Lymphatic vasculature is increased in heart valves, ischaemic and inflamed hearts and in cholesterol-rich and calcified atherosclerotic lesions

BACKGROUND: Despite the importance of myocardial vasculature in many pathological conditions, little information is available about cardiac and coronary lymphatic vessels in normal and pathological conditions. MATERIALS AND METHODS: Vasculature was assessed by immunohistochemistry with CD 31 and lymphatic endothelium with markers podoplanin and LYVE-1 in 16 children and 20 adult autopsy hearts. Valve biopsies were collected from eight adults. RESULTS: The highest number of lymphatics was found in valves in infective endocarditis, where they accounted nearly 100% of all vessels in certain areas. An increased number of lymphatics was also found in degenerative calcified stenosis, whereas the number was reduced in myxoid degeneration. Lymphatics grew in areas rich in extracellular matrix, whereas inflammatory cell-rich areas were more prone to angiogenesis. Progressive atherosclerotic lesions rich in calcium and cholesterol crystals revealed increased lymphangiogenesis in media. The highest number of myocardial lymphatics was found in epicardium of ischaemic hearts in both acute and chronic phase. Additionally, an increased number of lymphatics accompanied myocarditis and acute myocardial infarction. CONCLUSIONS: The highest number of lymphatics was found in valves in infective endocarditis. Increases in lymphatics also accompanied major cardiac pathological changes, such as acute and chronic ischaemia, progressive atherosclerosis, myocarditis and hypertrophy. Thus, blocking of excess lymphangiogenesis might be useful in progressive atherosclerosis, whereas stimulation of lymphatic vascular growth and function might be useful in cardiac hypertrophy and heart failure.