Basic ECG

Question 1

Which are the septal leads?

Answer 1

• facing: v1, v2

- no reciprocal

Question 2

Which are the anterior leads?

Answer 2

• facing: v3, v4

- no reciprocal

Question 3

Which are the anteroseptal leads?

Answer 3

• facing: v1, v2, v3, v4

- no reciprocal

Question 4

Which are the lateral leads?

Answer 4

• facing: I, aVL, V5, V6

- reciprocal: II, III, aVF

Question 5

Which are the anterolateral leads?

Answer 5

• facing: I, aVL, V3, V4, V5, V6

- reciprocal: II, III, aVF

Question 6

Which are the inferior leads?

Answer 6

• facing: II, III, aVF

- opposite: I, aVL

Question 7

Which are the posterior leads?

Answer 7

• facing: none

- opposite: v1, v2, v3, v4

Question 8

What does a positive lead I and negative aVF suggest?

Answer 8

left axis deviation

Question 9

What does a negative lead I and positive aVF suggest?

Answer 9

right axis deviation

Question 10

What does a negative lead I and negative aVF suggest?

Answer 10

extreme axis deviation

Question 11

How does a normal P wave look like?

Answer 11

• P wave positive in leads II, III, AVF
• P wave duration <0.12s
• P wave height <2.5mm

Question 12

What is normal q wave duration?

Answer 12

Duration <0.04s (1 small sq)

Question 13

What does a normal qrs complex look like?

Answer 13

• Duration <0.12s (3 small sq)

- Normal R wave progression from V1 to V4 (should get more positive)

Question 14

What is the normal PR interval?

Answer 14

0.12-0.20s (3-5 small squares)

Question 15

What is the normal QT Interval?

Answer 15

0.38-0.42s (9.5 - 10.5 small squares) or grossly

Question 16

What does the P wave represent?

Answer 16

atrial depolarisation originating in the sinoatrial node (SA node)

Question 17

What does the PR interval represent?

Answer 17

depolarization originating in the SA node and traveling through the atria, the AV node, and the His-Purkinje system

Question 18

What does the QRS complex represent?

Answer 18

ventricular depolarisation

Question 19

What does the ST segment represent?

Answer 19

the segment between ventricular depolarization and repolarization

Question 20

What does T wave represent?

Answer 20

ventricular repolarization

Question 21

What does the QT interval represent?

Answer 21

total time of ventricular depolarisation and repolarisation

Question 22

What are the causes of right atrial enlargement?

Answer 22

Caused by pulmonary HTN

• Chronic lung disease (Cor Pulmonale)
• Pulmonary embolism
• Tricuspid Stenosis
• Tricuspid Regurgitation

Question 23

How does right atrial enlargement appear on ECG?

Answer 23

• Axis deviation of P wave to right
• Amplitude of 1st part of P wave increases (>2.5mm)
• P wave width no change (because 2nd part of P wave is left atrial in origin, hides prolonged depolarization of right atrium)

Question 24

What are the causes of left atrial enlargement?

Answer 24

If in isolation, classically seen with MS

If in association with LVH

• Systemic HTN
• Aortic stenosis
• Mitral regurgitation
• Hypertrophic Cardiomyopathy

Question 25

How does left atrial enlargement appear on ECG?

Answer 25

- No significant axis deviation (because left atrium is normally already electrically dominant) - 2nd part of P wave increase in amplitude (i.e. >1mm below isoelectric line in V1; not visible in lead II) - Increase in duration of P wave

Question 26

What are the causes of right ventricular enlargement?

Answer 26

- Chronic lung disease (cor pulmonale) - Pulmonary embolism - Pulmonary stenosis - Pulmonary hypertension - Congenital heart disease (e.g. ToF)

Question 27

What are the ecg changes seen in right ventricular enlargement?

Answer 27

Right axis deviation (>100) - Lead I more –ve than +ve Poor R wave progression - V1: R wave larger than S wave - V6: S wave larger than R wave +/- RV Strain Pattern (Downward sloping ST Depression + T wave inversion)

Question 28

What are the causes of left ventricular enlargement?

Answer 28

- Hypertension (most common cause) - Aortic stenosis - Aortic regurgitation - Mitral regurgitation - Coarctation of the aorta

Question 29

What are the ecg changes seen in left ventricular enlargement?

Answer 29

kolov-Lyon criteria: R wave amplitude (V5 or 6) + S wave amplitude (V1 or 2) is >35mm (>7 large squares) Left axis deviation (not as useful in Dx) +/- LV Strain Pattern (Downward sloping ST Depression + T wave inversion)

Question 30

In which leads can T wave inversion be physiological?

Answer 30

May be inverted in III, aVR, V1 & V2 without being abnormal