BASIC ARRHYTHMIA SENTARA TEST Questions &
Answer Bank (2026/2027 Update) | 100% Verified Pass
Guide
Section 1: Sinus Rhythms and Pacemaker Site Identification
(Questions 1–30)
1. Which finding on an ECG confirms that the electrical impulse
originated in the sinoatrial (SA) node and followed the normal
conduction pathway?
A. Absent P waves with a wide QRS complex
B. Rounded, upright, uniform P waves before each QRS complex
C. Inverted P waves with a narrow QRS complex
D. Saw-tooth flutter waves between QRS complexes
Answer: B
Rationale: Sinus node origin is confirmed by the presence of rounded, upright, uniform
P waves preceding each QRS complex. This indicates normal atrial depolarization from
the SA node and conduction through the atria. Option A describes a ventricular or
junctional rhythm. Option C suggests an ectopic atrial or junctional origin. Option D is
characteristic of atrial flutter .
2. A patient's ECG shows a regular rhythm at a rate of 42 bpm
with upright, uniform P waves before each QRS. The PR interval is
0.16 seconds, and the QRS duration is 0.08 seconds. What is the
correct interpretation?
,A. Normal sinus rhythm
B. Sinus bradycardia
C. Sinus arrhythmia
D. Junctional bradycardia
Answer: B
Rationale: Sinus bradycardia is identified by a regular sinus rhythm with a rate below 60
bpm. The presence of upright, uniform P waves before each QRS confirms the impulse
originated in the SA node. Normal sinus rhythm requires a rate of 60–100 bpm. Sinus
arrhythmia would show irregularity, and junctional bradycardia would lack P waves or
show retrograde P waves .
3. A patient presents with a heart rate of 145 bpm, regular
rhythm, and upright P waves preceding each QRS complex. The
PR interval is 0.14 seconds. What is the rhythm?
A. Sinus tachycardia
B. Supraventricular tachycardia
C. Atrial flutter
D. Ventricular tachycardia
Answer: A
Rationale: Sinus tachycardia is identified by a regular rhythm, normal P-wave
morphology, and rates typically between 100–150 bpm. Upright, uniform P waves
preceding each QRS confirm sinus origin. While supraventricular tachycardia can also
present with tachycardia, the presence of distinct upright P waves makes sinus
tachycardia the correct interpretation. Atrial flutter would show saw-tooth flutter waves,
and ventricular tachycardia would show wide QRS complexes .
4. An ECG strip shows an irregularly irregular rhythm with a rate
of 78 bpm. The rhythm varies with the respiratory cycle, and all P
waves are upright and uniform. What is the most likely rhythm?
A. Atrial fibrillation
B. Sinus arrhythmia
,C. Sinus bradycardia
D. Wandering atrial pacemaker
Answer: B
Rationale: Sinus arrhythmia is characterized by an irregularly irregular rhythm where the
heart rate varies with the respiratory cycle (increases with inspiration, decreases with
expiration). All P waves originate from the sinus node and are upright and uniform.
Atrial fibrillation shows no P waves and a grossly irregular rhythm. Wandering atrial
pacemaker would show varying P-wave morphology .
5. The normal PR interval should measure between:
A. 0.04–0.08 seconds
B. 0.08–0.12 seconds
C. 0.12–0.20 seconds
D. 0.20–0.30 seconds
Answer: C
Rationale: The PR interval represents conduction from the atria through the AV node
and His-Purkinje system before ventricular depolarization. The normal PR interval is
0.12–0.20 seconds (3–5 small boxes). A prolonged PR interval suggests first-degree AV
block. A shortened PR interval may indicate pre-excitation (WPW syndrome) or
junctional rhythm .
6. What is the normal duration of the QRS complex?
A. <0.06 seconds
B. <0.12 seconds
C. 0.12–0.20 seconds
D. 0.20–0.40 seconds
Answer: B
Rationale: The QRS complex represents ventricular depolarization. The normal QRS
duration is <0.12 seconds (less than 3 small boxes). A QRS duration >0.12 seconds
indicates a bundle branch block or ventricular origin of the rhythm .
, 7. A patient on a cardiac monitor shows a regular rhythm at 75
bpm with upright P waves. Suddenly, a pause occurs on the
monitor with no P wave or QRS complex for 2 seconds. After the
pause, the rhythm resumes at 75 bpm. This is most consistent
with:
A. Second-degree AV block type II
B. Sinus arrest
C. Sinus block
D. Premature atrial contraction
Answer: B
Rationale: Sinus arrest is characterized by a sudden pause in the sinus rhythm with no P
wave, QRS, or T wave. The pause length is not a multiple of the baseline R-R interval.
The underlying rhythm resumes after the pause. Sinus block would show a pause that is
a multiple of the baseline R-R interval. Premature atrial contractions are early beats, not
pauses .
8. How do you calculate the length of a pause during sinus arrest?
A. Count the R waves in the pause and multiply by 0.02 seconds
B. Count the number of large boxes between the R waves that come right before and
after the pause and multiply by 0.20 seconds
C. Count the number of small boxes between the two R waves that come right before
and right after the pause and multiply by 0.04 seconds
D. Count the number of QRS complexes missed during the pause
Answer: C
Rationale: To calculate the length of a pause in sinus arrest, count the number of small
boxes between the two R waves that come right before and right after the pause, then
multiply by 0.04 seconds (the duration of one small box). This gives the total time of the
pause, which helps determine if it is clinically significant .
Answer Bank (2026/2027 Update) | 100% Verified Pass
Guide
Section 1: Sinus Rhythms and Pacemaker Site Identification
(Questions 1–30)
1. Which finding on an ECG confirms that the electrical impulse
originated in the sinoatrial (SA) node and followed the normal
conduction pathway?
A. Absent P waves with a wide QRS complex
B. Rounded, upright, uniform P waves before each QRS complex
C. Inverted P waves with a narrow QRS complex
D. Saw-tooth flutter waves between QRS complexes
Answer: B
Rationale: Sinus node origin is confirmed by the presence of rounded, upright, uniform
P waves preceding each QRS complex. This indicates normal atrial depolarization from
the SA node and conduction through the atria. Option A describes a ventricular or
junctional rhythm. Option C suggests an ectopic atrial or junctional origin. Option D is
characteristic of atrial flutter .
2. A patient's ECG shows a regular rhythm at a rate of 42 bpm
with upright, uniform P waves before each QRS. The PR interval is
0.16 seconds, and the QRS duration is 0.08 seconds. What is the
correct interpretation?
,A. Normal sinus rhythm
B. Sinus bradycardia
C. Sinus arrhythmia
D. Junctional bradycardia
Answer: B
Rationale: Sinus bradycardia is identified by a regular sinus rhythm with a rate below 60
bpm. The presence of upright, uniform P waves before each QRS confirms the impulse
originated in the SA node. Normal sinus rhythm requires a rate of 60–100 bpm. Sinus
arrhythmia would show irregularity, and junctional bradycardia would lack P waves or
show retrograde P waves .
3. A patient presents with a heart rate of 145 bpm, regular
rhythm, and upright P waves preceding each QRS complex. The
PR interval is 0.14 seconds. What is the rhythm?
A. Sinus tachycardia
B. Supraventricular tachycardia
C. Atrial flutter
D. Ventricular tachycardia
Answer: A
Rationale: Sinus tachycardia is identified by a regular rhythm, normal P-wave
morphology, and rates typically between 100–150 bpm. Upright, uniform P waves
preceding each QRS confirm sinus origin. While supraventricular tachycardia can also
present with tachycardia, the presence of distinct upright P waves makes sinus
tachycardia the correct interpretation. Atrial flutter would show saw-tooth flutter waves,
and ventricular tachycardia would show wide QRS complexes .
4. An ECG strip shows an irregularly irregular rhythm with a rate
of 78 bpm. The rhythm varies with the respiratory cycle, and all P
waves are upright and uniform. What is the most likely rhythm?
A. Atrial fibrillation
B. Sinus arrhythmia
,C. Sinus bradycardia
D. Wandering atrial pacemaker
Answer: B
Rationale: Sinus arrhythmia is characterized by an irregularly irregular rhythm where the
heart rate varies with the respiratory cycle (increases with inspiration, decreases with
expiration). All P waves originate from the sinus node and are upright and uniform.
Atrial fibrillation shows no P waves and a grossly irregular rhythm. Wandering atrial
pacemaker would show varying P-wave morphology .
5. The normal PR interval should measure between:
A. 0.04–0.08 seconds
B. 0.08–0.12 seconds
C. 0.12–0.20 seconds
D. 0.20–0.30 seconds
Answer: C
Rationale: The PR interval represents conduction from the atria through the AV node
and His-Purkinje system before ventricular depolarization. The normal PR interval is
0.12–0.20 seconds (3–5 small boxes). A prolonged PR interval suggests first-degree AV
block. A shortened PR interval may indicate pre-excitation (WPW syndrome) or
junctional rhythm .
6. What is the normal duration of the QRS complex?
A. <0.06 seconds
B. <0.12 seconds
C. 0.12–0.20 seconds
D. 0.20–0.40 seconds
Answer: B
Rationale: The QRS complex represents ventricular depolarization. The normal QRS
duration is <0.12 seconds (less than 3 small boxes). A QRS duration >0.12 seconds
indicates a bundle branch block or ventricular origin of the rhythm .
, 7. A patient on a cardiac monitor shows a regular rhythm at 75
bpm with upright P waves. Suddenly, a pause occurs on the
monitor with no P wave or QRS complex for 2 seconds. After the
pause, the rhythm resumes at 75 bpm. This is most consistent
with:
A. Second-degree AV block type II
B. Sinus arrest
C. Sinus block
D. Premature atrial contraction
Answer: B
Rationale: Sinus arrest is characterized by a sudden pause in the sinus rhythm with no P
wave, QRS, or T wave. The pause length is not a multiple of the baseline R-R interval.
The underlying rhythm resumes after the pause. Sinus block would show a pause that is
a multiple of the baseline R-R interval. Premature atrial contractions are early beats, not
pauses .
8. How do you calculate the length of a pause during sinus arrest?
A. Count the R waves in the pause and multiply by 0.02 seconds
B. Count the number of large boxes between the R waves that come right before and
after the pause and multiply by 0.20 seconds
C. Count the number of small boxes between the two R waves that come right before
and right after the pause and multiply by 0.04 seconds
D. Count the number of QRS complexes missed during the pause
Answer: C
Rationale: To calculate the length of a pause in sinus arrest, count the number of small
boxes between the two R waves that come right before and right after the pause, then
multiply by 0.04 seconds (the duration of one small box). This gives the total time of the
pause, which helps determine if it is clinically significant .
