Antegrade filling of an occluded right coronary artery via collaterals from a separate conus artery, a previously undescribed collateral pathway.

The conus artery is known to be a frequent supplier of collaterals to the LAD and distal marginal branches of the RCA. In this report we describe a patient with an ostial RCA occlusion who was found to have, during selective conus artery injection, excellent collaterals directly to the proximal RCA. This anatomy was initially mistaken for diffuse disease of the ostium and proximal portion of the RCA.