Right bundle branch
Crus dextrum fasciculi atrioventricularis
Also known as: RBB
The right bundle branch is a thin, cord-like branch of the bundle of His. It runs down the right side of the interventricular septum and through the moderator band to the anterior papillary muscle and the Purkinje network of the right ventricle.
Overview
The right bundle branch runs as a single, narrow fascicle down the right side of the septum, just beneath the endocardium. It then crosses the ventricle in the moderator band and fans out into Purkinje fibres. Because it is a long, thin, discrete structure, it is easily blocked by stretch or ischaemia. It is also sometimes blocked in otherwise healthy people. Its blood supply comes mainly from the septal perforators of the LAD.
- Location
Right side of the interventricular septum, then through the moderator band.
Function
- Activates the right ventricle and its anterior papillary muscle.
Clinical significance
Right bundle branch block
In RBBB the QRS is 120 ms or wider. Lead V1 shows an rsR′ "M" pattern, and leads I and V6 show a wide, slurred S wave. S2 splits widely. RBBB can be a normal variant, or it can be caused by an ASD, acute right ventricular strain (pulmonary embolism), ischaemic heart disease or cor pulmonale.
Mnemonics
WiLLiaM MaRRoW
WiLLiaM (LBBB): a W shape in V1 and an M shape in V6. MaRRoW (RBBB): an M shape in V1 and a W shape in V6.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.