Bundle branch blocks

Question 1

Which leads look at bundle branches

Answer 1

V1- RBB
V6- LBB

Question 2

What is a bundle branch block

Answer 2

-interruption to normal transmission of depolarisation through the bundle branch
-caused by infarction, structural changes, trauma, pressure
-this means transmission isn’t able to pass through that bundle branch in the normal way
-impulse therefore is conducted through the opposite branch first
-opposite ventricle to where the block is will depolarise first, the other ventricle will depolarise later due to the block

Question 3

RBBB causes

Answer 3

-can be normal in patients with no heart disease
If symptomatic likely to be pathological which can be caused by:
-myocardial infarction
-myocarditis
-cardiomyopathy
-PE

Question 4

RBBB criteria and how it happens

Answer 4

-left ventricle depolarises first
-therefore ventricles depolarise from left to right through contractile cells
-QRS= bigger than 3 small squares
-V1/V2- either RSR pattern to QRS (M shaped) or broad monophasic R wave
-V5/ V6, 1/ aVL= wide slurred S wave

Question 5

LBBB causes and what pathway

Answer 5

ALWAYS pathological
-myocardial infarction
-cardiomyopathy
-myo/ endocarditis
-valvular disease
-congenital defect

New/ presumed new LBBB with AMI symptoms= pathway 1 so direct to PPCI

Question 6

LBBB ECG criteria

Answer 6

-wide QRS complex
-dominant (big) S wave in V1/V2
V5/V6/aVL:
-broad monophasic R wave
and/ or absence of Q waves

Question 7

What is appropriate discordance

Answer 7

-means abnormal depolarisation should be followed by abnormal repolarisation
-therefore if there’s a deep S wave, there is expected to be a big T wave