ECG INTERPRETATION EXAM | 2026 UPDATE
WITH COMPLETE SOLUTIONS.
SECTION 1: NORMAL ECG & BASIC MEASUREMENTS
1. What is the normal duration of the PR interval?
• A) 0.04–0.10 seconds (1–2.5 small boxes)
• B) 0.12–0.20 seconds (3–5 small boxes)
• C) 0.20–0.30 seconds (5–7.5 small boxes)
• D) 0.30–0.40 seconds (7.5–10 small boxes)
Correct Answer: B
*Rationale: The normal PR interval (from P wave onset to QRS onset) is 0.12–0.20
seconds (3–5 small boxes). Prolonged PR interval (> 0.20 seconds) indicates first-
degree AV block. Short PR interval (< 0.12 seconds) suggests pre-excitation (WPW
syndrome).*
2. What is the normal duration of the QRS complex?
• A) < 0.06 seconds (< 1.5 small boxes)
• B) < 0.10 seconds (< 2.5 small boxes)
• C) < 0.12 seconds (< 3 small boxes)
• D) < 0.20 seconds (< 5 small boxes)
Correct Answer: C
Rationale: The normal QRS duration is ≤ 0.12 seconds (≤ 3 small boxes). Prolonged
,QRS (> 0.12 seconds) indicates bundle branch block or ventricular conduction
delay. Wide QRS complexes (> 0.12 seconds) are seen in ventricular tachycardia
and bundle branch block.
3. What is the normal QTc interval?
• A) < 0.36 seconds
• B) < 0.40 seconds
• C) < 0.44 seconds
• D) < 0.48 seconds
Correct Answer: C
*Rationale: The normal QTc (corrected QT) interval is ≤ 0.44 seconds in men and ≤
0.46 seconds in women. Prolonged QTc (> 0.47 seconds in men, > 0.48 seconds in
women) increases the risk of torsades de pointes. The QT interval should be
corrected for heart rate using Bazett's formula (QTc = QT / √RR).*
4. In which lead is the P wave best seen?
• A) Lead I
• B) Lead II
• C) Lead V1
• D) Lead V6
Correct Answer: B
*Rationale: Lead II is the best lead to visualize the P wave because it is oriented
parallel to the atrial vector (from SA node to AV node). The normal P wave is
upright in leads I, II, aVF, and V4–V6. P wave axis should be between 0° and +75°.*
5. What is the normal heart rate in a healthy adult at rest?
, • A) 30–50 bpm
• B) 60–100 bpm
• C) 100–140 bpm
• D) 140–180 bpm
Correct Answer: B
*Rationale: The normal resting heart rate for adults is 60–100 bpm. Athletes may
have rates below 60 (sinus bradycardia). Rates above 100 indicate tachycardia and
require further evaluation. Heart rate can be calculated by counting R-R intervals
(300 ÷ number of large boxes between QRS complexes).*
6. What is the normal axis of the heart?
• A) -30° to +90°
• B) 0° to +90°
• C) -30° to +110°
• D) 0° to +110°
Correct Answer: A
*Rationale: The normal QRS axis ranges from -30° to +90°. Left axis deviation
(LAD) is defined as axis between -30° and -90°. Right axis deviation (RAD) is axis
between +90° and +180°. Extreme axis deviation (northwest axis) is between -90°
and -180°.*
7. Which of the following ECG findings is consistent with a normal ECG?
• A) Prolonged PR interval
• B) QRS duration > 0.12 seconds
• C) Normal sinus rhythm with rate 70 bpm
• D) Pathologic Q waves in leads V1–V3
, Correct Answer: C
*Rationale: Normal sinus rhythm with a rate of 60–100 bpm is a normal ECG
finding. Prolonged PR (> 0.20 sec) indicates first-degree AV block. QRS > 0.12 sec
indicates bundle branch block. Pathologic Q waves indicate prior myocardial
infarction.*
8. What is the standard paper speed for a 12-lead ECG?
• A) 10 mm/sec
• B) 25 mm/sec
• C) 50 mm/sec
• D) 100 mm/sec
Correct Answer: B
*Rationale: The standard ECG paper speed is 25 mm/sec. At this speed, 1 small
square (1 mm) = 0.04 seconds, and 1 large square (5 mm) = 0.20 seconds. At 50
mm/sec, 1 small square = 0.02 seconds. The standard calibration is 10 mm/mV.*
9. What does the "J-point" represent on an ECG?
• A) The end of the QRS complex and the beginning of the ST segment
• B) The beginning of the P wave
• C) The end of the T wave
• D) The peak of the R wave
Correct Answer: A
Rationale: The J-point is the point where the QRS complex ends and the ST
segment begins. It marks the end of ventricular depolarization. ST-segment
elevation or depression is measured at the J-point. J-point elevation (early
repolarization) is a normal variant in young adults.
WITH COMPLETE SOLUTIONS.
SECTION 1: NORMAL ECG & BASIC MEASUREMENTS
1. What is the normal duration of the PR interval?
• A) 0.04–0.10 seconds (1–2.5 small boxes)
• B) 0.12–0.20 seconds (3–5 small boxes)
• C) 0.20–0.30 seconds (5–7.5 small boxes)
• D) 0.30–0.40 seconds (7.5–10 small boxes)
Correct Answer: B
*Rationale: The normal PR interval (from P wave onset to QRS onset) is 0.12–0.20
seconds (3–5 small boxes). Prolonged PR interval (> 0.20 seconds) indicates first-
degree AV block. Short PR interval (< 0.12 seconds) suggests pre-excitation (WPW
syndrome).*
2. What is the normal duration of the QRS complex?
• A) < 0.06 seconds (< 1.5 small boxes)
• B) < 0.10 seconds (< 2.5 small boxes)
• C) < 0.12 seconds (< 3 small boxes)
• D) < 0.20 seconds (< 5 small boxes)
Correct Answer: C
Rationale: The normal QRS duration is ≤ 0.12 seconds (≤ 3 small boxes). Prolonged
,QRS (> 0.12 seconds) indicates bundle branch block or ventricular conduction
delay. Wide QRS complexes (> 0.12 seconds) are seen in ventricular tachycardia
and bundle branch block.
3. What is the normal QTc interval?
• A) < 0.36 seconds
• B) < 0.40 seconds
• C) < 0.44 seconds
• D) < 0.48 seconds
Correct Answer: C
*Rationale: The normal QTc (corrected QT) interval is ≤ 0.44 seconds in men and ≤
0.46 seconds in women. Prolonged QTc (> 0.47 seconds in men, > 0.48 seconds in
women) increases the risk of torsades de pointes. The QT interval should be
corrected for heart rate using Bazett's formula (QTc = QT / √RR).*
4. In which lead is the P wave best seen?
• A) Lead I
• B) Lead II
• C) Lead V1
• D) Lead V6
Correct Answer: B
*Rationale: Lead II is the best lead to visualize the P wave because it is oriented
parallel to the atrial vector (from SA node to AV node). The normal P wave is
upright in leads I, II, aVF, and V4–V6. P wave axis should be between 0° and +75°.*
5. What is the normal heart rate in a healthy adult at rest?
, • A) 30–50 bpm
• B) 60–100 bpm
• C) 100–140 bpm
• D) 140–180 bpm
Correct Answer: B
*Rationale: The normal resting heart rate for adults is 60–100 bpm. Athletes may
have rates below 60 (sinus bradycardia). Rates above 100 indicate tachycardia and
require further evaluation. Heart rate can be calculated by counting R-R intervals
(300 ÷ number of large boxes between QRS complexes).*
6. What is the normal axis of the heart?
• A) -30° to +90°
• B) 0° to +90°
• C) -30° to +110°
• D) 0° to +110°
Correct Answer: A
*Rationale: The normal QRS axis ranges from -30° to +90°. Left axis deviation
(LAD) is defined as axis between -30° and -90°. Right axis deviation (RAD) is axis
between +90° and +180°. Extreme axis deviation (northwest axis) is between -90°
and -180°.*
7. Which of the following ECG findings is consistent with a normal ECG?
• A) Prolonged PR interval
• B) QRS duration > 0.12 seconds
• C) Normal sinus rhythm with rate 70 bpm
• D) Pathologic Q waves in leads V1–V3
, Correct Answer: C
*Rationale: Normal sinus rhythm with a rate of 60–100 bpm is a normal ECG
finding. Prolonged PR (> 0.20 sec) indicates first-degree AV block. QRS > 0.12 sec
indicates bundle branch block. Pathologic Q waves indicate prior myocardial
infarction.*
8. What is the standard paper speed for a 12-lead ECG?
• A) 10 mm/sec
• B) 25 mm/sec
• C) 50 mm/sec
• D) 100 mm/sec
Correct Answer: B
*Rationale: The standard ECG paper speed is 25 mm/sec. At this speed, 1 small
square (1 mm) = 0.04 seconds, and 1 large square (5 mm) = 0.20 seconds. At 50
mm/sec, 1 small square = 0.02 seconds. The standard calibration is 10 mm/mV.*
9. What does the "J-point" represent on an ECG?
• A) The end of the QRS complex and the beginning of the ST segment
• B) The beginning of the P wave
• C) The end of the T wave
• D) The peak of the R wave
Correct Answer: A
Rationale: The J-point is the point where the QRS complex ends and the ST
segment begins. It marks the end of ventricular depolarization. ST-segment
elevation or depression is measured at the J-point. J-point elevation (early
repolarization) is a normal variant in young adults.
