A type A aortic dissection involves the ascending aorta. Hypertension is the biggest risk factor. Unlike type B aortic dissection which involves only the descending aorta, type A dissection is a surgical emergency. Type B dissection is usually being treated medically.

The patients usually present with severe chest pain radiating to the back.

On the upper image above the true lumen (black arrow) is being compressed by the false lumen (labeled FL on the upper image). The involvement of the ascending aorta makes it a type A dissection.

Significant dilation of the aortic root (black arrow on the bottom image) is noted.

The patient underwent emergent replacement of the aortic valve, aortic root, ascending aorta, transverse arch and proximal descending aorta.

83 year old gentlemen presented with the sudden onset of sharp chest pain radiating to his back. CT angiography of his chest and abdomen revealed a type B (descending aorta only) dissection. Aggressive blood pressure control measures were initiated.

On the image above you can, actually, see the ruptured atheromatous ulcer which likely initiated the aortic dissection.

Type A Aortic dissection

79 year old male with a past medical history significant for hypertension and diabetes presented with a sharp stabbing pain in his mid-chest and back.
CT angiography of his chest revealed type A aortic dissection (involving ascending aorta – see image above with arrow pointing to the intimal flap)

Classification
Aortic dissection is being classified into types A and B depending on the site of origin. Type A dissection involves ascending aorta. Type B begins in the descending part of the aorta.

Treatment
Type A dissection is considered to be a surgical emergency and should be treated surgically. The complications of the type A dissection include aortic regurgitation, myocardial infarction and cardiac tamponade.

Type B aortic dissection is generally being treated medically. Blood pressure and pain control are the main goals of the therapy. Intravenous B-blockers are the preferred agents for blood pressure control in these patients.

Outcomes
The outcomes for both types of dissection are generally good with appropriate therapy.
The patient above underwent a surgical repair of the dissection with an uneventful recovery.