Continuous left hemidiaphragm sign revisited: a case of spontaneous pneumopericardium and literature review

Abstract

In pneumopericardium, a rare but potentially life threatening differential diagnosis of chest pain with a broad variety of causes, rapid diagnosis and adequate treatment are crucial. In upright posteroanterior chest radiography, the apical limit of a radiolucent rim, outlining both the left ventricle and the right atrium, lies at the level of the pulmonary artery and ascending aorta, reflecting the anatomical limits of the pericardium. The band of gas surrounding the heart may outline the normally invisible parts of the diaphragm, producing the continuous left hemidiaphragm sign in an upright lateral chest radiograph. If haemodynamic conditions are stable, the underlying condition should be treated and the patient should be monitored closely. Acute haemodynamic deterioration should prompt rapid further investigation and cardiac tamponade must be actively ruled out. Spontaneous pneumopericardium in a 20 year old man is presented, and its pathophysiology described.

Figure 1

Posteroanterior chest radiograph. Continuous radiolucent stripes follow the right and left cardiac borders and are outlined by a fine line (arrows) representing the pericardial sac. The stripes are limited at the level of the pulmonary artery and ascending aorta by the pericardial reflection.

Figure 2

Upright lateral chest radiograph. The normally invisible ventral part of the left hemidiaphragm (arrows) is outlined by a radiolucent rim, producing the continuous left hemidiaphragm sign. The air bubble in the stomach identifies the left hemidiaphragm.