A Syndrome Occurring in Pulmonary Embolism

R ECENTLY two cases of pulmonary infarction were encountered which showed atypical clinical manifestations. At autopsy, in each instance a thrombus was found straddling a patent foramen ovale, suggesting a functional shunt during life. It is the purpose of this paper to describe the associated syndrome. Although some 48 instances of a clot caught in a patent foramen ovale have been described since 1859, there has been no uniformity in terminology or clarity of thought regarding it. Many have been described as "paradoxic embolism" and a recent paper' refers to it as "Lodging of an Embolus in a Patent Foramen Ovale." The term "paradoxic embolism" was originally devised by Zahn2 in 1885 to describe a condition in which emboli derived from the systemic venous system reached the systemic arterial system by passing through an abnormal communication between the chambers of the heart. It is apparent that this occurs when a small thrombus passes through a cardiac septal defect, but this is quite different from the event of a large thrombus being caught in the septal defect with consequent occlusion of its lumen. Thus embolic occlusion of a patent foramen ovale is to be distinguished from "paradoxic embolism" which may or may not accompany it. Autopsy specimens showing a thrombus caught in the act of traversing an atrial septal defect have been of interest only as anatomic