Basic Arrhythmia (EKG) Exam | Complete Rhythm
Recognition Questions, Answers & Explanations
2026/2027
QUESTION 1 What is the normal duration of a standard QRS complex in
healthy adult patients?
A. 0.06 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.40 seconds
D. Less than 0.04 seconds
Correct Answer: A. 0.06 to 0.10 seconds
Detailed Rationale: A normal QRS complex reflects rapid ventricular
depolarization and typically measures between 1.5 and 2.5 small boxes
(0.06 to 0.10 seconds) on standard ECG graph paper.
QUESTION 2 How is the heart rate rapidly calculated on a standard 6-
second ECG rhythm strip?
A. Count the number of complete QRS complexes in the 6-second strip
and multiply by 10
B. Count the number of small boxes between two R waves and divide
into 1500
C. Measure the R-R interval in seconds and divide by 60
D. Multiply the number of P waves in 1 minute by 5
,Correct Answer: A. Count the number of complete QRS complexes in
the 6-second strip and multiply by 10
Detailed Rationale: The 6-second method is a reliable clinical technique
for estimating both regular and irregular heart rates by multiplying the
number of QRS complexes in a 6-second window by 10 to yield beats
per minute.
QUESTION 3 What physiological event does the P wave represent on a
standard ECG?
A. Atrial depolarization
B. Ventricular repolarization
C. Atrial repolarization
D. Ventricular depolarization
Correct Answer: A. Atrial depolarization
Detailed Rationale: The P wave corresponds to the spread of electrical
activation through the right and left atria, initiating atrial contraction
prior to ventricular activation.
QUESTION 4 What is the normal clinical measurement range for a
standard PR interval?
A. 0.12 to 0.20 seconds
B. 0.06 to 0.10 seconds
C. 0.20 to 0.40 seconds
D. 0.04 to 0.08 seconds
Correct Answer: A. 0.12 to 0.20 seconds
,Detailed Rationale: The PR interval spans from the beginning of the P
wave to the beginning of the QRS complex, representing the time
required for electrical impulses to travel from the SA node through the
AV node and bundle system (3 to 5 small boxes).
QUESTION 5 Which standard ECG lead is most frequently selected for
continuous bedside rhythm monitoring?
A. Lead II
B. Lead aVR
C. Lead V3
D. Lead III
Correct Answer: A. Lead II
Detailed Rationale: Lead II aligns closely with the normal electrical axis
of the heart, providing an optimal view for identifying upright P waves,
QRS complexes, and T wave morphology.
QUESTION 6 What characterizes Sinus Bradycardia on an ECG monitor?
A. A regular rhythm with a rate below 60 beats per minute, normal
upright P waves in leads II, III, and aVF, and a 1:1 AV conduction ratio.
B. An irregular rhythm exceeding 100 beats per minute with absent P
waves.
C. A slow rhythm under 40 beats per minute with wide bizarre QRS
complexes.
D. Sawtooth baseline flutter waves with slow ventricular response.
, Correct Answer: A. A regular rhythm with a rate below 60 beats per
minute, normal upright P waves in leads II, III, and aVF, and a 1:1 AV
conduction ratio.
Detailed Rationale: Sinus bradycardia originates normally in the SA
node but fires at a rate slower than 60 beats per minute while
maintaining normal waveform morphology.
QUESTION 7 What are the primary ECG criteria for Sinus Tachycardia?
A. A regular rhythm with a rate exceeding 100 beats per minute,
preceded by normal upright P waves and consistent PR intervals.
B. A rapid, irregular rhythm with fibrillatory baseline waves.
C. Narrow QRS complexes occurring at 75 beats per minute with
inverted P waves.
D. Prolonged PR intervals exceeding 0.24 seconds with a rate of 110
bpm.
Correct Answer: A. A regular rhythm with a rate exceeding 100 beats
per minute, preceded by normal upright P waves and consistent PR
intervals.
Detailed Rationale: Sinus tachycardia reflects normal SA node
activation accelerating past 100 beats per minute in response to
physiological stressors such as fever, exercise, or anxiety.
QUESTION 8 How is a Premature Atrial Contraction (PAC) identified on a
rhythm strip?
A. An early, abnormal P wave that alters the expected rhythm regularity,
followed by a QRS complex that is usually narrow.
Recognition Questions, Answers & Explanations
2026/2027
QUESTION 1 What is the normal duration of a standard QRS complex in
healthy adult patients?
A. 0.06 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.40 seconds
D. Less than 0.04 seconds
Correct Answer: A. 0.06 to 0.10 seconds
Detailed Rationale: A normal QRS complex reflects rapid ventricular
depolarization and typically measures between 1.5 and 2.5 small boxes
(0.06 to 0.10 seconds) on standard ECG graph paper.
QUESTION 2 How is the heart rate rapidly calculated on a standard 6-
second ECG rhythm strip?
A. Count the number of complete QRS complexes in the 6-second strip
and multiply by 10
B. Count the number of small boxes between two R waves and divide
into 1500
C. Measure the R-R interval in seconds and divide by 60
D. Multiply the number of P waves in 1 minute by 5
,Correct Answer: A. Count the number of complete QRS complexes in
the 6-second strip and multiply by 10
Detailed Rationale: The 6-second method is a reliable clinical technique
for estimating both regular and irregular heart rates by multiplying the
number of QRS complexes in a 6-second window by 10 to yield beats
per minute.
QUESTION 3 What physiological event does the P wave represent on a
standard ECG?
A. Atrial depolarization
B. Ventricular repolarization
C. Atrial repolarization
D. Ventricular depolarization
Correct Answer: A. Atrial depolarization
Detailed Rationale: The P wave corresponds to the spread of electrical
activation through the right and left atria, initiating atrial contraction
prior to ventricular activation.
QUESTION 4 What is the normal clinical measurement range for a
standard PR interval?
A. 0.12 to 0.20 seconds
B. 0.06 to 0.10 seconds
C. 0.20 to 0.40 seconds
D. 0.04 to 0.08 seconds
Correct Answer: A. 0.12 to 0.20 seconds
,Detailed Rationale: The PR interval spans from the beginning of the P
wave to the beginning of the QRS complex, representing the time
required for electrical impulses to travel from the SA node through the
AV node and bundle system (3 to 5 small boxes).
QUESTION 5 Which standard ECG lead is most frequently selected for
continuous bedside rhythm monitoring?
A. Lead II
B. Lead aVR
C. Lead V3
D. Lead III
Correct Answer: A. Lead II
Detailed Rationale: Lead II aligns closely with the normal electrical axis
of the heart, providing an optimal view for identifying upright P waves,
QRS complexes, and T wave morphology.
QUESTION 6 What characterizes Sinus Bradycardia on an ECG monitor?
A. A regular rhythm with a rate below 60 beats per minute, normal
upright P waves in leads II, III, and aVF, and a 1:1 AV conduction ratio.
B. An irregular rhythm exceeding 100 beats per minute with absent P
waves.
C. A slow rhythm under 40 beats per minute with wide bizarre QRS
complexes.
D. Sawtooth baseline flutter waves with slow ventricular response.
, Correct Answer: A. A regular rhythm with a rate below 60 beats per
minute, normal upright P waves in leads II, III, and aVF, and a 1:1 AV
conduction ratio.
Detailed Rationale: Sinus bradycardia originates normally in the SA
node but fires at a rate slower than 60 beats per minute while
maintaining normal waveform morphology.
QUESTION 7 What are the primary ECG criteria for Sinus Tachycardia?
A. A regular rhythm with a rate exceeding 100 beats per minute,
preceded by normal upright P waves and consistent PR intervals.
B. A rapid, irregular rhythm with fibrillatory baseline waves.
C. Narrow QRS complexes occurring at 75 beats per minute with
inverted P waves.
D. Prolonged PR intervals exceeding 0.24 seconds with a rate of 110
bpm.
Correct Answer: A. A regular rhythm with a rate exceeding 100 beats
per minute, preceded by normal upright P waves and consistent PR
intervals.
Detailed Rationale: Sinus tachycardia reflects normal SA node
activation accelerating past 100 beats per minute in response to
physiological stressors such as fever, exercise, or anxiety.
QUESTION 8 How is a Premature Atrial Contraction (PAC) identified on a
rhythm strip?
A. An early, abnormal P wave that alters the expected rhythm regularity,
followed by a QRS complex that is usually narrow.
