Evidence is presented which indicates that shunting of small amounts of blood from right to left occurs frequently through interatrial communications. Such right-to-left shunts are of small magnitude in the usual case of atrial septal defect, but it appears that of the fractions of blood shunted, a greater proportion has originated from the inferior vena cava than from the superior vena cava.
Although most patients with coarctation of the aorta survive to early adult life, it has been adequately demonstrated that some patients die in infancy and early childhood as a result of their coarctation. In selected cases, then, operation is advisable at a very early age. Cardiac failure in a 10 week old infant necessitated operation at this age in the case reported.