Development of significant left and right ventricular hypoplasia in the second and third trimester fetus

Although most forms of fetal heart disease are present by the end of the first trimester, after embryogenesis is complete, some lesions may evolve late in gestation, resulting in more severe disease at birth. Coarctation of the aorta can be associated with progression in the severity of distal arch hypoplasia.(1) Development or progression in severity of pulmonary artery hypoplasia can occur in tetralogy of Fallot.(2) Right ventricular outflow tract obstruction can develop or worsen as an isolated lesion(3) or in the presence of a dysplastic or Ebstein-Like tricuspid valve with tricuspid regurgitation,(4) tetralogy of Fallot,2 or more complex cardiac lesions.(5) The early prenatal appearance of the fetal heart may not always represent the final extent of the lesion in the neonate.(6) We have recently encountered two cases in which serial prenatal and postnatal study revealed development of significant left (one case) and right (one case) ventricular hypoplasia through the second half of gestation in fetuses with severe aortic stenosis or pulmonary stenosis, respectively, and intact ventricular septum.