, Relias Dysrhythmia Basic A Exam
2026/2027 | 35 Verified Questions &
Answers | Relias Learning Competency
Prep | 7 Core Domains | Instant
Download | rated 100% correct.
DOMAIN 1: ECG FUNDAMENTALS & CONDUCTION
SYSTEM
1. Which structure normally functions as the primary pacemaker of the
heart?
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B (Sinoatrial [SA] node)
Rationale: The SA node normally initiates the electrical impulse that
produces sinus rhythm. It has the fastest intrinsic firing rate (60-100 bpm)
among the normal cardiac pacemakers. The AV node fires at 40-60 bpm, the
Bundle of His at 40-45 bpm, and Purkinje fibers at 20-40 bpm .
Teaching Point: SA node = primary pacemaker (60-100 bpm).
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
2. The AV node delays the electrical impulse primarily to:
, A. Prevent ventricular repolarization
B. Allow complete atrial emptying into the ventricles
C. Initiate the QRS complex
D. Slow the heart rate permanently
Correct Answer: B (Allow complete atrial emptying into the
ventricles)
Rationale: The AV node delays the impulse approximately 0.1 seconds to
allow complete atrial emptying into the ventricles before ventricular
contraction. This ensures optimal ventricular filling .
Teaching Point: AV node delay = allows complete atrial emptying.
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
3. On a standard ECG tracing, the P wave represents:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B (Atrial depolarization)
Rationale: The P wave represents atrial depolarization. The QRS complex
represents ventricular depolarization; the T wave represents ventricular
repolarization. Atrial repolarization is typically hidden within the QRS
complex .
Teaching Point: P wave = atrial depolarization.
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
4. What is the normal duration range for the PR interval?
2026/2027 | 35 Verified Questions &
Answers | Relias Learning Competency
Prep | 7 Core Domains | Instant
Download | rated 100% correct.
DOMAIN 1: ECG FUNDAMENTALS & CONDUCTION
SYSTEM
1. Which structure normally functions as the primary pacemaker of the
heart?
A. Atrioventricular (AV) node
B. Sinoatrial (SA) node
C. Bundle of His
D. Purkinje fibers
Correct Answer: B (Sinoatrial [SA] node)
Rationale: The SA node normally initiates the electrical impulse that
produces sinus rhythm. It has the fastest intrinsic firing rate (60-100 bpm)
among the normal cardiac pacemakers. The AV node fires at 40-60 bpm, the
Bundle of His at 40-45 bpm, and Purkinje fibers at 20-40 bpm .
Teaching Point: SA node = primary pacemaker (60-100 bpm).
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
2. The AV node delays the electrical impulse primarily to:
, A. Prevent ventricular repolarization
B. Allow complete atrial emptying into the ventricles
C. Initiate the QRS complex
D. Slow the heart rate permanently
Correct Answer: B (Allow complete atrial emptying into the
ventricles)
Rationale: The AV node delays the impulse approximately 0.1 seconds to
allow complete atrial emptying into the ventricles before ventricular
contraction. This ensures optimal ventricular filling .
Teaching Point: AV node delay = allows complete atrial emptying.
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
3. On a standard ECG tracing, the P wave represents:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: B (Atrial depolarization)
Rationale: The P wave represents atrial depolarization. The QRS complex
represents ventricular depolarization; the T wave represents ventricular
repolarization. Atrial repolarization is typically hidden within the QRS
complex .
Teaching Point: P wave = atrial depolarization.
Source: Relias Dysrhythmia Basic A Test Comprehensive Examination
2026/2027
4. What is the normal duration range for the PR interval?
