Relias Dysrhythmia Basic Test ECG
Interpretation Study Guide 2026/2027
| 100% Complete & Verified Real Exam
Questions and Answers | Detailed Step-by-
Step Electrophysiology Rationales |
Guaranteed Pass A+ Graded Resource for
Telemetry Nurses and Nursing Students
Which component of the ECG represents atrial depolarization?
A. QRS complex
B. T wave
C. P wave
D. ST segment
Answer: C. P wave
Rationale: The P wave represents electrical depolarization of the atria, which
precedes atrial contraction. The QRS complex represents ventricular
depolarization, while the T wave represents ventricular repolarization.
A nurse observes a regular rhythm with a rate of 76 beats/min, a normal P wave
before every QRS complex, and a consistent PR interval. Which rhythm is most
likely?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular tachycardia
,D. Junctional rhythm
Answer: B. Normal sinus rhythm
Rationale: Normal sinus rhythm generally has a rate of 60–100 beats/min, regular
R-R intervals, consistent sinus P waves before each QRS complex, and a PR
interval of 0.12–0.20 seconds.
What is the normal duration of the PR interval in an adult?
A. 0.04–0.08 seconds
B. 0.08–0.10 seconds
C. 0.12–0.20 seconds
D. 0.24–0.36 seconds
Answer: C. 0.12–0.20 seconds
Rationale: The normal PR interval is 0.12–0.20 seconds. It measures conduction
time from the beginning of atrial depolarization to the beginning of ventricular
depolarization.
Which ECG finding is most characteristic of atrial fibrillation?
A. Regular R-R intervals with identical P waves
B. Irregularly irregular rhythm without distinct P waves
C. Wide QRS complexes occurring at a regular rate
D. Progressive PR interval prolongation followed by a dropped QRS
Answer: B. Irregularly irregular rhythm without distinct P waves
Rationale: Atrial fibrillation produces disorganized atrial electrical activity, absent
distinct P waves, and irregularly irregular ventricular responses. Patients may
require assessment for hemodynamic instability and thromboembolic risk.
A patient has a heart rate of 48 beats/min. The rhythm is regular, and each normal-
appearing P wave is followed by a QRS complex. Which rhythm is most likely?
,A. Sinus tachycardia
B. Sinus bradycardia
C. Ventricular fibrillation
D. Atrial flutter
Answer: B. Sinus bradycardia
Rationale: Sinus bradycardia is a sinus rhythm with a rate below 60 beats/min in
adults. Assess the patient for symptoms such as dizziness, hypotension, altered
mental status, chest discomfort, or syncope rather than treating the rate alone.
Which ECG characteristic is most associated with atrial flutter?
A. Sawtooth-shaped flutter waves
B. Completely absent electrical activity
C. Progressive widening of every QRS complex
D. A prolonged QT interval in every patient
Answer: A. Sawtooth-shaped flutter waves
Rationale: Atrial flutter commonly produces repetitive flutter waves, often with a
sawtooth appearance, especially in the inferior ECG leads. The ventricular rate
depends on the degree of AV conduction.
A patient has a regular narrow-complex tachycardia at 180 beats/min. P waves are
difficult to identify. The patient is alert and has a stable blood pressure. Which
rhythm is most likely?
A. Sinus bradycardia
B. Supraventricular tachycardia (SVT)
C. Ventricular fibrillation
D. Complete heart block
, Answer: B. Supraventricular tachycardia (SVT)
Rationale: SVT commonly presents as a rapid, regular, narrow-complex rhythm
with P waves that may be hidden within the QRS complexes. In a stable patient,
assess the rhythm and consider appropriate interventions under current clinical
protocols.
Which ECG finding is typical of first-degree AV block?
A. A PR interval longer than 0.20 seconds, with every P wave conducted
B. A missing P wave before every QRS complex
C. Progressive QRS widening until cardiac arrest
D. Irregular baseline with no organized ventricular complexes
Answer: A. A PR interval longer than 0.20 seconds, with every P wave conducted
Rationale: First-degree AV block involves delayed conduction from the atria to the
ventricles. Every P wave is followed by a QRS complex, but the PR interval is
consistently prolonged.
An ECG shows progressive lengthening of the PR interval until a P wave is not
followed by a QRS complex. What is the most likely diagnosis?
A. First-degree AV block
B. Second-degree AV block, Mobitz type I
C. Second-degree AV block, Mobitz type II
D. Third-degree AV block
Answer: B. Second-degree AV block, Mobitz type I
Rationale: Mobitz type I, also called Wenckebach, is characterized by progressive
PR interval prolongation followed by a nonconducted P wave. The pattern repeats
as conduction resumes.
Which finding is most characteristic of second-degree AV block, Mobitz type II?
Interpretation Study Guide 2026/2027
| 100% Complete & Verified Real Exam
Questions and Answers | Detailed Step-by-
Step Electrophysiology Rationales |
Guaranteed Pass A+ Graded Resource for
Telemetry Nurses and Nursing Students
Which component of the ECG represents atrial depolarization?
A. QRS complex
B. T wave
C. P wave
D. ST segment
Answer: C. P wave
Rationale: The P wave represents electrical depolarization of the atria, which
precedes atrial contraction. The QRS complex represents ventricular
depolarization, while the T wave represents ventricular repolarization.
A nurse observes a regular rhythm with a rate of 76 beats/min, a normal P wave
before every QRS complex, and a consistent PR interval. Which rhythm is most
likely?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular tachycardia
,D. Junctional rhythm
Answer: B. Normal sinus rhythm
Rationale: Normal sinus rhythm generally has a rate of 60–100 beats/min, regular
R-R intervals, consistent sinus P waves before each QRS complex, and a PR
interval of 0.12–0.20 seconds.
What is the normal duration of the PR interval in an adult?
A. 0.04–0.08 seconds
B. 0.08–0.10 seconds
C. 0.12–0.20 seconds
D. 0.24–0.36 seconds
Answer: C. 0.12–0.20 seconds
Rationale: The normal PR interval is 0.12–0.20 seconds. It measures conduction
time from the beginning of atrial depolarization to the beginning of ventricular
depolarization.
Which ECG finding is most characteristic of atrial fibrillation?
A. Regular R-R intervals with identical P waves
B. Irregularly irregular rhythm without distinct P waves
C. Wide QRS complexes occurring at a regular rate
D. Progressive PR interval prolongation followed by a dropped QRS
Answer: B. Irregularly irregular rhythm without distinct P waves
Rationale: Atrial fibrillation produces disorganized atrial electrical activity, absent
distinct P waves, and irregularly irregular ventricular responses. Patients may
require assessment for hemodynamic instability and thromboembolic risk.
A patient has a heart rate of 48 beats/min. The rhythm is regular, and each normal-
appearing P wave is followed by a QRS complex. Which rhythm is most likely?
,A. Sinus tachycardia
B. Sinus bradycardia
C. Ventricular fibrillation
D. Atrial flutter
Answer: B. Sinus bradycardia
Rationale: Sinus bradycardia is a sinus rhythm with a rate below 60 beats/min in
adults. Assess the patient for symptoms such as dizziness, hypotension, altered
mental status, chest discomfort, or syncope rather than treating the rate alone.
Which ECG characteristic is most associated with atrial flutter?
A. Sawtooth-shaped flutter waves
B. Completely absent electrical activity
C. Progressive widening of every QRS complex
D. A prolonged QT interval in every patient
Answer: A. Sawtooth-shaped flutter waves
Rationale: Atrial flutter commonly produces repetitive flutter waves, often with a
sawtooth appearance, especially in the inferior ECG leads. The ventricular rate
depends on the degree of AV conduction.
A patient has a regular narrow-complex tachycardia at 180 beats/min. P waves are
difficult to identify. The patient is alert and has a stable blood pressure. Which
rhythm is most likely?
A. Sinus bradycardia
B. Supraventricular tachycardia (SVT)
C. Ventricular fibrillation
D. Complete heart block
, Answer: B. Supraventricular tachycardia (SVT)
Rationale: SVT commonly presents as a rapid, regular, narrow-complex rhythm
with P waves that may be hidden within the QRS complexes. In a stable patient,
assess the rhythm and consider appropriate interventions under current clinical
protocols.
Which ECG finding is typical of first-degree AV block?
A. A PR interval longer than 0.20 seconds, with every P wave conducted
B. A missing P wave before every QRS complex
C. Progressive QRS widening until cardiac arrest
D. Irregular baseline with no organized ventricular complexes
Answer: A. A PR interval longer than 0.20 seconds, with every P wave conducted
Rationale: First-degree AV block involves delayed conduction from the atria to the
ventricles. Every P wave is followed by a QRS complex, but the PR interval is
consistently prolonged.
An ECG shows progressive lengthening of the PR interval until a P wave is not
followed by a QRS complex. What is the most likely diagnosis?
A. First-degree AV block
B. Second-degree AV block, Mobitz type I
C. Second-degree AV block, Mobitz type II
D. Third-degree AV block
Answer: B. Second-degree AV block, Mobitz type I
Rationale: Mobitz type I, also called Wenckebach, is characterized by progressive
PR interval prolongation followed by a nonconducted P wave. The pattern repeats
as conduction resumes.
Which finding is most characteristic of second-degree AV block, Mobitz type II?
