Most common site of aoic dissection is ?

<p> Aoic dissection Dissection of the media of the aoa after splitting through intima creating a channel in the media of the vessel wall. Causes- hypeension, marfan&;s syndrome, collagen diseases, trauma, weakening of elastic layers of the media due to shear forces. Features:- Commonly seen in thoracic aoa(ascending aoa). Dissected aoic arch channel gets lined by endothelium, often reopens distally into the aoa causing double barrelled aoa. Atherosclerosis is not a usual cause for dissecting aneurysm. Clinical features- Pain in the chest, back which is excruciating. Features of ischemia. Treatment- Antihypeensives Surgery: using Dacron graft reconstruction of aoa. {Reference: SRB&;s manual of surgery, 5th edition , page no. 198}