[Pathologic anatomy of congenital heart defects]

The heart of neonates and infants with marked hypoplastic left- or right-heart-syndrome contains--despite the very low weight in the hypoplastic parts--myocytes of approximately the same size as in the non-hypoplastic ventricular wall. This means that the number of cells is not constant, because in contrast to the regularly developed right and left ventricular walls, the total number of myocytes in the hypoplastic parts is significantly lower. Hypertrophy of the myocardium in congenital heart disease shows histological and ultrastructural findings that are similar to those found in other forms of myocardial hypertrophy. Hypertrophy is reversible after successful surgical correction. However, regression is often incomplete, especially if surgery is delayed until adolescent or adult life. During this time scar formation in the hypertrophic ventricular wall may develop. In addition to these scars, also postoperative scar formation may contribute to the origin of arrhythmias. In hearts with cyanotic and non-cyanotic vitia distances between capillaries and capillary lengths are approximately the same as in normal hearts. Obviously, these parameters are genetically determined.