Figure 5. Vieussens’ arterial ring; Proposed anatomical classification and clinical significance.

(A) The ring’s anatomic course is determined from its origin, either from the conus branch or from the isolated conus artery and its site of drainage to the LAD, either proximal, medial or distal. Accordingly, six types of VAR are formed, with type IA being the most common one. (B) In coronary artery disease of either RCA or LAD, VAR can naturally bypass the obstructions, providing a life-saving collateral network towards the occluded coronary system. Also, its use during the percutaneous intervention can confirm the intraluminal wire position after crossing and provide an alternative to the anterograde approach in case of crossing failure.

LAD = left anterior descending artery, RCA = right coronary artery, VAR = Vieussens’ arterial ring