Basic Arrhythmia Sentara Comprehensive Mock
Exam Questions and Verified Answers with
Rationale Latest Edition 2026/2027
Question 1
A rhythm strip shows a heart rate of 75 bpm, a regular rhythm, a
P wave before every QRS, a PR interval of 0.16 seconds, and a
QRS duration of 0.08 seconds. What is the interpretation?
A Normal Sinus Rhythm
B Sinus Bradycardia
C Sinus Tachycardia
D First-degree AV Block
Correct Answer: A
Rationale: This rhythm meets all criteria for Normal Sinus
Rhythm: rate 60–100, regular, 1:1 P:QRS ratio, normal PR
(0.12–0.20s), and normal QRS (0.06–0.10s).
Question 2
You identify a rhythm with a rate of 120 bpm, narrow QRS
complexes, and a sawtooth baseline pattern between the QRS
complexes. What is the most likely rhythm?
A Atrial Fibrillation
B Atrial Flutter
, C Ventricular Tachycardia
D Supraventricular Tachycardia
Correct Answer: B
Rationale: The "sawtooth" or "picket-fence" baseline is the
hallmark of Atrial Flutter, which is caused by a macro-reentrant
circuit in the right atrium.
Question 3
In a patient with a suspected second-degree AV block, Type 2
(Mobitz II), what specific ECG feature do you expect to see?
A Progressively lengthening PR intervals until a beat is
dropped
B Constant PR intervals with intermittently dropped QRS
complexes
C Complete dissociation between P waves and QRS
complexes
D A fixed PR interval of 0.24 seconds with every P wave
conducted
Correct Answer: B
Rationale: Mobitz II is characterized by intermittent, non-
conducted P waves, but the PR interval of the conducted beats
remains constant. This rhythm is dangerous because it often
progresses to complete heart block.
Question 4
,A patient on a cardiac monitor suddenly exhibits a wide-
complex, regular rhythm at a rate of 160 bpm. There are no P
waves visible. What is the most appropriate initial action if the
patient is symptomatic and hypotensive?
A Administer Adenosine 6mg IV push
B Perform synchronized cardioversion
C Start a lidocaine drip
D Administer Atropine 1mg IV
Correct Answer: B
Rationale: The patient is in unstable Ventricular Tachycardia
(wide complex, no P waves, hypotensive). Unstable
tachyarrhythmias with a pulse require immediate synchronized
cardioversion.
Question 5
What is the primary purpose of the "300-150-100-75-60-50" rule
in ECG interpretation?
A Measuring the QRS duration
B Calculating the heart rate for regular rhythms using large
boxes
C Determining the QT interval
D Calculating the axis of the heart
Correct Answer: B
, Rationale: This is the standard "large box" method for
estimating heart rate on a regular rhythm strip. You count the
number of large boxes (0.20s each) between two R waves and
divide 300 by that number.
Question 6
You are analyzing a rhythm and notice that the PR interval is
consistently 0.28 seconds, but every P wave is followed by a
QRS complex. How do you interpret this?
A First-degree AV Block
B Second-degree AV Block, Type 1
C Second-degree AV Block, Type 2
D Third-degree AV Block
Correct Answer: A
Rationale: First-degree AV block is defined by a constant PR
interval that exceeds the upper limit of normal (0.20 seconds).
Question 7
What is the distinguishing feature of a "Junctional Escape
Rhythm"?
A A rate of 40-60 bpm with absent or retrograde P waves
B A rate of 20-40 bpm with wide QRS complexes
C A rate of 100-150 bpm with narrow QRS complexes
Exam Questions and Verified Answers with
Rationale Latest Edition 2026/2027
Question 1
A rhythm strip shows a heart rate of 75 bpm, a regular rhythm, a
P wave before every QRS, a PR interval of 0.16 seconds, and a
QRS duration of 0.08 seconds. What is the interpretation?
A Normal Sinus Rhythm
B Sinus Bradycardia
C Sinus Tachycardia
D First-degree AV Block
Correct Answer: A
Rationale: This rhythm meets all criteria for Normal Sinus
Rhythm: rate 60–100, regular, 1:1 P:QRS ratio, normal PR
(0.12–0.20s), and normal QRS (0.06–0.10s).
Question 2
You identify a rhythm with a rate of 120 bpm, narrow QRS
complexes, and a sawtooth baseline pattern between the QRS
complexes. What is the most likely rhythm?
A Atrial Fibrillation
B Atrial Flutter
, C Ventricular Tachycardia
D Supraventricular Tachycardia
Correct Answer: B
Rationale: The "sawtooth" or "picket-fence" baseline is the
hallmark of Atrial Flutter, which is caused by a macro-reentrant
circuit in the right atrium.
Question 3
In a patient with a suspected second-degree AV block, Type 2
(Mobitz II), what specific ECG feature do you expect to see?
A Progressively lengthening PR intervals until a beat is
dropped
B Constant PR intervals with intermittently dropped QRS
complexes
C Complete dissociation between P waves and QRS
complexes
D A fixed PR interval of 0.24 seconds with every P wave
conducted
Correct Answer: B
Rationale: Mobitz II is characterized by intermittent, non-
conducted P waves, but the PR interval of the conducted beats
remains constant. This rhythm is dangerous because it often
progresses to complete heart block.
Question 4
,A patient on a cardiac monitor suddenly exhibits a wide-
complex, regular rhythm at a rate of 160 bpm. There are no P
waves visible. What is the most appropriate initial action if the
patient is symptomatic and hypotensive?
A Administer Adenosine 6mg IV push
B Perform synchronized cardioversion
C Start a lidocaine drip
D Administer Atropine 1mg IV
Correct Answer: B
Rationale: The patient is in unstable Ventricular Tachycardia
(wide complex, no P waves, hypotensive). Unstable
tachyarrhythmias with a pulse require immediate synchronized
cardioversion.
Question 5
What is the primary purpose of the "300-150-100-75-60-50" rule
in ECG interpretation?
A Measuring the QRS duration
B Calculating the heart rate for regular rhythms using large
boxes
C Determining the QT interval
D Calculating the axis of the heart
Correct Answer: B
, Rationale: This is the standard "large box" method for
estimating heart rate on a regular rhythm strip. You count the
number of large boxes (0.20s each) between two R waves and
divide 300 by that number.
Question 6
You are analyzing a rhythm and notice that the PR interval is
consistently 0.28 seconds, but every P wave is followed by a
QRS complex. How do you interpret this?
A First-degree AV Block
B Second-degree AV Block, Type 1
C Second-degree AV Block, Type 2
D Third-degree AV Block
Correct Answer: A
Rationale: First-degree AV block is defined by a constant PR
interval that exceeds the upper limit of normal (0.20 seconds).
Question 7
What is the distinguishing feature of a "Junctional Escape
Rhythm"?
A A rate of 40-60 bpm with absent or retrograde P waves
B A rate of 20-40 bpm with wide QRS complexes
C A rate of 100-150 bpm with narrow QRS complexes
