ECG/EKG Competency Exam — Code:
NUR-EKG-COMP | 100-Question
Advanced Practice Exam 2026 |
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. A patient with crushing substernal chest pain has an ECG showing ST-
segment elevation in leads II, III, and aVF. Which coronary artery is most
commonly associated with this pattern?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Left main coronary artery
Answer: Right coronary artery
,Rationale: Inferior ST-segment elevation in leads II, III, and aVF most commonly
indicates an inferior STEMI involving the right coronary artery, although the left
circumflex artery can also be responsible.
2. Which ECG finding is most characteristic of hyperkalemia in its early stage?
A. Prolonged QT interval
B. Peaked T waves
C. U waves
D. Widened QRS complexes
Answer: Peaked T waves
Rationale: Early hyperkalemia classically produces tall, narrow, peaked T waves.
As potassium rises further, PR prolongation, P-wave flattening or loss, QRS
widening, and eventually a sine-wave pattern may occur.
3. A rhythm strip shows a regular ventricular rate of 150/min, narrow QRS
complexes, and sawtooth flutter waves. Which rhythm is most likely?
A. Atrial fibrillation
B. Atrial flutter with 2:1 conduction
C. Sinus tachycardia
D. Multifocal atrial tachycardia
Answer: Atrial flutter with 2:1 conduction
Rationale: Atrial flutter commonly has an atrial rate near 300/min. With 2:1 AV
conduction, the ventricular rate is approximately 150/min and flutter waves
may be difficult to recognize.
4. Which ECG lead is considered the best single lead for monitoring P waves
and atrial activity in many clinical settings?
A. Lead II
B. Lead III
C. aVR
D. V6
,Answer: Lead II
Rationale: Lead II often provides excellent visualization of P waves because the
normal atrial depolarization vector travels toward the positive electrode of lead
II.
5. A patient has a regular rhythm at 42/min. Each QRS is preceded by a
normal P wave, and the PR interval is constant. Which rhythm is present?
A. Junctional rhythm
B. Sinus bradycardia
C. Complete heart block
D. Ventricular escape rhythm
Answer: Sinus bradycardia
Rationale: Sinus bradycardia has a sinus P wave before every QRS with a
consistent PR interval and a rate below 60/min in adults.
6. Which ECG interval represents the total time required for ventricular
depolarization?
A. PR interval
B. QT interval
C. QRS duration
D. ST interval
Answer: QRS duration
Rationale: The QRS complex represents ventricular depolarization. A QRS
duration of 0.12 seconds or greater is generally considered prolonged.
7. A patient has an irregularly irregular rhythm, no clearly identifiable P
waves, and narrow QRS complexes. Which rhythm is most likely?
A. Atrial flutter
B. Atrial fibrillation
, C. Sinus arrhythmia
D. Junctional tachycardia
Answer: Atrial fibrillation
Rationale: Atrial fibrillation is characterized by chaotic atrial activity, absent
organized P waves, and an irregularly irregular ventricular response when AV
conduction is variable.
8. Which ECG change is most concerning for acute myocardial ischemia?
A. ST-segment elevation in contiguous leads
B. Sinus arrhythmia
C. Isolated first-degree AV block
D. Mild respiratory variation
Answer: ST-segment elevation in contiguous leads
Rationale: New ST-segment elevation in anatomically contiguous leads can
indicate acute coronary occlusion and requires immediate clinical evaluation.
9. A patient has a PR interval of 0.24 seconds, with every P wave followed by a
QRS complex. Which conduction abnormality is present?
A. Mobitz I second-degree AV block
B. Mobitz II second-degree AV block
C. First-degree AV block
D. Complete heart block
Answer: First-degree AV block
Rationale: First-degree AV block is defined by a PR interval greater than 0.20
seconds with every atrial impulse conducted to the ventricles.
10.Which finding differentiates Mobitz II from Mobitz I second-degree AV
block?
NUR-EKG-COMP | 100-Question
Advanced Practice Exam 2026 |
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. A patient with crushing substernal chest pain has an ECG showing ST-
segment elevation in leads II, III, and aVF. Which coronary artery is most
commonly associated with this pattern?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Left main coronary artery
Answer: Right coronary artery
,Rationale: Inferior ST-segment elevation in leads II, III, and aVF most commonly
indicates an inferior STEMI involving the right coronary artery, although the left
circumflex artery can also be responsible.
2. Which ECG finding is most characteristic of hyperkalemia in its early stage?
A. Prolonged QT interval
B. Peaked T waves
C. U waves
D. Widened QRS complexes
Answer: Peaked T waves
Rationale: Early hyperkalemia classically produces tall, narrow, peaked T waves.
As potassium rises further, PR prolongation, P-wave flattening or loss, QRS
widening, and eventually a sine-wave pattern may occur.
3. A rhythm strip shows a regular ventricular rate of 150/min, narrow QRS
complexes, and sawtooth flutter waves. Which rhythm is most likely?
A. Atrial fibrillation
B. Atrial flutter with 2:1 conduction
C. Sinus tachycardia
D. Multifocal atrial tachycardia
Answer: Atrial flutter with 2:1 conduction
Rationale: Atrial flutter commonly has an atrial rate near 300/min. With 2:1 AV
conduction, the ventricular rate is approximately 150/min and flutter waves
may be difficult to recognize.
4. Which ECG lead is considered the best single lead for monitoring P waves
and atrial activity in many clinical settings?
A. Lead II
B. Lead III
C. aVR
D. V6
,Answer: Lead II
Rationale: Lead II often provides excellent visualization of P waves because the
normal atrial depolarization vector travels toward the positive electrode of lead
II.
5. A patient has a regular rhythm at 42/min. Each QRS is preceded by a
normal P wave, and the PR interval is constant. Which rhythm is present?
A. Junctional rhythm
B. Sinus bradycardia
C. Complete heart block
D. Ventricular escape rhythm
Answer: Sinus bradycardia
Rationale: Sinus bradycardia has a sinus P wave before every QRS with a
consistent PR interval and a rate below 60/min in adults.
6. Which ECG interval represents the total time required for ventricular
depolarization?
A. PR interval
B. QT interval
C. QRS duration
D. ST interval
Answer: QRS duration
Rationale: The QRS complex represents ventricular depolarization. A QRS
duration of 0.12 seconds or greater is generally considered prolonged.
7. A patient has an irregularly irregular rhythm, no clearly identifiable P
waves, and narrow QRS complexes. Which rhythm is most likely?
A. Atrial flutter
B. Atrial fibrillation
, C. Sinus arrhythmia
D. Junctional tachycardia
Answer: Atrial fibrillation
Rationale: Atrial fibrillation is characterized by chaotic atrial activity, absent
organized P waves, and an irregularly irregular ventricular response when AV
conduction is variable.
8. Which ECG change is most concerning for acute myocardial ischemia?
A. ST-segment elevation in contiguous leads
B. Sinus arrhythmia
C. Isolated first-degree AV block
D. Mild respiratory variation
Answer: ST-segment elevation in contiguous leads
Rationale: New ST-segment elevation in anatomically contiguous leads can
indicate acute coronary occlusion and requires immediate clinical evaluation.
9. A patient has a PR interval of 0.24 seconds, with every P wave followed by a
QRS complex. Which conduction abnormality is present?
A. Mobitz I second-degree AV block
B. Mobitz II second-degree AV block
C. First-degree AV block
D. Complete heart block
Answer: First-degree AV block
Rationale: First-degree AV block is defined by a PR interval greater than 0.20
seconds with every atrial impulse conducted to the ventricles.
10.Which finding differentiates Mobitz II from Mobitz I second-degree AV
block?
