Thebesian Drainage in the Left Heart of the Dog

Direct left heart drainage from the common left coronary artery has been demonstrated in the normally beating dog heart by an isotope dilution technique. The major portion of this drainage has been shown to be through the left circumflex branch of the common left coronary artery. The left anterior atrial artery, a branch of the left circumflex, has in turn been shown to be the major pathway of drainage from the latter. Left heart drainage could not be demonstrated from isotope injections into the left anterior descendens artery, and in only one preparation could such drainage be documented from the septal branch of the common left artery. The magnitude of left heart Thebesian drainage has been estimated by analysis of time-concentration curves recorded from the aorta. An average of 2% of total common left coronary artery inflow drains directly into the left heart. Although the major drainage is probably into the left atrium, left ventricular drainage has not been excluded.