Anatomic variations of the orifice of the human coronary sinus.

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 particularly 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 explained on anatomic bases. Since in previous studies8-'0 the anatomic variations of the human 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 human 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 150 514 hearts chosen at random from the large collection of formalin fixed specimens at the Institute of Pathology, Western Reserve University. The hearts had been opened in the customary routine manner, so that the eustachian valve was usually sectioned near the middle by an incision extending between the orifices of the venae cavae. In examining the eustachian valve, special care was taken to reappose the cut edges, and examine its structure from the lateral aspect of the opened right atrium. The thebesian valve and orifice of the coronary sinus were intact in each case. All descriptions and measurements of the valves were made with the heart held in a position similar to that occupied in the intact body-the superior and inferior venae cavae in an axis parallel to …