Lymphatics of the heart

The anatomy of the cardiac lymphatic system of pigs, dogs, and humans has been studied by topical application of hydrogen peroxide and also by injection technics. In general, all three species have extensive subepicardial and subendocardial networks with collecting channels directed toward large ducts in the AV sulcus continuous with the main cardiac lymph duct. The subepicardial and subendocardial systems in dogs and pigs communicate via transmyocardial channels and channels in the supporting structures of the AV valves; in humans these communications have not been identified with certainty. Lymphatics are seen in both AV valves of dogs and pigs but have been seen only in the mitral valves of humans. The possible significance of these observations has been discussed.