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
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
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
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
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
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)
7
Q
Occasionally, the right precordial leads in RBBB exhibit what feature?
A
T-wave inversion/STD
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