MAYO ECG EXAM STUDY GUIDE – UPDATED
COMPREHENSIVE REVIEW & PRACTICE SUPPORT
Section 1: Basic Principles & Waveforms (Questions 1-20)
1. What does the P wave on an ECG represent?
A. Ventricular repolarization
B. Atrial depolarization
C. Ventricular depolarization
D. Atrial repolarization
Answer: B. Atrial depolarization
2. The PR interval is measured from the:
A. Start of the P wave to the end of the QRS complex.
B. Start of the P wave to the start of the QRS complex.
C. Peak of the P wave to the peak of the R wave.
D. End of the P wave to the start of the QRS complex.
Answer: B. Start of the P wave to the start of the QRS complex.
3. A normal PR interval duration is:
A. 0.06 - 0.10 seconds
B. 0.12 - 0.20 seconds
C. 0.20 - 0.30 seconds
D. < 0.06 seconds
Answer: B. 0.12 - 0.20 seconds
4. The QRS complex represents which electrical event?
A. Atrial depolarization
B. Ventricular repolarization
C. Atrial repolarization
D. Ventricular depolarization
Answer: D. Ventricular depolarization
5. A normal QRS complex duration is less than:
A. 0.12 seconds
B. 0.20 seconds
C. 0.06 seconds
D. 0.24 seconds
Answer: A. 0.12 seconds
,6. The T wave on an ECG corresponds to:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: C. Ventricular repolarization
7. The QT interval varies with heart rate. What is the corrected QT (QTc) formula used to
account for this?
A. Friedewald formula
B. Bazett's formula
C. Cockcroft-Gault formula
D. CHA₂DS₂-VASc formula
Answer: B. Bazett's formula
8. A normal QTc interval for men is typically less than:
A. 440 ms
B. 470 ms
C. 500 ms
D. 520 ms
Answer: A. 440 ms
9. The isoelectric line between the S wave and the T wave is called the:
A. PR segment
B. ST segment
C. TP segment
D. QU interval
Answer: B. ST segment
10. On a standard ECG, how long is one small box (1 mm) on the horizontal axis?
A. 0.02 seconds
B. 0.04 seconds
C. 0.10 seconds
D. 0.20 seconds
Answer: B. 0.04 seconds
11. On a standard ECG, how much voltage does one small box (1 mm) represent on the
vertical axis?
A. 0.1 mV
B. 0.5 mV
,C. 1.0 mV
D. 1.5 mV
Answer: A. 0.1 mV
12. To calculate the heart rate using the "300 method," you would:
A. Divide 300 by the number of small boxes between two R waves.
B. Divide 1500 by the number of small boxes between two R waves.
C. Multiply the number of R waves in 6 seconds by 10.
D. Divide 60 by the RR interval in seconds.
Answer: B. Divide 1500 by the number of small boxes between two R waves.
13. Lead II is a(n):
A. Augmented limb lead
B. Precordial lead
C. Bipolar limb lead
D. Unipolar lead
Answer: C. Bipolar limb lead
14. The precordial leads (V1-V6) view the heart in which plane?
A. Frontal plane
B. Horizontal plane
C. Sagittal plane
D. Coronal plane
Answer: B. Horizontal plane
15. Which lead is typically placed in the fourth intercostal space at the right sternal border?
A. V1
B. V2
C. V3
D. V4
Answer: A. V1
16. The normal QRS axis in adults lies between:
A. -30° and +90°
B. -90° and +180°
C. 0° and +180°
D. -30° and -90°
Answer: A. -30° and +90°
17. If the QRS complex is positive in lead I and negative in lead aVF, the axis is:
A. Normal
, B. Left Axis Deviation
C. Right Axis Deviation
D. Extreme Axis Deviation
Answer: B. Left Axis Deviation
18. Atrial repolarization is usually not seen on a surface ECG because:
A. It occurs too quickly.
B. It is hidden by the much larger QRS complex.
C. It occurs during the PR segment.
D. It has a very low amplitude.
Answer: B. It is hidden by the much larger QRS complex.
19. The "J point" is defined as the:
A. Start of the P wave.
B. Point where the QRS complex ends and the ST segment begins.
C. Peak of the T wave.
D. End of the T wave.
Answer: B. Point where the QRS complex ends and the ST segment begins.
20. The U wave, when present, is thought to represent:
A. Late atrial depolarization
B. Repolarization of the Purkinje fibers
C. Early ventricular depolarization
D. Artifact from muscle tremor
Answer: B. Repolarization of the Purkinje fibers
Section 2: Rhythm Interpretation & Arrhythmias (Questions 21-60)
21. A normal sinus rhythm requires all of the following EXCEPT:
A. A consistent, regular rhythm.
B. A P wave before every QRS complex.
C. A PR interval that progressively lengthens.
D. A heart rate between 60-100 bpm.
Answer: C. A PR interval that progressively lengthens.
22. Sinus bradycardia is defined as a sinus rhythm with a heart rate of:
A. < 100 bpm
B. < 60 bpm
C. < 40 bpm
COMPREHENSIVE REVIEW & PRACTICE SUPPORT
Section 1: Basic Principles & Waveforms (Questions 1-20)
1. What does the P wave on an ECG represent?
A. Ventricular repolarization
B. Atrial depolarization
C. Ventricular depolarization
D. Atrial repolarization
Answer: B. Atrial depolarization
2. The PR interval is measured from the:
A. Start of the P wave to the end of the QRS complex.
B. Start of the P wave to the start of the QRS complex.
C. Peak of the P wave to the peak of the R wave.
D. End of the P wave to the start of the QRS complex.
Answer: B. Start of the P wave to the start of the QRS complex.
3. A normal PR interval duration is:
A. 0.06 - 0.10 seconds
B. 0.12 - 0.20 seconds
C. 0.20 - 0.30 seconds
D. < 0.06 seconds
Answer: B. 0.12 - 0.20 seconds
4. The QRS complex represents which electrical event?
A. Atrial depolarization
B. Ventricular repolarization
C. Atrial repolarization
D. Ventricular depolarization
Answer: D. Ventricular depolarization
5. A normal QRS complex duration is less than:
A. 0.12 seconds
B. 0.20 seconds
C. 0.06 seconds
D. 0.24 seconds
Answer: A. 0.12 seconds
,6. The T wave on an ECG corresponds to:
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: C. Ventricular repolarization
7. The QT interval varies with heart rate. What is the corrected QT (QTc) formula used to
account for this?
A. Friedewald formula
B. Bazett's formula
C. Cockcroft-Gault formula
D. CHA₂DS₂-VASc formula
Answer: B. Bazett's formula
8. A normal QTc interval for men is typically less than:
A. 440 ms
B. 470 ms
C. 500 ms
D. 520 ms
Answer: A. 440 ms
9. The isoelectric line between the S wave and the T wave is called the:
A. PR segment
B. ST segment
C. TP segment
D. QU interval
Answer: B. ST segment
10. On a standard ECG, how long is one small box (1 mm) on the horizontal axis?
A. 0.02 seconds
B. 0.04 seconds
C. 0.10 seconds
D. 0.20 seconds
Answer: B. 0.04 seconds
11. On a standard ECG, how much voltage does one small box (1 mm) represent on the
vertical axis?
A. 0.1 mV
B. 0.5 mV
,C. 1.0 mV
D. 1.5 mV
Answer: A. 0.1 mV
12. To calculate the heart rate using the "300 method," you would:
A. Divide 300 by the number of small boxes between two R waves.
B. Divide 1500 by the number of small boxes between two R waves.
C. Multiply the number of R waves in 6 seconds by 10.
D. Divide 60 by the RR interval in seconds.
Answer: B. Divide 1500 by the number of small boxes between two R waves.
13. Lead II is a(n):
A. Augmented limb lead
B. Precordial lead
C. Bipolar limb lead
D. Unipolar lead
Answer: C. Bipolar limb lead
14. The precordial leads (V1-V6) view the heart in which plane?
A. Frontal plane
B. Horizontal plane
C. Sagittal plane
D. Coronal plane
Answer: B. Horizontal plane
15. Which lead is typically placed in the fourth intercostal space at the right sternal border?
A. V1
B. V2
C. V3
D. V4
Answer: A. V1
16. The normal QRS axis in adults lies between:
A. -30° and +90°
B. -90° and +180°
C. 0° and +180°
D. -30° and -90°
Answer: A. -30° and +90°
17. If the QRS complex is positive in lead I and negative in lead aVF, the axis is:
A. Normal
, B. Left Axis Deviation
C. Right Axis Deviation
D. Extreme Axis Deviation
Answer: B. Left Axis Deviation
18. Atrial repolarization is usually not seen on a surface ECG because:
A. It occurs too quickly.
B. It is hidden by the much larger QRS complex.
C. It occurs during the PR segment.
D. It has a very low amplitude.
Answer: B. It is hidden by the much larger QRS complex.
19. The "J point" is defined as the:
A. Start of the P wave.
B. Point where the QRS complex ends and the ST segment begins.
C. Peak of the T wave.
D. End of the T wave.
Answer: B. Point where the QRS complex ends and the ST segment begins.
20. The U wave, when present, is thought to represent:
A. Late atrial depolarization
B. Repolarization of the Purkinje fibers
C. Early ventricular depolarization
D. Artifact from muscle tremor
Answer: B. Repolarization of the Purkinje fibers
Section 2: Rhythm Interpretation & Arrhythmias (Questions 21-60)
21. A normal sinus rhythm requires all of the following EXCEPT:
A. A consistent, regular rhythm.
B. A P wave before every QRS complex.
C. A PR interval that progressively lengthens.
D. A heart rate between 60-100 bpm.
Answer: C. A PR interval that progressively lengthens.
22. Sinus bradycardia is defined as a sinus rhythm with a heart rate of:
A. < 100 bpm
B. < 60 bpm
C. < 40 bpm
