Bundle Branch Blocks

Question 1

Anatomy—> Bundle of Hiss splits into…

Answer 1

L and R bundles, L bundle —> anterior and posterior fascicles

Question 2

Left axis deviation

Answer 2

-30 Q4 = left anterior fascicular block

Question 3

Right axis deviation

Answer 3

> 120 —> RVH (big R in V1) if no evidence of RVH then left posterior fascicular block

90-120 is RVH

Question 4

Right bundle branch block

Answer 4

Bunny ears in V1

Fatta essa

Question 5

Left bundle branch block

Answer 5

Big QRS

Question 6

S4

Answer 6

Stiff LV
HOCM
stenosis
Ischemia

Question 7

S1 loud

Answer 7

Mitral stenosis, short PR

Question 8

S1 soft

Answer 8

Mitral regurg, Long PR

Question 9

S1 variable

Answer 9

A fib
Heart block (complete)
VT

Question 10

Fixed split S2

Answer 10

ASD

Question 11

Physiologic split S2

Answer 11

A2 P2
I I inspiration
I I expiration

RBBB exaggerated splitting —>
I I insp
I I exp

LBBB paradoxical splitting —>
P2 A2
II insp
I I exp

Question 12

MV prolapse

Answer 12

Mid systolic click,
Earlier w/ abrupt standing
Later w/ squatting

Question 13

Narrow QRS

Answer 13

Problem above the bundle

Question 14

Wide QRS (>3 boxes)

Answer 14

Prob below the bundle

Question 15

How do you know if an LAFB is 2/2 inferior MI?

Answer 15

No Rs in II, III, avF

Question 16

Method to ID LAFB

Answer 16

1) Look at the axis, < -30

2) Look at II, III,avF —> Rs=anatomical LAFB, Qs=IMI (can have Rs and Qs)

Question 17

Method to ID LPFB

Answer 17

1) axis >120

2) look at V1 —> if R is normal it’s LPFB

Question 18

Method to ID RBBB

Answer 18

1) V1 bunny ears (little R, big R)
2) I, avL, V6 (lat leads) fatta essa

subtract last 0.04s of QRS to read axis

Can have nl axis, right dev (120) = bifascicular + LPFB, L dev (-30) = bifascicular + LAFB

Question 19

Reversed rabbit ears

Answer 19

Ventricular beat, MI

Question 20

Method to ID LBBB

Answer 20

1) QRS>3 boxes
2) V1 Q
3) I, avL, V6 NO Qs

*axis can be nl, L or R

Question 21

Looking for MI w/ a LBBB

Answer 21

QRS and ST-T waves should be OPPOSITE
Concordance is already weird w a LBBB, look for even small 1mm ST elev
Discordance, need bigger ST elev > 25% S

Question 22

If you have an LBBB w/ Qs in the lateral leads I, avL

Answer 22

It’s a SEPTAL (not high lateral) infarct!

Question 23

If you have a LBBB w notched Qs in V2,3,4

Answer 23

Old infarct, non-localizing (Cabrera sign)