SCST-D1 SCST DIPLOMA IN ECG
INTERPRETATION EXAM 200
QUESTIONS | VERIFIED ANSWERS &
DETAILED RATIONALES | 2026
EDITION
Exam Blueprint (Based on SCST Syllabus):
The Normal ECG, Leads & Axis (15%) – 30 Qs
Tachyarrhythmias (15%) – 30 Qs
Bradyarrhythmias & Conduction Disturbances (15%) – 30 Qs
Myocardial Ischaemia & Infarction (15%) – 30 Qs
Morphological Abnormalities (Hypertrophy, Atrial Enlargement) (10%) – 20
Qs
Drug & Electrolyte Effects (10%) – 20 Qs
Special Syndromes (WPW, Brugada, Pulmonary Embolism, Pericarditis)
(10%) – 20 Qs
Pacing & Artefacts (5%) – 10 Qs
Professional Practice & Exam Technique (5%) – 10 Qs
Exam Format: Single Best Answer / Multiple Choice
Time limit (simulated): 3 hours
Passing threshold: 70% (140/200)
SECTION 1: THE NORMAL ECG, LEADS & AXIS – Questions 1–30
1. The P wave on a standard 12-lead ECG represents:
,A) AV nodal conduction
B) Atrial depolarisation
C) Ventricular depolarisation
D) Ventricular repolarisation
Answer: B
Rationale: The P wave reflects the electrical impulse originating from the SA
node and spreading through the atria. The PR interval represents AV nodal
delay, the QRS is ventricular depolarisation, and the T wave is ventricular
repolarisation .
2. A normal PR interval should measure:
A) 80–120 ms (2–3 small squares)
B) 120–200 ms (3–5 small squares)
C) 200–240 ms (5–6 small squares)
D) 240–300 ms (6–7.5 small squares)
Answer: B
Rationale: The normal PR interval is between 120 and 200 ms (3-5 small
squares or 1-2 large squares). A shorter interval suggests pre-excitation
(WPW), and a longer interval indicates first-degree AV block .
3. The normal QRS duration is:
A) <100 ms (<2.5 small squares)
B) <120 ms (<3 small squares)
C) <140 ms (<3.5 small squares)
D) <160 ms (<4 small squares)
Answer: B
Rationale: Normal ventricular depolarisation takes less than 120 ms (≤0.11–
0.12 s or up to 3 small squares). QRS >120 ms suggests bundle branch block
or intraventricular conduction delay .
,4. The T wave represents:
A) Atrial repolarisation
B) Ventricular depolarisation
C) Ventricular repolarisation
D) Pericardial inflammation
Answer: C
Rationale: The T wave represents ventricular repolarisation. Atrial
repolarisation is usually hidden within the QRS complex. The QRS complex
represents ventricular depolarisation .
5. Which lead set primarily views the inferior wall of the heart?
A) V1–V3
B) I and aVL
C) II, III, aVF
D) V4–V6
Answer: C
*Rationale: The inferior leads are II, III, and aVF, which view the inferior
surface of the heart (right coronary artery territory typically). Leads V1–V3
view the septal/anterior wall, I and aVL view the high lateral wall, and V4–
V6 view the lateral wall .*
6. The normal range for the QRS axis in a healthy adult is:
A) –30° to +90°
B) –90° to +180°
C) 0° to +90°
D) +120° to +180°
Answer: A (with C also considered normal by some texts)
*Rationale: The normal QRS axis is between –30° and +90°. Some texts use 0°
, to +90°. Left axis deviation is beyond –30°, right axis deviation beyond
+90° .*
7. To quickly estimate the QRS axis, which two leads are most helpful?
A) V1 and V6
B) I and aVF
C) II and III
D) aVR and aVL
Answer: B
Rationale: The quadrant method uses leads I and aVF. Both positive
indicates normal axis. Lead I positive and aVF negative suggests left axis
deviation (LAD). Lead I negative and aVF positive suggests right axis
deviation (RAD) .
8. Which ECG lead is oriented from the right shoulder towards the heart and
normally shows negative P waves and QRS complexes?
A) Lead I
B) Lead II
C) aVR
D) aVF
Answer: C
Rationale: aVR (augmented Vector Right) is oriented towards the right
shoulder. Because of this vector, a normal aVR frequently shows a negative
(downward) P wave, QRS complex, and T wave .
9. The transition zone (where the R wave becomes taller than the S wave is
deep) is usually located at which precordial lead?
A) V1
B) V2
C) V3 or V4
INTERPRETATION EXAM 200
QUESTIONS | VERIFIED ANSWERS &
DETAILED RATIONALES | 2026
EDITION
Exam Blueprint (Based on SCST Syllabus):
The Normal ECG, Leads & Axis (15%) – 30 Qs
Tachyarrhythmias (15%) – 30 Qs
Bradyarrhythmias & Conduction Disturbances (15%) – 30 Qs
Myocardial Ischaemia & Infarction (15%) – 30 Qs
Morphological Abnormalities (Hypertrophy, Atrial Enlargement) (10%) – 20
Qs
Drug & Electrolyte Effects (10%) – 20 Qs
Special Syndromes (WPW, Brugada, Pulmonary Embolism, Pericarditis)
(10%) – 20 Qs
Pacing & Artefacts (5%) – 10 Qs
Professional Practice & Exam Technique (5%) – 10 Qs
Exam Format: Single Best Answer / Multiple Choice
Time limit (simulated): 3 hours
Passing threshold: 70% (140/200)
SECTION 1: THE NORMAL ECG, LEADS & AXIS – Questions 1–30
1. The P wave on a standard 12-lead ECG represents:
,A) AV nodal conduction
B) Atrial depolarisation
C) Ventricular depolarisation
D) Ventricular repolarisation
Answer: B
Rationale: The P wave reflects the electrical impulse originating from the SA
node and spreading through the atria. The PR interval represents AV nodal
delay, the QRS is ventricular depolarisation, and the T wave is ventricular
repolarisation .
2. A normal PR interval should measure:
A) 80–120 ms (2–3 small squares)
B) 120–200 ms (3–5 small squares)
C) 200–240 ms (5–6 small squares)
D) 240–300 ms (6–7.5 small squares)
Answer: B
Rationale: The normal PR interval is between 120 and 200 ms (3-5 small
squares or 1-2 large squares). A shorter interval suggests pre-excitation
(WPW), and a longer interval indicates first-degree AV block .
3. The normal QRS duration is:
A) <100 ms (<2.5 small squares)
B) <120 ms (<3 small squares)
C) <140 ms (<3.5 small squares)
D) <160 ms (<4 small squares)
Answer: B
Rationale: Normal ventricular depolarisation takes less than 120 ms (≤0.11–
0.12 s or up to 3 small squares). QRS >120 ms suggests bundle branch block
or intraventricular conduction delay .
,4. The T wave represents:
A) Atrial repolarisation
B) Ventricular depolarisation
C) Ventricular repolarisation
D) Pericardial inflammation
Answer: C
Rationale: The T wave represents ventricular repolarisation. Atrial
repolarisation is usually hidden within the QRS complex. The QRS complex
represents ventricular depolarisation .
5. Which lead set primarily views the inferior wall of the heart?
A) V1–V3
B) I and aVL
C) II, III, aVF
D) V4–V6
Answer: C
*Rationale: The inferior leads are II, III, and aVF, which view the inferior
surface of the heart (right coronary artery territory typically). Leads V1–V3
view the septal/anterior wall, I and aVL view the high lateral wall, and V4–
V6 view the lateral wall .*
6. The normal range for the QRS axis in a healthy adult is:
A) –30° to +90°
B) –90° to +180°
C) 0° to +90°
D) +120° to +180°
Answer: A (with C also considered normal by some texts)
*Rationale: The normal QRS axis is between –30° and +90°. Some texts use 0°
, to +90°. Left axis deviation is beyond –30°, right axis deviation beyond
+90° .*
7. To quickly estimate the QRS axis, which two leads are most helpful?
A) V1 and V6
B) I and aVF
C) II and III
D) aVR and aVL
Answer: B
Rationale: The quadrant method uses leads I and aVF. Both positive
indicates normal axis. Lead I positive and aVF negative suggests left axis
deviation (LAD). Lead I negative and aVF positive suggests right axis
deviation (RAD) .
8. Which ECG lead is oriented from the right shoulder towards the heart and
normally shows negative P waves and QRS complexes?
A) Lead I
B) Lead II
C) aVR
D) aVF
Answer: C
Rationale: aVR (augmented Vector Right) is oriented towards the right
shoulder. Because of this vector, a normal aVR frequently shows a negative
(downward) P wave, QRS complex, and T wave .
9. The transition zone (where the R wave becomes taller than the S wave is
deep) is usually located at which precordial lead?
A) V1
B) V2
C) V3 or V4
