Final answer:
Coarctation of the aorta is a congenital abnormal narrowing of the aorta that causes various symptoms and requires medical intervention.
Step-by-step explanation:
Based on the symptoms described, the disease process that would have a widened mediastinum, tracheal deviation, and obliteration of the aortic knob is Coarctation of the aorta. This condition is a congenital abnormal narrowing of the aorta, which restricts blood flow through the primary systemic artery. Symptoms may include difficulty breathing, poor appetite, chest pain, fatigue, and nosebleeds. Treatment usually involves surgery to remove the affected region or angioplasty to open the narrow passageway.