What are the named arteries that can arise from the right coronary artery (RCA) on coronary computed tomography angiography (CCTA)?

Updated: Dec 21, 2017
  • Author: Eugene C Lin, MD; Chief Editor: Eugene C Lin, MD  more...
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Answer

Answer

There are 3 "named" arteries that can arise from the RCA, as follows:

  • The first branch off the RCA is often the conus artery. In 50% of cases, the conus artery arises from the RCA; in the other 50%, it arises from the aorta. The conus artery heads anteriorly toward the conus (right ventricular outflow tract). (See the image below.)

    Conus artery: Axial maximum intensity projection ( Conus artery: Axial maximum intensity projection (MIP) image demonstrates the conus artery (arrow) arising from the right coronary artery (RCA).
  • The second branch off the RCA is often the sinoatrial (SA) nodal artery. In 55% of cases, the SA nodal artery arises from the RCA; in the other 45%, it arises from the circumflex. The SA nodal artery heads posteriorly toward the sinoatrial node. The sinoatrial node is located in the superior aspect of crista terminalis of the right atrium (near where the superior vena cava joins the right atrium). The crista terminalis is a vestigial remnant located between the right atrial appendage and the sinus venosus. The crista terminalis can be seen as a right atrial "pseudomass" on computed tomography (CT) scanning, magnetic resonance imaging (MRI), or echocardiography. (See the images below.)

    Sinoatrial node artery: Axial maximum intensity pr Sinoatrial node artery: Axial maximum intensity projection (MIP) image demonstrates the sinoatrial node artery (arrow) arising from the right coronary artery (RCA).
    Conus and sinoatrial node arteries: Volume-rendere Conus and sinoatrial node arteries: Volume-rendered CT image of the right coronary artery demonstrates the conus artery (arrow) heading anteriorly and the sinoatrial node artery (arrowhead) heading posteriorly.
    Crista terminalis: Axial CT image demonstrates the Crista terminalis: Axial CT image demonstrates the crista terminalis (arrow) in the superior right atrium.
  • The last named branch off the RCA is the atrioventricular (AV) nodal artery, which arises from the RCA in 80-87% of cases. It can also arise from the circumflex or from both the RCA and the circumflex. If it originates from the RCA, it typically arises from the proximal posterolateral branch. It heads superiorly through the septum to the AV node, which is in the inferior aspect of the interatrial septum.


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