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Bundle Branches

A Cath Lab Anatomy & Hemodynamics term on the RCIS exam blueprint, defined for cath lab and EP clinicians.

The AV bundle branch is supplied by the RCA (10% of cases), the LCA (73%), or both (17%). The right bundle branch (running through the moderator band) is supplied primarily by septal branches of the LAD. The left bundle branch is supplied by branches from both the RCA and LAD. *Note: some board-review sources use simplified conduction-artery figures (SA nodal artery: RCA ~60%/LCx ~40%; AV nodal artery: RCA ~80-90%) rather than the granular bundle-branch breakdown above.*

Blood supply of the distal conduction system: the AV bundle branch mainly from the left coronary artery, the right bundle branch from LAD septal branches through the moderator band, and the left bundle branch from both the RCA and the LAD.
Why a proximal LAD lesion threatens the right bundle and a bifascicular block matters.

Domain: Cath Lab Anatomy & Hemodynamics · Blueprint: RCIS exam guide

Related RCIS terms

Atrioventricular (AV) Node Left Anterior Descending (LAD) Artery Left Circumflex (LCX) Artery Left Main Coronary Artery (LMCA) Posterior Descending Artery (PDA)

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Written and reviewed by John-Philip (JP) Maarschalk, BSN, RN, CNML — a nurse manager who runs operations for the cardiac cath lab, electrophysiology, and interventional service lines at an academic health system in North Carolina. He hires and develops the staff who sit for these exams. More about JP and how this content is made →
Cardiac Codex is an independent study tool published by MdoubleA LLC, not affiliated with or endorsed by CCI or any certifying body. This glossary entry is exam-preparation information, not medical advice or a substitute for clinical judgment. Always verify current clinical practice against primary sources and institutional protocol.