A 55-Year-old Male with DM and Hypertension for the past 14years is on OHA and Insulin, antihypertensive drugs. Today he came with (new onset B.asthma) congestion in chest and dyspnoea, red face.

Urgent ECG, CBC are normal, BP 150/80 mmHg, Blood Sugar level normal, X-ray chest PA view shows a vessel like shadow as marked in red, and tracheal air shadow is also at the lateral side of the mediastinum and at Rt cardiac border, what is this structure?