Thebesian Drainage of the Septal Artery

Direct right ventricular drainage of I 131 serum albumin injected into the septal artery of the normally beating dog heart has been demonstrated. By the application of standard dilution equations to the time-concentration curves recorded in the pulmonary artery, estimates of the magnitude of this Thebesian drainage have been made. Approximately 80% of septal artery outflow has been estimated to drain directly into the right ventricle; this amount comprises about 12.8% of total common left coronary flow and, in part, explains the discrepancy found between common left coronary inflow and coronary sinus outflow. The implications of Thebesian drainage of a branch of the common left coronary artery relative to the use of coronary sinus sampling for left ventricular metabolic studies have been discussed.