Aortic Dissection
A tear in the aortic intima drives blood into the media, splitting it into a true and a false lumen that can rupture or occlude branch arteries.
Definition
Blood enters the aortic wall through an intimal tear and splits the media, creating a true and a false lumen. Modern Stanford anatomy defines type A by ascending-aortic involvement; type B excludes the ascending aorta, and isolated arch disease may be termed non-A-non-B. The current NHS England South operational pathway routes ascending and/or arch disease as type A, so follow the receiving aortic service classification. Dissection, intramural haematoma and penetrating aortic ulcer together make up acute aortic syndrome. The diagnosis is made on CT aortography.
First principles
Blood in the wall creates a second channel
The intima tears and blood is driven into the media, splitting it into a true lumen and a false lumen. The false lumen expands with each systole, so it can rupture outwards into pericardium, pleura or retroperitoneum, or press inwards and strangle the true lumen. Intramural haematoma and penetrating aortic ulcer share the same emergency pathway and are grouped with dissection as acute aortic syndrome.
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