Relias Dysrhythmia Basic A Exam Question Bank
(Latest 2026/2027 Edition) – Questions, Answers &
Detailed Rationales
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SECTION 1: ECG FUNDAMENTALS AND CONDUCTION SYSTEM
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Question 1
A nurse is reviewing the electrical conduction pathway of the heart. Which structure is
responsible for delaying the electrical impulse to allow ventricular filling before
contraction?
A. Sinoatrial node
B. Atrioventricular node
C. Bundle of His
D. Purkinje fibers
Correct Answer:
B — Atrioventricular node
Rationale:
The AV node delays the impulse approximately 0.1 seconds to allow complete atrial
emptying into the ventricles. The SA node initiates the impulse; the Bundle of His and
Purkinje fibers conduct the impulse rapidly through the ventricles.
Question 2
On a standard ECG tracing, the P wave corresponds to which physiological event?
A. Ventricular depolarization
B. Atrial depolarization
,C. Ventricular repolarization
D. Atrial repolarization
Correct Answer:
B — Atrial depolarization
Rationale:
The P wave represents atrial depolarization. The QRS complex represents ventricular
depolarization; the T wave represents ventricular repolarization. Atrial repolarization is
typically hidden within the QRS complex.
Question 3
A nurse measures the PR interval on a rhythm strip. What is the normal duration range
for the PR interval?
A. 0.06 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.30 seconds
D. 0.36 to 0.44 seconds
Correct Answer:
B — 0.12 to 0.20 seconds
Rationale:
The normal PR interval is 0.12 to 0.20 seconds (3 to 5 small boxes). Values below 0.12
seconds suggest pre-excitation; values above 0.20 seconds indicate first-degree AV
block.
Question 4
The nurse notes that a patient's QRS complex measures 0.14 seconds. Which clinical
implication is most appropriate?
A. The impulse originated above the ventricles with normal conduction
,B. The patient has a normal ventricular conduction time
C. The impulse is being conducted through abnormal ventricular pathways
D. The PR interval is prolonged
Correct Answer:
C — The impulse is being conducted through abnormal ventricular pathways
Rationale:
A QRS duration >0.12 seconds indicates abnormal ventricular depolarization, typically
from a ventricular origin or bundle branch block. Normal QRS is <0.12 seconds; a wide
QRS does not indicate PR prolongation or supraventricular origin with normal
conduction.
Question 5
A telemetry technician is evaluating a rhythm strip printed at standard gain and speed.
What is the standard paper speed for ECG monitoring?
A. 10 mm per second
B. 25 mm per second
C. 50 mm per second
D. 100 mm per second
Correct Answer:
B — 25 mm per second
Rationale:
Standard ECG paper speed is 25 mm per second, where each small box equals 0.04
seconds and each large box equals 0.20 seconds. 50 mm per second is used
occasionally for detailed analysis but is not standard.
Question 6
, A nurse needs to quickly estimate a patient's heart rate from the telemetry monitor.
Using the large-box method, the R-R interval spans 4 large boxes. What is the calculated
heart rate?
A. 50 beats per minute
B. 60 beats per minute
C. 75 beats per minute
D. 100 beats per minute
Correct Answer:
C — 75 beats per minute
Rationale:
The 300 method divides 300 by the number of large boxes between R waves; 300 ÷ 4 =
75 bpm. This is a standard rapid calculation technique for regular rhythms.
Question 7
A patient is on continuous cardiac monitoring. The nurse notes artifact that obscures
the rhythm. Which action should the nurse take first to reduce artifact?
A. Increase the monitor gain to 20 mm/mV
B. Check and clean the electrode sites and replace dried electrodes
C. Switch the monitor to diagnostic mode
D. Administer an antiarrhythmic medication
Correct Answer:
B — Check and clean the electrode sites and replace dried electrodes
Rationale:
Poor electrode contact is the most common cause of artifact; cleaning the skin and
replacing dried electrodes restores signal quality. Increasing gain amplifies artifact;
diagnostic mode does not fix poor contact; antiarrhythmics are unrelated to artifact.
Question 8
(Latest 2026/2027 Edition) – Questions, Answers &
Detailed Rationales
──────────────────────────────
SECTION 1: ECG FUNDAMENTALS AND CONDUCTION SYSTEM
──────────────────────────────
Question 1
A nurse is reviewing the electrical conduction pathway of the heart. Which structure is
responsible for delaying the electrical impulse to allow ventricular filling before
contraction?
A. Sinoatrial node
B. Atrioventricular node
C. Bundle of His
D. Purkinje fibers
Correct Answer:
B — Atrioventricular node
Rationale:
The AV node delays the impulse approximately 0.1 seconds to allow complete atrial
emptying into the ventricles. The SA node initiates the impulse; the Bundle of His and
Purkinje fibers conduct the impulse rapidly through the ventricles.
Question 2
On a standard ECG tracing, the P wave corresponds to which physiological event?
A. Ventricular depolarization
B. Atrial depolarization
,C. Ventricular repolarization
D. Atrial repolarization
Correct Answer:
B — Atrial depolarization
Rationale:
The P wave represents atrial depolarization. The QRS complex represents ventricular
depolarization; the T wave represents ventricular repolarization. Atrial repolarization is
typically hidden within the QRS complex.
Question 3
A nurse measures the PR interval on a rhythm strip. What is the normal duration range
for the PR interval?
A. 0.06 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.30 seconds
D. 0.36 to 0.44 seconds
Correct Answer:
B — 0.12 to 0.20 seconds
Rationale:
The normal PR interval is 0.12 to 0.20 seconds (3 to 5 small boxes). Values below 0.12
seconds suggest pre-excitation; values above 0.20 seconds indicate first-degree AV
block.
Question 4
The nurse notes that a patient's QRS complex measures 0.14 seconds. Which clinical
implication is most appropriate?
A. The impulse originated above the ventricles with normal conduction
,B. The patient has a normal ventricular conduction time
C. The impulse is being conducted through abnormal ventricular pathways
D. The PR interval is prolonged
Correct Answer:
C — The impulse is being conducted through abnormal ventricular pathways
Rationale:
A QRS duration >0.12 seconds indicates abnormal ventricular depolarization, typically
from a ventricular origin or bundle branch block. Normal QRS is <0.12 seconds; a wide
QRS does not indicate PR prolongation or supraventricular origin with normal
conduction.
Question 5
A telemetry technician is evaluating a rhythm strip printed at standard gain and speed.
What is the standard paper speed for ECG monitoring?
A. 10 mm per second
B. 25 mm per second
C. 50 mm per second
D. 100 mm per second
Correct Answer:
B — 25 mm per second
Rationale:
Standard ECG paper speed is 25 mm per second, where each small box equals 0.04
seconds and each large box equals 0.20 seconds. 50 mm per second is used
occasionally for detailed analysis but is not standard.
Question 6
, A nurse needs to quickly estimate a patient's heart rate from the telemetry monitor.
Using the large-box method, the R-R interval spans 4 large boxes. What is the calculated
heart rate?
A. 50 beats per minute
B. 60 beats per minute
C. 75 beats per minute
D. 100 beats per minute
Correct Answer:
C — 75 beats per minute
Rationale:
The 300 method divides 300 by the number of large boxes between R waves; 300 ÷ 4 =
75 bpm. This is a standard rapid calculation technique for regular rhythms.
Question 7
A patient is on continuous cardiac monitoring. The nurse notes artifact that obscures
the rhythm. Which action should the nurse take first to reduce artifact?
A. Increase the monitor gain to 20 mm/mV
B. Check and clean the electrode sites and replace dried electrodes
C. Switch the monitor to diagnostic mode
D. Administer an antiarrhythmic medication
Correct Answer:
B — Check and clean the electrode sites and replace dried electrodes
Rationale:
Poor electrode contact is the most common cause of artifact; cleaning the skin and
replacing dried electrodes restores signal quality. Increasing gain amplifies artifact;
diagnostic mode does not fix poor contact; antiarrhythmics are unrelated to artifact.
Question 8
