Aortic dissection

What it is

Aortic dissection is separation of the layers within the aortic wall. Tears in the intimal layer result in the propagation of dissection, proximally or distally, secondary to blood entering the intima-media space. Two classifications are used. De Bakey:

• Type I originates in the ascending aorta and propagates at least to the aortic arch, often beyond it distally
• Type II originates in and is confined to the ascending aorta
• Type III originates in the descending aorta and extends distally down the aorta or, rarely, retrograde into the aortic arch and ascending aorta

Stanford:

• Type A is all dissections involving the ascending aorta, regardless of the site of origin
• Type B is all dissections not involving the ascending aorta

Causes and risk

The major risk factor is HTN. The rest are one flat list, not divided into groups:

• Marfan's syndrome
• Ehlers-Danlos syn
• APCK
• Turner syndrome
• Noonan syndrome
• Osteogenesis imperfecta
• Bicuspid aortic valve
• Coarctation of the aorta
• Connective tissue disorder
• Metabolic disorder (homocystinuria, familial hypercholesteremia)
• Pregnancy
• Syphilitic aortitis
• Cocaine use
• Arteritis such as Takayasu's or giant cell
• Aortic aneurysm
• Trauma

Marfan syndrome has it as a complication. It comes from mutation of the fibrillin-1 gene (FBN1) on chromosome 15 with autosomal dominant inheritance, and aortic dilatation or dissection is one of its three major Ghent criteria, which are: 1) ectopia lentis, 2) aortic dilatation or dissection, and 3) family history. Osteogenesis imperfecta lists cervical artery and aortic dissection among its complications.