Moderator band (septomarginal trabecula)

Fascicles, Purkinje, muscle · detail

Muscular bridge crossing the RV cavity from the lower interventricular septum to the base of the anterior papillary muscle. It carries the right bundle branch across the ventricle, giving the anterior papillary muscle an early start so the tricuspid valve is braced before RV pressure rises.

Traced from the start

  1. Sinoatrial node
  2. Internodal pathways (anterior, middle, posterior)Right atrial myocardium
  3. Atrioventricular node
  4. Bundle of His (atrioventricular bundle)
  5. Right bundle branch
  6. Moderator band (septomarginal trabecula)

Detail

Contains
The distal right bundle branch and its Purkinje ramifications
Arterial supply
Septal perforators of the LAD, with variable RCA branches
Function
Shortens the conduction path to the RV free wall and limits over-distension of the ventricle

When it goes wrong

Injury during endomyocardial biopsy, catheter manipulation or surgery; sarcoid or infarct involving the band

Distal RBBB pattern; the band is also a recognised source of Purkinje-triggered ventricular ectopics and idiopathic VF

Practise this structure

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