E1: Axis And Chamber Enlargement

Question 1

What leads do you look at to determine axis?

What is considered a normal axis with these leads?

Answer 1

Leads 1 and aVF

If the predominant direction is positive in non of these leads, the axis is normal

Question 2

The mean QRS axis is normally between what degrees?

Answer 2

Between 0 and +90

Question 3

If there is left axis deviation, the axis is between what degrees?

Answer 3

0 and -90

Question 4

If there is RAD, the axis is between what degrees?

Answer 4

+90 and +180

Question 5

What does it mean if lead 1 is negative and aVF is positive?

Answer 5

RAD

Question 6

What does it mean if lead 1 is positive and aVF is negative?

Answer 6

LAD

Question 7

What does it mean if both lead 1 and aVF are negative?

Answer 7

Indeterminate axis

Question 8

What is a vertical heart?

Answer 8

Tall and thin individuals may have a more vertical heart, with a shift in the QRS axis toward +90

Question 9

What is a horizontal heart?

Answer 9

Obese or pregnant individuals may have a more horizontal heart with a mean QRS axis shifting more leftward

Question 10

What leads are used to assess for atrial enlargement?

Answer 10

Leads II and V1

Question 11

What P wave finding is suggestive of RAE?

Answer 11

P wave amplitude >2.5mm

Question 12

What P wave finding is suggestive of LAE?

Answer 12

P wave duration >0.10 seconds

Question 13

How can you assess for RAE using V1 where the P wave is biphasic?

Answer 13

The initial component of the P wave in V1 is larger than the terminal component

Question 14

What 2 conditions are common with RAE?

Answer 14

Pulmonic stenosis, tricuspid stenosis, and Tricuspid regurgitation

Question 15

How can you assess for LAE using V1 where the P wave is biphasic?

Answer 15

The terminal portion of the P wave in V1 is negative with a duration of ≥0.04 seconds and a depth of >1mm

Question 16

What conditions are common with LAE?

Answer 16

Mitral stenosis and mitral regurgitation

Question 17

What are the common causes of LVH?

Answer 17

HTN and valvular heart disease

Question 18

What are the 3 criteria that indicate LVH?

Answer 18

Any 1 of the following:

• Sum of the seeping S in V1 or V2 plus the tallest R in V5 or V5 >35mm
• R in aVL >11
• R in lead 1 plus S in Lead III >25

Question 19

What commonly causes RVH?

Answer 19

Pulmonary HTN or pulmonic stenosis

Question 20

What are the criteria that are indicative of RVH?

Answer 20

Any 1 of the following:

• RAD
• R wave >S wave in V1
• S wave >R wave in V6