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In 85% of patients the right coronary artery (RCA) is said to be "dominant"
because it supplies circulation to the inferior portion of the inter-ventricular
septum via the right posterior descending coronary artery or PDA branch.
In these cases the RCA travels to the cross-section of the AV
groove and the posterior inter-ventricular (IV groove). Here, it gives
rise to the right posterior descending coronary artery (PDA) branch
which travels in the posterior IV groove and gives off several
septal perforator branches (SP). The SP supply blood to the lower portion
of the IV septum.
Generally, the dominant RCA also gives
rise to the AV nodal branch which supplies blood to the AV
node.
The dominant RCA also provides the right postero-lateral
(PLA) branch to the lower postero-lateral portion of
the left ventricle. Frequently, the circumflex (Cx)
may also provide additional PLA branches which are known
as the left PLA branches.
The sinus or sino-atrial (SA) node branch originates in the proximal portion
of the RCA in 60% of cases and as a left atrial branch of the Cx in the
remaining 40% of cases. This is unrelated to whether the artery is "dominant"
or not.
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