Relias Dysrhythmia Basic A Exam: Comprehensive 150-Question Practice Test Bank with Verified
Answers and Clinical Rationales (2025/2026 Update)
A Complete Certification Preparation Resource for Healthcare Professionals Mastering Cardiac Rhythm Interpretation, ECG Analysis, and Emergency
Dysrhythmia Management
Table of Contents
Section Topic Area Questions
I ECG Fundamentals & Waveform Analysis 1–15
II Sinus Rhythms 16–25
III Atrial Dysrhythmias 26–40
IV Junctional Rhythms 41–50
V Ventricular Dysrhythmias 51–65
VI Heart Blocks (AV Blocks) 66–80
VII Pacemaker Rhythms & Artifact Interpretation 81–90
VIII Antiarrhythmic Pharmacology 91–100
IX Emergency Interventions & ACLS Algorithms 101–115
X Clinical Scenarios & Prioritization 116–130
XI Mixed Rhythm Identification (Strip Descriptions) 131–145
XII Comprehensive Review & High-Yield Concepts 146–150
Section I: ECG Fundamentals & Waveform Analysis
🟢 1. A 6-second ECG rhythm strip contains 30 large boxes. At a standard paper speed of 25 mm/second, how many seconds of cardiac activity does this
strip represent?
🟢 A) 3 seconds
🔴🔴 B) 6 seconds
🟢 C) 10 seconds
🟢 D) 12 seconds
Rationale: Standard ECG paper runs at 25 mm/second. Each large box (5 mm) represents 0.20 seconds. A 6-second strip contains 30 large boxes (30 × 0.20
= 6 seconds). This is the standard length used for calculating heart rate by counting QRS complexes and multiplying by 10.
🟢 2. What does the vertical axis on an ECG tracing measure?
🟢 A) Time
🔴🔴 B) Voltage (amplitude)
🟢 C) Resistance
🟢 D) Speed
Rationale: The vertical axis on ECG paper measures voltage or amplitude in millimeters (mV). Standard calibration is 10 mm = 1 mV. The horizontal axis
measures time.
,🟢 3. How many seconds does one small box represent on standard ECG paper?
🟢 A) 0.20 seconds
🟢 B) 0.12 seconds
🔴🔴 C) 0.04 seconds
🟢 D) 0.08 seconds
Rationale: At 25 mm/second, each small box (1 mm) represents 0.04 seconds. Five small boxes equal one large box (0.20 seconds).
🟢 4. A nurse notes that the PR interval on a patient's ECG measures 0.24 seconds. What is the appropriate interpretation?
🟢 A) Normal PR interval
🟢 B) Shortened PR interval
🔴🔴 C) Prolonged PR interval (first-degree AV block)
🟢 D) Inconsistent PR interval
Rationale: The normal PR interval is 0.12–0.20 seconds. A PR interval >0.20 seconds indicates first-degree AV block (prolonged AV conduction). This is a
delay in conduction from the atria to the ventricles through the AV node.
🟢 5. What is the normal duration of the QRS complex?
🟢 A) 0.04–0.08 seconds
🔴🔴 B) Less than 0.12 seconds
🟢 C) 0.12–0.20 seconds
🟢 D) Greater than 0.20 seconds
Rationale: The normal QRS duration is ≤0.12 seconds (less than 3 small boxes). A widened QRS (>0.12 seconds) indicates ventricular conduction delay,
bundle branch block, or ventricular origin of the rhythm.
🟢 6. The normal intrinsic firing rate of the sinoatrial (SA) node is:
🟢 A) 20–40 beats per minute
🟢 B) 40–60 beats per minute
🔴🔴 C) 60–100 beats per minute
🟢 D) 100–150 beats per minute
Rationale: The SA node, the primary pacemaker of the heart, naturally fires at 60–100 beats per minute. It is located in the right atrium and generates the
fastest intrinsic rate among all cardiac pacemaker tissues.
🟢 7. The normal intrinsic firing rate of the atrioventricular (AV) junction is:
🟢 A) 20–40 beats per minute
🔴🔴 B) 40–60 beats per minute
🟢 C) 60–100 beats per minute
🟢 D) 100–150 beats per minute
Rationale: The AV junction has an intrinsic rate of 40–60 beats per minute. It serves as the secondary pacemaker when the SA node fails or when
conduction is blocked.
🟢 8. Which of the following correctly identifies the sequence of the cardiac conduction system?
🟢 A) AV node → SA node → Bundle of His → Purkinje fibers → Bundle branches
🔴🔴 B) SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
🟢 C) SA node → Bundle of His → AV node → Purkinje fibers → Bundle branches
🟢 D) AV node → SA node → Bundle branches → Bundle of His → Purkinje fibers
Rationale: The cardiac conduction system sequence is: SA node (60–100 bpm) → AV node (40–60 bpm) → Bundle of His (40–45 bpm) → Right and Left
Bundle Branches (40–45 bpm) → Purkinje fibers (20–50 bpm). This ordered pathway ensures coordinated atrial and ventricular contraction.
🟢 9. A patient's ECG shows a heart rate of 150 bpm. What is the approximate duration of one cardiac cycle (R-R interval) at this rate?
, 🟢 A) 0.20 seconds
🟢 B) 0.30 seconds
🔴🔴 C) 0.40 seconds
🟢 D) 0.60 seconds
Rationale: Heart rate is calculated as 300 divided by the number of large boxes between R waves, or 1500 divided by the number of small boxes. At 150
bpm, the R-R interval is 300/150 = 2 large boxes = 0.40 seconds.
🟢 10. The P wave on an ECG represents:
🔴🔴 A) Atrial depolarization
🟢 B) Ventricular depolarization
🟢 C) Atrial repolarization
🟢 D) Ventricular repolarization
Rationale: The P wave represents atrial depolarization (contraction). The QRS complex represents ventricular depolarization, and the T wave represents
ventricular repolarization. Atrial repolarization is typically hidden within the QRS complex.
🟢 11. A patient's ECG shows a PR interval that progressively lengthens until a QRS complex is dropped, then the pattern repeats. This is characteristic of:
🟢 A) First-degree AV block
🔴🔴 B) Second-degree AV block Type I (Mobitz I/Wenckebach)
🟢 C) Second-degree AV block Type II (Mobitz II)
🟢 D) Third-degree AV block
Rationale: Second-degree AV block Type I (Mobitz I/Wenckebach) is characterized by progressive PR interval prolongation until a QRS complex is dropped.
This pattern repeats cyclically and is typically benign, often occurring at the AV node level.
🟢 12. In third-degree AV block, which of the following is true regarding the relationship between P waves and QRS complexes?
🟢 A) Each P wave is followed by a QRS complex
🟢 B) There is a 2:1 ratio of P waves to QRS complexes
🔴🔴 C) There is no consistent relationship between P waves and QRS complexes
🟢 D) P waves occur only after QRS complexes
Rationale: In third-degree (complete) AV block, the atria and ventricles beat independently. There is no relationship between P waves and QRS complexes
—the atria are paced by the SA node, and the ventricles are paced by an escape rhythm from the junction or ventricles. P-P and R-R intervals are regular
but unrelated.
🟢 13. Which ECG finding is most consistent with hypokalemia?
🟢 A) Tall, peaked T waves
🔴🔴 B) Prominent U waves and flattened T waves
🟢 C) Prolonged QT interval
🟢 D) ST-segment elevation
Rationale: Hypokalemia typically presents with flattened T waves and prominent U waves on ECG. Hyperkalemia presents with tall, peaked T waves.
Prolonged QT interval is associated with hypocalcemia or certain medications.
🟢 14. What is the approximate ventricular rate if there are 8 QRS complexes in a 6-second rhythm strip?
🟢 A) 60 bpm
🟢 B) 72 bpm
🔴🔴 C) 80 bpm
🟢 D) 96 bpm
Rationale: To calculate heart rate from a 6-second strip, count the number of QRS complexes in 6 seconds and multiply by 10. 8 complexes × 10 = 80 beats
per minute.
🟢 15. The QRS complex is >0.12 seconds and has a bizarre morphology. This finding suggests:
Answers and Clinical Rationales (2025/2026 Update)
A Complete Certification Preparation Resource for Healthcare Professionals Mastering Cardiac Rhythm Interpretation, ECG Analysis, and Emergency
Dysrhythmia Management
Table of Contents
Section Topic Area Questions
I ECG Fundamentals & Waveform Analysis 1–15
II Sinus Rhythms 16–25
III Atrial Dysrhythmias 26–40
IV Junctional Rhythms 41–50
V Ventricular Dysrhythmias 51–65
VI Heart Blocks (AV Blocks) 66–80
VII Pacemaker Rhythms & Artifact Interpretation 81–90
VIII Antiarrhythmic Pharmacology 91–100
IX Emergency Interventions & ACLS Algorithms 101–115
X Clinical Scenarios & Prioritization 116–130
XI Mixed Rhythm Identification (Strip Descriptions) 131–145
XII Comprehensive Review & High-Yield Concepts 146–150
Section I: ECG Fundamentals & Waveform Analysis
🟢 1. A 6-second ECG rhythm strip contains 30 large boxes. At a standard paper speed of 25 mm/second, how many seconds of cardiac activity does this
strip represent?
🟢 A) 3 seconds
🔴🔴 B) 6 seconds
🟢 C) 10 seconds
🟢 D) 12 seconds
Rationale: Standard ECG paper runs at 25 mm/second. Each large box (5 mm) represents 0.20 seconds. A 6-second strip contains 30 large boxes (30 × 0.20
= 6 seconds). This is the standard length used for calculating heart rate by counting QRS complexes and multiplying by 10.
🟢 2. What does the vertical axis on an ECG tracing measure?
🟢 A) Time
🔴🔴 B) Voltage (amplitude)
🟢 C) Resistance
🟢 D) Speed
Rationale: The vertical axis on ECG paper measures voltage or amplitude in millimeters (mV). Standard calibration is 10 mm = 1 mV. The horizontal axis
measures time.
,🟢 3. How many seconds does one small box represent on standard ECG paper?
🟢 A) 0.20 seconds
🟢 B) 0.12 seconds
🔴🔴 C) 0.04 seconds
🟢 D) 0.08 seconds
Rationale: At 25 mm/second, each small box (1 mm) represents 0.04 seconds. Five small boxes equal one large box (0.20 seconds).
🟢 4. A nurse notes that the PR interval on a patient's ECG measures 0.24 seconds. What is the appropriate interpretation?
🟢 A) Normal PR interval
🟢 B) Shortened PR interval
🔴🔴 C) Prolonged PR interval (first-degree AV block)
🟢 D) Inconsistent PR interval
Rationale: The normal PR interval is 0.12–0.20 seconds. A PR interval >0.20 seconds indicates first-degree AV block (prolonged AV conduction). This is a
delay in conduction from the atria to the ventricles through the AV node.
🟢 5. What is the normal duration of the QRS complex?
🟢 A) 0.04–0.08 seconds
🔴🔴 B) Less than 0.12 seconds
🟢 C) 0.12–0.20 seconds
🟢 D) Greater than 0.20 seconds
Rationale: The normal QRS duration is ≤0.12 seconds (less than 3 small boxes). A widened QRS (>0.12 seconds) indicates ventricular conduction delay,
bundle branch block, or ventricular origin of the rhythm.
🟢 6. The normal intrinsic firing rate of the sinoatrial (SA) node is:
🟢 A) 20–40 beats per minute
🟢 B) 40–60 beats per minute
🔴🔴 C) 60–100 beats per minute
🟢 D) 100–150 beats per minute
Rationale: The SA node, the primary pacemaker of the heart, naturally fires at 60–100 beats per minute. It is located in the right atrium and generates the
fastest intrinsic rate among all cardiac pacemaker tissues.
🟢 7. The normal intrinsic firing rate of the atrioventricular (AV) junction is:
🟢 A) 20–40 beats per minute
🔴🔴 B) 40–60 beats per minute
🟢 C) 60–100 beats per minute
🟢 D) 100–150 beats per minute
Rationale: The AV junction has an intrinsic rate of 40–60 beats per minute. It serves as the secondary pacemaker when the SA node fails or when
conduction is blocked.
🟢 8. Which of the following correctly identifies the sequence of the cardiac conduction system?
🟢 A) AV node → SA node → Bundle of His → Purkinje fibers → Bundle branches
🔴🔴 B) SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
🟢 C) SA node → Bundle of His → AV node → Purkinje fibers → Bundle branches
🟢 D) AV node → SA node → Bundle branches → Bundle of His → Purkinje fibers
Rationale: The cardiac conduction system sequence is: SA node (60–100 bpm) → AV node (40–60 bpm) → Bundle of His (40–45 bpm) → Right and Left
Bundle Branches (40–45 bpm) → Purkinje fibers (20–50 bpm). This ordered pathway ensures coordinated atrial and ventricular contraction.
🟢 9. A patient's ECG shows a heart rate of 150 bpm. What is the approximate duration of one cardiac cycle (R-R interval) at this rate?
, 🟢 A) 0.20 seconds
🟢 B) 0.30 seconds
🔴🔴 C) 0.40 seconds
🟢 D) 0.60 seconds
Rationale: Heart rate is calculated as 300 divided by the number of large boxes between R waves, or 1500 divided by the number of small boxes. At 150
bpm, the R-R interval is 300/150 = 2 large boxes = 0.40 seconds.
🟢 10. The P wave on an ECG represents:
🔴🔴 A) Atrial depolarization
🟢 B) Ventricular depolarization
🟢 C) Atrial repolarization
🟢 D) Ventricular repolarization
Rationale: The P wave represents atrial depolarization (contraction). The QRS complex represents ventricular depolarization, and the T wave represents
ventricular repolarization. Atrial repolarization is typically hidden within the QRS complex.
🟢 11. A patient's ECG shows a PR interval that progressively lengthens until a QRS complex is dropped, then the pattern repeats. This is characteristic of:
🟢 A) First-degree AV block
🔴🔴 B) Second-degree AV block Type I (Mobitz I/Wenckebach)
🟢 C) Second-degree AV block Type II (Mobitz II)
🟢 D) Third-degree AV block
Rationale: Second-degree AV block Type I (Mobitz I/Wenckebach) is characterized by progressive PR interval prolongation until a QRS complex is dropped.
This pattern repeats cyclically and is typically benign, often occurring at the AV node level.
🟢 12. In third-degree AV block, which of the following is true regarding the relationship between P waves and QRS complexes?
🟢 A) Each P wave is followed by a QRS complex
🟢 B) There is a 2:1 ratio of P waves to QRS complexes
🔴🔴 C) There is no consistent relationship between P waves and QRS complexes
🟢 D) P waves occur only after QRS complexes
Rationale: In third-degree (complete) AV block, the atria and ventricles beat independently. There is no relationship between P waves and QRS complexes
—the atria are paced by the SA node, and the ventricles are paced by an escape rhythm from the junction or ventricles. P-P and R-R intervals are regular
but unrelated.
🟢 13. Which ECG finding is most consistent with hypokalemia?
🟢 A) Tall, peaked T waves
🔴🔴 B) Prominent U waves and flattened T waves
🟢 C) Prolonged QT interval
🟢 D) ST-segment elevation
Rationale: Hypokalemia typically presents with flattened T waves and prominent U waves on ECG. Hyperkalemia presents with tall, peaked T waves.
Prolonged QT interval is associated with hypocalcemia or certain medications.
🟢 14. What is the approximate ventricular rate if there are 8 QRS complexes in a 6-second rhythm strip?
🟢 A) 60 bpm
🟢 B) 72 bpm
🔴🔴 C) 80 bpm
🟢 D) 96 bpm
Rationale: To calculate heart rate from a 6-second strip, count the number of QRS complexes in 6 seconds and multiply by 10. 8 complexes × 10 = 80 beats
per minute.
🟢 15. The QRS complex is >0.12 seconds and has a bizarre morphology. This finding suggests:
