Thebesian Drainage of the Septal Artery

Direct right ventricular drainage of I131 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.