Relias Dysrhythmia Basic A Test Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
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1. Which structure normally serves as the primary pacemaker of the
heart?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node
D. Purkinje fibers
Answer: C. Sinoatrial (SA) node
Rationale: The SA node is the heart’s normal pacemaker because it
has the fastest intrinsic firing rate, typically 60–100 impulses per
minute. The electrical impulse begins in the SA node and spreads
through the atria before reaching the AV node.
,2. Which ECG component represents atrial depolarization?
A. QRS complex
B. T wave
C. ST segment
D. P wave
Answer: D. P wave
Rationale: The P wave represents electrical depolarization of the atria.
A normal P wave is usually smooth and upright in most standard ECG
leads and precedes the QRS complex when the rhythm originates in
the sinus node.
3. What does the QRS complex represent?
A. Atrial repolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial contraction only
Answer: C. Ventricular depolarization
Rationale: The QRS complex represents electrical depolarization of the
ventricles, which initiates ventricular contraction. Atrial repolarization
,occurs at approximately the same time and is normally hidden within
the QRS complex.
4. What does the T wave represent?
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. AV nodal conduction
Answer: B. Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, when the
ventricular cells recover electrically after depolarization. Abnormal T-
wave morphology can occur with ischemia, electrolyte abnormalities,
and other cardiac conditions.
5. What is the normal resting heart rate for an adult?
A. 30–50 beats/minute
B. 40–60 beats/minute
C. 60–100 beats/minute
D. 100–140 beats/minute
, Answer: C. 60–100 beats/minute
Rationale: A normal adult sinus rhythm generally has a rate between
60 and 100 beats per minute. Rates below 60 are generally classified
as bradycardia, while rates above 100 are generally classified as
tachycardia.
6. Which characteristic is expected in normal sinus rhythm?
A. No identifiable P waves
B. Irregularly irregular R-R intervals
C. Wide QRS complexes
D. A P wave before every QRS complex
Answer: D. A P wave before every QRS complex
Rationale: Normal sinus rhythm originates in the SA node and
therefore produces consistent atrial depolarization. Each normal P
wave should be followed by a QRS complex, with a regular rhythm
and an appropriate rate.
7. When measuring the PR interval, which portion of cardiac
conduction is primarily assessed?
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. Which structure normally serves as the primary pacemaker of the
heart?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node
D. Purkinje fibers
Answer: C. Sinoatrial (SA) node
Rationale: The SA node is the heart’s normal pacemaker because it
has the fastest intrinsic firing rate, typically 60–100 impulses per
minute. The electrical impulse begins in the SA node and spreads
through the atria before reaching the AV node.
,2. Which ECG component represents atrial depolarization?
A. QRS complex
B. T wave
C. ST segment
D. P wave
Answer: D. P wave
Rationale: The P wave represents electrical depolarization of the atria.
A normal P wave is usually smooth and upright in most standard ECG
leads and precedes the QRS complex when the rhythm originates in
the sinus node.
3. What does the QRS complex represent?
A. Atrial repolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial contraction only
Answer: C. Ventricular depolarization
Rationale: The QRS complex represents electrical depolarization of the
ventricles, which initiates ventricular contraction. Atrial repolarization
,occurs at approximately the same time and is normally hidden within
the QRS complex.
4. What does the T wave represent?
A. Atrial depolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. AV nodal conduction
Answer: B. Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, when the
ventricular cells recover electrically after depolarization. Abnormal T-
wave morphology can occur with ischemia, electrolyte abnormalities,
and other cardiac conditions.
5. What is the normal resting heart rate for an adult?
A. 30–50 beats/minute
B. 40–60 beats/minute
C. 60–100 beats/minute
D. 100–140 beats/minute
, Answer: C. 60–100 beats/minute
Rationale: A normal adult sinus rhythm generally has a rate between
60 and 100 beats per minute. Rates below 60 are generally classified
as bradycardia, while rates above 100 are generally classified as
tachycardia.
6. Which characteristic is expected in normal sinus rhythm?
A. No identifiable P waves
B. Irregularly irregular R-R intervals
C. Wide QRS complexes
D. A P wave before every QRS complex
Answer: D. A P wave before every QRS complex
Rationale: Normal sinus rhythm originates in the SA node and
therefore produces consistent atrial depolarization. Each normal P
wave should be followed by a QRS complex, with a regular rhythm
and an appropriate rate.
7. When measuring the PR interval, which portion of cardiac
conduction is primarily assessed?
