ENDOCARDIAL FIBROLASTOSIS IN CHICK MODEL OF HYPOPLASTIC LEFT HEART SYNDROME

Abstract

Endocardial fibroelastosis (EFE) is a diffuse thickening of the ventricular endocardium, causing myocardial dysfunction and presenting as unexplained heart failure in infants and children. It is believed to be caused by persistent and increased wall tension in the ventricles. . Its frequent association with hypoplastic left heart syndrome (HLHS) lead us to hypothesize abnormal hemodynamic loading is an important factor in its pathogenesis. We have tested this theory in a chick model of HLHS induced by left atrial ligation (LAL). At ED8 and 12 modifications of myocardial architecture and fibrosis were studied by histology and immunoconfocal microscopy, and the amount of collagen was quantified by image analysis.Histology with H&E / Alcian Blue staining did not reveal any significant fibrosis in the LAL hearts with the exception of cardiac skeleton and valves. Immunohistochemistry with collagen I antibody clearly showed a thickening of the layer of subendocardial fibrous tissue. Quantification of staining area normalized by endocardial circumference showed a significant increase at ED12, but not ED8 in the LAL group. We conclude that abnormal hemodynamic loading stimulates fibrous production in the subendocardium of the hypoplastic left ventricle. Therefore, EFE in HLHS clearly appears to be a secondary effect of abnormal hemodynamics.Grant Funding Source: Supported by Ministry of Education, Youth and Sports PRVOUK‐P35/LF1/5, Academy of Sciences RVO: 67985823, and Grant Agency of the Czech Republic P302/11/1308