Thread by @akhadilkarMD

One of the most important diagnostic tests in Cardiology to interpret is the EKG.

Here are my thoughts and notes. Will continue to this thread. Let me know what you think!

Thread #9: Left Bundle Branch Block (LBBB)

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LBBB:
- Similar to a RBBB, produces a wide QRS and affects the early phase of depolarization
- Septum will depolarize from (right to left; instead of normal left to right).
- Will see the loss of septal r-wave in V1 and septal q-wave in V6

LBBB:
- V1: Negative QRS complex b/c the LV is still electrically predominant (initial depolarization is negative and remains negative in the right-sided chest lead) (W-shape)
- V6: Entirely positive R-wave ('M'- Pattern)

LBBB:
- Usually a sign of organic heart disease
- May develop in patients with long-standing hypertensive heart disease, valvular lesion (calcification of mitral annuls), aortic stenosis, aortic regurgitation, different types of cardiomyopathy, CAD

LBBB:
- Most patients with LBBB have underlying LVH
- Degenerative changes in the conduction system may lead to LBBB, especially in the elderly
- Complete > 0.12 sec; incomplete < 0.12 sec
- TTE may show septal dyssynchrony due to an abnormal ventricular activation patterns

This is an important pattern to recognize on ECG! Thanks to this amazing website for the graphics: litfl.com/left-bundle-br…

Stay tuned for the next thread on fascicular blocks!