Normal Sinus Rhythm & Cardiac Rhythms
Study Guide Questions And Answers
[Verified Answers] Plus Rationales Latest
2026/27 | Qs & Ans Instant Pdf Download
1. Which rhythm is considered the normal rhythm of the heart?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular tachycardia
D. Asystole
Rationale: Normal sinus rhythm (NSR) originates from the
sinoatrial node and follows normal conduction pathways.
2. What is the normal adult heart rate in normal sinus rhythm?
A. 20–40 bpm
B. 60–100 bpm
C. 110–150 bpm
D. 150–220 bpm
Rationale: NSR in adults is typically 60–100 beats per minute.
3. Which structure is the heart’s natural pacemaker?
A. AV node
B. SA node
, C. Bundle branches
D. Purkinje fibers
Rationale: The sinoatrial node initiates the normal heartbeat.
4. Where is the SA node located?
A. Left ventricle
B. Right atrium near the superior vena cava
C. Septum only
D. Pulmonary artery
Rationale: The SA node sits in the right atrium near the SVC
opening.
5. Which ECG wave represents atrial depolarization?
A. QRS complex
B. P wave
C. T wave
D. U wave
Rationale: The P wave reflects atrial depolarization.
6. Which ECG complex represents ventricular depolarization?
A. P wave
B. QRS complex
C. T wave
D. PR segment
,Rationale: QRS represents depolarization of the ventricles.
7. Which ECG wave represents ventricular repolarization?
A. P wave
B. T wave
C. QRS complex
D. U wave only
Rationale: T wave reflects ventricular recovery/repolarization.
8. What is the normal PR interval?
A. 0.02–0.06 sec
B. 0.12–0.20 sec
C. 0.30–0.40 sec
D. 0.50–0.60 sec
Rationale: PR interval measures conduction from atria
through AV node.
9. What is the normal QRS duration?
A. 0.20–0.30 sec
B. Less than 0.12 sec
C. 0.20 sec exactly
D. More than 0.16 sec always
Rationale: Narrow QRS suggests normal ventricular
conduction.
, 10. Which feature defines normal sinus rhythm?
A. Irregular rhythm without P waves
B. Regular rhythm with a P wave before each QRS
C. Wide QRS only
D. Chaotic baseline
Rationale: NSR requires regular rhythm with normal atrial
impulse preceding each ventricular beat.
11. Sinus bradycardia is defined as a sinus rhythm with
heart rate below:
A. 80 bpm
B. 60 bpm
C. 100 bpm
D. 120 bpm
Rationale: Sinus bradycardia is HR <60 bpm with sinus origin.
12. Sinus tachycardia is defined as sinus rhythm with heart
rate above:
A. 60 bpm
B. 100 bpm
C. 90 bpm
D. 75 bpm
Rationale: Sinus tachycardia is HR >100 bpm.
Study Guide Questions And Answers
[Verified Answers] Plus Rationales Latest
2026/27 | Qs & Ans Instant Pdf Download
1. Which rhythm is considered the normal rhythm of the heart?
A. Atrial fibrillation
B. Normal sinus rhythm
C. Ventricular tachycardia
D. Asystole
Rationale: Normal sinus rhythm (NSR) originates from the
sinoatrial node and follows normal conduction pathways.
2. What is the normal adult heart rate in normal sinus rhythm?
A. 20–40 bpm
B. 60–100 bpm
C. 110–150 bpm
D. 150–220 bpm
Rationale: NSR in adults is typically 60–100 beats per minute.
3. Which structure is the heart’s natural pacemaker?
A. AV node
B. SA node
, C. Bundle branches
D. Purkinje fibers
Rationale: The sinoatrial node initiates the normal heartbeat.
4. Where is the SA node located?
A. Left ventricle
B. Right atrium near the superior vena cava
C. Septum only
D. Pulmonary artery
Rationale: The SA node sits in the right atrium near the SVC
opening.
5. Which ECG wave represents atrial depolarization?
A. QRS complex
B. P wave
C. T wave
D. U wave
Rationale: The P wave reflects atrial depolarization.
6. Which ECG complex represents ventricular depolarization?
A. P wave
B. QRS complex
C. T wave
D. PR segment
,Rationale: QRS represents depolarization of the ventricles.
7. Which ECG wave represents ventricular repolarization?
A. P wave
B. T wave
C. QRS complex
D. U wave only
Rationale: T wave reflects ventricular recovery/repolarization.
8. What is the normal PR interval?
A. 0.02–0.06 sec
B. 0.12–0.20 sec
C. 0.30–0.40 sec
D. 0.50–0.60 sec
Rationale: PR interval measures conduction from atria
through AV node.
9. What is the normal QRS duration?
A. 0.20–0.30 sec
B. Less than 0.12 sec
C. 0.20 sec exactly
D. More than 0.16 sec always
Rationale: Narrow QRS suggests normal ventricular
conduction.
, 10. Which feature defines normal sinus rhythm?
A. Irregular rhythm without P waves
B. Regular rhythm with a P wave before each QRS
C. Wide QRS only
D. Chaotic baseline
Rationale: NSR requires regular rhythm with normal atrial
impulse preceding each ventricular beat.
11. Sinus bradycardia is defined as a sinus rhythm with
heart rate below:
A. 80 bpm
B. 60 bpm
C. 100 bpm
D. 120 bpm
Rationale: Sinus bradycardia is HR <60 bpm with sinus origin.
12. Sinus tachycardia is defined as sinus rhythm with heart
rate above:
A. 60 bpm
B. 100 bpm
C. 90 bpm
D. 75 bpm
Rationale: Sinus tachycardia is HR >100 bpm.
