Congenital Mitral Atresia with Hypoplastic Nonfunctioning Left Heart

Congenital hypoplasia of the left heart is characterized pathologically by the presence of a diminutive left atrium and a markedly hypoplastic, nonfunctioning left ventricle. This failure in development of cardiac chambers is uniformly associated with an obstructing deformity, either atresia or severe stenosis, at one or both of the valvular orifices on the left side of the heart. The variability of the valve areas involved provides a convenient basis for a simple classification of these malformations into three distinct pathologic groups. The first of these consists of those instances of hypoplasia of the left heart in which the aortic valve is atretic or sufficiently stenosed to prevent the egress of more than a minute amount of blood through this orifice. The mitral valve in this group is perfectly formed but diminutive. The second variety includes those cases in which the mitral valve is the major site of obstruction, while the