A 40-year-old man involved in a high-speed frontal vehicle collision has chest pain and hypotension. Chest radiograph shows a widened superior mediastinum, depression of the left main bronchus and deviation of the nasogastric tube to the right, with fractures of the first and second ribs. At which site is traumatic aortic rupture most likely?
- A Ascending aorta just above the aortic valve
- B Aortic arch at the origin of the brachiocephalic trunk
- C Aortic isthmus, just distal to the origin of the left subclavian artery ✓
- D Abdominal aorta at the level of the renal arteries
Correct answer: C. Aortic isthmus, just distal to the origin of the left subclavian artery
Explanation
About 80 to 90 percent of blunt traumatic aortic injuries occur at the isthmus of the descending thoracic aorta, just distal to the left subclavian artery origin. This relatively mobile arch meets the fixed descending aorta tethered by the ligamentum arteriosum, so deceleration concentrates shear stress exactly there. The classic chest radiograph signs of widened mediastinum, depressed left main bronchus and rightward nasogastric tube deviation reflect the mediastinal haematoma. Ascending aortic rupture occurs but is usually fatal at the scene.
Reference: Sabiston Textbook of Surgery, 21st ed.
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