Basic ECG Interpretation
1. What is the normal duration of the PR interval on an ECG?
A. 0.08 – 0.12 seconds
B. 0.12 – 0.20 seconds
C. 0.20 – 0.30 seconds
D. 0.30 – 0.40 seconds
Answer: B.
Explanation: The normal PR interval is 0.12 – 0.20 seconds, representing the time from atrial depolarization to ventricular depolarization.
2. Which part of the ECG represents ventricular depolarization?
A. P wave
B. QRS complex
C. T wave
D. PR segment
Answer: B.
Explanation: The QRS complex represents ventricular depolarization, which leads to ventricular contraction.
3. What does a tall, peaked T wave indicate?
A. Hypokalemia
B. Hyperkalemia
C. Hypocalcemia
D. Hypercalcemia
Answer: B.
Explanation: Hyperkalemia causes tall, peaked T waves, due to increased potassium levels affecting myocardial repolarization.
B. Hyperkalemia
C. Hypocalcemia
D. Hypercalcemia
Answer: B.
Explanation: Hyperkalemia causes tall, peaked T waves, due to increased potassium levels affecting myocardial repolarization.
4. A wide QRS complex (> 0.12 sec) suggests:
A. Atrial fibrillation
B. Ventricular conduction delay
C. Sinus tachycardia
D. First-degree heart block
Answer: B.
Explanation: A wide QRS suggests a ventricular conduction delay, such as bundle branch block or ventricular rhythm.
5. What is the normal heart rate range in a normal sinus rhythm?
A. 40 – 60 bpm
B. 60 – 100 bpm
C. 100 – 120 bpm
D. > 120 bpm
Answer: B.
Explanation: Normal sinus rhythm has a heart rate of 60 – 100 bpm.
B. 60 – 100 bpm
C. 100 – 120 bpm
D. > 120 bpm
Answer: B.
Explanation: Normal sinus rhythm has a heart rate of 60 – 100 bpm.
Identification of Common Cardiac Abnormalities
6. Which ECG finding is characteristic of atrial fibrillation?
A. Regular rhythm with no P waves
B. Irregularly irregular rhythm with no distinct P waves
C. Wide QRS complexes
D. PR interval > 0.20 seconds
Answer: B.
Explanation: Atrial fibrillation is identified by an irregularly irregular rhythm with no distinct P waves.
7. Which of the following rhythms is considered life-threatening and requires immediate defibrillation?
A. Atrial fibrillation
B. Sinus tachycardia
C. Ventricular fibrillation
D. First-degree AV block
Answer: C.
Explanation: Ventricular fibrillation is a lethal rhythm with no cardiac output, requiring immediate defibrillation.
8. What is the hallmark ECG change in myocardial infarction (MI)?
A. Peaked T waves
B. ST elevation
C. Widened PR interval
D. Deep Q waves
Answer: B.
Explanation: ST elevation is a classic sign of acute myocardial infarction (MI) due to complete coronary artery occlusion.
B. ST elevation
C. Widened PR interval
D. Deep Q waves
Answer: B.
Explanation: ST elevation is a classic sign of acute myocardial infarction (MI) due to complete coronary artery occlusion.
9. Which of the following suggests an old (previous) myocardial infarction?
A. T wave inversion
B. ST segment depression
C. Q waves
D. Prolonged PR interval
Answer: C.
Explanation: Pathologic Q waves indicate a previous MI due to permanent myocardial damage.
10. Which of the following best describes second-degree AV block Type I (Wenckebach)?
A. PR interval remains constant
B. PR interval progressively lengthens until a QRS is dropped
C. Wide QRS complexes with slow heart rate
D. Regularly irregular rhythm
Answer: B.
Explanation: In Mobitz Type I (Wenckebach), the PR interval gradually lengthens until a QRS complex is dropped.
Advanced ECG Analysis
11. Which rhythm is commonly seen in patients with chronic obstructive pulmonary disease (COPD)?
A. Sinus bradycardia
B. Multifocal atrial tachycardia (MAT)
C. Ventricular tachycardia
D. Atrial flutter
Answer: B.
Explanation: Multifocal atrial tachycardia (MAT) is associated with COPD, showing three or more different P-wave morphologies.
12. What is the heart rate in sinus tachycardia?
A. 60 – 100 bpm
B. > 100 bpm
C. < 60 bpm
D. 40 – 60 bpm
Answer: B.
Explanation: Sinus tachycardia is when the heart rate exceeds 100 bpm, usually due to stress, fever, or hypoxia.
13. What ECG finding is seen in a patient with pulmonary embolism?
A. Peaked P waves
B. S1Q3T3 pattern
C. Widened QRS complexes
D. Prolonged PR interval
Answer: B.
Explanation: The S1Q3T3 pattern (deep S wave in lead I, Q wave in lead III, and inverted T wave in lead III) is seen in pulmonary embolism.
B. S1Q3T3 pattern
C. Widened QRS complexes
D. Prolonged PR interval
Answer: B.
Explanation: The S1Q3T3 pattern (deep S wave in lead I, Q wave in lead III, and inverted T wave in lead III) is seen in pulmonary embolism.
14. Which of the following is a characteristic finding of left ventricular hypertrophy (LVH) on ECG?
A. Widened PR interval
B. ST depression
C. Tall R waves in V5 and V6
D. Deep Q waves
Answer: C.
Explanation: LVH shows tall R waves in V5 and V6 due to increased ventricular mass.
15. What is the first-line treatment for stable supraventricular tachycardia (SVT)?
A. Defibrillation
B. Vagal maneuvers
C. Epinephrine
D. Atropine
Answer: B.
Explanation: Vagal maneuvers, such as the Valsalva maneuver, can slow conduction through the AV node in SVT.
16. Which ECG finding is indicative of hyperkalemia?
A. Flattened T waves
B. Tall, peaked T waves
C. ST segment depression
D. U waves
Answer: B.
Explanation: Hyperkalemia causes tall, peaked T waves due to altered myocardial repolarization.
B. Tall, peaked T waves
C. ST segment depression
D. U waves
Answer: B.
Explanation: Hyperkalemia causes tall, peaked T waves due to altered myocardial repolarization.
17. Which ECG abnormality is characterized by a sawtooth pattern?
A. Atrial fibrillation
B. Atrial flutter
C. Ventricular tachycardia
D. First-degree AV block
Answer: B.
Explanation: Atrial flutter presents with a sawtooth pattern due to rapid atrial depolarization.
18. What is the primary characteristic of ventricular tachycardia (VT) on an ECG?
A. Narrow QRS complexes
B. Wide QRS complexes
C. Regular P waves
D. PR interval prolongation
Answer: B.
Explanation: Ventricular tachycardia (VT) is identified by wide QRS complexes originating from the ventricles.
19. Which electrolyte imbalance is most likely to cause prolonged QT interval?
A. Hyperkalemia
B. Hypokalemia
C. Hypercalcemia
D. Hypocalcemia
Answer: D.
Explanation: Hypocalcemia can prolong the QT interval, increasing the risk of torsades de pointes.
20. Which rhythm is characterized by a complete absence of electrical activity on ECG?
A. Atrial fibrillation
B. Ventricular fibrillation
C. Asystole
D. Sinus arrest
Answer: C.
Explanation: Asystole is a flatline ECG with no electrical activity, indicating cardiac arrest.
B. Ventricular fibrillation
C. Asystole
D. Sinus arrest
Answer: C.
Explanation: Asystole is a flatline ECG with no electrical activity, indicating cardiac arrest.
21. Which medication is commonly used to treat atrial fibrillation with a rapid ventricular response?
A. Epinephrine
B. Amiodarone
C. Atropine
D. Adenosine
Answer: B.
Explanation: Amiodarone is an antiarrhythmic medication effective in controlling atrial fibrillation with rapid ventricular response.
22. What ECG finding suggests pericarditis?
A. ST elevation in all leads
B. ST depression in all leads
C. Tall T waves
D. Inverted P waves
Answer: A.
Explanation: Diffuse ST elevation in multiple leads is characteristic of pericarditis, indicating inflammation of the pericardium.
B. ST depression in all leads
C. Tall T waves
D. Inverted P waves
Answer: A.
Explanation: Diffuse ST elevation in multiple leads is characteristic of pericarditis, indicating inflammation of the pericardium.
23. Which of the following indicates right bundle branch block (RBBB) on ECG?
A. Wide QRS with a slurred S wave in V6
B. Tall R waves in V5 and V6
C. RSR' pattern in V1 and V2
D. Prolonged PR interval
Answer: C.
Explanation: Right Bundle Branch Block (RBBB) shows an RSR' pattern (rabbit ears) in V1 and V2 with a wide QRS complex.
24. Which arrhythmia is most commonly associated with chronic alcohol use?
A. Atrial fibrillation
B. Sinus bradycardia
C. Ventricular tachycardia
D. Atrial flutter
Answer: A.
Explanation: Atrial fibrillation is often associated with chronic alcohol use, also known as "holiday heart syndrome."
B. Sinus bradycardia
C. Ventricular tachycardia
D. Atrial flutter
Answer: A.
Explanation: Atrial fibrillation is often associated with chronic alcohol use, also known as "holiday heart syndrome."
24. Which finding is most suggestive of ischemia on an ECG?
A. ST elevation
B. ST depression
C. Peaked T waves
D. U waves
Answer: B.
Explanation: ST depression suggests subendocardial ischemia, commonly seen in angina or non-ST elevation myocardial infarction (NSTEMI).
26. Which ECG change is expected in a patient with hypercalcemia?
A. Prolonged QT interval
B. Shortened QT interval
C. Peaked T waves
D. ST elevation
Answer: B.
Explanation: Hypercalcemia shortens the QT interval due to faster repolarization.
27. What is the characteristic finding of Wolff-Parkinson-White (WPW) syndrome on ECG?
A. Delta wave
B. Inverted T waves
C. Long PR interval
D. Irregularly irregular rhythm
Answer: A.
Explanation: WPW syndrome is identified by a delta wave, a slurred upstroke in the QRS complex due to an accessory pathway.
28. Which of the following is true about third-degree (complete) heart block?
A. Regular P-P and R-R intervals with no relationship between them
B. Prolonged PR interval with some dropped beats
C. Wide QRS complexes with no P waves
D. Irregularly irregular rhythm
Answer: A.
Explanation: In third-degree heart block, P waves and QRS complexes occur independently, with regular P-P and R-R intervals.
29. What is the typical rate of ventricular fibrillation (VF)?
A. 60 – 100 bpm
B. 100 – 200 bpm
C. 200 – 300 bpm
D. > 300 bpm
Answer: D.
Explanation: Ventricular fibrillation (VF) is a chaotic rhythm with rates typically above 300 bpm, causing no effective cardiac output.
30. Which ECG finding is associated with hypothermia?
A. Tall T waves
B. Osborn (J) waves
C. Prolonged PR interval
D. Delta wave
Answer: B.
Explanation: Osborn (J) waves are characteristic of hypothermia, appearing as a positive deflection at the end of the QRS complex.