Bundle Branch Blocks - lecture

Question 1

Intrinsic deflection (intrinscoid) ID

Answer 1

time lapse from the beginning of the QRS to the peak of R wave - measured horizontally

Measure time when impulse reaches the epicardial surface of ventricle: V1 = 0.02 s, V6 0.04 s

If it takes longer for the ID to start downward, it means impulse is late in reaching the epicardial surface

Late ID: BBB, Hypertrophy/dilated

Question 2

Common features of BBB

Answer 2

Wide QRS complex (.12 sec or greater)

ST segment - T wave slopes off in opposite direction to QRS

Question 3

Sequence of ventricular activation in LBBB

Answer 3

Septum activated from right side, nearly same time as RV is activated, strong septal forces, therefore neg. reflection in V1 (QS)
positive deflection V6 - monophonic R

Question 4

Sequence of ventricular activation in RBBB

Answer 4

after septal activation, then activation begins in LV free wall

Question 5

LBBB more apt to occur with…

Answer 5

HTN, ischemia, aortic stenosis, cardiomyopathy

Question 6

LBBB with LAD

Answer 6

more myocardial dysfunction
more disease in conduction system
maybe higher mortality

Question 7

LBBB with RAD

Answer 7

think congestive cardiomyopathy

Question 8

Limb leads in BBB

Answer 8

I and AVL usually have features of V6

Question 9

T wave in BBB

Answer 9

polarity is opposite QRS direction

due to BBB, there is disturbance in depol-repol

secondary T wave changes

If T wave polarity is in the same direction of the QRS complex - primary T wave change
due to ischemia