**3.6 Inflammatory or infectious conditions**

Inflammatory or infectious diseases that lead to vasculitis (like giant cell arteritis, rheumatoid arthritis, takayasu arteritis, syphilitic aortitis, etc.) affect the vaso vasorum or small arteries that supply blood to the aortic wall [11]. When these small arteries are compromised, they lead to the ischemic injury to the aortic wall and predisposes to aortic dissection. For example, in tertiary syphilis, inflammation begins at adventitia of the aortic arch leading to obliterative endarteritis of the vasa vasorum, luminal narrowing, ischemic injury of medial aortic arch, and finally loss of elastic support and vessel dilatation.
