Hypoplastic left heart syndrome (HLHS) is found in a wide spectrum of changes of the mitral valve, left ventricle and aorta. It represents a critical congenital heart disease with a small left ventricle and stenosis or atresia of the aortic and the mitral valve. The knowledge of a detailed anatomy of this lesion is necessary from the viewpoint of assessment of all possibilities of the surgical treatment, interventional cardiological procedures or foetal cardiac surgery. Sixty one hearts with HLHS from the collection of heart specimens with congenital heart malfor- mations were reviewed. The existence of a wide spectrum of malformations of all heart structures was proved. In all the cases enlarged right atrium and right ventricle was found. In 23,0% of specimens foramen ovale was restrictive or closed. The left ventricle was small in all the hearts, extreme hypoplasia was observed in 26,2% in presence of a combination of the mitral and the aortic atresia. Most commonly, the combination of mitral stenosis with aortic atresia (36,1%) and combination of mitral and aortic stenosis (32,8%) were present. Mitral atresia with aortic stenosis was identified in 4,9% cases. The mitral valve was usually dysplastic with short and thick chordae and smaller annulus. In 39,3% of all hearts fibroelastosis of the left ventricular endocardium was present. In these cases moderate degree hypoplasia of the left ventricle in combination with mitral and aortic stenosis was often found (65,0%). All the aorta was hypoplastic starting from the aortic valve, across the ascendent part and aortic arch untill the isthmus. Its diameter usually varied between 2 and 4 mm. Coarctation of the aorta was found in 16,4% hearts. Persistent left superior caval vein represented the most common associated heart lesion. From the surgical point of view, nearly in all reviewed hearts Norwood surgery, consisting in aortic reconstruction from aorta, main pulmonary artery and a patch from the pulmonary homo- graft could be performed. Reconstruction would be very difficult in presence of an extreme hypoplasia of the ascending aorta. Untill present, possibilities to prevent the development of the left ventricular hypoplasia by a foetal surgical intervention or possibility of the surgical augmentation of the left ventricle by excision of a thick endocardium do not cross the horizons of theory.

        Key words: circulation – congenital heart disease – hypoplastic left heart syndrome - morphology – cardiac surgery