Right coronary angiogram in LAO (left anterior oblique) cranial view shows proximal luminal irregularities with narrowest segment near the origin of a right ventricular (RV) branch. The right coronary artery (RCA) divides into posterior descending artery (PDA) and posterior left ventricular (PLV) branches at the crux. Crux is the junction of the interventricular and atrioventricular grooves on the posterior surface of the heart. The artery which crosses the crux to the opposite side is called as the dominant artery. In this case it is a right dominant system. The outline of two domes (left and right) of the diaphragm are seen in the background in this cranial view. It is common to see the contour of the diaphragm in all cranial views of coronary angiograms.
The RAO (right anterior oblique) view shows the proximal part of the right coronary artery in a vertical line. RAO view is identified with the spine seen on the right side. The lesion in the RCA just before the RV branch is seen to be more tight than from the LAO view, suggesting that it is an eccentric lesion. Several septal branches arising from the PDA can be seen well in this view. In fact, the identification of PDA in a coronary angiogram is by the septal branches which arises from it.