Relias DysRhythmias exam B
masteRy GuiDe: Real exam Q&as,
DetaileD Rationales & eKG
PaRameteRs (Basic & aDvanceD)
2026-2027
Pass your Relias Dysrhythmias Exam B on the first try. This definitive study resource
delivers real practice questions with deep analytical rationales across 100+ core
cardiac profiles. Master normal EKG parameters (PR, QRS, QT intervals), lethal
ventricular arrhythmias (V-Fib, pulseless VT, PEA), heart blocks (Wenckebach vs.
Mobitz II), and junctional pathways. Includes ACLS emergency nursing interventions
and telemetry guidelines. Perfect for basic and advanced clinical nurse competency
evaluations.
1. Which of the following PR interval durations represents a first-degree AV block?
A. 0.08 seconds
B. 0.12 seconds
C. 0.16 seconds
D. 0.24 seconds
Rationale: A normal PR interval is 0.12 to 0.20 seconds. A first-degree AV block is
characterized by a prolonged PR interval greater than 0.20 seconds that remains
constant from beat to beat.
2. A patient's ECG shows a completely irregular rhythm with no discernible P waves,
replaced instead by fine, chaotic baseline ripples. What is this rhythm?
A. Atrial Fibrillation
B. Atrial Flutter
C. Sinus Arrhythmia
D. Junctional Rhythm
Rationale: Atrial fibrillation is characterized by a grossly irregular ventricular rhythm and
an absence of distinct P waves, which are replaced by fibrillatory (f) waves representing
chaotic atrial activity.
3. What is the intrinsic firing rate of the sinoatrial (SA) node in an adult at rest?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–100 beats/minute
, D. 100–150 beats/minute
Rationale: The SA node is the primary pacemaker of the heart and possesses an intrinsic
automaticity rate of 60 to 100 beats per minute.
4. Which statement accurately describes the baseline appearance of Atrial Flutter?
A. Completely flat baseline
B. Sawtooth pattern baseline
C. Sharp, spiking spikes before every QRS
D. Wavy, chaotic, inconsistent baseline ripples
Rationale: Atrial flutter is distinctively characterized by regular, rapid atrial
depolarizations that create a characteristic "sawtooth" or picket-fence pattern, known as
flutter (F) waves.
5. A patient is in ventricular fibrillation, unresponsive, and pulseless. What is the priority
nursing action?
A. Administer a 150 mg bolus of Amiodarone IV
B. Initiate synchronized cardioversion at 100 Joules
C. Activate the emergency response system and perform immediate defibrillation
D. Establish large-bore IV access and infuse a normal saline fluid bolus
Rationale: Ventricular fibrillation is a lethal, non-perfusing rhythm. The definitive
treatment is immediate unsynchronized shock (defibrillation) paired with high-quality
CPR to restore a perfusing rhythm.
6. What configuration do P waves typically take during a Junctional Rhythm?
A. Inverted, hidden, or retrograde
B. Tall, peaked, and notched
C. Wide and broad following the T wave
D. Spiked and matching the QRS amplitude
Rationale: In a junctional rhythm, the impulse originates in the AV node and travels
backward (retrograde) to depolarize the atria, causing P waves to be inverted, buried
inside the QRS, or positioned immediately after the QRS.
7. Which hallmark ECG finding distinguishes a Second-Degree Type I AV block
(Wenckebach) from a Type II block?
A. Fixed, prolonged PR intervals followed by unexpected dropped QRS complexes
B. Progressive lengthening of the PR interval until a QRS complex is dropped
C. Completely independent, unrelated atrial and ventricular rates
D. Continuously widening QRS complexes greater than 0.16 seconds
Rationale: Second-degree Type I AV block features a cyclical pattern where the PR
, interval lengthens successively with each beat until an atrial impulse fails to conduct to
the ventricles, resulting in a dropped QRS.
8. Which rhythm is characterized by organized electrical activity on the cardiac monitor but
no palpable pulse in the patient?
A. Ventricular Tachycardia
B. Asystole
C. Third-Degree Heart Block
D. Pulseless Electrical Activity (PEA)
Rationale: Pulseless Electrical Activity (PEA) occurs when the heart's electrical conduction
system functions in an organized fashion, but the myocardial muscle fails to respond
mechanically, resulting in no palpable pulse.
9. What is the standard duration of a normal QRS complex?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.32 seconds
D. 0.36 to 0.44 seconds
Rationale: A normal, narrow QRS complex reflecting rapid ventricular depolarization
spans 0.04 to 0.10 seconds (1 to 2.5 small boxes).
10. A patient has a heart rate of 48 beats/minute with a regular rhythm, upright P waves
before every QRS complex, and normal PR and QRS intervals. How is this rhythm
classified?
A. Idioventricular Rhythm
B. Junctional Escape Rhythm
C. Sinus Bradycardia
D. First-Degree AV Block
Rationale: Sinus bradycardia retains all the normal conduction characteristics of
standard sinus rhythm (upright P waves, regular intervals) but features a heart rate
below 60 beats per minute.
11. Which medication is considered the first-line first-dose pharmacological treatment for
symptomatic bradycardia?
A. Amiodarone
B. Atropine
C. Epinephrine
D. Adenosine
Rationale: Atropine is an anticholinergic drug that increases the firing rate of the SA
, node and conduction through the AV node, making it the primary medication for
unstable, symptomatic bradycardia.
12. What occurs during third-degree (complete) heart block?
A. The PR interval shortens progressively until a QRS complex is dropped.
B. The ventricles stop depolarizing entirely while the atria fire normally.
C. Atria and ventricles beat independently with no conduction between them.
D. Conduction slows down inside the bundle branches, widening the QRS complex.
Rationale: In complete heart block, no electrical impulses from the atria reach the
ventricles. The atria fire at their own intrinsic sinus rate, and the ventricles fire at their
own slow escape rate, creating complete AV dissociation.
13. Which of the following is a key identifying feature of a premature ventricular contraction
(PVC)?
A. A narrow QRS complex preceded by an inverted P wave
B. A wide, distorted QRS complex occurring earlier than expected without a preceding
P wave
C. A prolonged PR interval followed by a shortened ST segment
D. A sudden, sharp spike immediately preceding a normal P wave
Rationale: PVCs originate from an ectopic focus within the ventricles, causing a
premature, wide, and bizarrely shaped QRS complex (>0.12 seconds) that lacks a
preceding sinus P wave.
14. What is the intrinsic pacemaker rate of the ventricular Purkinje fibers?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–80 beats/minute
D. 80–100 beats/minute
Rationale: If the SA and AV nodes fail, the ventricular escape rhythm takes over at its
native intrinsic rate of 20 to 40 beats per minute.
15. What immediate intervention is indicated for an unstable patient in rapid Ventricular
Tachycardia who still has a palpable pulse?
A. Unsynchronized Defibrillation
B. Synchronized Cardioversion
C. Administration of IV Atropine
D. Vagal maneuvers
Rationale: For tachyarrhythmias causing instability (e.g., hypotension, altered
consciousness) where a pulse is present, synchronized cardioversion is indicated to avoid
shocking during the vulnerable T-wave period.
masteRy GuiDe: Real exam Q&as,
DetaileD Rationales & eKG
PaRameteRs (Basic & aDvanceD)
2026-2027
Pass your Relias Dysrhythmias Exam B on the first try. This definitive study resource
delivers real practice questions with deep analytical rationales across 100+ core
cardiac profiles. Master normal EKG parameters (PR, QRS, QT intervals), lethal
ventricular arrhythmias (V-Fib, pulseless VT, PEA), heart blocks (Wenckebach vs.
Mobitz II), and junctional pathways. Includes ACLS emergency nursing interventions
and telemetry guidelines. Perfect for basic and advanced clinical nurse competency
evaluations.
1. Which of the following PR interval durations represents a first-degree AV block?
A. 0.08 seconds
B. 0.12 seconds
C. 0.16 seconds
D. 0.24 seconds
Rationale: A normal PR interval is 0.12 to 0.20 seconds. A first-degree AV block is
characterized by a prolonged PR interval greater than 0.20 seconds that remains
constant from beat to beat.
2. A patient's ECG shows a completely irregular rhythm with no discernible P waves,
replaced instead by fine, chaotic baseline ripples. What is this rhythm?
A. Atrial Fibrillation
B. Atrial Flutter
C. Sinus Arrhythmia
D. Junctional Rhythm
Rationale: Atrial fibrillation is characterized by a grossly irregular ventricular rhythm and
an absence of distinct P waves, which are replaced by fibrillatory (f) waves representing
chaotic atrial activity.
3. What is the intrinsic firing rate of the sinoatrial (SA) node in an adult at rest?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–100 beats/minute
, D. 100–150 beats/minute
Rationale: The SA node is the primary pacemaker of the heart and possesses an intrinsic
automaticity rate of 60 to 100 beats per minute.
4. Which statement accurately describes the baseline appearance of Atrial Flutter?
A. Completely flat baseline
B. Sawtooth pattern baseline
C. Sharp, spiking spikes before every QRS
D. Wavy, chaotic, inconsistent baseline ripples
Rationale: Atrial flutter is distinctively characterized by regular, rapid atrial
depolarizations that create a characteristic "sawtooth" or picket-fence pattern, known as
flutter (F) waves.
5. A patient is in ventricular fibrillation, unresponsive, and pulseless. What is the priority
nursing action?
A. Administer a 150 mg bolus of Amiodarone IV
B. Initiate synchronized cardioversion at 100 Joules
C. Activate the emergency response system and perform immediate defibrillation
D. Establish large-bore IV access and infuse a normal saline fluid bolus
Rationale: Ventricular fibrillation is a lethal, non-perfusing rhythm. The definitive
treatment is immediate unsynchronized shock (defibrillation) paired with high-quality
CPR to restore a perfusing rhythm.
6. What configuration do P waves typically take during a Junctional Rhythm?
A. Inverted, hidden, or retrograde
B. Tall, peaked, and notched
C. Wide and broad following the T wave
D. Spiked and matching the QRS amplitude
Rationale: In a junctional rhythm, the impulse originates in the AV node and travels
backward (retrograde) to depolarize the atria, causing P waves to be inverted, buried
inside the QRS, or positioned immediately after the QRS.
7. Which hallmark ECG finding distinguishes a Second-Degree Type I AV block
(Wenckebach) from a Type II block?
A. Fixed, prolonged PR intervals followed by unexpected dropped QRS complexes
B. Progressive lengthening of the PR interval until a QRS complex is dropped
C. Completely independent, unrelated atrial and ventricular rates
D. Continuously widening QRS complexes greater than 0.16 seconds
Rationale: Second-degree Type I AV block features a cyclical pattern where the PR
, interval lengthens successively with each beat until an atrial impulse fails to conduct to
the ventricles, resulting in a dropped QRS.
8. Which rhythm is characterized by organized electrical activity on the cardiac monitor but
no palpable pulse in the patient?
A. Ventricular Tachycardia
B. Asystole
C. Third-Degree Heart Block
D. Pulseless Electrical Activity (PEA)
Rationale: Pulseless Electrical Activity (PEA) occurs when the heart's electrical conduction
system functions in an organized fashion, but the myocardial muscle fails to respond
mechanically, resulting in no palpable pulse.
9. What is the standard duration of a normal QRS complex?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.32 seconds
D. 0.36 to 0.44 seconds
Rationale: A normal, narrow QRS complex reflecting rapid ventricular depolarization
spans 0.04 to 0.10 seconds (1 to 2.5 small boxes).
10. A patient has a heart rate of 48 beats/minute with a regular rhythm, upright P waves
before every QRS complex, and normal PR and QRS intervals. How is this rhythm
classified?
A. Idioventricular Rhythm
B. Junctional Escape Rhythm
C. Sinus Bradycardia
D. First-Degree AV Block
Rationale: Sinus bradycardia retains all the normal conduction characteristics of
standard sinus rhythm (upright P waves, regular intervals) but features a heart rate
below 60 beats per minute.
11. Which medication is considered the first-line first-dose pharmacological treatment for
symptomatic bradycardia?
A. Amiodarone
B. Atropine
C. Epinephrine
D. Adenosine
Rationale: Atropine is an anticholinergic drug that increases the firing rate of the SA
, node and conduction through the AV node, making it the primary medication for
unstable, symptomatic bradycardia.
12. What occurs during third-degree (complete) heart block?
A. The PR interval shortens progressively until a QRS complex is dropped.
B. The ventricles stop depolarizing entirely while the atria fire normally.
C. Atria and ventricles beat independently with no conduction between them.
D. Conduction slows down inside the bundle branches, widening the QRS complex.
Rationale: In complete heart block, no electrical impulses from the atria reach the
ventricles. The atria fire at their own intrinsic sinus rate, and the ventricles fire at their
own slow escape rate, creating complete AV dissociation.
13. Which of the following is a key identifying feature of a premature ventricular contraction
(PVC)?
A. A narrow QRS complex preceded by an inverted P wave
B. A wide, distorted QRS complex occurring earlier than expected without a preceding
P wave
C. A prolonged PR interval followed by a shortened ST segment
D. A sudden, sharp spike immediately preceding a normal P wave
Rationale: PVCs originate from an ectopic focus within the ventricles, causing a
premature, wide, and bizarrely shaped QRS complex (>0.12 seconds) that lacks a
preceding sinus P wave.
14. What is the intrinsic pacemaker rate of the ventricular Purkinje fibers?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–80 beats/minute
D. 80–100 beats/minute
Rationale: If the SA and AV nodes fail, the ventricular escape rhythm takes over at its
native intrinsic rate of 20 to 40 beats per minute.
15. What immediate intervention is indicated for an unstable patient in rapid Ventricular
Tachycardia who still has a palpable pulse?
A. Unsynchronized Defibrillation
B. Synchronized Cardioversion
C. Administration of IV Atropine
D. Vagal maneuvers
Rationale: For tachyarrhythmias causing instability (e.g., hypotension, altered
consciousness) where a pulse is present, synchronized cardioversion is indicated to avoid
shocking during the vulnerable T-wave period.
