The levophase of left coronary injection shows filling of the coronary sinus and prominent oblique vein of Marshall.

The oblique vein of Marshall (arrow 1) runs along the posterior left atrium and joins the great cardiac vein (arrow 3) at the point where the latter becomes the coronary sinus (arrow 2). It is small in humans and is the residua of the embryonic left superior cardinal vein. The oblique vein is continuous above with the ligament of the left vena cava. The point where it joins the coronary sinus is occasionally marked by a small indentation produced by the venous valve of Vieussens.