“…Failure to develop good collaterals may be of major importance in the development of cardiac failure in infants with postductal coarctation (Olney and Stephens, 1950;Calodney and Carson, 1950;Bahn et al, 1951). However, in the two infants described, collaterals were well shown angiocardiographically, and thus this factor did not seem to be the determining cause of their heart failure.…”