Congenital pericardial defects.

Abstract

AbstractA congenital partial defect of the left pericardium associated with a left diaphragmatic hernia and total myeloschisis in a stillborn dicephalus dibrachius triotus female monster is described. It is pointed out that the generally accepted view, viz., that pericardial defects result from either a failure of closure or incomplete closure of the pleuropericardial foramen, holds good only for the partial forms of the pericardial defects. It is proposed that complete defects of the pericardium are due to imperfect development of the pleuropericardial membrane, resulting in a rent, either medial or lateral to the phrenic nerve, through which the lung bud grows into the pericardial cavity. The hypothesis that imperfect development of the pleuropericardial membrane is due to a primary defect in the septum transversum is discussed. Rotation of the heart is proposed as an additional possible factor responsible for preponderance of left‐sided defects.