APEX EKG TEST QUESTIONS WITH CORRECT
ANSWERS & RATIONALES | MASTER ECG
INTERPRETATION FOR NURSING &
CARDIOLOGY CERTIFICATION
Question 1
Atrial Fibrillation
Correct Answer
Regularity: atrial and ventricular rate irregularly irregular
Rate:
Atrial rate: unable to determine they are beating in excess of 350 to 700 beats per
minute
Ventricular rate: when the HR is 100 or less beats per minute, the rate is said to be
"controlled"; if the ventricular rate is > 100 beats per minute then the rhythm is said
to have a RVR (rapid ventricular response)
P wave: absent, indiscernible, replaced by fibrillatory waves
PRI : indiscernible
QRS: 0.06 to 0.10 seconds
QTI: may be indiscernible
T wave: may be indiscernible
Question 2
Accelerated Junctional Rhythm
Correct Answer
Regularity: atrial and ventricular rate is regular
Rate: > 60 but less than 100
P wave: inverted or absent, may be before, within or after the QRS
PRI : less than 0.12 seconds if the P wave precedes the QRS complex
QRS: 0.06 to 0.10 seconds and usually normal
QTI: 0.36 to 0.46 seconds
T wave: usually normal, upright, smooth and round uniform shape
Page 1 of 74
,Question 3
Wandering Atrial Pacemaker
Correct Answer
If you have three or more different looking P waves but the strip meets the rest of
sinus criteria it is call Wandering Atrial Pacemaker (WAP)
Less than 100
Irregular
Question 4
The 6 Second Strip Method
Correct Answer
Least accurate, but quickest way to estimate rate especially in irregular rhythms
Question 5
QT Interval
Correct Answer
Normal 0.36-0.46
Page 2 of 74
,Question 6
Ventricular Fibrillation (LETHAL)
Correct Answer
Regularity: indeterminable
Rate: unable to measure, ventricles are beating in excess of 400 beats per minute
P wave: none
PRI : none
QRS: none
QTI: none
T wave: none
There are NO waveforms only an irregular wavy chaotic baseline
Question 1: Which of the following best describes the normal duration of the
PR interval on a standard 12-lead ECG?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.28 seconds
D. 0.30 to 0.40 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The normal PR interval measures from the beginning of the P wave to the
beginning of the QRS complex and represents atrioventricular conduction time. A
duration of 0.12 to 0.20 seconds (3 to 5 small boxes) is considered normal; values
outside this range suggest conduction abnormalities such as first-degree AV block
or pre-excitation.
Question 2: On a standard ECG tracing, one small box on the horizontal axis
represents which time interval?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 0.40 seconds
CORRECT ANSWER: A. 0.04 seconds
Rationale: Standard ECG paper speed is 25 mm/second. Each small box (1 mm)
equals 0.04 seconds, and each large box (5 mm) equals 0.20 seconds. Accurate
measurement of intervals depends on this calibration.
Question 3: Which lead is most commonly used to monitor rhythm
continuously in a clinical setting because it provides a clear view of P waves?
Page 3 of 74
, A. Lead I
B. Lead II
C. Lead aVR
D. Lead V1
CORRECT ANSWER: B. Lead II
Rationale: Lead II orients positively toward the left leg and aligns well with the
normal atrial depolarization vector, producing upright P waves of good amplitude.
This makes it the preferred lead for continuous rhythm monitoring in most patients.
Question 4: A patient presents with a regular rhythm, rate of 72 beats per
minute, upright P waves preceding every QRS, and a PR interval of 0.16
seconds. What is the most accurate rhythm interpretation?
A. Sinus bradycardia
B. Normal sinus rhythm
C. Sinus tachycardia
D. First-degree AV block
CORRECT ANSWER: B. Normal sinus rhythm
Rationale: Normal sinus rhythm is defined by a rate of 60–100 beats per minute,
regular rhythm, upright P waves in leads I, II, and aVF that precede each QRS
complex, and a normal PR interval (0.12–0.20 seconds). All criteria are met in this
description.
Question 5: Which of the following ECG findings is characteristic of sinus
bradycardia?
A. Rate greater than 100 beats per minute with upright P waves
B. Rate less than 60 beats per minute with upright P waves preceding each QRS
C. Irregular rhythm with no identifiable P waves
D. Rate of 60–100 with inverted P waves in lead II
CORRECT ANSWER: B. Rate less than 60 beats per minute with upright P waves
preceding each QRS
Rationale: Sinus bradycardia originates from the sinoatrial node but occurs at a rate
below 60 beats per minute. P-wave morphology remains normal and each P wave is
followed by a QRS complex, distinguishing it from other slow rhythms.
Question 6: What is the most common cause of a prolonged QT interval that
can predispose a patient to torsades de pointes?
A. Hyperkalemia
B. Hypokalemia or medication effect
Page 4 of 74
ANSWERS & RATIONALES | MASTER ECG
INTERPRETATION FOR NURSING &
CARDIOLOGY CERTIFICATION
Question 1
Atrial Fibrillation
Correct Answer
Regularity: atrial and ventricular rate irregularly irregular
Rate:
Atrial rate: unable to determine they are beating in excess of 350 to 700 beats per
minute
Ventricular rate: when the HR is 100 or less beats per minute, the rate is said to be
"controlled"; if the ventricular rate is > 100 beats per minute then the rhythm is said
to have a RVR (rapid ventricular response)
P wave: absent, indiscernible, replaced by fibrillatory waves
PRI : indiscernible
QRS: 0.06 to 0.10 seconds
QTI: may be indiscernible
T wave: may be indiscernible
Question 2
Accelerated Junctional Rhythm
Correct Answer
Regularity: atrial and ventricular rate is regular
Rate: > 60 but less than 100
P wave: inverted or absent, may be before, within or after the QRS
PRI : less than 0.12 seconds if the P wave precedes the QRS complex
QRS: 0.06 to 0.10 seconds and usually normal
QTI: 0.36 to 0.46 seconds
T wave: usually normal, upright, smooth and round uniform shape
Page 1 of 74
,Question 3
Wandering Atrial Pacemaker
Correct Answer
If you have three or more different looking P waves but the strip meets the rest of
sinus criteria it is call Wandering Atrial Pacemaker (WAP)
Less than 100
Irregular
Question 4
The 6 Second Strip Method
Correct Answer
Least accurate, but quickest way to estimate rate especially in irregular rhythms
Question 5
QT Interval
Correct Answer
Normal 0.36-0.46
Page 2 of 74
,Question 6
Ventricular Fibrillation (LETHAL)
Correct Answer
Regularity: indeterminable
Rate: unable to measure, ventricles are beating in excess of 400 beats per minute
P wave: none
PRI : none
QRS: none
QTI: none
T wave: none
There are NO waveforms only an irregular wavy chaotic baseline
Question 1: Which of the following best describes the normal duration of the
PR interval on a standard 12-lead ECG?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.28 seconds
D. 0.30 to 0.40 seconds
CORRECT ANSWER: B. 0.12 to 0.20 seconds
Rationale: The normal PR interval measures from the beginning of the P wave to the
beginning of the QRS complex and represents atrioventricular conduction time. A
duration of 0.12 to 0.20 seconds (3 to 5 small boxes) is considered normal; values
outside this range suggest conduction abnormalities such as first-degree AV block
or pre-excitation.
Question 2: On a standard ECG tracing, one small box on the horizontal axis
represents which time interval?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 0.40 seconds
CORRECT ANSWER: A. 0.04 seconds
Rationale: Standard ECG paper speed is 25 mm/second. Each small box (1 mm)
equals 0.04 seconds, and each large box (5 mm) equals 0.20 seconds. Accurate
measurement of intervals depends on this calibration.
Question 3: Which lead is most commonly used to monitor rhythm
continuously in a clinical setting because it provides a clear view of P waves?
Page 3 of 74
, A. Lead I
B. Lead II
C. Lead aVR
D. Lead V1
CORRECT ANSWER: B. Lead II
Rationale: Lead II orients positively toward the left leg and aligns well with the
normal atrial depolarization vector, producing upright P waves of good amplitude.
This makes it the preferred lead for continuous rhythm monitoring in most patients.
Question 4: A patient presents with a regular rhythm, rate of 72 beats per
minute, upright P waves preceding every QRS, and a PR interval of 0.16
seconds. What is the most accurate rhythm interpretation?
A. Sinus bradycardia
B. Normal sinus rhythm
C. Sinus tachycardia
D. First-degree AV block
CORRECT ANSWER: B. Normal sinus rhythm
Rationale: Normal sinus rhythm is defined by a rate of 60–100 beats per minute,
regular rhythm, upright P waves in leads I, II, and aVF that precede each QRS
complex, and a normal PR interval (0.12–0.20 seconds). All criteria are met in this
description.
Question 5: Which of the following ECG findings is characteristic of sinus
bradycardia?
A. Rate greater than 100 beats per minute with upright P waves
B. Rate less than 60 beats per minute with upright P waves preceding each QRS
C. Irregular rhythm with no identifiable P waves
D. Rate of 60–100 with inverted P waves in lead II
CORRECT ANSWER: B. Rate less than 60 beats per minute with upright P waves
preceding each QRS
Rationale: Sinus bradycardia originates from the sinoatrial node but occurs at a rate
below 60 beats per minute. P-wave morphology remains normal and each P wave is
followed by a QRS complex, distinguishing it from other slow rhythms.
Question 6: What is the most common cause of a prolonged QT interval that
can predispose a patient to torsades de pointes?
A. Hyperkalemia
B. Hypokalemia or medication effect
Page 4 of 74
