Histological changes in the left and right ventricle in hearts with Ebsteinʹs malformation and tricuspid valvar dysplasia: A morphometric study of patients dying in the fetal and perinatal periods

Both Ebsteinʹs malformation and the related tricuspid valvar dysplasia are often associated with tricuspid regurgitation, and impaired right ventricular function may develop. Impaired function of the left ventricle in Ebsteinʹs malformation has also been described. Interstitial fibrosis has been shown in the right and left ventricles of hearts with Ebsteinʹs malformation from neonates, children, and adults. The objective of this study was to determine whether interstitial fibrosis seen in Ebsteinʹs malformation is an intrinsic part of the congenital malformation or is acquired. From the fetal and perinatal periods, we compared 13 hearts with Ebsteinʹs malformation (6 isolated and 7 with additional abnormalities) and 11 with tricuspid valvar dysplasia (3 isolated and 8 with additional abnormalities) with 16 controls. Three adult cases of isolated Ebsteinʹs malformation in patients aged 17 to 20 years, were compared with 5 controls. The percentage of interstitial fibrous tissue and the thickness of the endocardium in the right and left ventricles were measured using histomorphometry. There were similar findings in Ebsteinʹs malformation and tricuspid valvar dysplasia. Of 24 fetal and perinatal cases, 23 had normal interstitial fibrous tissue. Interstitial fibrosis was found in the right ventricle of only 1 perinatal heart with Ebsteinʹs malformation and pulmonary stenosis. Of the 9 fetal cases, 4 had minimal right ventricular endocardial thickening (up to 10 μm). The left ventricular endocardium was normal in this group. Of the 6 perinatal cases with isolated Ebsteinʹs malformation or tricuspid valvar dysplasia, 4 had right and 2 had left ventricular endocardial thickening (up to 345 μm). Of the 3 adult hearts with Ebsteinʹs malformation, 2 had right ventricular endocardial thickening (47 and 225 μm) and 2 had right and 1 had left ventricular interstitial fibrosis. These results indicate that in both Ebsteinʹs malformation and tricuspid valvar dysplasia the endocardial thickening develops in perinatal life, and in Ebsteinʹs malformation the interstitial fibrosis develops in later life.