ECG Question-2

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What is the diagnosis of ECG?

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A. LBBB + LAFB

B. LBBB + LPFB

C. RBBB + LAFB

D. RBBB + LPFB

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What is Bifascicular Block?

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RBBB + LAFB is called Bifascicular Block ?

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What are the types of bifascicular block [ECG patterns]?

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• Right bundle branch block (RBBB) with left anterior fascicular block (LAFB) – left axis deviation (LAD)
• RBBB and left posterior fascicular block (LPFB) – right axis deviation (RAD) in the absence of other causes

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	Bifascicular Block
1	RBBB + LAFB	More common
2	RBBB + LPFB	Less common

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Why RBBB + LAFB is more common than RBBB + LPFB in bifascicular block?

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Why commonest type of bifascicular block is RBBB + LAFB ? [ECG patterns]	Vulnerability to Damage
The LAF is supplied by a single branch of the left anterior descending artery (LAD). The LPF, on the other hand, receives a dual blood supply from both the right and left circumflex arteries.	Because the LAF has a single blood supply, it’s more susceptible to damage and block due to ischemia or other factors affecting the LAD. The LPF’s dual blood supply makes it more resistant to damage and block compared to the LAF.

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Anatomy and Blood Supply:

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The LAF is supplied by a single branch of the left anterior descending artery (LAD).
The LPF, on the other hand, receives a dual blood supply from both the right and left circumflex arteries.

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Vulnerability to Damage:

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Because the LAF has a single blood supply, it’s more susceptible to damage and block due to ischemia or other factors affecting the LAD.
The LPF’s dual blood supply makes it more resistant to damage and block compared to the LAF.
Location and Relation to LV Outflow Tract:
The LAF’s location and relationship to the left ventricular (LV) outflow tract can also contribute to its vulnerability to damage, as it can be subjected to mechanical trauma.

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Clinical Significance:

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RBBB + LAFB is a common finding in patients with coronary artery disease (CAD), and its presence can indicate underlying structural and electrical abnormalities.
RBBB + LPFB is less common and may be associated with more extensive underlying cardiac pathology.

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Blood supply
Left anterior fascicle (LAF)	More common for block	Single blood supply	LAD
Left posterior fascicle (LPF)	Less common for block	Dual blood supply	RCA + LCX

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