Patency of the Ductus Arteriosus After Birth: A New Theory

¹ Research Associate under a Teaching Grant of the U.S.P.H. Service, National Heart Institute and Clinical Associate, Department of Medicine, Chicago Medical School.

The cause of patent ductus with different clinical manifestations and pathological findings—elevated or normal pulmonary pressures—can not be explained by Spitzer's theory of an arrest of development. Premature closure of the foramen ovale is the only isolated congenital malformation which could cause varying degrees of right ventricular hypertrophy, persistence of the fetal characteristics of the pulmonary vascular bed, and occasionally early left ventricular failure.

Two observations support this theory: (a) autopsy findings in infants only a few hours old, revealing a patent ductus with hypertrophied walls and a closed foramen ovale; (b) the knowledge that, except in complex congenital malformations, simultaneous patency of the ductus and of the foramen ovale is practically never found.