Hemiblocks (Johnston)

Question 1

What are some criteria for Left anterior hemiblock?

Answer 1

Left axis deviation (usually > -60)
Small Q in leads I and aVL, small R in II, III, and aVF
Usually normal QRS duration or slightly widened Q1S3 (Q in I and S in III)

Question 2

In left anterior hemiblock, which leads will have small R waves?

Answer 2

II, III, aVF

Question 3

In left anterior hemiblock which leads will have small Q waves?

Answer 3

I and aVL

Question 4

Whats the axis deviation in left anterior hemiblock?

Answer 4

Left axis deviation

Look for I=up, aVF=down

Question 5

What is the etiology of left posterior hemiblock?

Answer 5

Disease in conduction system

This is less common

Question 6

What is the axis deviation in left posterior hemiblock?

Answer 6

Right axis (usually > or equal to 120 degrees)

I=down, aVF=up

Question 7

In left posterior hemiblock, where do you have a small R?

Answer 7

Leads I and aVL

Question 8

In left posterior hemiblock, where do you have a small Q?

Answer 8

Leads II, III, aVF

Question 9

S1Q3 is associated with ___

Answer 9

Left posterior hemiblock

Question 10

List etiologies of Left Anterior Hemiblock:

Answer 10

Disease in conduction system

Often associated with MI (Left anterior descending-LAD occlusion)