IN 1706, Raymond Vieussens1 discovered the small openings on the endocardium which communicate with the coronary arteries. Two years later, Thebesius described the numerous openings for venous blood in the auricles and ventricles2 which are now commonly referred to as the thebesian circulation. In 1933, Wearn3 demonstrated direct communications between the heart chambers and the myocardial sinusoids, which he called "arterioluminal" and "arteriosinusoidal" vessels. In the event of gradual closure of the orifices of the coronary arteries, the thebesian circulation of Wearn's circulation can supply the heart muscle with sufficient blood to enable it to maintain an efficient circulation.4 Nordenstroem5 demonstrated the passage of contrast media from the myocardium ("myocardiogram") to the left ventricular lumen in a patient with coronary artery stenosis, which he thought might be radiological expression of the thebesian circulation. Thebesian or Wearn's circulation might play an important role in the blood