Smallest cardiac veins

The smallest cardiac veins (or Thebesian veins) are minute valveless veins in the walls of all four heart chambers. The veins are sometimes accurately referred to as vessels, but they are frequently confused with a distinct set of artery connections eponymously referred to as the "vessels of Wearn". The Thebesian veins are reportedly most abundant in the right atrium and least in the left ventricle. They drain the myocardium and run a perpendicular course to the endocardial surface, directly connecting the right atrium to the medium sized, and larger coronary veins.Thebesian veins have been successfully identified by following the route of contrast flow - during catheterization procedures - from the subendocardium, through the thebesian veins, into larger veins, and into the coronary sinus. The coronary sinus empties into the right atrium.