RBBB Flashcards

1
Q

In the RBBB ECG, normal depolarization occurs in the (Left bundle of His/Right bundle of His)

A

Left bundle of His

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2
Q

Describe the vectors that produce ECG changes in the right bundle branch ECG.

A
  • Blockage of normal depolarization of the right Bundle of His produces ECG changes.
    - LBB depolarizes normally - meaning the early part of the QRS is unchanged
    - Delayed RBB activation changes the vector of depolarization (right ventricle is depolarized by the action potential spreading from the left bundle branch)
    - This delayed RBB depolarization adds a prime wave in the right precordial leads (V1-V3) and a slurred S save in the lateral leads (V4-V6)
    - There may also be STD/TWI in the right precordial leads
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3
Q

What is the Dx criteria for RBBB?

A
  • QRS > 120 ms (.12 s)
  • RSR’ pattern in V1-V3
  • Wide, slurred S-waves in I, aVL, V5-V6
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4
Q

Occasionally, a _____ may be found in V1 of the RBBB.

A. QRS < 120 ms
B. Monophasic R/qR complex
C. STE

A

B. Monophasic R/qR complex

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5
Q

What are the causes of RBBB?

A
  • RVH/cor pulmonale
  • PE
  • Ischemia
  • Rheumatic heart disease
  • Myocarditis/cardiomyopathy
  • Degenerative diseases of conduction
  • Atrial septal defect
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6
Q

Mnemonic for differentiating RBBB vs. LBBB

A

“WiLLiaM MaRRoW”

WiLLiaM:

- Block: Left Bundle
- Lead I findings: W-shaped QRS (Slurred S)
- Lead V6 findings: M-shaped QRS (RSR’)

MaRRoW:

- Block: Right Bundle
- Lead I findings: M-shaped QRS (RSR’)
- Lead V6 findings: W-shaped QRS (Slurred S)
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7
Q

Occasionally, the right precordial leads in RBBB exhibit what feature?

A

T-wave inversion/STD

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8
Q

Sometimes rather than an RSR’ pattern in V1, there may be _____ in RBBB.

A

a broad monophasic R wave or a qR complex

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