Relias Dysrhythmia Basic A
( Update)
Relias Learning | Comprehensive Competency Examination | 100% Verified
Answers
Total Questions 50 Cognitive Mix 25% Recall / 50% Application / 25% Analysis
Sections 6 Question Style 75% Scenario-based / 25% Direct Recall
Format Multiple Choice (A-D) Each Question Stem + 4 Options + Correct Answer + Rationale
Section 1: Cardiac Conduction System and EKG Fundamentals (Q1 -
Q10)
Q1: The normal electrical impulse in the heart begins at the SA node and travels
through the conduction pathway. Which sequence represents the correct order of
electrical conduction?
A. AV node -> SA node -> Bundle of His -> Purkinje fibers
B. SA node -> AV node -> Bundle of His -> Bundle branches -> Purkinje fibers
[CORRECT]
C. SA node -> Bundle branches -> AV node -> Purkinje fibers -> Bundle of His
D. Purkinje fibers -> Bundle of His -> AV node -> SA node
Correct Answer: B
Rationale:
The normal cardiac impulse originates in the SA node (the heart's primary pacemaker, firing
60-100 times per minute), travels to the AV node (where it is briefly delayed to allow for
ventricular filling), then proceeds to the Bundle of His, through the right and left bundle
branches, and finally to the Purkinje fibers for ventricular depolarization. Relias emphasizes
that any disturbance along this pathway produces characteristic EKG changes, so
understanding the normal sequence is foundational to identifying conduction abnormalities
such as AV blocks and bundle branch blocks.
Q2: On a normal EKG tracing, what electrical event does the P wave represent?
A. Ventricular depolarization
B. Atrial depolarization [CORRECT]
C. Atrial repolarization
D. Ventricular repolarization
Correct Answer: B
Rationale:
The P wave represents atrial depolarization, the electrical activation of the right and left atria
that precedes atrial contraction. Ventricular depolarization is represented by the QRS
complex. Atrial repolarization occurs during the QRS complex and is typically obscured by it.
Ventricular repolarization is represented by the T wave. Relias candidates must identify P
wave presence, morphology, and relationship to the QRS to differentiate sinus, atrial, and
junctional rhythms.
,Q3: A nurse is measuring the PR interval on a normal sinus rhythm strip. The PR
interval begins at the start of the P wave and ends at the start of the QRS complex.
What is the normal duration of the PR interval?
A. 0.04 - 0.10 seconds
B. 0.12 - 0.20 seconds [CORRECT]
C. 0.20 - 0.40 seconds
D. 0.36 - 0.44 seconds
Correct Answer: B
Rationale:
The normal PR interval is 0.12 to 0.20 seconds (3-5 small boxes). This represents the time for
the electrical impulse to travel from the atria through the AV node to the ventricles. A PR
interval greater than 0.20 seconds indicates a first-degree AV block. A PR interval less than
0.12 seconds may indicate a junctional rhythm or pre-excitation syndrome such as
Wolff-Parkinson-White. The 0.04-0.10 range corresponds to QRS duration, not PR. Relias
tests interval measurement accuracy because errors lead to misclassification of AV blocks.
Q4: The QRS complex on an EKG represents which of the following?
A. Atrial depolarization only
B. Ventricular depolarization [CORRECT]
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B
Rationale:
The QRS complex represents ventricular depolarization, the electrical activation of the
ventricles that precedes ventricular contraction. The normal QRS duration is less than 0.12
seconds (3 small boxes). A wide QRS (greater than 0.12 seconds) indicates delayed ventricular
conduction, as seen in ventricular rhythms, bundle branch blocks, or paced rhythms. Relias
candidates must distinguish narrow-complex (supraventricular) from wide-complex
(ventricular or abnormal conduction) rhythms because treatment pathways differ
significantly.
Q5: On standard EKG paper, what is the duration represented by ONE SMALL box
horizontally?
A. 0.04 seconds [CORRECT]
B. 0.20 seconds
C. 0.10 seconds
D. 0.50 seconds
Correct Answer: A
Rationale:
One small box on EKG paper represents 0.04 seconds horizontally, and one large box
(containing 5 small boxes) represents 0.20 seconds. Vertically, one small box represents 1
mm (0.1 mV). These measurements are critical for calculating heart rate and measuring
intervals. The 0.20-second value corresponds to one large box. Relias candidates must master
the small-box and large-box measurements because all interval calculations and rate
determinations depend on them.
, Q6: A nurse is using the 6-second method to calculate heart rate. The rhythm strip
has 12 QRS complexes in a 6-second interval. What is the ventricular rate?
A. 60 bpm
B. 72 bpm
C. 120 bpm [CORRECT]
D. 180 bpm
Correct Answer: C
Rationale:
The 6-second method multiplies the number of QRS complexes in a 6-second strip by 10
(because there are 10 six-second intervals in one minute). 12 x 10 = 120 bpm. This method is
most accurate for irregular rhythms where the 1500 (small box) method would yield an
average rate that does not reflect the irregularity. For regular rhythms, the 1500 method
(1500 divided by small boxes between R waves) or the large-box method (300 divided by large
boxes between R waves) provides more precise rates. Relias tests multiple rate calculation
methods because clinical situations vary.
Q7: Which EKG lead is most commonly used for continuous cardiac monitoring at
the bedside?
A. Lead aVR
B. Lead II [CORRECT]
C. Lead V1
D. Lead III
Correct Answer: B
Rationale:
Lead II is the most commonly used lead for continuous cardiac monitoring because it
produces a positive P wave, positive QRS complex, and positive T wave, providing a clear
view of atrial activity and conduction. Lead V1 is also used in critical care for distinguishing
bundle branch blocks and PVC morphology, but Lead II remains the standard monitoring
lead. Lead aVR is rarely used for monitoring because it has inverted waveforms. Relias
emphasizes proper lead selection because the wrong lead can obscure or distort P waves and
QRS morphology.
Q8: The intrinsic firing rate of the SA node is:
A. 20 - 40 beats per minute
B. 40 - 60 beats per minute
C. 60 - 100 beats per minute [CORRECT]
D. 100 - 250 beats per minute
Correct Answer: C
Rationale:
The SA node, the heart's primary pacemaker, has an intrinsic firing rate of 60-100 beats per
minute. The AV junction (AV node and Bundle of His) fires at 40-60 bpm as a secondary
pacemaker. The Purkinje fibers and ventricular muscle fire at 20-40 bpm as a tertiary escape
pacemaker. Rates above 100 from the SA node indicate sinus tachycardia. Relias candidates
must know these intrinsic rates to identify escape rhythms and pacemaker site of origin
when the SA node fails.
( Update)
Relias Learning | Comprehensive Competency Examination | 100% Verified
Answers
Total Questions 50 Cognitive Mix 25% Recall / 50% Application / 25% Analysis
Sections 6 Question Style 75% Scenario-based / 25% Direct Recall
Format Multiple Choice (A-D) Each Question Stem + 4 Options + Correct Answer + Rationale
Section 1: Cardiac Conduction System and EKG Fundamentals (Q1 -
Q10)
Q1: The normal electrical impulse in the heart begins at the SA node and travels
through the conduction pathway. Which sequence represents the correct order of
electrical conduction?
A. AV node -> SA node -> Bundle of His -> Purkinje fibers
B. SA node -> AV node -> Bundle of His -> Bundle branches -> Purkinje fibers
[CORRECT]
C. SA node -> Bundle branches -> AV node -> Purkinje fibers -> Bundle of His
D. Purkinje fibers -> Bundle of His -> AV node -> SA node
Correct Answer: B
Rationale:
The normal cardiac impulse originates in the SA node (the heart's primary pacemaker, firing
60-100 times per minute), travels to the AV node (where it is briefly delayed to allow for
ventricular filling), then proceeds to the Bundle of His, through the right and left bundle
branches, and finally to the Purkinje fibers for ventricular depolarization. Relias emphasizes
that any disturbance along this pathway produces characteristic EKG changes, so
understanding the normal sequence is foundational to identifying conduction abnormalities
such as AV blocks and bundle branch blocks.
Q2: On a normal EKG tracing, what electrical event does the P wave represent?
A. Ventricular depolarization
B. Atrial depolarization [CORRECT]
C. Atrial repolarization
D. Ventricular repolarization
Correct Answer: B
Rationale:
The P wave represents atrial depolarization, the electrical activation of the right and left atria
that precedes atrial contraction. Ventricular depolarization is represented by the QRS
complex. Atrial repolarization occurs during the QRS complex and is typically obscured by it.
Ventricular repolarization is represented by the T wave. Relias candidates must identify P
wave presence, morphology, and relationship to the QRS to differentiate sinus, atrial, and
junctional rhythms.
,Q3: A nurse is measuring the PR interval on a normal sinus rhythm strip. The PR
interval begins at the start of the P wave and ends at the start of the QRS complex.
What is the normal duration of the PR interval?
A. 0.04 - 0.10 seconds
B. 0.12 - 0.20 seconds [CORRECT]
C. 0.20 - 0.40 seconds
D. 0.36 - 0.44 seconds
Correct Answer: B
Rationale:
The normal PR interval is 0.12 to 0.20 seconds (3-5 small boxes). This represents the time for
the electrical impulse to travel from the atria through the AV node to the ventricles. A PR
interval greater than 0.20 seconds indicates a first-degree AV block. A PR interval less than
0.12 seconds may indicate a junctional rhythm or pre-excitation syndrome such as
Wolff-Parkinson-White. The 0.04-0.10 range corresponds to QRS duration, not PR. Relias
tests interval measurement accuracy because errors lead to misclassification of AV blocks.
Q4: The QRS complex on an EKG represents which of the following?
A. Atrial depolarization only
B. Ventricular depolarization [CORRECT]
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B
Rationale:
The QRS complex represents ventricular depolarization, the electrical activation of the
ventricles that precedes ventricular contraction. The normal QRS duration is less than 0.12
seconds (3 small boxes). A wide QRS (greater than 0.12 seconds) indicates delayed ventricular
conduction, as seen in ventricular rhythms, bundle branch blocks, or paced rhythms. Relias
candidates must distinguish narrow-complex (supraventricular) from wide-complex
(ventricular or abnormal conduction) rhythms because treatment pathways differ
significantly.
Q5: On standard EKG paper, what is the duration represented by ONE SMALL box
horizontally?
A. 0.04 seconds [CORRECT]
B. 0.20 seconds
C. 0.10 seconds
D. 0.50 seconds
Correct Answer: A
Rationale:
One small box on EKG paper represents 0.04 seconds horizontally, and one large box
(containing 5 small boxes) represents 0.20 seconds. Vertically, one small box represents 1
mm (0.1 mV). These measurements are critical for calculating heart rate and measuring
intervals. The 0.20-second value corresponds to one large box. Relias candidates must master
the small-box and large-box measurements because all interval calculations and rate
determinations depend on them.
, Q6: A nurse is using the 6-second method to calculate heart rate. The rhythm strip
has 12 QRS complexes in a 6-second interval. What is the ventricular rate?
A. 60 bpm
B. 72 bpm
C. 120 bpm [CORRECT]
D. 180 bpm
Correct Answer: C
Rationale:
The 6-second method multiplies the number of QRS complexes in a 6-second strip by 10
(because there are 10 six-second intervals in one minute). 12 x 10 = 120 bpm. This method is
most accurate for irregular rhythms where the 1500 (small box) method would yield an
average rate that does not reflect the irregularity. For regular rhythms, the 1500 method
(1500 divided by small boxes between R waves) or the large-box method (300 divided by large
boxes between R waves) provides more precise rates. Relias tests multiple rate calculation
methods because clinical situations vary.
Q7: Which EKG lead is most commonly used for continuous cardiac monitoring at
the bedside?
A. Lead aVR
B. Lead II [CORRECT]
C. Lead V1
D. Lead III
Correct Answer: B
Rationale:
Lead II is the most commonly used lead for continuous cardiac monitoring because it
produces a positive P wave, positive QRS complex, and positive T wave, providing a clear
view of atrial activity and conduction. Lead V1 is also used in critical care for distinguishing
bundle branch blocks and PVC morphology, but Lead II remains the standard monitoring
lead. Lead aVR is rarely used for monitoring because it has inverted waveforms. Relias
emphasizes proper lead selection because the wrong lead can obscure or distort P waves and
QRS morphology.
Q8: The intrinsic firing rate of the SA node is:
A. 20 - 40 beats per minute
B. 40 - 60 beats per minute
C. 60 - 100 beats per minute [CORRECT]
D. 100 - 250 beats per minute
Correct Answer: C
Rationale:
The SA node, the heart's primary pacemaker, has an intrinsic firing rate of 60-100 beats per
minute. The AV junction (AV node and Bundle of His) fires at 40-60 bpm as a secondary
pacemaker. The Purkinje fibers and ventricular muscle fire at 20-40 bpm as a tertiary escape
pacemaker. Rates above 100 from the SA node indicate sinus tachycardia. Relias candidates
must know these intrinsic rates to identify escape rhythms and pacemaker site of origin
when the SA node fails.
