Relias Dysrhythmia Basic A Examination — 2026/2027 35 Questions | 60 Minutes
Relias Dysrhythmia Basic A Examination
35 Questions and Answers — Edition
Basic A Dysrhythmia Competency Assessment | Aligned with 2026–2027 AHA ACLS Guidelines
Time Limit: 60 Minutes | Total Questions: 35 | Passing Score: 80% | Cognitive Distribution: 30% Recall / 50%
Application / 20% Analysis
Directions: Select the ONE best answer for each question. Each item presents a clinical scenario, rhythm
strip description, or direct knowledge recall of ECG interpretation. The correct option is marked
[CORRECT], followed by the answer key letter and a 2–3 sentence rationale explaining the rhythm's rate,
regularity, P wave characteristics, PR interval, QRS width, and clinical significance. Use the rationales to
review systematically using the six-step interpretation method: Rate → Rhythm → P waves → PR
interval → QRS width → Relationship.
SECTION 1 — Cardiac Anatomy, Conduction System, and ECG Fundamentals
(Q1–Q7)
Topics: SA node, AV node, Bundle of His, Bundle branches, Purkinje fibers, ECG waveforms, intervals, and lead
placement
Q1. Which structure of the heart's conduction system normally serves as the primary
pacemaker and initiates each heartbeat with an intrinsic firing rate of 60–100 beats per
minute?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node [CORRECT]
D. Purkinje fibers
Correct Answer: C
Rationale: The sinoatrial (SA) node, located in the upper right atrium, is the heart's dominant pacemaker
with an intrinsic rate of 60–100 bpm. The AV node fires at 40–60 bpm and the Purkinje/ventricular tissue at
20–40 bpm, becoming escape pacemakers only when higher pacemakers fail.
Q2. A patient's ECG shows a regular rhythm with a normal P wave preceding each QRS
complex. The PR interval measures 0.16 seconds. What is the correct interpretation of this
finding?
A. First-degree AV block; PR interval is prolonged
B. Normal PR interval; conduction through the AV node is intact [CORRECT]
C. Junctional rhythm; P wave is retrograde
D. Bundle branch block; QRS will be wide
Correct Answer: B
Rationale: The normal PR interval ranges from 0.12 to 0.20 seconds (3–5 small boxes), representing the
time for atrial depolarization and the delay through the AV node. A PR interval of 0.16 seconds is within
normal limits. First-degree AV block requires a PR interval greater than 0.20 seconds.
Basic A Dysrhythmia Competency Assessment Page 1
, Relias Dysrhythmia Basic A Examination — 2026/2027 35 Questions | 60 Minutes
Q3. On a standard rhythm strip, the QRS complex for a patient measures 0.14 seconds in
width. What does this finding indicate, and which rhythm feature is most likely affected?
A. Normal QRS duration; no concern
B. Wide QRS indicating delayed ventricular depolarization, consistent with a bundle branch
block or ventricular origin [CORRECT]
C. Shortened QRS indicating pre-excitation syndrome
D. QT prolongation increasing risk for torsades
Correct Answer: B
Rationale: A normal QRS complex measures 0.06–0.10 seconds (1.5–2.5 small boxes). A QRS of 0.14
seconds is wide, indicating delayed ventricular depolarization — typical of bundle branch block, ventricular
paced beats, or rhythms of ventricular origin such as PVCs or ventricular tachycardia.
Q4. When applying a 5-lead ECG monitoring system for continuous cardiac monitoring, which
lead is most commonly used as the primary monitoring lead for routine rhythm interpretation
because it best displays P waves, QRS amplitude, and ST segment changes?
A. Lead I
B. Lead II [CORRECT]
C. Lead III
D. MCL1 (modified chest lead V1)
Correct Answer: B
Rationale: Lead II is the standard monitoring lead because its axis (positive at the leg, negative at the right
arm) closely parallels the heart's normal electrical axis, producing upright P waves, tall R waves, and clear
ST segments. MCL1 is preferred for differentiate wide-complex tachycardias and bundle branch blocks, but
is not the routine primary lead.
Q5. Place the following structures of the cardiac conduction system in the correct sequence
of an electrical impulse traveling from initiation to ventricular depolarization: (1) AV node, (2)
Bundle branches, (3) SA node, (4) Purkinje fibers, (5) Bundle of His.
A. 3 → 1 → 5 → 2 → 4 [CORRECT]
B. 3 → 5 → 1 → 4 → 2
C. 1 → 3 → 5 → 2 → 4
D. 3 → 1 → 2 → 5 → 4
Correct Answer: A
Rationale: The normal conduction pathway is: SA node (3) initiates the impulse → AV node (1) delays it
~0.1 seconds → Bundle of His (5) conducts to the ventricles → Bundle branches (2) divide the impulse to
right and left ventricles → Purkinje fibers (4) distribute it throughout the ventricular myocardium for
synchronized contraction.
Basic A Dysrhythmia Competency Assessment Page 2
Relias Dysrhythmia Basic A Examination
35 Questions and Answers — Edition
Basic A Dysrhythmia Competency Assessment | Aligned with 2026–2027 AHA ACLS Guidelines
Time Limit: 60 Minutes | Total Questions: 35 | Passing Score: 80% | Cognitive Distribution: 30% Recall / 50%
Application / 20% Analysis
Directions: Select the ONE best answer for each question. Each item presents a clinical scenario, rhythm
strip description, or direct knowledge recall of ECG interpretation. The correct option is marked
[CORRECT], followed by the answer key letter and a 2–3 sentence rationale explaining the rhythm's rate,
regularity, P wave characteristics, PR interval, QRS width, and clinical significance. Use the rationales to
review systematically using the six-step interpretation method: Rate → Rhythm → P waves → PR
interval → QRS width → Relationship.
SECTION 1 — Cardiac Anatomy, Conduction System, and ECG Fundamentals
(Q1–Q7)
Topics: SA node, AV node, Bundle of His, Bundle branches, Purkinje fibers, ECG waveforms, intervals, and lead
placement
Q1. Which structure of the heart's conduction system normally serves as the primary
pacemaker and initiates each heartbeat with an intrinsic firing rate of 60–100 beats per
minute?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node [CORRECT]
D. Purkinje fibers
Correct Answer: C
Rationale: The sinoatrial (SA) node, located in the upper right atrium, is the heart's dominant pacemaker
with an intrinsic rate of 60–100 bpm. The AV node fires at 40–60 bpm and the Purkinje/ventricular tissue at
20–40 bpm, becoming escape pacemakers only when higher pacemakers fail.
Q2. A patient's ECG shows a regular rhythm with a normal P wave preceding each QRS
complex. The PR interval measures 0.16 seconds. What is the correct interpretation of this
finding?
A. First-degree AV block; PR interval is prolonged
B. Normal PR interval; conduction through the AV node is intact [CORRECT]
C. Junctional rhythm; P wave is retrograde
D. Bundle branch block; QRS will be wide
Correct Answer: B
Rationale: The normal PR interval ranges from 0.12 to 0.20 seconds (3–5 small boxes), representing the
time for atrial depolarization and the delay through the AV node. A PR interval of 0.16 seconds is within
normal limits. First-degree AV block requires a PR interval greater than 0.20 seconds.
Basic A Dysrhythmia Competency Assessment Page 1
, Relias Dysrhythmia Basic A Examination — 2026/2027 35 Questions | 60 Minutes
Q3. On a standard rhythm strip, the QRS complex for a patient measures 0.14 seconds in
width. What does this finding indicate, and which rhythm feature is most likely affected?
A. Normal QRS duration; no concern
B. Wide QRS indicating delayed ventricular depolarization, consistent with a bundle branch
block or ventricular origin [CORRECT]
C. Shortened QRS indicating pre-excitation syndrome
D. QT prolongation increasing risk for torsades
Correct Answer: B
Rationale: A normal QRS complex measures 0.06–0.10 seconds (1.5–2.5 small boxes). A QRS of 0.14
seconds is wide, indicating delayed ventricular depolarization — typical of bundle branch block, ventricular
paced beats, or rhythms of ventricular origin such as PVCs or ventricular tachycardia.
Q4. When applying a 5-lead ECG monitoring system for continuous cardiac monitoring, which
lead is most commonly used as the primary monitoring lead for routine rhythm interpretation
because it best displays P waves, QRS amplitude, and ST segment changes?
A. Lead I
B. Lead II [CORRECT]
C. Lead III
D. MCL1 (modified chest lead V1)
Correct Answer: B
Rationale: Lead II is the standard monitoring lead because its axis (positive at the leg, negative at the right
arm) closely parallels the heart's normal electrical axis, producing upright P waves, tall R waves, and clear
ST segments. MCL1 is preferred for differentiate wide-complex tachycardias and bundle branch blocks, but
is not the routine primary lead.
Q5. Place the following structures of the cardiac conduction system in the correct sequence
of an electrical impulse traveling from initiation to ventricular depolarization: (1) AV node, (2)
Bundle branches, (3) SA node, (4) Purkinje fibers, (5) Bundle of His.
A. 3 → 1 → 5 → 2 → 4 [CORRECT]
B. 3 → 5 → 1 → 4 → 2
C. 1 → 3 → 5 → 2 → 4
D. 3 → 1 → 2 → 5 → 4
Correct Answer: A
Rationale: The normal conduction pathway is: SA node (3) initiates the impulse → AV node (1) delays it
~0.1 seconds → Bundle of His (5) conducts to the ventricles → Bundle branches (2) divide the impulse to
right and left ventricles → Purkinje fibers (4) distribute it throughout the ventricular myocardium for
synchronized contraction.
Basic A Dysrhythmia Competency Assessment Page 2
