The Stanford system is used more commonly now as it is more attuned to the management of the patient.
The DeBakey system, named after surgeon and aortic dissection sufferer Michael E. DeBakey, is an anatomical description of the aortic dissection. It categorizes the dissection based on where the original intimal tear is located and the extent of the dissection (localized to either the ascending aorta or descending aorta, or involves both the ascending and descending aorta.
Type I – Originates in ascending aorta, propagates at least to the aortic arch and often beyond it distally. It is most often seen in patients less than 65 years of age and is the most lethal form of the disease.
Type II – Originates in and is confined to the ascending aorta.
Type III – Originates in descending aorta, rarely extends proximally but will extend distally. It most often occurs in elderly patients with atherosclerosis and hypertension.
The Stanford classification is divided into 2 groups; A and B depending on whether the ascending aorta is involved.
A – Involves the ascending aorta and/or aortic arch, and possibly the descending aorta. The tear can originate in the ascending aorta, the aortic arch, or, more rarely, in the descending aorta.It includes DeBakey type I, II and retrograde type III (dissection originating in the descending aorta or aortic arch but extending into the ascending aorta).
B – Involves the descending aorta or the arch (distal to right brachiocephalic artery origin), without involvement of the ascending aorta. It includes DeBakey type III without retrograde extension into the ascending aorta.
Source : Wikipedia