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Topic

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Right branch of atrioventricular bundle

The right branch of the atrioventricular bundle, commonly called the right bundle branch (RBB), is one of the two terminal divisions of the bundle of His. After originating from the common AV bundle at the superior interventricular septum, it travels down the right side of the interventricular septum, continuing toward the apex of the right ventricle.

The right bundle branch conducts impulses rapidly through specialized Purkinje fibers, ensuring synchronous contraction of the right ventricle. It courses toward the moderator band (septomarginal trabecula), where it crosses to the anterior papillary muscle and then disperses into subendocardial Purkinje networks.

Pathology of this branch produces the right bundle branch block (RBBB) pattern on ECG, an important clinical marker in cardiology.

Synonyms

  • Right bundle branch (RBB)

  • Right branch of bundle of His

  • Right AV bundle branch

Function

  • Conducts electrical impulses from the AV node to the right ventricle

  • Ensures synchronous contraction of the right ventricular myocardium

  • Coordinates activation of the anterior papillary muscle and septal wall

  • Plays a role in maintaining normal QRS morphology on ECG

MRI Appearance

T1-weighted images:

  • The right bundle branch is not directly visible due to microscopic size

  • Indirectly evaluated by assessing septal anatomy and myocardial scarring in the right septal region

T2 Cine (Cardiac-gated):

  • High-resolution cine imaging can demonstrate functional consequences of conduction abnormalities (delayed septal wall motion in RBBB)

  • Septal contraction timing can be compared with left ventricular septum

STIR (Short Tau Inversion Recovery):

  • Detects edema or inflammation in the interventricular septum that may impair bundle conduction (e.g., myocarditis, sarcoidosis)

  • Appears as hyperintense septal signal in the bundle’s course

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Late gadolinium enhancement (LGE): shows fibrosis or scarring along the interventricular septum, which may involve the right bundle branch

  • Useful in ischemic or infiltrative cardiomyopathies associated with conduction blocks

CT Appearance

Contrast-Enhanced Cardiac CT:

  • Right bundle branch is not directly seen due to its microscopic size

  • CT helps assess interventricular septum integrity, calcifications, or fibrosis affecting conduction pathways

  • Useful for mapping septal thickness in congenital heart disease, hypertrophic cardiomyopathy, or post-infarct remodeling

CT Coronary Angiography (CCTA):

  • Demonstrates septal perforating branches of LAD, which supply the conduction system including the right bundle branch

  • Indirectly evaluates potential ischemic injury to conduction pathways

CT images

Right branch of atrioventricular bundle anatomy CT axial image -img-00000-00000