Relias Dysrhythmias Exam B (Basic & Advanced)
Complete Test Prep Bank: ECG Rhythm
Interpretation, Waveform Measurements, and
ACLS Nursing Interventions Guide 2026
Pass your Relias Dysrhythmias Exam B confidently. This premium study resource features authentic practice questions, verified
answers, and comprehensive clinical rationales. Master critical baseline measurements (PR, QRS, QT intervals), heart blocks
(Wenckebach vs. Mobitz II), junctional rhythms, and lethal code scenarios like V-Fib, asystole, and PEA. Includes targeted
telemetry tracking metrics and ACLS nursing intervention pathways to secure your clinical competency certification.
1. What is the standard measurement criteria for a normal, non-delayed PR interval?
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 PR interval, which measures the time from the onset of atrial
activation to the onset of ventricular activation, spans 0.12 to 0.20 seconds (3 to 5 small
boxes).
2. Which structural part of the cardiac conduction pathway possesses an intrinsic pacing
rate of 40 to 60 beats per minute?
A. Sinoatrial (SA) node
B. Purkinje fibers
C. Atrioventricular (AV) junction
D. Bundle of His
Rationale: The AV junction acts as the secondary pacemaker of the heart, stepping in
with an inherent automaticity rate of 40 to 60 beats per minute if the SA node fails to
fire.
3. What EKG baseline feature is unique to Atrial Fibrillation?
A. A distinct sawtooth waveform
B. An irregularly irregular ventricular rhythm with absent P waves
C. Multiple wide QRS complexes with fixed PR intervals
D. Regular variations matching the respiratory cycle
Rationale: Atrial fibrillation is defined by a chaotic, quivering atrial baseline containing
no clear P waves, combined with a completely unpredictable, irregularly irregular R-R
interval sequence.
,4. A patient's monitor shows an regular rhythm with a heart rate of 140 beats/minute,
narrow QRS complexes, and uniform, upright P waves preceding every QRS. How is this
classified?
A. Sinus Tachycardia
B. Supraventricular Tachycardia
C. Atrial Flutter with 2:1 block
D. Junctional Tachycardia
Rationale: Sinus tachycardia matches all morphological criteria of a normal sinus rhythm,
but presents with an elevated physiological firing rate between 101 and 160 beats per
minute.
5. What immediate clinical intervention must be performed for an unresponsive, pulseless
patient in Ventricular Fibrillation?
A. Deliver a synchronized cardioversion shock at 50 Joules
B. Infuse a 150 mg loading dose of Amiodarone IV
C. Activate the emergency code response and perform immediate unsynchronized
defibrillation
D. Initiate external transcutaneous pacing at 80 beats/minute
Rationale: Ventricular fibrillation is a non-perfusing lethal rhythm requiring immediate
unsynchronized defibrillation combined with high-quality CPR to restore functional
cardiac activity.
6. What is the correct classification for a rhythm with a regular rate of 82 beats/minute,
normal narrow QRS complexes, and inverted P waves that immediately follow the QRS?
A. Junctional Escape Rhythm
B. Accelerated Junctional Rhythm
C. Junctional Tachycardia
D. Normal Sinus Rhythm
Rationale: Junctional rhythms feature retrograde P waves (inverted, hidden, or following
the QRS). When the automaticity rate exceeds the intrinsic 40–60 bpm limit but stays
under 100 bpm, it is classified as accelerated.
7. Which hallmark sequence defines a Second-Degree Type I AV block (Wenckebach)?
A. Progressive lengthening of the PR interval until a QRS complex is entirely dropped
B. Constant, fixed PR intervals followed by intermittent dropped QRS complexes
C. A complete dissociation between independent atrial and ventricular rates
D. Continuously widening QRS complexes with a constant PR interval
Rationale: Second-degree Type I AV block is characterized by a repeating cyclical pattern
, where the PR interval grows progressively longer with each beat until an atrial impulse
fails to conduct, leaving a lone P wave.
8. A patient exhibits an organized sinus rhythm on the cardiac monitor but lacks any
palpable pulse or measurable blood pressure. What is this emergency condition?
A. Ventricular Tachycardia
B. Asystole
C. Third-Degree Heart Block
D. Pulseless Electrical Activity (PEA)
Rationale: PEA occurs when the heart's electrical system continues to generate organized
conduction waveforms, but the mechanical myocardium fails to contract, resulting in
zero peripheral perfusion.
9. What is the upper duration limit for a normal, narrow QRS complex reflecting rapid
ventricular depolarization?
A. 0.10 seconds
B. 0.12 seconds
C. 0.20 seconds
D. 0.24 seconds
Rationale: A normal, narrow QRS complex spans between 0.04 and 0.10 seconds. A
duration of 0.12 seconds or greater indicates a conduction delay or ventricular origin.
10. A patient's EKG demonstrates a regular rhythm at 44 beats/minute with upright P waves,
a constant PR interval of 0.16 seconds, and a narrow QRS. What is the diagnosis?
A. Idioventricular Rhythm
B. Junctional Escape Rhythm
C. Sinus Bradycardia
D. First-Degree AV Block
Rationale: Sinus bradycardia retains normal sinus conduction features (upright P waves,
fixed normal intervals) but fires below the standard rate of 60 beats per minute.
11. Which emergency medication is indicated as the first-line drug intervention for unstable,
symptomatic sinus bradycardia?
A. Amiodarone
B. Atropine
C. Adenosine
D. Epinephrine
Rationale: Atropine is an anticholinergic agent that blocks vagal tone, successfully
accelerating the SA node firing rate and improving AV node conduction during
symptomatic bradycardia.
, 12. What mechanical and electrical breakdown occurs during a Third-Degree (Complete)
Heart Block?
A. The PR interval extends further out with every beat until a ventricular response is
missed.
B. The bundle branches fail entirely while the atria stop firing.
C. Atria and ventricles fire completely independently, resulting in absolute AV
dissociation.
D. Electrical impulses travel backward from the ventricles to the atria.
Rationale: In third-degree block, structural damage blocks all supraventricular impulses
at the AV node. The atria and ventricles beat independently under their own separate
pacemakers.
13. What is a key identifying morphological feature of a premature ventricular contraction
(PVC)?
A. A premature narrow QRS preceded by an inverted P wave
B. A premature, wide, and distorted QRS complex lacking a preceding P wave
C. A prolonged PR interval matching the subsequent sinus cycle
D. A sharp pacing spike positioned immediately before the P wave
Rationale: PVCs originate from an ectopic focus within the ventricular walls, spreading
slowly via cell-to-cell conduction to create an early, wide, and bizarre QRS complex (>0.12
seconds).
14. What is the native, intrinsic automaticity rate of the ventricular Purkinje network?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–80 beats/minute
D. 80–100 beats/minute
Rationale: If the primary SA node and secondary AV node pacemakers fail, the deep
ventricular conduction fibers act as a final backup, pacing at 20 to 40 beats per minute.
15. An unstable patient experiences sustained Ventricular Tachycardia at 170 beats/minute
but still maintains a palpable carotid pulse. What is the indicated treatment?
A. Deliver an immediate unsynchronized 200 Joule defibrillation shock
B. Initiate immediate synchronized cardioversion
C. Administer 1 mg of IV Atropine push
D. Perform aggressive vagal maneuvers
Rationale: For an unstable tachyarrhythmia presenting with a pulse, synchronized
cardioversion is required. The machine syncs with the R wave to avoid a shock landing on
the T wave, which could cause V-Fib.
Complete Test Prep Bank: ECG Rhythm
Interpretation, Waveform Measurements, and
ACLS Nursing Interventions Guide 2026
Pass your Relias Dysrhythmias Exam B confidently. This premium study resource features authentic practice questions, verified
answers, and comprehensive clinical rationales. Master critical baseline measurements (PR, QRS, QT intervals), heart blocks
(Wenckebach vs. Mobitz II), junctional rhythms, and lethal code scenarios like V-Fib, asystole, and PEA. Includes targeted
telemetry tracking metrics and ACLS nursing intervention pathways to secure your clinical competency certification.
1. What is the standard measurement criteria for a normal, non-delayed PR interval?
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 PR interval, which measures the time from the onset of atrial
activation to the onset of ventricular activation, spans 0.12 to 0.20 seconds (3 to 5 small
boxes).
2. Which structural part of the cardiac conduction pathway possesses an intrinsic pacing
rate of 40 to 60 beats per minute?
A. Sinoatrial (SA) node
B. Purkinje fibers
C. Atrioventricular (AV) junction
D. Bundle of His
Rationale: The AV junction acts as the secondary pacemaker of the heart, stepping in
with an inherent automaticity rate of 40 to 60 beats per minute if the SA node fails to
fire.
3. What EKG baseline feature is unique to Atrial Fibrillation?
A. A distinct sawtooth waveform
B. An irregularly irregular ventricular rhythm with absent P waves
C. Multiple wide QRS complexes with fixed PR intervals
D. Regular variations matching the respiratory cycle
Rationale: Atrial fibrillation is defined by a chaotic, quivering atrial baseline containing
no clear P waves, combined with a completely unpredictable, irregularly irregular R-R
interval sequence.
,4. A patient's monitor shows an regular rhythm with a heart rate of 140 beats/minute,
narrow QRS complexes, and uniform, upright P waves preceding every QRS. How is this
classified?
A. Sinus Tachycardia
B. Supraventricular Tachycardia
C. Atrial Flutter with 2:1 block
D. Junctional Tachycardia
Rationale: Sinus tachycardia matches all morphological criteria of a normal sinus rhythm,
but presents with an elevated physiological firing rate between 101 and 160 beats per
minute.
5. What immediate clinical intervention must be performed for an unresponsive, pulseless
patient in Ventricular Fibrillation?
A. Deliver a synchronized cardioversion shock at 50 Joules
B. Infuse a 150 mg loading dose of Amiodarone IV
C. Activate the emergency code response and perform immediate unsynchronized
defibrillation
D. Initiate external transcutaneous pacing at 80 beats/minute
Rationale: Ventricular fibrillation is a non-perfusing lethal rhythm requiring immediate
unsynchronized defibrillation combined with high-quality CPR to restore functional
cardiac activity.
6. What is the correct classification for a rhythm with a regular rate of 82 beats/minute,
normal narrow QRS complexes, and inverted P waves that immediately follow the QRS?
A. Junctional Escape Rhythm
B. Accelerated Junctional Rhythm
C. Junctional Tachycardia
D. Normal Sinus Rhythm
Rationale: Junctional rhythms feature retrograde P waves (inverted, hidden, or following
the QRS). When the automaticity rate exceeds the intrinsic 40–60 bpm limit but stays
under 100 bpm, it is classified as accelerated.
7. Which hallmark sequence defines a Second-Degree Type I AV block (Wenckebach)?
A. Progressive lengthening of the PR interval until a QRS complex is entirely dropped
B. Constant, fixed PR intervals followed by intermittent dropped QRS complexes
C. A complete dissociation between independent atrial and ventricular rates
D. Continuously widening QRS complexes with a constant PR interval
Rationale: Second-degree Type I AV block is characterized by a repeating cyclical pattern
, where the PR interval grows progressively longer with each beat until an atrial impulse
fails to conduct, leaving a lone P wave.
8. A patient exhibits an organized sinus rhythm on the cardiac monitor but lacks any
palpable pulse or measurable blood pressure. What is this emergency condition?
A. Ventricular Tachycardia
B. Asystole
C. Third-Degree Heart Block
D. Pulseless Electrical Activity (PEA)
Rationale: PEA occurs when the heart's electrical system continues to generate organized
conduction waveforms, but the mechanical myocardium fails to contract, resulting in
zero peripheral perfusion.
9. What is the upper duration limit for a normal, narrow QRS complex reflecting rapid
ventricular depolarization?
A. 0.10 seconds
B. 0.12 seconds
C. 0.20 seconds
D. 0.24 seconds
Rationale: A normal, narrow QRS complex spans between 0.04 and 0.10 seconds. A
duration of 0.12 seconds or greater indicates a conduction delay or ventricular origin.
10. A patient's EKG demonstrates a regular rhythm at 44 beats/minute with upright P waves,
a constant PR interval of 0.16 seconds, and a narrow QRS. What is the diagnosis?
A. Idioventricular Rhythm
B. Junctional Escape Rhythm
C. Sinus Bradycardia
D. First-Degree AV Block
Rationale: Sinus bradycardia retains normal sinus conduction features (upright P waves,
fixed normal intervals) but fires below the standard rate of 60 beats per minute.
11. Which emergency medication is indicated as the first-line drug intervention for unstable,
symptomatic sinus bradycardia?
A. Amiodarone
B. Atropine
C. Adenosine
D. Epinephrine
Rationale: Atropine is an anticholinergic agent that blocks vagal tone, successfully
accelerating the SA node firing rate and improving AV node conduction during
symptomatic bradycardia.
, 12. What mechanical and electrical breakdown occurs during a Third-Degree (Complete)
Heart Block?
A. The PR interval extends further out with every beat until a ventricular response is
missed.
B. The bundle branches fail entirely while the atria stop firing.
C. Atria and ventricles fire completely independently, resulting in absolute AV
dissociation.
D. Electrical impulses travel backward from the ventricles to the atria.
Rationale: In third-degree block, structural damage blocks all supraventricular impulses
at the AV node. The atria and ventricles beat independently under their own separate
pacemakers.
13. What is a key identifying morphological feature of a premature ventricular contraction
(PVC)?
A. A premature narrow QRS preceded by an inverted P wave
B. A premature, wide, and distorted QRS complex lacking a preceding P wave
C. A prolonged PR interval matching the subsequent sinus cycle
D. A sharp pacing spike positioned immediately before the P wave
Rationale: PVCs originate from an ectopic focus within the ventricular walls, spreading
slowly via cell-to-cell conduction to create an early, wide, and bizarre QRS complex (>0.12
seconds).
14. What is the native, intrinsic automaticity rate of the ventricular Purkinje network?
A. 20–40 beats/minute
B. 40–60 beats/minute
C. 60–80 beats/minute
D. 80–100 beats/minute
Rationale: If the primary SA node and secondary AV node pacemakers fail, the deep
ventricular conduction fibers act as a final backup, pacing at 20 to 40 beats per minute.
15. An unstable patient experiences sustained Ventricular Tachycardia at 170 beats/minute
but still maintains a palpable carotid pulse. What is the indicated treatment?
A. Deliver an immediate unsynchronized 200 Joule defibrillation shock
B. Initiate immediate synchronized cardioversion
C. Administer 1 mg of IV Atropine push
D. Perform aggressive vagal maneuvers
Rationale: For an unstable tachyarrhythmia presenting with a pulse, synchronized
cardioversion is required. The machine syncs with the R wave to avoid a shock landing on
the T wave, which could cause V-Fib.
