Identification of surface morphologic changes in the mitral valve leaflets and chordae tendineae of dogs with myxomatous degeneration

Abstract

Morphologic changes associated with mitral valve endocardiosis in dogs were similar to those observed in humans with mitral valve prolapse. In dogs with mitral valve endocardiosis, gross changes in the valve complex may affect hemodynamics in the heart; alterations in the leaflet and chordal endothelium may contribute to pathogenesis of this disease.

Pathology, protein expression and signaling in myxomatous mitral valve degeneration: Comparison of dogs and humans

“…The ECM components, collagen VI and laminin were mildly increased and spread into the atrialis layer. Collagen I and III were no longer arranged in their typical layers, but formed a loose -Beginning in the endothelium 28 and in the atrialis layer 29,31,33 -Accumulation of glycosaminoglycans in the spongiosa layer and fragmentation of collagen bundles and elastic fibers 30,31 -Anterior leaflet is more affected by degeneration. 38 -No study of structural changes associated with disease progression -Accumulation of glycosminaglycans in the spongiosa layer and fragmentation of collagen bundles and elastic fibers 32,37,41,42 -Posterior leaflet is more prone to the degeneration and to ruptured chordae tendineae.…”

“…Damaged or denuded areas of the endothelial layer have been identified in dogs and humans with MMVD. 28,90,91 The damaged area was mostly seen in the distal part of the leaflets. The endothelial cells in affected valves were swollen, separated or had loose contact to each other.…”

“…14,28 It remains to be determined whether abnormalities of platelet function and morphology 11,39 or abnormalities in coagulation factors such as plasminogen, are responsible for this finding. 28 The occurrence of stroke secondary to emboli has been reported in humans affected with MMVD. However, some studies suggested that this phenomenon might be …”

Pathology of myxomatous mitral valve disease in the dog

“…These are most prominent at their mid-portion. 4,15,24,36,78,79 From the atrial to ventricular aspect, the atrialis comprises a thin layer of endothelial cells supported by scattered collagen fibers, elastic fibers, fibroblasts, and smooth muscle cells; the spongiosa, a layer rich in proteoglycans and glycosaminoglycans, extends from the annulus to the free edge of the leaflet, contains ground substance embedding a loose collection of collagen, elastic fibers, fibroblasts, and Anichkov's cells. The spongiosa of the proximal third of the anterior leaflet contains adipose cells; the fibrosa is a dense layer of compact collagen bundles with scattered fibroblasts that continues with the annulus proximally, and central core of chordae tendineae distally; and the ventricularis, a thin layer similar to the atrialis but without smooth muscle cells.…”

C‐Reactive Protein Concentration in Dogs with Chronic Valvular Disease

“…6 Two studies have supported the hypothesis that repeated trauma of the valve leaflets at the line of closure could result in alterations in endothelial cell structure or function. 9,10 Endothelin receptors were expressed on the thickened areas of the valve leaflets, which suggests that increased expression or activity of endothelin might contribute to degeneration of the valves. 9,11 C-reactive protein (CRP) is an acute-phase reactant protein that is increased in a number of disease states.…”