NURS 5337 Module 5 EKG Quiz | 40 Questions & Answers
with Rationales | Verified | Latest Update - University of
Texas, Arlington| 2026
1. On a 12 lead ECG, the P waves represents:
Atrial depolarization
2. T wave inversion eight hours after a myocardial infarction may
indicate:
Ischemia
3. Left ventricular hypertrophy is is diagnosed by measuring R waves in
leads:
V5 and V6
4. The ECG tech seems to be in a big rush to get the patient's ECG
completed. What common placement error can cause the wave
pattern to look like the patient is having a myocardial infarction when
they are not?
(incorrect) V1 and V2 are not placed in the 4th
intercostal space correctly.
5. The NP notes tall peaked T waves when reviewing a patient's ECG.
The most likely cause of this phenomenon is:
Hyperkalemia
6. To differentiate between left bundle branch block and anterior wall
infarction, the NP considers:
QRS duration and T wave inversion
7. Axis is determined by the position of the QRS in leads:
Lead I and aVf
8. Select the correct location for the placement of precordial lead V1.
4th intercostal space to the right of the sternum
9. The most common cause of acute MI is
Coronary thrombosis
10. What is the normal, dominant pacemaker of the heart?
SA node
,M5 EKG EXAM Full 40 Questions and
Answers
SECTION I: ECG FUNDAMENTALS AND
CARDIAC CONDUCTION
Question 1
On a standard 12-lead electrocardiogram (ECG), what does the P wave represent?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization alone
Correct Answer: B. Atrial depolarization
Rationale: The P wave represents electrical depolarization of the atria, which precedes atrial
contraction. Ventricular depolarization is represented by the QRS complex, while ventricular
repolarization is represented by the T wave. Atrial repolarization is usually obscured by the QRS
complex.
Question 2
What is the normal dominant pacemaker of the heart?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node
D. Purkinje fibers
Correct Answer: C. Sinoatrial (SA) node
Rationale: The SA node normally initiates the electrical impulse that establishes sinus rhythm.
Its intrinsic firing rate is typically about 60–100 beats per minute in adults. The AV junction and
ventricular conduction system can act as backup pacemakers if the SA node fails or impulses do
not reach the ventricles normally.
Question 3
Which ECG component represents ventricular depolarization?
A. P wave
B. PR interval
C. QRS complex
D. T wave
, Correct Answer: C. QRS complex
Rationale: The QRS complex represents ventricular depolarization, which initiates ventricular
contraction. A normal QRS duration is generally less than 120 milliseconds. A widened QRS can
occur with bundle branch block, ventricular rhythms, or delayed intraventricular conduction.
Question 4
Which ECG component primarily represents ventricular repolarization?
A. P wave
B. QRS complex
C. PR segment
D. T wave
Correct Answer: D. T wave
Rationale: The T wave represents ventricular repolarization, the electrical recovery phase
following ventricular depolarization. T-wave abnormalities can occur with ischemia, electrolyte
disturbances, medications, and other cardiac conditions. Interpretation must consider the overall
ECG and clinical presentation.
Question 5
What does the PR interval measure?
A. The time from the beginning of atrial depolarization to the beginning of ventricular
depolarization
B. The duration of ventricular repolarization only
C. The time required for the ventricles to complete repolarization
D. The duration of the QRS complex alone
Correct Answer: A. The time from the beginning of atrial depolarization to the beginning
of ventricular depolarization
Rationale: The PR interval extends from the beginning of the P wave to the beginning of the
QRS complex. It reflects atrial depolarization and conduction through the AV junction and
associated conduction pathways. A normal PR interval is generally 120–200 milliseconds.
Question 6
Which ECG finding is generally consistent with a normal QRS duration?
A. 80 milliseconds
B. 140 milliseconds
C. 180 milliseconds
D. 220 milliseconds
Correct Answer: A. 80 milliseconds
with Rationales | Verified | Latest Update - University of
Texas, Arlington| 2026
1. On a 12 lead ECG, the P waves represents:
Atrial depolarization
2. T wave inversion eight hours after a myocardial infarction may
indicate:
Ischemia
3. Left ventricular hypertrophy is is diagnosed by measuring R waves in
leads:
V5 and V6
4. The ECG tech seems to be in a big rush to get the patient's ECG
completed. What common placement error can cause the wave
pattern to look like the patient is having a myocardial infarction when
they are not?
(incorrect) V1 and V2 are not placed in the 4th
intercostal space correctly.
5. The NP notes tall peaked T waves when reviewing a patient's ECG.
The most likely cause of this phenomenon is:
Hyperkalemia
6. To differentiate between left bundle branch block and anterior wall
infarction, the NP considers:
QRS duration and T wave inversion
7. Axis is determined by the position of the QRS in leads:
Lead I and aVf
8. Select the correct location for the placement of precordial lead V1.
4th intercostal space to the right of the sternum
9. The most common cause of acute MI is
Coronary thrombosis
10. What is the normal, dominant pacemaker of the heart?
SA node
,M5 EKG EXAM Full 40 Questions and
Answers
SECTION I: ECG FUNDAMENTALS AND
CARDIAC CONDUCTION
Question 1
On a standard 12-lead electrocardiogram (ECG), what does the P wave represent?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization alone
Correct Answer: B. Atrial depolarization
Rationale: The P wave represents electrical depolarization of the atria, which precedes atrial
contraction. Ventricular depolarization is represented by the QRS complex, while ventricular
repolarization is represented by the T wave. Atrial repolarization is usually obscured by the QRS
complex.
Question 2
What is the normal dominant pacemaker of the heart?
A. Atrioventricular (AV) node
B. Bundle of His
C. Sinoatrial (SA) node
D. Purkinje fibers
Correct Answer: C. Sinoatrial (SA) node
Rationale: The SA node normally initiates the electrical impulse that establishes sinus rhythm.
Its intrinsic firing rate is typically about 60–100 beats per minute in adults. The AV junction and
ventricular conduction system can act as backup pacemakers if the SA node fails or impulses do
not reach the ventricles normally.
Question 3
Which ECG component represents ventricular depolarization?
A. P wave
B. PR interval
C. QRS complex
D. T wave
, Correct Answer: C. QRS complex
Rationale: The QRS complex represents ventricular depolarization, which initiates ventricular
contraction. A normal QRS duration is generally less than 120 milliseconds. A widened QRS can
occur with bundle branch block, ventricular rhythms, or delayed intraventricular conduction.
Question 4
Which ECG component primarily represents ventricular repolarization?
A. P wave
B. QRS complex
C. PR segment
D. T wave
Correct Answer: D. T wave
Rationale: The T wave represents ventricular repolarization, the electrical recovery phase
following ventricular depolarization. T-wave abnormalities can occur with ischemia, electrolyte
disturbances, medications, and other cardiac conditions. Interpretation must consider the overall
ECG and clinical presentation.
Question 5
What does the PR interval measure?
A. The time from the beginning of atrial depolarization to the beginning of ventricular
depolarization
B. The duration of ventricular repolarization only
C. The time required for the ventricles to complete repolarization
D. The duration of the QRS complex alone
Correct Answer: A. The time from the beginning of atrial depolarization to the beginning
of ventricular depolarization
Rationale: The PR interval extends from the beginning of the P wave to the beginning of the
QRS complex. It reflects atrial depolarization and conduction through the AV junction and
associated conduction pathways. A normal PR interval is generally 120–200 milliseconds.
Question 6
Which ECG finding is generally consistent with a normal QRS duration?
A. 80 milliseconds
B. 140 milliseconds
C. 180 milliseconds
D. 220 milliseconds
Correct Answer: A. 80 milliseconds
