Paper II
Question
Aortic dissection
Answer
Aortic dissection is a condition in which blood enters and tracks within a tear in the aortic media, creating a false lumen that dissects (splits) the layers of the aortic wall, potentially propagating along the length of the vessel.
Pathogenesis
- Requires a pre-existing degenerative change in the aortic media (cystic medial degeneration/necrosis) — loss of elastic tissue integrity and smooth muscle
- Most commonly associated with hypertension (the major risk factor), and connective tissue disorders (Marfan syndrome, Ehlers-Danlos syndrome) affecting elastic fibre/collagen integrity
- An intimal tear allows blood under arterial pressure to enter the weakened media, creating and propagating a false lumen, either proximally or distally along the vessel
Classification (Stanford)
- Type A: Involves the ascending aorta (with or without descending involvement) — higher risk, usually requires emergency surgery
- Type B: Confined to the descending aorta (distal to the left subclavian artery origin) — often managed medically unless complicated
Clinical features
- Sudden onset of severe, tearing/ripping chest pain, often radiating to the back, classically migrating as the dissection propagates
- Can cause cardiac tamponade (if it ruptures into the pericardial sac), aortic regurgitation, occlusion of branch vessels (causing stroke, limb ischaemia, renal failure, myocardial infarction), or fatal rupture