RELIAS Dysrhythmia Basic Test Updated 2026 | Comprehensive
Study Guide, Practice Exam Questions and Answers, Exam Prep
Test Bank, ECG Rhythm Interpretation, Cardiac Conduction
System Review, Arrhythmia Recognition, Heart Rate Analysis,
Telemetry Monitoring Concepts, and Detailed Rationales for
Nursing Exam Preparation
Question 1: Which lead is most commonly used for continuous monitoring of
cardiac rhythm in a hospital setting?
A. Lead I
B. Lead II
C. Lead III
D. Lead aVR
CORRECT ANSWER: B. Lead II
Rationale: Lead II is the standard lead for continuous cardiac monitoring because it
provides a clear view of the P wave and QRS complex, facilitating easy identification of
atrial and ventricular activity. It aligns well with the normal electrical axis of the heart.
Question 2: What is the normal duration of the PR interval on an ECG?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.30 seconds
D. 0.30 to 0.40 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The PR interval represents the time from the onset of atrial depolarization to
the onset of ventricular depolarization. A normal PR interval ranges from 0.12 to 0.20
seconds (3 to 5 small boxes). Intervals outside this range indicate conduction
abnormalities.
Question 3: Which component of the ECG represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
CORRECT ANSWER: C. T wave
Rationale: The T wave represents the repolarization of the ventricles, which is the
recovery phase of the ventricular myocardium after contraction. The P wave represents
atrial depolarization, and the QRS complex represents ventricular depolarization.
Question 4: In a standard ECG paper, one small box represents how much time?
,A. 0.02 seconds
B. 0.04 seconds
C. 0.10 seconds
D. 0.20 seconds
CORRECT ANSWER: B. 0.04 seconds
Rationale: Standard ECG paper runs at a speed of 25 mm/second. Each small box is 1
mm wide, representing 0.04 seconds. Five small boxes make one large box, which
equals 0.20 seconds.
Question 5: Which electrolyte imbalance is most commonly associated with
peaked T waves on an ECG?
A. Hypokalemia
B. Hyperkalemia
C. Hypocalcemia
D. Hypercalcemia
CORRECT ANSWER: B. Hyperkalemia
Rationale: Hyperkalemia (elevated potassium levels) causes characteristic changes in
the ECG, including tall, peaked T waves, widened QRS complexes, and eventually a sine
wave pattern. Hypokalemia typically causes flattened T waves and U waves.
Question 6: What is the primary pacemaker of the heart under normal conditions?
A. AV node
B. Bundle of His
C. SA node
D. Purkinje fibers
CORRECT ANSWER: C. SA node
Rationale: The sinoatrial (SA) node is the natural pacemaker of the heart, located in the
right atrium. It generates electrical impulses at a rate of 60-100 beats per minute,
initiating each heartbeat under normal sinus rhythm.
Question 7: Which dysrhythmia is characterized by the absence of P waves and an
irregularly irregular ventricular response?
A. Atrial flutter
B. Atrial fibrillation
C. Sinus arrhythmia
D. Junctional rhythm
CORRECT ANSWER: B. Atrial fibrillation
Rationale: Atrial fibrillation is identified by chaotic atrial activity resulting in no
discernible P waves and an irregularly irregular R-R interval. The atria quiver rather than
contract effectively, leading to potential blood stasis and clot formation.
,Question 8: What is the hallmark ECG finding in First-Degree AV Block?
A. Progressive lengthening of the PR interval until a beat is dropped
B. Constant PR interval greater than 0.20 seconds
C. No relationship between P waves and QRS complexes
D. Narrow QRS complexes with inverted P waves
CORRECT ANSWER: B. Constant PR interval greater than 0.20 seconds
Rationale: First-degree AV block is defined by a prolonged but constant PR interval
exceeding 0.20 seconds. Every P wave is followed by a QRS complex, indicating that
conduction is delayed but not blocked completely.
Question 9: Which medication class is commonly used to treat symptomatic
bradycardia?
A. Beta-blockers
B. Calcium channel blockers
C. Anticholinergics (e.g., Atropine)
D. Digoxin
CORRECT ANSWER: C. Anticholinergics (e.g., Atropine)
Rationale: Atropine is an anticholinergic drug that blocks vagal tone on the SA node,
thereby increasing the heart rate. It is the first-line pharmacological treatment for
symptomatic bradycardia according to ACLS guidelines.
Question 10: What is the defining characteristic of Premature Ventricular
Contractions (PVCs)?
A. Narrow QRS complex occurring early
B. Wide, bizarre QRS complex occurring early without a preceding P wave
C. Normal QRS complex with a compensatory pause
D. Inverted P waves before each QRS
CORRECT ANSWER: B. Wide, bizarre QRS complex occurring early without a
preceding P wave
Rationale: PVCs originate in the ventricles, bypassing the normal conduction system,
which results in a wide (>0.12 seconds) and bizarre-looking QRS complex. They occur
prematurely and are not preceded by a P wave.
Question 11: Which rhythm is considered a lethal dysrhythmia requiring immediate
defibrillation?
A. Asystole
B. Pulseless Electrical Activity (PEA)
C. Ventricular Fibrillation
D. Third-Degree AV Block
CORRECT ANSWER: C. Ventricular Fibrillation
, Rationale: Ventricular Fibrillation (VF) is a chaotic, disorganized electrical activity in the
ventricles that results in no effective cardiac output. It is a shockable rhythm, and
immediate defibrillation is critical for survival. Asystole and PEA are non-shockable
rhythms.
Question 12: What does the QT interval represent on an ECG?
A. Atrial depolarization and repolarization
B. Ventricular depolarization and repolarization
C. Time between two consecutive heartbeats
D. Conduction time through the AV node
CORRECT ANSWER: B. Ventricular depolarization and repolarization
Rationale: The QT interval measures the total time for ventricular depolarization (QRS)
and repolarization (T wave). Prolonged QT intervals increase the risk of dangerous
arrhythmias such as Torsades de Pointes.
Question 13: In Second-Degree AV Block Type I (Wenckebach), what happens to the
PR interval?
A. It remains constant
B. It progressively lengthens until a QRS complex is dropped
C. It is consistently shorter than 0.12 seconds
D. It varies randomly without pattern
CORRECT ANSWER: B. It progressively lengthens until a QRS complex is dropped
Rationale: Wenckebach (Mobitz I) is characterized by a progressive prolongation of the
PR interval with each beat until a P wave fails to conduct, resulting in a dropped QRS
complex. The cycle then repeats.
Question 14: Which lead placement corresponds to the fourth intercostal space at
the right sternal border?
A. V1
B. V2
C. V3
D. V4
CORRECT ANSWER: A. V1
Rationale: The precordial lead V1 is placed at the fourth intercostal space at the right
sternal border. V2 is placed at the fourth intercostal space at the left sternal border.
These positions are crucial for accurate ECG interpretation.
Question 15: What is the typical heart rate range for Sinus Tachycardia?
A. 40-60 bpm
B. 60-100 bpm
Study Guide, Practice Exam Questions and Answers, Exam Prep
Test Bank, ECG Rhythm Interpretation, Cardiac Conduction
System Review, Arrhythmia Recognition, Heart Rate Analysis,
Telemetry Monitoring Concepts, and Detailed Rationales for
Nursing Exam Preparation
Question 1: Which lead is most commonly used for continuous monitoring of
cardiac rhythm in a hospital setting?
A. Lead I
B. Lead II
C. Lead III
D. Lead aVR
CORRECT ANSWER: B. Lead II
Rationale: Lead II is the standard lead for continuous cardiac monitoring because it
provides a clear view of the P wave and QRS complex, facilitating easy identification of
atrial and ventricular activity. It aligns well with the normal electrical axis of the heart.
Question 2: What is the normal duration of the PR interval on an ECG?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.30 seconds
D. 0.30 to 0.40 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The PR interval represents the time from the onset of atrial depolarization to
the onset of ventricular depolarization. A normal PR interval ranges from 0.12 to 0.20
seconds (3 to 5 small boxes). Intervals outside this range indicate conduction
abnormalities.
Question 3: Which component of the ECG represents ventricular repolarization?
A. P wave
B. QRS complex
C. T wave
D. U wave
CORRECT ANSWER: C. T wave
Rationale: The T wave represents the repolarization of the ventricles, which is the
recovery phase of the ventricular myocardium after contraction. The P wave represents
atrial depolarization, and the QRS complex represents ventricular depolarization.
Question 4: In a standard ECG paper, one small box represents how much time?
,A. 0.02 seconds
B. 0.04 seconds
C. 0.10 seconds
D. 0.20 seconds
CORRECT ANSWER: B. 0.04 seconds
Rationale: Standard ECG paper runs at a speed of 25 mm/second. Each small box is 1
mm wide, representing 0.04 seconds. Five small boxes make one large box, which
equals 0.20 seconds.
Question 5: Which electrolyte imbalance is most commonly associated with
peaked T waves on an ECG?
A. Hypokalemia
B. Hyperkalemia
C. Hypocalcemia
D. Hypercalcemia
CORRECT ANSWER: B. Hyperkalemia
Rationale: Hyperkalemia (elevated potassium levels) causes characteristic changes in
the ECG, including tall, peaked T waves, widened QRS complexes, and eventually a sine
wave pattern. Hypokalemia typically causes flattened T waves and U waves.
Question 6: What is the primary pacemaker of the heart under normal conditions?
A. AV node
B. Bundle of His
C. SA node
D. Purkinje fibers
CORRECT ANSWER: C. SA node
Rationale: The sinoatrial (SA) node is the natural pacemaker of the heart, located in the
right atrium. It generates electrical impulses at a rate of 60-100 beats per minute,
initiating each heartbeat under normal sinus rhythm.
Question 7: Which dysrhythmia is characterized by the absence of P waves and an
irregularly irregular ventricular response?
A. Atrial flutter
B. Atrial fibrillation
C. Sinus arrhythmia
D. Junctional rhythm
CORRECT ANSWER: B. Atrial fibrillation
Rationale: Atrial fibrillation is identified by chaotic atrial activity resulting in no
discernible P waves and an irregularly irregular R-R interval. The atria quiver rather than
contract effectively, leading to potential blood stasis and clot formation.
,Question 8: What is the hallmark ECG finding in First-Degree AV Block?
A. Progressive lengthening of the PR interval until a beat is dropped
B. Constant PR interval greater than 0.20 seconds
C. No relationship between P waves and QRS complexes
D. Narrow QRS complexes with inverted P waves
CORRECT ANSWER: B. Constant PR interval greater than 0.20 seconds
Rationale: First-degree AV block is defined by a prolonged but constant PR interval
exceeding 0.20 seconds. Every P wave is followed by a QRS complex, indicating that
conduction is delayed but not blocked completely.
Question 9: Which medication class is commonly used to treat symptomatic
bradycardia?
A. Beta-blockers
B. Calcium channel blockers
C. Anticholinergics (e.g., Atropine)
D. Digoxin
CORRECT ANSWER: C. Anticholinergics (e.g., Atropine)
Rationale: Atropine is an anticholinergic drug that blocks vagal tone on the SA node,
thereby increasing the heart rate. It is the first-line pharmacological treatment for
symptomatic bradycardia according to ACLS guidelines.
Question 10: What is the defining characteristic of Premature Ventricular
Contractions (PVCs)?
A. Narrow QRS complex occurring early
B. Wide, bizarre QRS complex occurring early without a preceding P wave
C. Normal QRS complex with a compensatory pause
D. Inverted P waves before each QRS
CORRECT ANSWER: B. Wide, bizarre QRS complex occurring early without a
preceding P wave
Rationale: PVCs originate in the ventricles, bypassing the normal conduction system,
which results in a wide (>0.12 seconds) and bizarre-looking QRS complex. They occur
prematurely and are not preceded by a P wave.
Question 11: Which rhythm is considered a lethal dysrhythmia requiring immediate
defibrillation?
A. Asystole
B. Pulseless Electrical Activity (PEA)
C. Ventricular Fibrillation
D. Third-Degree AV Block
CORRECT ANSWER: C. Ventricular Fibrillation
, Rationale: Ventricular Fibrillation (VF) is a chaotic, disorganized electrical activity in the
ventricles that results in no effective cardiac output. It is a shockable rhythm, and
immediate defibrillation is critical for survival. Asystole and PEA are non-shockable
rhythms.
Question 12: What does the QT interval represent on an ECG?
A. Atrial depolarization and repolarization
B. Ventricular depolarization and repolarization
C. Time between two consecutive heartbeats
D. Conduction time through the AV node
CORRECT ANSWER: B. Ventricular depolarization and repolarization
Rationale: The QT interval measures the total time for ventricular depolarization (QRS)
and repolarization (T wave). Prolonged QT intervals increase the risk of dangerous
arrhythmias such as Torsades de Pointes.
Question 13: In Second-Degree AV Block Type I (Wenckebach), what happens to the
PR interval?
A. It remains constant
B. It progressively lengthens until a QRS complex is dropped
C. It is consistently shorter than 0.12 seconds
D. It varies randomly without pattern
CORRECT ANSWER: B. It progressively lengthens until a QRS complex is dropped
Rationale: Wenckebach (Mobitz I) is characterized by a progressive prolongation of the
PR interval with each beat until a P wave fails to conduct, resulting in a dropped QRS
complex. The cycle then repeats.
Question 14: Which lead placement corresponds to the fourth intercostal space at
the right sternal border?
A. V1
B. V2
C. V3
D. V4
CORRECT ANSWER: A. V1
Rationale: The precordial lead V1 is placed at the fourth intercostal space at the right
sternal border. V2 is placed at the fourth intercostal space at the left sternal border.
These positions are crucial for accurate ECG interpretation.
Question 15: What is the typical heart rate range for Sinus Tachycardia?
A. 40-60 bpm
B. 60-100 bpm
