May be total or partial. Partial absence is MORE common, occurs mainly on the LEFT, and is usually ASYMPTOMATIC. Large defects may cause cardiac strangulation. Small defects are usually asymptomatic.
Radiographic Features:
Total absence of the pericardium: Mimics the appearance of the large silhouette seen in pericardial effusions.
Partial absence of the pericardium: Heart is shifted and rotated into left pleural cavity. PA view looks like an RAO view. Heart is separated from the sternum on crosstable lateral view. Left hilar mass: herniated left atrial appendage and pulmonary trunk.