Dysrhythmia Basic A Updated 2026 | Comprehensive Study Guide,
Practice Exam Questions and Answers, Exam Prep Test Bank, ECG
Rhythm Interpretation, Cardiac Conduction System Review,
Arrhythmia Recognition and Analysis, Heart Rate Calculation
Methods, Telemetry Monitoring Concepts, and Detailed Rationales
for Nursing and Cardiac Care Preparation
Question 1: What does the horizontal axis on an ECG measure? A. Voltage B. Time C.
Amplitude D. Resistance CORRECT ANSWER: B. Time Rationale: The horizontal axis on
ECG paper measures time.
Question 2: How many seconds does one large box represent? A. 0.04 seconds B.
0.20 seconds C. 0.10 seconds D. 1.00 seconds CORRECT ANSWER: B. 0.20 seconds
Rationale: One large box equals five small boxes, representing 0.20 seconds.
Question 3: What is the duration of one small box 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 Rationale: Each small box on the horizontal axis represents 0.04 seconds.
Question 4: What voltage does one small box on the vertical axis represent? A. 0.1
mV B. 0.5 mV C. 1.0 mV D. 0.01 mV CORRECT ANSWER: A. 0.1 mV Rationale:
Vertically, each small box represents 0.1 millivolts of amplitude.
Question 5: What is the standard paper speed for an ECG? A. 10 mm/sec B. 25
mm/sec C. 50 mm/sec D. 100 mm/sec CORRECT ANSWER: B. 25 mm/sec Rationale:
The standard recording speed for an ECG is 25 mm per second.
Question 6: Where is the SA node located? A. Left atrium B. Right atrium C. Left
ventricle D. Interventricular septum CORRECT ANSWER: B. Right atrium Rationale:
The sinoatrial node is located in the upper wall of the right atrium.
Question 7: Where is the AV node located? A. Floor of the right atrium B. Apex of the
right ventricle C. Interventricular septum D. Left atrium CORRECT ANSWER: A. Floor of
the right atrium Rationale: The atrioventricular node is located in the floor of the right
atrium near the septum.
Question 8: What structure directly follows the AV node in the conduction
pathway? A. Bundle branches B. Purkinje fibers C. Bundle of His D. Internodal
pathways CORRECT ANSWER: C. Bundle of His Rationale: The electrical impulse
travels from the AV node to the Bundle of His.
Question 9: What is the normal intrinsic firing rate of the SA node? A. 20-40 bpm B.
40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: C. 60-100 bpm
Rationale: The SA node naturally fires at a rate of 60 to 100 beats per minute.
Question 10: What is the normal intrinsic firing rate of the AV junction? A. 20-40 bpm
B. 40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: B. 40-60 bpm
Rationale: The AV junction has an intrinsic rate of 40 to 60 beats per minute.
,Question 11: What is the normal intrinsic firing rate of the ventricles? A. 20-40 bpm
B. 40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: A. 20-40 bpm
Rationale: Ventricular pacemaker cells fire at an intrinsic rate of 20 to 40 beats per
minute.
Question 12: What does the P wave represent? A. Atrial repolarization B. Atrial
depolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: B. Atrial depolarization Rationale: The P wave is generated by the
depolarization of the atria.
Question 13: What does the QRS complex represent? A. Atrial depolarization B. Atrial
repolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: C. Ventricular depolarization Rationale: The QRS complex represents the
depolarization of the ventricles.
Question 14: What does the T wave represent? A. Atrial depolarization B. Atrial
repolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: D. Ventricular repolarization Rationale: The T wave represents ventricular
repolarization or recovery.
Question 15: 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 Rationale: The normal PR interval measures between
0.12 and 0.20 seconds.
Question 16: What is the normal duration of the QRS complex? A. Less than 0.04
seconds B. Less than 0.12 seconds C. Less than 0.20 seconds D. Less than 0.30
seconds CORRECT ANSWER: B. Less than 0.12 seconds Rationale: A normal QRS
complex duration is less than 0.12 seconds.
Question 17: What does the PR interval primarily measure? A. Atrial depolarization
time B. Conduction delay through the AV node C. Ventricular depolarization time D.
Total ventricular activity CORRECT ANSWER: B. Conduction delay through the AV
node Rationale: The PR interval represents the time it takes for the impulse to travel
through the AV node.
Question 18: What does the QT interval represent? A. Total atrial activity B. Total
ventricular activity C. AV node conduction time D. Ventricular repolarization only
CORRECT ANSWER: B. Total ventricular activity Rationale: The QT interval represents
total ventricular depolarization and repolarization time.
Question 19: What is the first step in systematic ECG interpretation? A. Measure the
PR interval B. Determine the heart rate C. Assess the rhythm regularity D. Identify P
waves CORRECT ANSWER: C. Assess the rhythm regularity Rationale: Assessing
rhythm regularity is typically the first step in systematic interpretation.
Question 20: Which method is best for calculating the heart rate of an irregular
rhythm? A. 300 method B. 1500 method C. 6-second method D. 10-second method
, CORRECT ANSWER: C. 6-second method Rationale: The 6-second method is accurate
for irregular rhythms by counting QRS complexes and multiplying by 10.
Question 21: What is the normal heart rate range for Normal Sinus Rhythm (NSR)?
A. 40-60 bpm B. 60-100 bpm C. 100-150 bpm D. >150 bpm CORRECT ANSWER: B. 60-
100 bpm Rationale: NSR has a normal rate between 60 and 100 beats per minute.
Question 22: In NSR, what is the shape of the P wave in Lead II? A. Inverted B. Flat C.
Upright and rounded D. Biphasic CORRECT ANSWER: C. Upright and rounded
Rationale: In NSR, the impulse originates in the SA node, making P waves upright in
Lead II.
Question 23: What defines Sinus Bradycardia? A. Rate < 40 bpm B. Rate < 60 bpm C.
Rate > 100 bpm D. Irregular rhythm CORRECT ANSWER: B. Rate < 60 bpm Rationale:
Sinus bradycardia is a normal sinus rhythm with a rate less than 60 bpm.
Question 24: What is a common cause of Sinus Bradycardia? A. Fever B. Increased
vagal tone C. Hypovolemia D. Pain CORRECT ANSWER: B. Increased vagal tone
Rationale: Increased vagal tone slows the SA node firing rate, causing bradycardia.
Question 25: What is the first-line medication for symptomatic Sinus Bradycardia?
A. Epinephrine B. Amiodarone C. Atropine D. Adenosine CORRECT ANSWER: C.
Atropine Rationale: Atropine is the first-line drug to increase heart rate in symptomatic
bradycardia.
Question 26: What defines Sinus Tachycardia? A. Rate > 80 bpm B. Rate > 100 bpm C.
Rate > 120 bpm D. Rate > 150 bpm CORRECT ANSWER: B. Rate > 100 bpm Rationale:
Sinus tachycardia is a normal sinus rhythm with a rate greater than 100 bpm.
Question 27: Which of the following is a common cause of Sinus Tachycardia? A.
Sleep B. Hypothermia C. Exercise D. Vagal stimulation CORRECT ANSWER: C. Exercise
Rationale: Exercise increases sympathetic demand, causing sinus tachycardia.
Question 28: What characterizes Sinus Arrhythmia? A. Rate > 100 bpm B. Rate varies
with respiration C. Dropped P waves D. Inverted P waves CORRECT ANSWER: B. Rate
varies with respiration Rationale: Sinus arrhythmia is a phasic variation in heart rate
associated with breathing.
Question 29: Sinus Arrhythmia is most commonly seen in which population? A.
Elderly patients B. Healthy young people C. Post-MI patients D. Patients with heart
failure CORRECT ANSWER: B. Healthy young people Rationale: Sinus arrhythmia is a
normal, benign finding often seen in children and young adults.
Question 30: What characterizes a Premature Atrial Contraction (PAC)? A. Wide,
bizarre QRS B. Early, abnormal P wave C. Absent P wave D. Prolonged PR interval
CORRECT ANSWER: B. Early, abnormal P wave Rationale: A PAC is characterized by
an early, abnormally shaped P wave before a narrow QRS.
Practice Exam Questions and Answers, Exam Prep Test Bank, ECG
Rhythm Interpretation, Cardiac Conduction System Review,
Arrhythmia Recognition and Analysis, Heart Rate Calculation
Methods, Telemetry Monitoring Concepts, and Detailed Rationales
for Nursing and Cardiac Care Preparation
Question 1: What does the horizontal axis on an ECG measure? A. Voltage B. Time C.
Amplitude D. Resistance CORRECT ANSWER: B. Time Rationale: The horizontal axis on
ECG paper measures time.
Question 2: How many seconds does one large box represent? A. 0.04 seconds B.
0.20 seconds C. 0.10 seconds D. 1.00 seconds CORRECT ANSWER: B. 0.20 seconds
Rationale: One large box equals five small boxes, representing 0.20 seconds.
Question 3: What is the duration of one small box 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 Rationale: Each small box on the horizontal axis represents 0.04 seconds.
Question 4: What voltage does one small box on the vertical axis represent? A. 0.1
mV B. 0.5 mV C. 1.0 mV D. 0.01 mV CORRECT ANSWER: A. 0.1 mV Rationale:
Vertically, each small box represents 0.1 millivolts of amplitude.
Question 5: What is the standard paper speed for an ECG? A. 10 mm/sec B. 25
mm/sec C. 50 mm/sec D. 100 mm/sec CORRECT ANSWER: B. 25 mm/sec Rationale:
The standard recording speed for an ECG is 25 mm per second.
Question 6: Where is the SA node located? A. Left atrium B. Right atrium C. Left
ventricle D. Interventricular septum CORRECT ANSWER: B. Right atrium Rationale:
The sinoatrial node is located in the upper wall of the right atrium.
Question 7: Where is the AV node located? A. Floor of the right atrium B. Apex of the
right ventricle C. Interventricular septum D. Left atrium CORRECT ANSWER: A. Floor of
the right atrium Rationale: The atrioventricular node is located in the floor of the right
atrium near the septum.
Question 8: What structure directly follows the AV node in the conduction
pathway? A. Bundle branches B. Purkinje fibers C. Bundle of His D. Internodal
pathways CORRECT ANSWER: C. Bundle of His Rationale: The electrical impulse
travels from the AV node to the Bundle of His.
Question 9: What is the normal intrinsic firing rate of the SA node? A. 20-40 bpm B.
40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: C. 60-100 bpm
Rationale: The SA node naturally fires at a rate of 60 to 100 beats per minute.
Question 10: What is the normal intrinsic firing rate of the AV junction? A. 20-40 bpm
B. 40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: B. 40-60 bpm
Rationale: The AV junction has an intrinsic rate of 40 to 60 beats per minute.
,Question 11: What is the normal intrinsic firing rate of the ventricles? A. 20-40 bpm
B. 40-60 bpm C. 60-100 bpm D. 100-150 bpm CORRECT ANSWER: A. 20-40 bpm
Rationale: Ventricular pacemaker cells fire at an intrinsic rate of 20 to 40 beats per
minute.
Question 12: What does the P wave represent? A. Atrial repolarization B. Atrial
depolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: B. Atrial depolarization Rationale: The P wave is generated by the
depolarization of the atria.
Question 13: What does the QRS complex represent? A. Atrial depolarization B. Atrial
repolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: C. Ventricular depolarization Rationale: The QRS complex represents the
depolarization of the ventricles.
Question 14: What does the T wave represent? A. Atrial depolarization B. Atrial
repolarization C. Ventricular depolarization D. Ventricular repolarization CORRECT
ANSWER: D. Ventricular repolarization Rationale: The T wave represents ventricular
repolarization or recovery.
Question 15: 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 Rationale: The normal PR interval measures between
0.12 and 0.20 seconds.
Question 16: What is the normal duration of the QRS complex? A. Less than 0.04
seconds B. Less than 0.12 seconds C. Less than 0.20 seconds D. Less than 0.30
seconds CORRECT ANSWER: B. Less than 0.12 seconds Rationale: A normal QRS
complex duration is less than 0.12 seconds.
Question 17: What does the PR interval primarily measure? A. Atrial depolarization
time B. Conduction delay through the AV node C. Ventricular depolarization time D.
Total ventricular activity CORRECT ANSWER: B. Conduction delay through the AV
node Rationale: The PR interval represents the time it takes for the impulse to travel
through the AV node.
Question 18: What does the QT interval represent? A. Total atrial activity B. Total
ventricular activity C. AV node conduction time D. Ventricular repolarization only
CORRECT ANSWER: B. Total ventricular activity Rationale: The QT interval represents
total ventricular depolarization and repolarization time.
Question 19: What is the first step in systematic ECG interpretation? A. Measure the
PR interval B. Determine the heart rate C. Assess the rhythm regularity D. Identify P
waves CORRECT ANSWER: C. Assess the rhythm regularity Rationale: Assessing
rhythm regularity is typically the first step in systematic interpretation.
Question 20: Which method is best for calculating the heart rate of an irregular
rhythm? A. 300 method B. 1500 method C. 6-second method D. 10-second method
, CORRECT ANSWER: C. 6-second method Rationale: The 6-second method is accurate
for irregular rhythms by counting QRS complexes and multiplying by 10.
Question 21: What is the normal heart rate range for Normal Sinus Rhythm (NSR)?
A. 40-60 bpm B. 60-100 bpm C. 100-150 bpm D. >150 bpm CORRECT ANSWER: B. 60-
100 bpm Rationale: NSR has a normal rate between 60 and 100 beats per minute.
Question 22: In NSR, what is the shape of the P wave in Lead II? A. Inverted B. Flat C.
Upright and rounded D. Biphasic CORRECT ANSWER: C. Upright and rounded
Rationale: In NSR, the impulse originates in the SA node, making P waves upright in
Lead II.
Question 23: What defines Sinus Bradycardia? A. Rate < 40 bpm B. Rate < 60 bpm C.
Rate > 100 bpm D. Irregular rhythm CORRECT ANSWER: B. Rate < 60 bpm Rationale:
Sinus bradycardia is a normal sinus rhythm with a rate less than 60 bpm.
Question 24: What is a common cause of Sinus Bradycardia? A. Fever B. Increased
vagal tone C. Hypovolemia D. Pain CORRECT ANSWER: B. Increased vagal tone
Rationale: Increased vagal tone slows the SA node firing rate, causing bradycardia.
Question 25: What is the first-line medication for symptomatic Sinus Bradycardia?
A. Epinephrine B. Amiodarone C. Atropine D. Adenosine CORRECT ANSWER: C.
Atropine Rationale: Atropine is the first-line drug to increase heart rate in symptomatic
bradycardia.
Question 26: What defines Sinus Tachycardia? A. Rate > 80 bpm B. Rate > 100 bpm C.
Rate > 120 bpm D. Rate > 150 bpm CORRECT ANSWER: B. Rate > 100 bpm Rationale:
Sinus tachycardia is a normal sinus rhythm with a rate greater than 100 bpm.
Question 27: Which of the following is a common cause of Sinus Tachycardia? A.
Sleep B. Hypothermia C. Exercise D. Vagal stimulation CORRECT ANSWER: C. Exercise
Rationale: Exercise increases sympathetic demand, causing sinus tachycardia.
Question 28: What characterizes Sinus Arrhythmia? A. Rate > 100 bpm B. Rate varies
with respiration C. Dropped P waves D. Inverted P waves CORRECT ANSWER: B. Rate
varies with respiration Rationale: Sinus arrhythmia is a phasic variation in heart rate
associated with breathing.
Question 29: Sinus Arrhythmia is most commonly seen in which population? A.
Elderly patients B. Healthy young people C. Post-MI patients D. Patients with heart
failure CORRECT ANSWER: B. Healthy young people Rationale: Sinus arrhythmia is a
normal, benign finding often seen in children and young adults.
Question 30: What characterizes a Premature Atrial Contraction (PAC)? A. Wide,
bizarre QRS B. Early, abnormal P wave C. Absent P wave D. Prolonged PR interval
CORRECT ANSWER: B. Early, abnormal P wave Rationale: A PAC is characterized by
an early, abnormally shaped P wave before a narrow QRS.
