Lecture 5- BBBs

Question 1

How many subdivisions does the Right Bundle Branch have?

Answer 1

None, only the Left Bundle Branch subdivides (anterior and posterior fascicles)

Question 2

What should you do if you ID a wide QRS?

Answer 2

STOP and look for the BBB criteria

Question 3

What type of impulse conduction are you getting with BBBs?

Answer 3

Cell to cell transmission (slow and chaotic depolarization)&raquo_space;>results in wide QRS

Question 4

Right BBB criteria?

Answer 4

• QRS ≥ 0.12 sec
• RSR’ pattern in V1- rabbit ears!
• Deep S wave Leads I and V6 (slurred S)

Question 5

QR’ Wave (Instead of RSR’)

Answer 5

• Found with old anteroseptal infarct

- Q wave replaces initial R wave in V1 (like the bunny pic with one ear)

Question 6

You don’t always have classic RSR’ complex in V1 but the complex should be predominantly _____ with RBBB

Answer 6

POSITIVE*

Question 7

Left BBB criteria?

Answer 7

• QRS ≥ 0.12 sec
• Broad R waves in Leads I and V6- all positive
• Broad S waves in V1- all negative (may have small R wave)

Question 8

Clinical significance of LBBB?

Answer 8

Very difficult to diagnose infarction in the presence of LBBB

Question 9

New LBBB?

Answer 9

CAD until proven otherwise

Question 10

What are the 3 key leads in dx BBBs?

Answer 10

Lead I, V1, and V6

Question 11

What is Intraventricular Conduction Delay? (IVCD)

Answer 11

• QRS ≥ 0.12 seconds but does not have typical RBBB or LBBB pattern- “mixed”
• Electrolyte disturbances common, especially hyperkalemia* (until proven otherwise)

Question 12

ST and T waves in BB: What is concordance?

Answer 12

• If T wave in same direction as last wave of QRS

- signals ischemia, unless chronic

Question 13

What is discordance?

Answer 13

-T wave should always be in the opposite direction of the last wave of the QRS complex