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Conus artery

The conus artery, also known as the conus branch or third coronary artery, is a small but clinically significant vessel that most commonly arises from the proximal right coronary artery (RCA), near its origin at the right coronary sinus. In approximately 30–50% of individuals, it arises directly from the right coronary sinus of the aorta, separate from the RCA, in which case it is termed the third coronary artery.

The conus artery courses anteriorly to supply the right ventricular outflow tract (RVOT, also called the infundibulum or conus arteriosus), the upper interventricular septum, and portions of the anterior right ventricular wall. It also contributes to important anastomoses with the left anterior descending artery (LAD), forming part of the arterial circle of Vieussens, which provides a collateral pathway between the RCA and LCA systems.

Though small in size, the conus artery is clinically important in coronary interventions, congenital heart disease, and cases of proximal LAD or RCA occlusion where collateral flow through the conus branch can preserve myocardial perfusion.

Synonyms

  • Conus branch

  • Third coronary artery

  • Arteria coni arteriosi

  • RVOT branch

Function

  • Supplies the right ventricular outflow tract (conus arteriosus/infundibulum)

  • Provides branches to the upper interventricular septum

  • Contributes to the anterior wall of the right ventricle

  • Participates in collateral circulation with the LAD (arterial circle of Vieussens)

  • Plays a role in maintaining perfusion during proximal RCA or LAD occlusion

MRI Appearance

T1-weighted images (non-contrast):

  • Appears as a signal void (black lumen) due to flowing blood

  • Surrounded by epicardial fat, aiding localization near RCA origin

T2-weighted images:

  • Vessel lumen remains a signal void

  • Adjacent perivascular edema or inflammatory changes (e.g., myocarditis) may appear hyperintense

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights perivascular pathology

  • Vessel remains a void, while edema or infiltration around RVOT appears hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Conus artery enhances brightly

  • Useful for identifying small vessel origin, course, and anastomoses with LAD

  • Myocardial late gadolinium enhancement may show infarcts in RVOT or anterior septum

MRI Non-Contrast Cardiac-Gated 3D Coronary MRA:

  • Depicts conus artery as a small but continuous enhancing vessel from RCA or directly from the aortic sinus

  • Demonstrates collateral connection with LAD in the circle of Vieussens

  • Valuable in congenital anomalies or preoperative mapping

CT Appearance

Non-contrast CT (Calcium Scoring):

  • Conus artery usually not visualized unless calcified plaque is present at RCA ostium

CT Coronary Angiography (CCTA):

  • Best modality for non-invasive visualization

  • Clearly shows origin (from RCA or directly from right coronary sinus), course, and contribution to RVOT, anterior septum, and anastomoses with LAD

  • Detects stenosis, anomalous origin, aneurysm, or involvement in coronary anomalies

  • Multiplanar and 3D reconstructions useful in PCI and congenital heart surgery planning

CT image

Conus artery anantomy CT axial image -img-00000-00000

MRI image

Conus artery mri axial