What imaging features may be seen with congenital absence of the pericardium?
Congenital absence of the pericardium is rare, may be partial (most commonly) or complete, and is associated with other congenital abnormalities (mostly cardiopulmonary) in 30% to 50% of patients. Partial absence most commonly occurs on the left. Imaging studies may show lucency between the aorta and main pulmonary artery in the aorticopulmonary window due to herniated lung parenchyma as well as nonvisualization of the pericardium. Focal bulging of the left atrial appendage through a pericardial defect may also be seen with partial pericardial absence. With complete pericardial absence, the heart may rotate up and to the left with associated straightening and elongation of the left cardiac border.