Hemiblocks - EKGs Flashcards
1
Q
2 types of hemiblocks
A
- Left anterior hemiblock (ant/superior division)
- Left posterior hemiblock (post/inferior division)
2
Q
More common hemiblock
A
LAH
3
Q
Causes of hemiblocks
A
LAH = LAD occlusion (anterior infarct) LPH = RCA occlusion (posterior/inferior infarct)
4
Q
LAH vs. LPH - EKG
A
LAH = left axis deviation (free wall supplied from L only) LPH = right axis deviation (free wall supplied from R only)
5
Q
What causes the axis deviations to not occur without a hemiblock?
A
The free wall of the LV is normally simultaneously innervated by each division in opposite directions, cancelling each other out in the EKG
6
Q
LAH - EKG
A
- Left axis deviation ( > -60º)
- Big S in 2, 3, F
- (Q in 1 and L) - not as apparent
7
Q
LPH - EKG
A
- Right axis deviation (> +120º)
- Big S in 1 and L
- (Q in 2, 3, F) - not as apparent
8
Q
How to differentiate hemiblock from ventricular hypertrophy?
A
Hemiblock = no sign of RVH or LVH (giant QRS complexes)
