The valves of patients with congestive heart failure often fail to close properly, allowing blood to leak back through the valve when the heart contracts. The problem, known as mitral regurgitation, has typically been ascribed to enlargement of the heart and other pathological problems associated with heart disease, but the new study suggests that changes in the valves themselves may contribute to the problem. This work was hailed as a "paradigm shift" in an accompanying editorial in the same journal.
"The most common form of valve disease -- a condition called myxomatous mitral valve disease is marked by a severe thickening of the valve tissue that is very easy to spot, either in surgery or on an electrocardiogram," said the study's lead researcher K. Jane Grande-Allen, assistant professor of bioengineering at Rice. " The changes we've documented are far more subtle. The valves look normal, both to the naked eye and on electrocardiogram, but at the cellular level, the tissue is quite different from that of healthy valves."
Grande-Allen's findings are based on a comparison of healthy heart valve tissue from cadavers with the mitral valve tissue from congestive heart failure patients who underwent heart transplantation.
Heart valves are connective tissue, and like skin, tendons and other connective tissues, the strength of the tissue derives not from the cells they contain but rather from the extracellular matrix that the cells secrete.
Grande-Allen and her colleagues found that the mitral valves of patients with advanced heart disease contained far more cells and collag
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