Relias Dysrhythmia - Basic A Test | 2026/2027 | 80 Questions A+ Graded | 100% Verified Answers
Relias Dysrhythmia - Basic A Test
2026/2027 Edition | A+ Graded | 100% Verified Answers
Basic Dysrhythmia Recognition and Intervention
Section 1: Cardiac Anatomy, Electrophysiology, & Lead
Placement (Q1-Q10)
1. The SA node is located in the _____ and serves as the primary pacemaker of the heart, normally firing
at a rate of _____.
A. Right atrium near the superior vena cava; 40-60 bpm
B. Left atrium near the pulmonary veins; 60-100 bpm
C. Right atrium near the superior vena cava; 60-100 bpm [CORRECT]
D. Left ventricle near the aortic valve; 40-60 bpm
Correct Answer: C
Rationale: The SA node resides in the upper wall of the right atrium near the opening of the superior
vena cava and normally discharges at 60-100 bpm, establishing the normal sinus rhythm. Option A
incorrectly states the rate as bradycardic, option B incorrectly locates the node in the left atrium, and
option D confuses the SA node with ventricular pacemaker sites.
2. The P wave on an ECG tracing represents which electrophysiological event?
A. Ventricular depolarization and contraction
B. Atrial repolarization and ventricular depolarization
C. Atrial depolarization and contraction [CORRECT]
D. Ventricular repolarization and recovery
Correct Answer: C
Rationale: The P wave corresponds to atrial depolarization, the electrical event that initiates atrial
contraction. Atrial repolarization is not visible on a standard ECG because it occurs during
ventricular depolarization (QRS complex). Ventricular depolarization is represented by the QRS
complex, and ventricular repolarization by the T wave.
3. The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex.
The normal PR interval duration is:
A. 0.08-0.10 seconds
B. 0.12-0.20 seconds [CORRECT]
C. 0.20-0.28 seconds
D. 0.36-0.44 seconds
Correct Answer: B
Rationale: The normal PR interval measures 0.12-0.20 seconds, representing the time for atrial
depolarization and conduction through the AV node, Bundle of His, and bundle branches to the
Purkinje fibers. Values below 0.12 seconds suggest pre-excitation (e.g., WPW syndrome), while values
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,Relias Dysrhythmia - Basic A Test | 2026/2027 | 80 Questions A+ Graded | 100% Verified Answers
exceeding 0.20 seconds indicate first-degree AV block.
4. Lead II is placed on the ECG with the positive electrode at the _____ and the negative electrode at the
_____.
A. Left arm; right arm
B. Right arm; left arm
C. Left leg; right arm [CORRECT]
D. Right arm; left leg
Correct Answer: C
Rationale: Lead II has the positive electrode on the left leg and the negative electrode on the right
arm, providing a view of the electrical axis directed from the upper right to the lower left, producing
a positive P wave and a predominantly positive QRS complex. Option A describes Lead I electrode
placement.
5. Which component of the cardiac conduction system is responsible for delaying the electrical impulse to
allow complete atrial contraction before ventricular activation?
A. SA node
B. Bundle of His
C. AV node [CORRECT]
D. Purkinje fibers
Correct Answer: C
Rationale: The AV node introduces a critical physiologic delay (approximately 0.04-0.10 seconds)
that permits the atria to fully depolarize and contract, maximizing ventricular filling before the
impulse proceeds to the ventricles. The SA node initiates the impulse, the Bundle of His transmits it
rapidly, and Purkinje fibers distribute it to the ventricular myocardium without significant delay.
6. The QRS complex represents ventricular depolarization. The normal duration of the QRS complex is:
A. Less than 0.04 seconds
B. 0.06-0.10 seconds
C. Less than 0.12 seconds [CORRECT]
D. 0.12-0.20 seconds
Correct Answer: C
Rationale: A normal narrow QRS complex measures less than 0.12 seconds (typically 0.06-0.10
seconds), indicating that the ventricular depolarization impulse travels normally through the
His-Purkinje system. A QRS of 0.12 seconds or greater is considered wide and indicates a ventricular
origin, bundle branch block, or conduction abnormality.
7. A nurse is performing a 6-second method to calculate heart rate on an ECG strip. If there are 8 R-to-R
intervals within 6 seconds, what is the heart rate?
A. 48 bpm
B. 60 bpm
C. 80 bpm [CORRECT]
D. 96 bpm
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, Relias Dysrhythmia - Basic A Test | 2026/2027 | 80 Questions A+ Graded | 100% Verified Answers
Correct Answer: C
Rationale: The 6-second method involves counting the number of R-to-R intervals in a 6-second strip
and multiplying by 10. Eight intervals in 6 seconds multiplied by 10 equals 80 bpm, which is within
the normal sinus rhythm range of 60-100 bpm. Option A results from not multiplying, and option D
would require 9.6 intervals.
8. The ST segment on an ECG represents:
A. Atrial repolarization
B. The period of complete ventricular depolarization
C. Ventricular repolarization
D. The period between ventricular depolarization and repolarization when the ventricles are
completely depolarized [CORRECT]
Correct Answer: D
Rationale: The ST segment is the isoelectric interval between the end of the QRS complex and the
beginning of the T wave, representing the period when the entire ventricular myocardium is
depolarized. Elevation or depression of the ST segment is a critical indicator of acute myocardial
ischemia or injury.
9. A patient has a QT interval measuring 0.48 seconds. This finding is most significant because:
A. It is within the normal range and indicates no cardiac abnormality
B. Prolonged QT intervals increase the risk of developing torsades de pointes, a life-threatening
ventricular arrhythmia [CORRECT]
C. It indicates the patient has atrial fibrillation
D. It suggests the patient has a first-degree AV block
Correct Answer: B
Rationale: The normal QT interval is 0.36-0.44 seconds, and exceeding 0.44 seconds is considered
prolonged. A prolonged QT interval predisposes the patient to torsades de pointes, a polymorphic
ventricular tachycardia that can degenerate into ventricular fibrillation. Prolongation may be
congenital or acquired from medications or electrolyte imbalances.
10. Which lead is considered the best single lead for rhythm strip monitoring because it provides a clear
view of atrial activity and ventricular depolarization?
A. Lead I
B. Lead II [CORRECT]
C. Lead aVR
D. Lead V1
Correct Answer: B
Rationale: Lead II is the preferred single lead for continuous rhythm monitoring because the
electrical axis of the heart aligns well with it, producing upright P waves and a predominantly
positive QRS complex. This makes it ideal for detecting atrial arrhythmias, AV conduction
abnormalities, and ventricular rhythms. Lead V1 is useful for differentiating wide-complex
tachycardias.
Page 3
Relias Dysrhythmia - Basic A Test
2026/2027 Edition | A+ Graded | 100% Verified Answers
Basic Dysrhythmia Recognition and Intervention
Section 1: Cardiac Anatomy, Electrophysiology, & Lead
Placement (Q1-Q10)
1. The SA node is located in the _____ and serves as the primary pacemaker of the heart, normally firing
at a rate of _____.
A. Right atrium near the superior vena cava; 40-60 bpm
B. Left atrium near the pulmonary veins; 60-100 bpm
C. Right atrium near the superior vena cava; 60-100 bpm [CORRECT]
D. Left ventricle near the aortic valve; 40-60 bpm
Correct Answer: C
Rationale: The SA node resides in the upper wall of the right atrium near the opening of the superior
vena cava and normally discharges at 60-100 bpm, establishing the normal sinus rhythm. Option A
incorrectly states the rate as bradycardic, option B incorrectly locates the node in the left atrium, and
option D confuses the SA node with ventricular pacemaker sites.
2. The P wave on an ECG tracing represents which electrophysiological event?
A. Ventricular depolarization and contraction
B. Atrial repolarization and ventricular depolarization
C. Atrial depolarization and contraction [CORRECT]
D. Ventricular repolarization and recovery
Correct Answer: C
Rationale: The P wave corresponds to atrial depolarization, the electrical event that initiates atrial
contraction. Atrial repolarization is not visible on a standard ECG because it occurs during
ventricular depolarization (QRS complex). Ventricular depolarization is represented by the QRS
complex, and ventricular repolarization by the T wave.
3. The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex.
The normal PR interval duration is:
A. 0.08-0.10 seconds
B. 0.12-0.20 seconds [CORRECT]
C. 0.20-0.28 seconds
D. 0.36-0.44 seconds
Correct Answer: B
Rationale: The normal PR interval measures 0.12-0.20 seconds, representing the time for atrial
depolarization and conduction through the AV node, Bundle of His, and bundle branches to the
Purkinje fibers. Values below 0.12 seconds suggest pre-excitation (e.g., WPW syndrome), while values
Page 1
,Relias Dysrhythmia - Basic A Test | 2026/2027 | 80 Questions A+ Graded | 100% Verified Answers
exceeding 0.20 seconds indicate first-degree AV block.
4. Lead II is placed on the ECG with the positive electrode at the _____ and the negative electrode at the
_____.
A. Left arm; right arm
B. Right arm; left arm
C. Left leg; right arm [CORRECT]
D. Right arm; left leg
Correct Answer: C
Rationale: Lead II has the positive electrode on the left leg and the negative electrode on the right
arm, providing a view of the electrical axis directed from the upper right to the lower left, producing
a positive P wave and a predominantly positive QRS complex. Option A describes Lead I electrode
placement.
5. Which component of the cardiac conduction system is responsible for delaying the electrical impulse to
allow complete atrial contraction before ventricular activation?
A. SA node
B. Bundle of His
C. AV node [CORRECT]
D. Purkinje fibers
Correct Answer: C
Rationale: The AV node introduces a critical physiologic delay (approximately 0.04-0.10 seconds)
that permits the atria to fully depolarize and contract, maximizing ventricular filling before the
impulse proceeds to the ventricles. The SA node initiates the impulse, the Bundle of His transmits it
rapidly, and Purkinje fibers distribute it to the ventricular myocardium without significant delay.
6. The QRS complex represents ventricular depolarization. The normal duration of the QRS complex is:
A. Less than 0.04 seconds
B. 0.06-0.10 seconds
C. Less than 0.12 seconds [CORRECT]
D. 0.12-0.20 seconds
Correct Answer: C
Rationale: A normal narrow QRS complex measures less than 0.12 seconds (typically 0.06-0.10
seconds), indicating that the ventricular depolarization impulse travels normally through the
His-Purkinje system. A QRS of 0.12 seconds or greater is considered wide and indicates a ventricular
origin, bundle branch block, or conduction abnormality.
7. A nurse is performing a 6-second method to calculate heart rate on an ECG strip. If there are 8 R-to-R
intervals within 6 seconds, what is the heart rate?
A. 48 bpm
B. 60 bpm
C. 80 bpm [CORRECT]
D. 96 bpm
Page 2
, Relias Dysrhythmia - Basic A Test | 2026/2027 | 80 Questions A+ Graded | 100% Verified Answers
Correct Answer: C
Rationale: The 6-second method involves counting the number of R-to-R intervals in a 6-second strip
and multiplying by 10. Eight intervals in 6 seconds multiplied by 10 equals 80 bpm, which is within
the normal sinus rhythm range of 60-100 bpm. Option A results from not multiplying, and option D
would require 9.6 intervals.
8. The ST segment on an ECG represents:
A. Atrial repolarization
B. The period of complete ventricular depolarization
C. Ventricular repolarization
D. The period between ventricular depolarization and repolarization when the ventricles are
completely depolarized [CORRECT]
Correct Answer: D
Rationale: The ST segment is the isoelectric interval between the end of the QRS complex and the
beginning of the T wave, representing the period when the entire ventricular myocardium is
depolarized. Elevation or depression of the ST segment is a critical indicator of acute myocardial
ischemia or injury.
9. A patient has a QT interval measuring 0.48 seconds. This finding is most significant because:
A. It is within the normal range and indicates no cardiac abnormality
B. Prolonged QT intervals increase the risk of developing torsades de pointes, a life-threatening
ventricular arrhythmia [CORRECT]
C. It indicates the patient has atrial fibrillation
D. It suggests the patient has a first-degree AV block
Correct Answer: B
Rationale: The normal QT interval is 0.36-0.44 seconds, and exceeding 0.44 seconds is considered
prolonged. A prolonged QT interval predisposes the patient to torsades de pointes, a polymorphic
ventricular tachycardia that can degenerate into ventricular fibrillation. Prolongation may be
congenital or acquired from medications or electrolyte imbalances.
10. Which lead is considered the best single lead for rhythm strip monitoring because it provides a clear
view of atrial activity and ventricular depolarization?
A. Lead I
B. Lead II [CORRECT]
C. Lead aVR
D. Lead V1
Correct Answer: B
Rationale: Lead II is the preferred single lead for continuous rhythm monitoring because the
electrical axis of the heart aligns well with it, producing upright P waves and a predominantly
positive QRS complex. This makes it ideal for detecting atrial arrhythmias, AV conduction
abnormalities, and ventricular rhythms. Lead V1 is useful for differentiating wide-complex
tachycardias.
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