Chest radiography showed bilateral reticular interstitial opacification and new onset of pneumomediastinum and subcutaneous emphysema. CT scan revealed how pneumomediastinum caused a posterior displacement of the heart, which compressed the right heart chambers. The patient underwent a 4 cm transverse cervicotomy and a Penrose drain was placed in the anterior mediastinum. Postoperative course was favorable and the patient was discharged on the 28th day.

Tension pneumomediastinum is an exceptional and potentially lethal condition. It causes an increase in intramediastinal pressure that leads to collapse of the cardiac chambers, restriction of cardiac filling, and reduction of stroke volume and cardiac output.

The Earth-heart Sign reflects cardiac compression caused by tension pneumomediastinum. The cardiac silhouette appears to be flattened. It was called Earth-Heart sign because the cardiac silhouette resembles the shape of an oblate sphere like planet Earth. If we compare with a previous normal chest x-ray, we can observe an increased transverse cardiac diameter (TCD) and a decreased vertical cardiac diameter (VCD). Moreover, the difference between TCD and VCD (TCD/VCD) is greater than on a normal chest x-ray ¹.

In an appropriate clinical setting, the presence of Earth-Heart sign, together with classic radiological features of pneumomediastinum, on a chest x-ray, are highly suggestive of tension pneumomediastinum. 

License: This radiological sign was published in Lancet in February 2014 ¹. The author has the copyright license to reproduce part of his publication on this case discussion at Radiopaedia. 

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