Relias Dysrhythmia Advanced Exam B
Practice Test 2026 | 150 ECG Measurements
Questions, Answers & Rationales | Cardiac
Rhythm Study Guide
Q1. Which measurement is best represented by the PR interval on an ECG?
A. The time from atrial depolarization to ventricular depolarization
B. The time from ventricular depolarization to repolarization
C. The duration of ventricular depolarization only (QRS duration)
D. The time from SA node firing to T-wave completion
E. The duration of atrial repolarization
Correct Answer: A
EXPERT RATIONALE (Correct option): The PR interval spans from the start of
the P wave (atrial depolarization) to the start of the QRS complex (ventricular
depolarization).
Q2. A regular narrow-complex tachycardia with sudden onset and sudden
offset most strongly suggests:
A. Sinus tachycardia
B. AV nodal re-entrant tachycardia (AVNRT)
C. Ventricular tachycardia
D. Atrial fibrillation with wide QRS
E. Sinus bradycardia
Correct Answer: B
EXPERT RATIONALE (Correct option): Sudden onset/offset and a regular
narrow-complex rhythm are classic for re-entrant SVTs such as AVNRT.
Q3. The QRS complex duration primarily reflects:
A. Atrial repolarization duration
B. Ventricular depolarization duration
C. Atrial depolarization duration
D. Ventricular repolarization duration
E. SA nodal recovery time
, Correct Answer: B
EXPERT RATIONALE (Correct option): The QRS complex represents ventricular
depolarization through the His-Purkinje system.
Q4. A prolonged QT interval is most directly associated with increased risk of:
A. Ventricular fibrillation only
B. Asystole only
C. Sinus arrest
D. First-degree AV block only
E. Torsades de pointes (polymorphic VT)
Correct Answer: E
EXPERT RATIONALE (Correct option): QT prolongation predisposes to early
afterdepolarizations, increasing risk for torsades de pointes.
Q5. In normal sinus rhythm, P waves are typically:
A. Absent
B. Present before each QRS and consistent in morphology
C. Larger than QRS
D. Only visible during tachycardia
E. Always inverted in lead II
Correct Answer: B
EXPERT RATIONALE (Correct option): Normal sinus rhythm requires atrial
activation before each ventricular beat with consistent P-wave appearance.
Q6. First-degree AV block is defined as:
A. PR interval > 200 ms with all P waves conducted
B. PR interval < 120 ms with dropped beats
C. QRS width > 120 ms
D. No P waves with irregular rhythm
E. PR interval intermittently absent
, Correct Answer: A
EXPERT RATIONALE (Correct option): First-degree AV block means PR
prolongation (>200 ms) while every P is followed by a QRS.
Q7. Mobitz I (Wenckebach) is characterized by:
A. Fixed PR interval with sudden failure
B. Progressive PR lengthening until a non-conducted P wave occurs
C. Completely absent QRS complexes
D. PR interval always normal
E. Alternating QRS widths every beat
Correct Answer: B
EXPERT RATIONALE (Correct option): Mobitz I shows a repeating cycle of
progressively longer PR intervals followed by a dropped QRS.
Q8. Mobitz II AV block is suggested by:
A. Progressive PR prolongation then drop
B. Sudden dropped QRS complexes with a constant PR interval
C. PR interval always > 300 ms without drops
D. Alternating P-wave polarity
E. Only one QRS in several seconds
Correct Answer: B
EXPERT RATIONALE (Correct option): Mobitz II typically has consistent PR
intervals until intermittent sudden failure of conduction.
Q9. Third-degree (complete) AV block shows:
A. One-to-one P to QRS conduction always
B. AV dissociation: P waves and QRS complexes occur independently
C. Only P waves with no ventricular activity
D. QRS always preceded by every P with constant PR and no exceptions
E. Alternating PR lengthening until sinus rhythm returns
, Correct Answer: B
EXPERT RATIONALE (Correct option): In complete heart block, atrial electrical
activity is independent from ventricular activation.
Q10. A wide-complex ventricular rhythm that is regular most strongly raises
suspicion for:
A. Sinus arrhythmia
B. Ventricular tachycardia
C. Premature atrial contractions only
D. Typical flutter with narrow complexes
E. First-degree AV block
Correct Answer: B
EXPERT RATIONALE (Correct option): Regular, wide-complex tachycardia is
highly suspicious for ventricular tachycardia.
Q11. Correct QT assessment requires:
A. Measuring QT only and ignoring heart rate
B. Using the QTc because QT varies with heart rate
C. Measuring PR instead of QT
D. Measuring QRS duration only
E. Correcting QT by changing lead placement
Correct Answer: B
EXPERT RATIONALE (Correct option): QTc adjusts QT for heart rate, improving
comparison across different rates.
Q12. The “correct” method for estimating heart rate from a standard ECG
strip when rhythm is regular is best described as:
A. Count QRS complexes in 1 second and multiply by 60
B. Count large squares between R waves and divide 300 by that number
C. Count large squares between T waves and divide 300
Practice Test 2026 | 150 ECG Measurements
Questions, Answers & Rationales | Cardiac
Rhythm Study Guide
Q1. Which measurement is best represented by the PR interval on an ECG?
A. The time from atrial depolarization to ventricular depolarization
B. The time from ventricular depolarization to repolarization
C. The duration of ventricular depolarization only (QRS duration)
D. The time from SA node firing to T-wave completion
E. The duration of atrial repolarization
Correct Answer: A
EXPERT RATIONALE (Correct option): The PR interval spans from the start of
the P wave (atrial depolarization) to the start of the QRS complex (ventricular
depolarization).
Q2. A regular narrow-complex tachycardia with sudden onset and sudden
offset most strongly suggests:
A. Sinus tachycardia
B. AV nodal re-entrant tachycardia (AVNRT)
C. Ventricular tachycardia
D. Atrial fibrillation with wide QRS
E. Sinus bradycardia
Correct Answer: B
EXPERT RATIONALE (Correct option): Sudden onset/offset and a regular
narrow-complex rhythm are classic for re-entrant SVTs such as AVNRT.
Q3. The QRS complex duration primarily reflects:
A. Atrial repolarization duration
B. Ventricular depolarization duration
C. Atrial depolarization duration
D. Ventricular repolarization duration
E. SA nodal recovery time
, Correct Answer: B
EXPERT RATIONALE (Correct option): The QRS complex represents ventricular
depolarization through the His-Purkinje system.
Q4. A prolonged QT interval is most directly associated with increased risk of:
A. Ventricular fibrillation only
B. Asystole only
C. Sinus arrest
D. First-degree AV block only
E. Torsades de pointes (polymorphic VT)
Correct Answer: E
EXPERT RATIONALE (Correct option): QT prolongation predisposes to early
afterdepolarizations, increasing risk for torsades de pointes.
Q5. In normal sinus rhythm, P waves are typically:
A. Absent
B. Present before each QRS and consistent in morphology
C. Larger than QRS
D. Only visible during tachycardia
E. Always inverted in lead II
Correct Answer: B
EXPERT RATIONALE (Correct option): Normal sinus rhythm requires atrial
activation before each ventricular beat with consistent P-wave appearance.
Q6. First-degree AV block is defined as:
A. PR interval > 200 ms with all P waves conducted
B. PR interval < 120 ms with dropped beats
C. QRS width > 120 ms
D. No P waves with irregular rhythm
E. PR interval intermittently absent
, Correct Answer: A
EXPERT RATIONALE (Correct option): First-degree AV block means PR
prolongation (>200 ms) while every P is followed by a QRS.
Q7. Mobitz I (Wenckebach) is characterized by:
A. Fixed PR interval with sudden failure
B. Progressive PR lengthening until a non-conducted P wave occurs
C. Completely absent QRS complexes
D. PR interval always normal
E. Alternating QRS widths every beat
Correct Answer: B
EXPERT RATIONALE (Correct option): Mobitz I shows a repeating cycle of
progressively longer PR intervals followed by a dropped QRS.
Q8. Mobitz II AV block is suggested by:
A. Progressive PR prolongation then drop
B. Sudden dropped QRS complexes with a constant PR interval
C. PR interval always > 300 ms without drops
D. Alternating P-wave polarity
E. Only one QRS in several seconds
Correct Answer: B
EXPERT RATIONALE (Correct option): Mobitz II typically has consistent PR
intervals until intermittent sudden failure of conduction.
Q9. Third-degree (complete) AV block shows:
A. One-to-one P to QRS conduction always
B. AV dissociation: P waves and QRS complexes occur independently
C. Only P waves with no ventricular activity
D. QRS always preceded by every P with constant PR and no exceptions
E. Alternating PR lengthening until sinus rhythm returns
, Correct Answer: B
EXPERT RATIONALE (Correct option): In complete heart block, atrial electrical
activity is independent from ventricular activation.
Q10. A wide-complex ventricular rhythm that is regular most strongly raises
suspicion for:
A. Sinus arrhythmia
B. Ventricular tachycardia
C. Premature atrial contractions only
D. Typical flutter with narrow complexes
E. First-degree AV block
Correct Answer: B
EXPERT RATIONALE (Correct option): Regular, wide-complex tachycardia is
highly suspicious for ventricular tachycardia.
Q11. Correct QT assessment requires:
A. Measuring QT only and ignoring heart rate
B. Using the QTc because QT varies with heart rate
C. Measuring PR instead of QT
D. Measuring QRS duration only
E. Correcting QT by changing lead placement
Correct Answer: B
EXPERT RATIONALE (Correct option): QTc adjusts QT for heart rate, improving
comparison across different rates.
Q12. The “correct” method for estimating heart rate from a standard ECG
strip when rhythm is regular is best described as:
A. Count QRS complexes in 1 second and multiply by 60
B. Count large squares between R waves and divide 300 by that number
C. Count large squares between T waves and divide 300
