Basic Arrhythmia Sentara Test Questions
and Verified Answers with Rationale Latest
Edition 2026/2027
Question 1
Which of the following characteristics is true regarding normal
sinus rhythm on an electrocardiogram strip
A Rate between 40 and 59 beats per minute
B Regular rhythm with a PR interval measuring 0.12 to 0.20
seconds
C PR interval greater than 0.20 seconds with dropped beats
D Wide QRS complex measuring more than 0.12 seconds
Correct Answer: B
Rationale: Normal sinus rhythm originates in the sinus node
and is characterized by a regular rhythm, a heart rate between 60
and 100 beats per minute, upright P waves preceding every QRS
complex, and a normal PR interval measuring 0.12 to 0.20
seconds. Rates below 60 indicate sinus bradycardia, and wide
QRS complexes indicate intraventricular conduction delays.
Question 2
A rhythm strip shows a heart rate of 42 beats per minute, normal
P waves preceding every QRS complex, and normal intervals.
What is the correct interpretation of this rhythm?
A Sinus tachycardia
, B Junctional escape rhythm
C Sinus bradycardia
D First-degree heart block
Correct Answer: C
Rationale: Sinus bradycardia shares all the identical criteria of a
normal sinus rhythm including upright P waves and normal PR
and QRS intervals, except the heart rate is slower than 60 beats
per minute. Junctional rhythms lack normal upright P waves,
and tachycardia involves rates above 100 beats per minute.
Question 3
What is the primary electrophysiological mechanism responsible
for atrial fibrillation?
A A single irritable ectopic focus firing rapidly
B Multiple micro-reentrant wavelets wandering through the
atrial myocardium
C Delayed conduction through the bundle of His
D Complete failure of the sinoatrial node to depolarize
Correct Answer: B
Rationale: Atrial fibrillation is caused by multiple micro-
reentrant wavelets circulating simultaneously and haphazardly
throughout the atria. This chaotic electrical activity prevents
coordinated atrial contraction, resulting in an irregularly
,irregular ventricular response and an absence of distinct P
waves.
Question 4
Which electrocardiogram finding is considered the hallmark
diagnostic indicator of ventricular fibrillation?
A Sawtooth flutter waves at a rate of 300 beats per minute
B Bizarre, wide QRS complexes occurring in a regular pattern
at 150 beats per minute
C Completely chaotic, irregular baseline with no discernible P
waves, QRS complexes, or T waves
D Prolonged PR intervals with intermittent dropped QRS
complexes
Correct Answer: C
Rationale: Ventricular fibrillation is a lethal arrhythmia
characterized by a chaotic, undulating baseline without any
recognizable waves or complexes. The ventricles quiver rather
than contract, resulting in an immediate loss of cardiac output
and cardiac arrest.
Question 5
A rhythm strip reveals a regular ventricular rate of 140 beats per
minute, narrow QRS complexes, and hidden or absent P waves
buried within the preceding T waves. Which rhythm is most
likely present?
, A Ventricular tachycardia
B Sinus tachycardia
C Supraventricular tachycardia
D Atrial flutter
Correct Answer: C
Rationale: Supraventricular tachycardia typically presents as a
regular, rapid rhythm with a rate between 150 and 250 beats per
minute, though lower rates can occur, featuring narrow QRS
complexes where P waves are frequently merged with or
obscured by T waves due to the rapid rate. Ventricular
tachycardia features wide QRS complexes.
Question 6
In a standard electrocardiogram grid, what duration of time is
represented by one small horizontal box?
A 0.01 seconds
B 0.04 seconds
C 0.20 seconds
D 0.50 seconds
Correct Answer: B
Rationale: Standard electrocardiogram paper moves at a speed
of 25 millimeters per second. Each small horizontal box
and Verified Answers with Rationale Latest
Edition 2026/2027
Question 1
Which of the following characteristics is true regarding normal
sinus rhythm on an electrocardiogram strip
A Rate between 40 and 59 beats per minute
B Regular rhythm with a PR interval measuring 0.12 to 0.20
seconds
C PR interval greater than 0.20 seconds with dropped beats
D Wide QRS complex measuring more than 0.12 seconds
Correct Answer: B
Rationale: Normal sinus rhythm originates in the sinus node
and is characterized by a regular rhythm, a heart rate between 60
and 100 beats per minute, upright P waves preceding every QRS
complex, and a normal PR interval measuring 0.12 to 0.20
seconds. Rates below 60 indicate sinus bradycardia, and wide
QRS complexes indicate intraventricular conduction delays.
Question 2
A rhythm strip shows a heart rate of 42 beats per minute, normal
P waves preceding every QRS complex, and normal intervals.
What is the correct interpretation of this rhythm?
A Sinus tachycardia
, B Junctional escape rhythm
C Sinus bradycardia
D First-degree heart block
Correct Answer: C
Rationale: Sinus bradycardia shares all the identical criteria of a
normal sinus rhythm including upright P waves and normal PR
and QRS intervals, except the heart rate is slower than 60 beats
per minute. Junctional rhythms lack normal upright P waves,
and tachycardia involves rates above 100 beats per minute.
Question 3
What is the primary electrophysiological mechanism responsible
for atrial fibrillation?
A A single irritable ectopic focus firing rapidly
B Multiple micro-reentrant wavelets wandering through the
atrial myocardium
C Delayed conduction through the bundle of His
D Complete failure of the sinoatrial node to depolarize
Correct Answer: B
Rationale: Atrial fibrillation is caused by multiple micro-
reentrant wavelets circulating simultaneously and haphazardly
throughout the atria. This chaotic electrical activity prevents
coordinated atrial contraction, resulting in an irregularly
,irregular ventricular response and an absence of distinct P
waves.
Question 4
Which electrocardiogram finding is considered the hallmark
diagnostic indicator of ventricular fibrillation?
A Sawtooth flutter waves at a rate of 300 beats per minute
B Bizarre, wide QRS complexes occurring in a regular pattern
at 150 beats per minute
C Completely chaotic, irregular baseline with no discernible P
waves, QRS complexes, or T waves
D Prolonged PR intervals with intermittent dropped QRS
complexes
Correct Answer: C
Rationale: Ventricular fibrillation is a lethal arrhythmia
characterized by a chaotic, undulating baseline without any
recognizable waves or complexes. The ventricles quiver rather
than contract, resulting in an immediate loss of cardiac output
and cardiac arrest.
Question 5
A rhythm strip reveals a regular ventricular rate of 140 beats per
minute, narrow QRS complexes, and hidden or absent P waves
buried within the preceding T waves. Which rhythm is most
likely present?
, A Ventricular tachycardia
B Sinus tachycardia
C Supraventricular tachycardia
D Atrial flutter
Correct Answer: C
Rationale: Supraventricular tachycardia typically presents as a
regular, rapid rhythm with a rate between 150 and 250 beats per
minute, though lower rates can occur, featuring narrow QRS
complexes where P waves are frequently merged with or
obscured by T waves due to the rapid rate. Ventricular
tachycardia features wide QRS complexes.
Question 6
In a standard electrocardiogram grid, what duration of time is
represented by one small horizontal box?
A 0.01 seconds
B 0.04 seconds
C 0.20 seconds
D 0.50 seconds
Correct Answer: B
Rationale: Standard electrocardiogram paper moves at a speed
of 25 millimeters per second. Each small horizontal box
