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

ABSTRACT

Both Ebstein's 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 Ebstein's malformation has also been described. Interstitial fibrosis has been shown in the right and left ventricles of hearts with Ebstein's malformation from neonates, children, and adults. The objective of this study was to determine whether interstitial fibrosis seen in Ebstein's malformation is an intrinsic part of the congenital malformation or is acquired. From the fetal and perinatal periods, we compared 13 hearts with Ebstein's 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 Ebstein's 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 Ebstein's 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 Ebstein's 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 Ebstein's 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 Ebstein's 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 Ebstein's malformation and tricuspid valvar dysplasia the endocardial thickening develops in perinatal life, and in Ebstein's malformation the interstitial fibrosis develops in later life.