Which dissecting aneurysm type involves the descending aorta below the left subclavian artery and has the lowest mortality rate?

Which dissecting aneurysm type involves the descending aorta below the left subclavian artery and has the lowest mortality rate?

• A. Type I
• B. Type II
• C. Type IV
• D. Type III

Answer: (D)

Dissections are categorized by where the tear starts in the aorta, which also guides prognosis and treatment. The description points to a tear that begins in the descending thoracic aorta, distal to the left subclavian artery. In the DeBakey system, that pattern is Type III. This location tends to have a lower early mortality compared with dissections that involve the ascending aorta or the aorta beyond the abdominal segment, because it spares the heart and proximal great vessels and is often managed medically or with endovascular approaches unless complications arise. The other patterns involve the ascending aorta (higher-risk scenarios) or the abdominal aorta (different pattern with distinct risks), so they don’t fit the described segment. Therefore, the type described is the one that originates in the descending thoracic aorta beyond the left subclavian and has the lowest mortality among the classical types.

Dissections are categorized by where the tear starts in the aorta, which also guides prognosis and treatment. The description points to a tear that begins in the descending thoracic aorta, distal to the left subclavian artery. In the DeBakey system, that pattern is Type III. This location tends to have a lower early mortality compared with dissections that involve the ascending aorta or the aorta beyond the abdominal segment, because it spares the heart and proximal great vessels and is often managed medically or with endovascular approaches unless complications arise. The other patterns involve the ascending aorta (higher-risk scenarios) or the abdominal aorta (different pattern with distinct risks), so they don’t fit the described segment. Therefore, the type described is the one that originates in the descending thoracic aorta beyond the left subclavian and has the lowest mortality among the classical types.