L.: Anatomic variations of the orifice of the human coronary sinus. Circulation 3: 514

Anatomic variations of the orifice of the human coronary sinus now have practical significance since the advent of catheterization of the coronary sinus. Six main types of variation of the valve of the coronary sinus of 150 hearts are described. The difficulties encountered in catheterization of the human coronary sinus are probably due to obstruction offered by large membranes, bars and networks, and less frequently due to the presence of a large eustachian ridge. On the basis of this study, catheterization of the human coronary sinus should be possible in a maximum of 75 per cent of the cases. M EASUREMENT of the coronary blood flow and myocardial metabolism-5 has been made possible by the technic of catheterization of the coronary sinus in the intact dog and man. Detailed knowledge of the structure of the right atrium, and par-ticularly of the variations and anomalies of the venous valves of the right atrium of the human heart (eustachian valve or the valve of the inferior vena cava, and the thebesian valve or the valve of the coronary sinus) now has practical significance. The failures reported in a large per cent of the attempts to cathe-terize the human coronary sinus can be ex-plained on anatomic bases. Since in previous studies8-'0 the anatomic variations of the hu-man coronary sinus were not considered from the viewpoint of their possible influence on catheterization, we believe it desirable to study anew the variations in the orifice of the hu-man coronary sinus in a large series of adult hearts. MATERIALS AND METHODS We have studied the eustachian and thebesian valves and the orifice of the coronary sinus in 15