The mitral and tricuspid valves of the mammalian heart have been investigated to determine whether lymphatic channels are present in the leaflets. Extracorporeal circulation and atriotomy were used in 32 animal experiments. India ink was injected into the leaflets. The leaflets were examined with light and electron microscopes. A second phase consisted of obstruction of the efferent cardiac lymphatics and after an interval of 7 to 45 days, similar examination of the valve leaflets was done.
Lymphatic channels in the valve leaflets could not be demonstrated grossly or by light microscopy. Electron microscopy revealed some very small channels which had the characteristics of lymphatic capillaries. The importance of cardiac lymphatics as possibly related to disease states is discussed.