Abstract

In all cases of primary endocardial fibroelastosis investigated diffuse degenerative changes in the ganglion cells were detected. Thickened endocardium was formed by the proliferation of mesenchymal cells located under the endothelial endocardium and of the mesenchyme surrounding the necrobiotic muscle cells. In some cases `axial' vacuolar degeneration, necrobiosis, and necrosis of muscle cells, interstitial oedema, and dilatation of capillaries and lymphatic spaces were found in the whole myocardium. In all cases these changes were in the subendocardial layer.

In the cases discussed morphological changes in the endocardium were seen to be secondary to lesions in myocardial and possibly in neural structures.