A 4 year old boy failed to thrive after the age of 5 months and was found to have an enlarged heart and systolic bruit. Electrocardiogram showed left ventricular strain and a clinical diagnosis of fibroelastosis was made. He gradually deteriorated and died despite digitalis and diuretic therapy.
The heart is sliced to display the left atrium, left ventricle and mitral valve as viewed from the left side. The left atrial and ventricular cavities are dilated and the left ventricular wall is thickened. The endocardium of both atria and ventricles is thickened and presents a pearly white appearance. The right sided chambers seen at the back of the specimen, are less severely affected. The yellow discolouration of the mitral valve and apparent ventricular septal defect are artefacts. This is an example of endocardial fibroelastosis - a thickening of the endocardium by collagenous and elastic fibres often associated with myocardial hypertrophy. The nature of the disease is obscure.