That the heart has an extensive arterial and venous circulation is common knowledge; that it also has a well-defined lymphatic system is not generally appreciated. In the October issue of the Archives of Internal Medicine,1 Miller reviews the pertinent literature and reports on recent experimental studies in dogs. The evidence appears convincing that the lymphatics of the heart are physiologically important. But perhaps more significant is the relationship of the lymphatic system to human disease, as suggested by experimental investigations.
Chronic impairment of lymph flow from a region of the body results in tissue fibrosis and predisposes to infection and inflammation. Chronic obstruction of the cardiac lymph drainage has been shown to result in a significant increase in fibrous and elastic tissue in the ventricular endocardium of the dog. Pathologically, these changes often appear to be similar to those of endocardial fibroelastosis seen in man. Ventricular subendocardial hemorrhages are