SCST-D1 SCST Diploma in ECG Interpretation Exam
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Answers) Plus Rationales 2025/2026 Q&A | Instant
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1. Which ECG lead is most commonly used to monitor rhythm during clinical
practice?
A. Lead I
B. Lead II
C. Lead III
D. aVR
Rationale:Lead II best aligns with the electrical axis of the heart, providing clear P
waves and QRS complexes.
2. The P wave represents:
A. Ventricular depolarization
B. Ventricular repolarization
C. Atrial depolarization
D. Atrial repolarization
Rationale:The P wave corresponds to atrial depolarization.
3. A normal PR interval is:
A. <0.08 sec
B. 0.12–0.20 sec
C. 0.20–0.28 sec
D. >0.28 sec
Rationale:Normal PR interval is between 120–200 ms.
4. The QRS complex width should normally be:
,A. >0.14 sec
B. <0.12 sec
C. 0.12–0.16 sec
D. >0.20 sec
Rationale:A normal QRS is narrow (<120 ms).
5. Which electrolyte abnormality is most associated with peaked T waves?
A. Hypocalcemia
B. Hypomagnesemia
C. Hyperkalemia
D. Hypernatremia
Rationale:Excess potassium causes tall, peaked T waves.
6. The ST segment elevation is classically associated with:
A. Pericarditis
B. Ventricular hypertrophy
C. Myocardial infarction
D. Atrial fibrillation
Rationale:ST elevation is a hallmark of acute myocardial injury.
7. The QT interval represents:
A. Total ventricular depolarization and repolarization
B. Atrial depolarization
C. PR conduction
D. SA node delay
Rationale:QT interval includes QRS, ST, and T wave—ventricular activity.
8. Atrial fibrillation is characterized by:
A. Sawtooth flutter waves
B. Irregularly irregular rhythm with absent P waves
C. Regular narrow QRS tachycardia
D. Wide QRS complexes
Rationale:AF shows fibrillatory baseline and irregularly irregular ventricular response.
, 9. Which lead is most useful for detecting atrial activity?
A. aVR
B. V1
C. Lead II
D. V6
Rationale:Lead II provides a clear view of atrial activity (P waves).
10. Mobitz type I AV block is also called:
A. High-grade block
B. Mobitz II block
C. Wenckebach block
D. Bundle branch block
Rationale:Progressive PR prolongation with dropped beat = Wenckebach.
11. The intrinsic rate of the SA node is:
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–120 bpm
Rationale:SA node normally fires 60–100 times per minute.
12. The paper speed on a standard ECG is:
A. 10 mm/sec
B. 25 mm/sec
C. 50 mm/sec
D. 100 mm/sec
Rationale:Standard ECG is recorded at 25 mm per second.
13. Which wave represents ventricular repolarization?
A. P
B. QRS
– Practice Questions And Correct Answers (Verified
Answers) Plus Rationales 2025/2026 Q&A | Instant
Download Pdf
correct answer coloured in black
1. Which ECG lead is most commonly used to monitor rhythm during clinical
practice?
A. Lead I
B. Lead II
C. Lead III
D. aVR
Rationale:Lead II best aligns with the electrical axis of the heart, providing clear P
waves and QRS complexes.
2. The P wave represents:
A. Ventricular depolarization
B. Ventricular repolarization
C. Atrial depolarization
D. Atrial repolarization
Rationale:The P wave corresponds to atrial depolarization.
3. A normal PR interval is:
A. <0.08 sec
B. 0.12–0.20 sec
C. 0.20–0.28 sec
D. >0.28 sec
Rationale:Normal PR interval is between 120–200 ms.
4. The QRS complex width should normally be:
,A. >0.14 sec
B. <0.12 sec
C. 0.12–0.16 sec
D. >0.20 sec
Rationale:A normal QRS is narrow (<120 ms).
5. Which electrolyte abnormality is most associated with peaked T waves?
A. Hypocalcemia
B. Hypomagnesemia
C. Hyperkalemia
D. Hypernatremia
Rationale:Excess potassium causes tall, peaked T waves.
6. The ST segment elevation is classically associated with:
A. Pericarditis
B. Ventricular hypertrophy
C. Myocardial infarction
D. Atrial fibrillation
Rationale:ST elevation is a hallmark of acute myocardial injury.
7. The QT interval represents:
A. Total ventricular depolarization and repolarization
B. Atrial depolarization
C. PR conduction
D. SA node delay
Rationale:QT interval includes QRS, ST, and T wave—ventricular activity.
8. Atrial fibrillation is characterized by:
A. Sawtooth flutter waves
B. Irregularly irregular rhythm with absent P waves
C. Regular narrow QRS tachycardia
D. Wide QRS complexes
Rationale:AF shows fibrillatory baseline and irregularly irregular ventricular response.
, 9. Which lead is most useful for detecting atrial activity?
A. aVR
B. V1
C. Lead II
D. V6
Rationale:Lead II provides a clear view of atrial activity (P waves).
10. Mobitz type I AV block is also called:
A. High-grade block
B. Mobitz II block
C. Wenckebach block
D. Bundle branch block
Rationale:Progressive PR prolongation with dropped beat = Wenckebach.
11. The intrinsic rate of the SA node is:
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–120 bpm
Rationale:SA node normally fires 60–100 times per minute.
12. The paper speed on a standard ECG is:
A. 10 mm/sec
B. 25 mm/sec
C. 50 mm/sec
D. 100 mm/sec
Rationale:Standard ECG is recorded at 25 mm per second.
13. Which wave represents ventricular repolarization?
A. P
B. QRS
