The following case is reported because of the presence of two rare anomalies in the same heart, namely, defective pericardial sac and unusually extensive defects of the atrial septum. In addition, there were other defects of the heart, as well as anomalies of other viscera, indicative of additional abnormalities in embryonic development.
In a recent article by Patten,1 which includes an excellent bibliography, various developmental defects at the foramen ovale are described and embryologic interpretations of them made. Up to 1936, 68 cases of deficient pericardial sac had been reported in the literature.2 The degree of deficiency varied from small circular defects of the sac to its complete absence. Much has been written on the embryologic explanation of this anomaly. It is generally agreed that it represents a patent pleuropericardial foramen resulting from a disturbance in the development of the celomic cavities and the pleuropericardial membrane.3
OSGOOD R, SPECTOR B. DEFECTIVE PERICARDIAL SAC AND INTERATRIAL SEPTUM AND ATRESIA OF PULMONIC ORIFICE. Am J Dis Child. 1941;61(5):1028-1033. doi:10.1001/archpedi.1941.02000110116010