Connell PS, Han RI, Grande-Allen KJ.
Rice University, Houston, TX, USA.
J Vet Cardiol 2012;14:31–45.
Editor’s note: In this article, research on the structure and function of the mitral apparatus (papillary muscles, chordate, and valve leaflets) in humans, pigs, and dogs is reviewed, with particular reference to changes that occur in aging and disease. It covers the recent, interesting discovery that the mitral valve is densely innervated and is now understood to be an active structure with sensory and motor functions. It is also now known to produce and react to many factors in signalling pathways that may be involved in the pathogenesis of age-related myxomatous change and degenerative disease in the mitral valve. During the aging process, the mitral valve leaflets become stiffer (through reduced elastin and increased collagen levels) and less well innervated, and they may have increased or altered endothelial and interstitial activity. The authors cover complex cellular and intracellular biology and conclude that distinguishing between age-related degenerative changes and pathological processes is difficult, but that some differences (which may be associated with genetic factors) are evident, and offer boundless opportunities for research.