Though there is great interest in the study of the heart, there is little general appreciation that the heart has a substantial lymph flow. The cardiac lymphatics have been neglected, probably because of the technical difficulties involved in their study.We have been studying the cardiac lymphatics in dogs for over four years—too short a time to amass any great amount of information, but long enough to become convinced that they are of considerable importance. Our initial interest was based on the consideration that impairment to cardiac lymph flow might be the cause of certain endocardial diseases of unknown etiology.1 Our base of interest is now considerably broader.2 The aim of this brief review will be to summarize some of the pertinent literature and to present some of our own concepts.
Phylogeny and Anatomy
Lymph hearts and venous lymphatics, which contain both blood and lymph, are seen