Bundle branch blocks

Question 1

What is the method of depolarisation in RBBB?

Answer 1

-Left bundle depolarises to right (towards V1)
-Depolarise left side first (move left to right)- away from V1
-depolarisation moves over to the right side (towards V1)

Question 2

Criteria for incomplete RBBB?

Answer 2

rSr and QRS <0.12 seconds

Question 3

Criteria for complete RBBB?

Answer 3

rSr and QRS >/= 0.12 seconds

Question 4

why cant you comment on ST and T wave changes in RBBB?

Answer 4

Due to aberrant conduction in right bundle

Question 5

Which demographic is RBBB common with and how can it develop?

Answer 5

Young men and can develop with exercise (phasic aberrancy)

Question 6

What does it mean to have a RBBB?

Answer 6

There is a delay in activation of the RV.
The activation of interventricular septum and free wall of the LV is normal (QRS normal)

Question 7

What are the causes of RBBB?

Answer 7

-often in congenital HD
-RVH or strain
-obstructive airways disease
-myocardial damage (common when disease of specialised conducting tissue)

Question 8

What does it mean to have LBBB?

Answer 8

Delay in Lv activation- broad, notched R wave in LV leads
-prolongation of duration of QRS

Question 9

What is the method of depolarisation in LBBB?

Answer 9

-right bundle depolarises to left (away from V1)
-depolarise the RV as normal
-depolarise the LV later on
(resulting in W shape in V1)

Question 10

What kind of morphology are the complexes in LBBB?

Answer 10

-Broad due to LV delayed activation
-qS wave as notched R wave

Question 11

What is the criteria for incomplete LBBB?

Answer 11

<0.12 seconds

Question 12

What is the criteria for complete LBBB?

Answer 12

> /= 0.12 seconds

Question 13

What is the ECG criteria for LBBB?

Answer 13

-notch, broad R in V5 and 6
-small. R in V1 and 2, then deep S wave
-absent septal Q waves in the left sided leads

Question 14

What morphology can you not comment on with LBBB?

Answer 14

ST and T changes (aberrant conduction)

Question 15

When is LBBB seen as significant?

Answer 15

New onset of chest pain and new LBBB

Question 16

What are the causes of LBBB?

Answer 16

-myocardial damage due to CAD or cardiomyopathy
-LVH
-disease of specialised conduction tissues

Question 17

Which consequence is associated with LBBB?

Answer 17

high risk of death (sudden death from coronary disease)

Question 18

ECG appearance/ criteria for RBBB?

Answer 18

-prolonged QRS of >0.12
-secondary R wave in leads facing RA (V1 and 2- therefore rSr)
-broad S wave in left ventricular leads and I