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Vein of Marshall (Ligament of Marshall)

An EP Anatomy & the Conduction System term on the RCES exam blueprint, defined for cath lab and EP clinicians.

An embryological remnant of the left superior cardinal vein running along the posterior left atrial wall between the left superior pulmonary vein and left atrial appendage; contains the Marshall bundle, which forms epicardial bypass connections that can maintain mitral isthmus conduction despite a seemingly complete endocardial ablation line, requiring ethanol infusion for definitive epicardial chemical ablation.

The vein of Marshall running obliquely along the posterior left atrial wall between the left superior pulmonary vein and the left atrial appendage, with a second panel showing the Marshall bundle still conducting epicardially around an endocardial mitral isthmus ablation line that appears complete.
The epicardial bypass that survives an apparently complete mitral isthmus line.

Domain: EP Anatomy & the Conduction System · Blueprint: RCES exam guide

Related RCES terms

Fossa Ovalis Kent Bundle (Accessory Pathway) Left Bundle Branch Area Pacing (LBBAP) Membranous Septum Subclavian Crush Syndrome

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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.