CXR AP at 2 days of age (above) shows air surrounding the heart and not rising above the great vessels. Air is also present in the right pulmonary interstitium in a branching pattern from the hilum to the periphery. CXR AP at 3 days of age (below) shows air no longer surrounding the heart and interval development of a large amount of lucency in the right pleural space with mediastinal shift to the left.