with first-degree AV block
B) Junctional bradycardia
C) Sinus bradycardia
D) Sinoatrial exit block
Answer: C
Rationale: The rate is <60 bpm with normal P waves and PR interval,
confirming sinus bradycardia. First-degree AV block requires PR >0.20 s.
Junctional bradycardia lacks P waves. SA exit block would show dropped P
waves.
2 Which mechanism most likely underlies the gradual increase in heart rate
from 70 to 110 bpm over 30 seconds during inspiration, with gradual
decrease on expiration, in a healthy individual?
A) Increased vagal tone during inspiration
B) Decreased sympathetic outflow during expiration
C) Stretch of the SA node during inspiration
D) Baroreceptor-mediated reflex
,Answer: B
Rationale: Sinus arrhythmia is due to respiratory variation in vagal tone. During
inspiration, vagal tone decreases (not increases), allowing heart rate to rise.
Stretch of SA node is not a primary mechanism. Baroreceptors respond to
blood pressure changes, not directly to respiration.
3 An ECG shows a regular rhythm at 140 bpm, P waves upright in lead II, PR
interval 0.12 s, QRS 0.08 s. The patient is febrile (39°C) and hypotensive.
Which of the following best explains the rate?
A) Increased automaticity of the AV junction
B) Enhanced sympathetic stimulation of the SA node
C) Reentrant tachycardia involving the AV node
D) Accelerated idioventricular rhythm
Answer: B
Rationale: The ECG criteria indicate sinus tachycardia (rate >100, normal P
waves, normal intervals). Fever and hypotension cause increased sympathetic
drive and decreased vagal tone, accelerating SA node firing. AV junctional
tachycardia would have absent or retrograde P waves. Reentrant SVT often has
P waves hidden or abnormal. Idioventricular rhythm is wide QRS.
4 A rhythm strip shows a pause of 2.8 seconds with no P wave or QRS
complex. The underlying rhythm is 72 bpm with normal sinus P waves.
What is the most likely cause?
A) Second-degree AV block type I
B) Sinoatrial arrest
C) Sinoatrial exit block
D) Ventricular pause due to concealed conduction
Answer: B
Rationale: A pause without any P wave indicates that the SA node failed to fire
(sinus arrest). In SA exit block, the SA node fires but the impulse is blocked,
so you would see a pause that is a multiple of the P-P interval. AV block would
still show P waves during the pause.
5 Which of the following is true regarding the effect of carotid sinus massage
on sinus tachycardia versus sinus node reentrant tachycardia?
A) Both typically terminate abruptly
,B) Sinus tachycardia gradually slows, while sinus node reentrant tachycardia
may terminate abruptly
C) Sinus tachycardia is unaffected, while sinus node reentrant tachycardia
slows gradually
D) Both show no response
Answer: B
Rationale: Carotid sinus massage increases vagal tone. Sinus tachycardia
responds with gradual slowing due to SA node suppression. Sinus node
reentrant tachycardia, a reentrant rhythm, may terminate abruptly if the circuit
is interrupted. Both can be affected, but the response pattern differs.
6 A patient with a history of heart transplant presents with a heart rate of 95
bpm, regular, P waves present but with variable morphology. Which rhythm
is most likely?
A) Wandering atrial pacemaker
B) Sinus rhythm with multifocal atrial tachycardia
C) Denervated sinus rhythm
D) Atrial fibrillation with slow ventricular response
Answer: C
Rationale: In heart transplant, the donor SA node is denervated, leading to a
higher resting rate (90-100 bpm) and blunted response to autonomic stimuli.
Variable P wave morphology can occur due to two atrial foci (native and
donor). Wandering atrial pacemaker is not specific to transplant. MAT requires
at least three P wave morphologies and rate >100.
7 Which finding would most reliably distinguish sinus bradycardia from
junctional bradycardia?
A) Rate less than 40 bpm
B) Presence of P waves before each QRS
C) QRS duration less than 0.12 s
D) Regularity of the rhythm
Answer: B
Rationale: Sinus bradycardia has P waves preceding each QRS with normal
axis. Junctional bradycardia typically has no P waves or inverted P waves after
QRS. Rate alone cannot distinguish (both can be slow). QRS is narrow in both.
Both are regular.
, 8 A 12-lead ECG shows a rhythm of 52 bpm, P waves upright in II, III, aVF,
PR interval 0.14 s, QRS 0.10 s. There is a 0.12 s pause every 8 beats. What is
the rhythm?
A) Sinus bradycardia with nonconducted PAC
B) Sinus arrhythmia
C) Sinus bradycardia with first-degree AV block
D) Sinoatrial exit block (type I)
Answer: A
Rationale: The pause is shorter than two P-P intervals, suggesting a blocked
premature atrial complex (PAC) that resets the sinus node. Sinus arrhythmia
would show gradual variation with respiration. First-degree AV block requires
PR >0.20 s. SA exit block type I would show progressive shortening of P-P
intervals before the pause.
9 Which of the following is a characteristic of inappropriate sinus tachycardia?
A) Heart rate >100 bpm at rest with exaggerated response to minimal
exertion
B) Episodic tachycardia with sudden onset and termination
C) P waves that are negative in leads II, III, aVF
D) Rate typically 150-250 bpm
Answer: A
Rationale: Inappropriate sinus tachycardia is defined by a resting heart rate
>100 bpm or an exaggerated heart rate response to exercise/stress, with normal
P wave axis. It is non-paroxysmal (not sudden onset/termination). Negative P
waves suggest ectopic atrial rhythm. Rates of 150-250 are typical of AVNRT or
atrial flutter.
10 A patient has a rhythm strip showing a pause of 1.6 seconds. The P-P
interval of the underlying rhythm is 0.8 seconds. What is the most likely
rhythm?
A) Sinus arrest
B) Sinoatrial exit block (type II)
C) Sinus arrhythmia
D) Second-degree AV block type I
Answer: B
