Basic Arrhythmia Sentara ECG Interpretation
Exam Questions and Verified Answers with
Rationale Latest Edition 2026/2027
1. Which of the following ECG changes is most
characteristic of acute transmural myocardial infarction?
A. Prolonged PR interval
B. ST segment elevation
C. Sinus bradycardia
D. Normal baseline with shortened QT interval
Correct Answer: B
Rationale: ST segment elevation is the classic hallmark of
acute transmural myocardial injury or infarction, reflecting
current of injury vectors pointing toward the affected
epicardial leads.
2. When calculating heart rate using the 1500 method on a
regular rhythm, what value is divided by the number of
small boxes between two consecutive R waves?
A. 300
B. 1500
C. 3000
D. 10 inches
Correct Answer: B
, Rationale: The 1500 method divides the constant 1500
(representing the number of small boxes in one minute at
standard 25 mm/s paper speed) by the total number of small
boxes between consecutive R waves to yield an accurate
heart rate for regular rhythms.
3. What is the intrinsic firing rate of the normal sinus node
pacemaker in an adult?
A. 20 to 40 beats per minute
B. 40 to 60 beats per minute
C. 60 to 100 beats per minute
D. 100 to 140 beats per minute
Correct Answer: C
Rationale: The sinoatrial node normally depolarizes at an
intrinsic rate of 60 to 100 beats per minute, establishing
normal sinus rhythm under autonomic nervous system
modulation.
4. Which rhythm strip finding differentiates Ventricular
Tachycardia from supraventricular tachycardia with
aberrant conduction?
A. Presence of delta waves
B. Fusion and capture beats
C. PR interval greater than 0.20 seconds
D. Narrow QRS complex duration
, Correct Answer: B
Rationale: Fusion beats and capture beats are diagnostic
indicators of ventricular tachycardia, occurring when
supraventricular impulses briefly capture the ventricles
during ongoing AV dissociation.
5. On a standard 12-lead ECG, what anatomical surface of
the heart is evaluated by leads V1 through V4?
A. Inferior wall
B. Lateral wall
C. Anterior wall
D. Posterior wall
Correct Answer: C
Rationale: Leads V1, V2, V3, and V4 directly view the
anterior wall of the left ventricle and portions of the
interventricular septum.
6. Which medication is the primary first-line
pharmacological treatment for stable symptomatic sinus
bradycardia?
A. Adenosine
B. Amiodarone
C. Atropine
D. Procainamide
Correct Answer: C
, Rationale: Atropine acts as a parasympatholytic agent to
inhibit vagal tone at the SA and AV nodes, accelerating
heart rate in symptomatic bradycardia.
7. What is the defining characteristic of a third-degree
(complete) atrioventricular block?
A. Progressive prolongation of the PR interval until a QRS is
dropped
B. Constant PR interval with intermittently dropped QRS
complexes
C. Complete absence of any P waves on the rhythm strip
D. Complete independence and lack of conduction relationship
between P waves and QRS complexes
Correct Answer: D
Rationale: Third-degree AV block is characterized by
complete dissociation between atrial and ventricular
activity due to total block at the AV node, bundle of His, or
bundle branches, resulting in independent atrial and
junctional or ventricular pacemaker rates.
8. Which of the following waveforms represents ventricular
repolarization on a standard ECG tracing?
A. P wave
B. QRS complex
C. T wave
Exam Questions and Verified Answers with
Rationale Latest Edition 2026/2027
1. Which of the following ECG changes is most
characteristic of acute transmural myocardial infarction?
A. Prolonged PR interval
B. ST segment elevation
C. Sinus bradycardia
D. Normal baseline with shortened QT interval
Correct Answer: B
Rationale: ST segment elevation is the classic hallmark of
acute transmural myocardial injury or infarction, reflecting
current of injury vectors pointing toward the affected
epicardial leads.
2. When calculating heart rate using the 1500 method on a
regular rhythm, what value is divided by the number of
small boxes between two consecutive R waves?
A. 300
B. 1500
C. 3000
D. 10 inches
Correct Answer: B
, Rationale: The 1500 method divides the constant 1500
(representing the number of small boxes in one minute at
standard 25 mm/s paper speed) by the total number of small
boxes between consecutive R waves to yield an accurate
heart rate for regular rhythms.
3. What is the intrinsic firing rate of the normal sinus node
pacemaker in an adult?
A. 20 to 40 beats per minute
B. 40 to 60 beats per minute
C. 60 to 100 beats per minute
D. 100 to 140 beats per minute
Correct Answer: C
Rationale: The sinoatrial node normally depolarizes at an
intrinsic rate of 60 to 100 beats per minute, establishing
normal sinus rhythm under autonomic nervous system
modulation.
4. Which rhythm strip finding differentiates Ventricular
Tachycardia from supraventricular tachycardia with
aberrant conduction?
A. Presence of delta waves
B. Fusion and capture beats
C. PR interval greater than 0.20 seconds
D. Narrow QRS complex duration
, Correct Answer: B
Rationale: Fusion beats and capture beats are diagnostic
indicators of ventricular tachycardia, occurring when
supraventricular impulses briefly capture the ventricles
during ongoing AV dissociation.
5. On a standard 12-lead ECG, what anatomical surface of
the heart is evaluated by leads V1 through V4?
A. Inferior wall
B. Lateral wall
C. Anterior wall
D. Posterior wall
Correct Answer: C
Rationale: Leads V1, V2, V3, and V4 directly view the
anterior wall of the left ventricle and portions of the
interventricular septum.
6. Which medication is the primary first-line
pharmacological treatment for stable symptomatic sinus
bradycardia?
A. Adenosine
B. Amiodarone
C. Atropine
D. Procainamide
Correct Answer: C
, Rationale: Atropine acts as a parasympatholytic agent to
inhibit vagal tone at the SA and AV nodes, accelerating
heart rate in symptomatic bradycardia.
7. What is the defining characteristic of a third-degree
(complete) atrioventricular block?
A. Progressive prolongation of the PR interval until a QRS is
dropped
B. Constant PR interval with intermittently dropped QRS
complexes
C. Complete absence of any P waves on the rhythm strip
D. Complete independence and lack of conduction relationship
between P waves and QRS complexes
Correct Answer: D
Rationale: Third-degree AV block is characterized by
complete dissociation between atrial and ventricular
activity due to total block at the AV node, bundle of His, or
bundle branches, resulting in independent atrial and
junctional or ventricular pacemaker rates.
8. Which of the following waveforms represents ventricular
repolarization on a standard ECG tracing?
A. P wave
B. QRS complex
C. T wave
