Relias Dysrhythmia Basic A Exam Prep:
120 Questions, Verified Answers &
Rationales (Latest 2026/2027 Version)
Question 1
A nurse is analyzing an ECG strip and notices a regular rhythm with a heart rate
of 72 bpm. The P waves are upright and uniform, preceding every QRS
complex. The PR interval measures 0.16 seconds, and the QRS complex
measures 0.08 seconds. Which rhythm is this?
A) Sinus Bradycardia
B) Normal Sinus Rhythm
C) First-Degree AV Block
D) Atrial Flutter
,Verified Answer: B) Normal Sinus Rhythm
Explanation: Normal Sinus Rhythm (NSR) is defined by a regular rhythm, a
heart rate between 60 and 100 bpm, a normal P wave shape and orientation, a
PR interval within the standard 0.12–0.20 second window, and a narrow QRS
complex under 0.12 seconds.
Question 2
An ECG monitor shows a patient's rhythm is highly irregular. There are no
identifiable P waves, and the baseline exhibits chaotic, fibrillatory waves. The
ventricular rate is fluctuating between 90 and 130 bpm. This rhythm is best
classified as:
A) Atrial Flutter
B) Ventricular Fibrillation
C) Atrial Fibrillation
D) Sinus Arrhythmia
Verified Answer: C) Atrial Fibrillation
Explanation: Atrial Fibrillation (AFib) is anatomically characterized by total
disorganization of atrial electrical activity without effective atrial contraction.
The diagnostic hallmarks are a highly irregular ventricular rhythm
(irregularly irregular) and an complete absence of distinct P waves, replaced
instead by chaotic fibrillatory lines.
Question 3
While reviewing a telemetry strip, a nurse measures a PR interval of 0.26
seconds. The rhythm is perfectly regular, every P wave is followed by a narrow
QRS complex, and the heart rate is 68 bpm. What is the correct interpretation?
A) Normal Sinus Rhythm
B) First-Degree AV Block
,C) Second-Degree AV Block Type 1
D) Complete Heart Block
Verified Answer: B) First-Degree AV Block
Explanation: A First-Degree AV Block is defined strictly by a prolonged PR
interval greater than 0.20 seconds (more than 5 small boxes) that remains
constant across all beats. Every atrial impulse is conducted to the ventricles,
meaning there are absolutely no dropped QRS complexes.
Question 4
A patient's ECG strip demonstrates a regular atrial rhythm and a regular
ventricular rhythm, but there is no structural relationship between the P waves
and the QRS complexes. The P waves seem to "march through" the QRS
complexes, and the ventricular rate is slow at 35 bpm. This represents:
A) Second-Degree AV Block Type 2
B) First-Degree AV Block
C) Third-Degree AV Block
D) Sinus Bradycardia
Verified Answer: C) Third-Degree AV Block
Explanation: Third-Degree AV Block, or Complete Heart Block, is
characterized by complete atrioventricular dissociation. The atria and
ventricles beat completely independently of each other. Because the impulses
do not cross the AV node, the ventricular rate is driven by an intrinsic
junctional or ventricular escape pacemaker, resulting in a very slow, regular
rate with inconsistent PR intervals.
Question 5
A nurse notes a rapid cardiac rhythm on the monitor screen showing a distinct
"sawtooth" baseline pattern in leads II, III, and aVF. The atrial rate is roughly
300 bpm, and the ventricular response is regular at 75 bpm. This rhythm is:
, A) Atrial Fibrillation
B) Atrial Flutter
C) Ventricular Tachycardia
D) Supraventricular Tachycardia
Verified Answer: B) Atrial Flutter
Explanation: Atrial Flutter is generated by a re-entry circuit within the atria,
producing rapid, regular, and uniform atrial depolarizations. This manifests
on an ECG as classic "F-waves" or a sawtooth baseline pattern. The AV node
usually blocks a fixed ratio of these impulses (e.g., 4:1 conduction yielding a
ventricular rate of 75 bpm from an atrial rate of 300 bpm).
Question 6
When counting small boxes on an ECG strip, the nurse notes that the QRS
complex spans exactly 3.5 small boxes. What is the duration of this QRS
complex, and how is it interpreted?
A) 0.07 seconds, normal duration
B) 0.14 seconds, abnormally prolonged
C) 0.35 seconds, dangerously prolonged
=D) 0.12 seconds, borderline normal
Verified Answer: B) 0.14 seconds, abnormally prolonged
Explanation: Each small box on standard ECG paper represents 0.04
seconds. Multiplying 3.5 boxes by 0.04 seconds equals 0.14 seconds. A normal
QRS complex duration must be less than 0.12 seconds (under 3 small boxes);
therefore, 0.14 seconds indicates a delayed ventricular depolarization, often
associated with a bundle branch block.
Question 7
An ECG strip shows a rhythm that has a progressively lengthening PR interval
over three consecutive beats, followed by a P wave that has no matching QRS
120 Questions, Verified Answers &
Rationales (Latest 2026/2027 Version)
Question 1
A nurse is analyzing an ECG strip and notices a regular rhythm with a heart rate
of 72 bpm. The P waves are upright and uniform, preceding every QRS
complex. The PR interval measures 0.16 seconds, and the QRS complex
measures 0.08 seconds. Which rhythm is this?
A) Sinus Bradycardia
B) Normal Sinus Rhythm
C) First-Degree AV Block
D) Atrial Flutter
,Verified Answer: B) Normal Sinus Rhythm
Explanation: Normal Sinus Rhythm (NSR) is defined by a regular rhythm, a
heart rate between 60 and 100 bpm, a normal P wave shape and orientation, a
PR interval within the standard 0.12–0.20 second window, and a narrow QRS
complex under 0.12 seconds.
Question 2
An ECG monitor shows a patient's rhythm is highly irregular. There are no
identifiable P waves, and the baseline exhibits chaotic, fibrillatory waves. The
ventricular rate is fluctuating between 90 and 130 bpm. This rhythm is best
classified as:
A) Atrial Flutter
B) Ventricular Fibrillation
C) Atrial Fibrillation
D) Sinus Arrhythmia
Verified Answer: C) Atrial Fibrillation
Explanation: Atrial Fibrillation (AFib) is anatomically characterized by total
disorganization of atrial electrical activity without effective atrial contraction.
The diagnostic hallmarks are a highly irregular ventricular rhythm
(irregularly irregular) and an complete absence of distinct P waves, replaced
instead by chaotic fibrillatory lines.
Question 3
While reviewing a telemetry strip, a nurse measures a PR interval of 0.26
seconds. The rhythm is perfectly regular, every P wave is followed by a narrow
QRS complex, and the heart rate is 68 bpm. What is the correct interpretation?
A) Normal Sinus Rhythm
B) First-Degree AV Block
,C) Second-Degree AV Block Type 1
D) Complete Heart Block
Verified Answer: B) First-Degree AV Block
Explanation: A First-Degree AV Block is defined strictly by a prolonged PR
interval greater than 0.20 seconds (more than 5 small boxes) that remains
constant across all beats. Every atrial impulse is conducted to the ventricles,
meaning there are absolutely no dropped QRS complexes.
Question 4
A patient's ECG strip demonstrates a regular atrial rhythm and a regular
ventricular rhythm, but there is no structural relationship between the P waves
and the QRS complexes. The P waves seem to "march through" the QRS
complexes, and the ventricular rate is slow at 35 bpm. This represents:
A) Second-Degree AV Block Type 2
B) First-Degree AV Block
C) Third-Degree AV Block
D) Sinus Bradycardia
Verified Answer: C) Third-Degree AV Block
Explanation: Third-Degree AV Block, or Complete Heart Block, is
characterized by complete atrioventricular dissociation. The atria and
ventricles beat completely independently of each other. Because the impulses
do not cross the AV node, the ventricular rate is driven by an intrinsic
junctional or ventricular escape pacemaker, resulting in a very slow, regular
rate with inconsistent PR intervals.
Question 5
A nurse notes a rapid cardiac rhythm on the monitor screen showing a distinct
"sawtooth" baseline pattern in leads II, III, and aVF. The atrial rate is roughly
300 bpm, and the ventricular response is regular at 75 bpm. This rhythm is:
, A) Atrial Fibrillation
B) Atrial Flutter
C) Ventricular Tachycardia
D) Supraventricular Tachycardia
Verified Answer: B) Atrial Flutter
Explanation: Atrial Flutter is generated by a re-entry circuit within the atria,
producing rapid, regular, and uniform atrial depolarizations. This manifests
on an ECG as classic "F-waves" or a sawtooth baseline pattern. The AV node
usually blocks a fixed ratio of these impulses (e.g., 4:1 conduction yielding a
ventricular rate of 75 bpm from an atrial rate of 300 bpm).
Question 6
When counting small boxes on an ECG strip, the nurse notes that the QRS
complex spans exactly 3.5 small boxes. What is the duration of this QRS
complex, and how is it interpreted?
A) 0.07 seconds, normal duration
B) 0.14 seconds, abnormally prolonged
C) 0.35 seconds, dangerously prolonged
=D) 0.12 seconds, borderline normal
Verified Answer: B) 0.14 seconds, abnormally prolonged
Explanation: Each small box on standard ECG paper represents 0.04
seconds. Multiplying 3.5 boxes by 0.04 seconds equals 0.14 seconds. A normal
QRS complex duration must be less than 0.12 seconds (under 3 small boxes);
therefore, 0.14 seconds indicates a delayed ventricular depolarization, often
associated with a bundle branch block.
Question 7
An ECG strip shows a rhythm that has a progressively lengthening PR interval
over three consecutive beats, followed by a P wave that has no matching QRS
