Page |1
RELIAS DYSRHYTHMIA – BASIC TEST REVIEW |
LATEST UPDATE 2026/2027 | STUDY GUIDE |
PRACTICE QUESTIONS AND ANSWERS | EXAM
REVIEW
Table of Contents
1. ECG Fundamentals and Cardiac Conduction System
2. Sinus Rhythms and Sinus Arrhythmias
3. Atrial Dysrhythmias: PACs, Atrial Fibrillation, and Atrial Flutter
4. Junctional Rhythms
5. Premature Ventricular Contractions (PVCs)
6. Ventricular Rhythms: VT, VF, Idioventricular, and Asystole
7. Heart Blocks: First, Second, and Third Degree
8. Supraventricular Tachycardia (SVT)
9. Pacemaker Rhythms and Malfunctions
10. Clinical Interventions and ACLS Management
, Page |2
Question 1: What does the horizontal axis on an ECG measure?
A) Voltage
B) Time
C) Amplitude
D) Resistance
Correct Answer: B) Time
The horizontal axis on an ECG tracing measures time, while the vertical axis measures voltage
or amplitude. At the standard paper speed of 25 mm per second, each small box represents 0.04
seconds, and each large box represents 0.20 seconds. Understanding the time scale is essential
for accurately measuring intervals and calculating heart rate.
Question 2: How many seconds does one small box represent on standard ECG paper?
A) 0.04 seconds
B) 0.20 seconds
C) 0.10 seconds
D) 0.01 seconds
Correct Answer: A) 0.04 seconds
At the standard paper speed of 25 mm per second, each small box on ECG paper equals 0.04
seconds. Each large box (composed of five small boxes) equals 0.20 seconds. This measurement
system is fundamental for calculating heart rate and measuring intervals such as the PR interval
and QRS duration.
Question 3: Which ECG wave represents atrial depolarization?
A) P wave
B) QRS complex
C) T wave
D) U wave
Correct Answer: A) P wave
The P wave represents atrial depolarization, which is the electrical activation of the atria that
precedes atrial contraction. The QRS complex represents ventricular depolarization, and the T
wave represents ventricular repolarization. Atrial repolarization is typically hidden within the
QRS complex.
Question 4: Which ECG component represents ventricular depolarization?
A) P wave
B) PR interval
C) QRS complex
D) QT interval
, Page |3
Correct Answer: C) QRS complex
The QRS complex represents ventricular depolarization, the electrical activation of the ventricles
that triggers ventricular contraction. A normal QRS duration is less than 0.12 seconds (less than
three small boxes). A widened QRS indicates abnormal ventricular conduction.
Question 5: What is the normal duration of the PR interval?
A) 0.04–0.08 seconds
B) 0.12–0.20 seconds
C) 0.20–0.24 seconds
D) 0.24–0.30 seconds
Correct Answer: B) 0.12–0.20 seconds
The normal PR interval is 0.12 to 0.20 seconds (three to five small boxes). It represents the time
from the onset of atrial depolarization to the onset of ventricular depolarization. A PR interval
longer than 0.20 seconds indicates first-degree AV block.
Question 6: What is the normal intrinsic firing rate of the sinoatrial (SA) node?
A) 20–40 bpm
B) 40–60 bpm
C) 60–100 bpm
D) 100–150 bpm
Correct Answer: C) 60–100 bpm
The SA node is the primary pacemaker of the heart, with an intrinsic firing rate of 60 to 100
beats per minute. The AV junction has an intrinsic rate of 40 to 60 bpm, and the Purkinje
system/ventricles have an intrinsic rate of 20 to 40 bpm. These rates represent the hierarchy of
pacemaker sites in the heart.
Question 7: Which structure is known as the heart's primary pacemaker?
A) Atrioventricular (AV) node
B) Bundle of His
C) Sinoatrial (SA) node
D) Purkinje fibers
Correct Answer: C) Sinoatrial (SA) node
The sinoatrial (SA) node is the primary pacemaker of the heart, located in the upper right
atrium. It initiates the normal cardiac impulse, which then spreads through the atria, AV node,
Bundle of His, and Purkinje fibers. If the SA node fails, subsidiary pacemakers take over at
slower rates.
Question 8: Which structure is responsible for delaying the electrical impulse to allow ventricular
filling before contraction?
RELIAS DYSRHYTHMIA – BASIC TEST REVIEW |
LATEST UPDATE 2026/2027 | STUDY GUIDE |
PRACTICE QUESTIONS AND ANSWERS | EXAM
REVIEW
Table of Contents
1. ECG Fundamentals and Cardiac Conduction System
2. Sinus Rhythms and Sinus Arrhythmias
3. Atrial Dysrhythmias: PACs, Atrial Fibrillation, and Atrial Flutter
4. Junctional Rhythms
5. Premature Ventricular Contractions (PVCs)
6. Ventricular Rhythms: VT, VF, Idioventricular, and Asystole
7. Heart Blocks: First, Second, and Third Degree
8. Supraventricular Tachycardia (SVT)
9. Pacemaker Rhythms and Malfunctions
10. Clinical Interventions and ACLS Management
, Page |2
Question 1: What does the horizontal axis on an ECG measure?
A) Voltage
B) Time
C) Amplitude
D) Resistance
Correct Answer: B) Time
The horizontal axis on an ECG tracing measures time, while the vertical axis measures voltage
or amplitude. At the standard paper speed of 25 mm per second, each small box represents 0.04
seconds, and each large box represents 0.20 seconds. Understanding the time scale is essential
for accurately measuring intervals and calculating heart rate.
Question 2: How many seconds does one small box represent on standard ECG paper?
A) 0.04 seconds
B) 0.20 seconds
C) 0.10 seconds
D) 0.01 seconds
Correct Answer: A) 0.04 seconds
At the standard paper speed of 25 mm per second, each small box on ECG paper equals 0.04
seconds. Each large box (composed of five small boxes) equals 0.20 seconds. This measurement
system is fundamental for calculating heart rate and measuring intervals such as the PR interval
and QRS duration.
Question 3: Which ECG wave represents atrial depolarization?
A) P wave
B) QRS complex
C) T wave
D) U wave
Correct Answer: A) P wave
The P wave represents atrial depolarization, which is the electrical activation of the atria that
precedes atrial contraction. The QRS complex represents ventricular depolarization, and the T
wave represents ventricular repolarization. Atrial repolarization is typically hidden within the
QRS complex.
Question 4: Which ECG component represents ventricular depolarization?
A) P wave
B) PR interval
C) QRS complex
D) QT interval
, Page |3
Correct Answer: C) QRS complex
The QRS complex represents ventricular depolarization, the electrical activation of the ventricles
that triggers ventricular contraction. A normal QRS duration is less than 0.12 seconds (less than
three small boxes). A widened QRS indicates abnormal ventricular conduction.
Question 5: What is the normal duration of the PR interval?
A) 0.04–0.08 seconds
B) 0.12–0.20 seconds
C) 0.20–0.24 seconds
D) 0.24–0.30 seconds
Correct Answer: B) 0.12–0.20 seconds
The normal PR interval is 0.12 to 0.20 seconds (three to five small boxes). It represents the time
from the onset of atrial depolarization to the onset of ventricular depolarization. A PR interval
longer than 0.20 seconds indicates first-degree AV block.
Question 6: What is the normal intrinsic firing rate of the sinoatrial (SA) node?
A) 20–40 bpm
B) 40–60 bpm
C) 60–100 bpm
D) 100–150 bpm
Correct Answer: C) 60–100 bpm
The SA node is the primary pacemaker of the heart, with an intrinsic firing rate of 60 to 100
beats per minute. The AV junction has an intrinsic rate of 40 to 60 bpm, and the Purkinje
system/ventricles have an intrinsic rate of 20 to 40 bpm. These rates represent the hierarchy of
pacemaker sites in the heart.
Question 7: Which structure is known as the heart's primary pacemaker?
A) Atrioventricular (AV) node
B) Bundle of His
C) Sinoatrial (SA) node
D) Purkinje fibers
Correct Answer: C) Sinoatrial (SA) node
The sinoatrial (SA) node is the primary pacemaker of the heart, located in the upper right
atrium. It initiates the normal cardiac impulse, which then spreads through the atria, AV node,
Bundle of His, and Purkinje fibers. If the SA node fails, subsidiary pacemakers take over at
slower rates.
Question 8: Which structure is responsible for delaying the electrical impulse to allow ventricular
filling before contraction?
