Aortic dissections classification

Classification of aortic dissection

Percentage	60%	10–15%	25–30%
Type	DeBakey I	DeBakey II	DeBakey III
	Stanford A (Proximal)		Stanford B (Distal)

Several different classification systems have been used to describe aortic dissections. The systems commonly in use are based on either the anatomy of the dissection or the duration of onset of symptoms prior to presentation. The Stanford system is used more commonly now, as it is more attuned to the management of the patient.

DeBakey

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 ascending aorta 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.

Stanford

The Stanford classification is divided into two 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 types I and II.
• B – Involves the descending aorta or the arch (distal to the left subclavian artery), without involvement of the ascending aorta. It includes DeBakey type III.

The Stanford classification is useful as it follows clinical practice, as type A ascending aortic dissections generally require primary surgical treatment whereas type B dissections generally are treated medically as initial treatment with surgery reserved for any complications.

The reason for surgical repair of Type A dissections is that ascending aortic dissections often involve the aortic valve, which, having lost its suspensory support, telescopes down into the aortic root, resulting in aortic incompetence. This needs resuspending to reseat the valve and repair / prevent coronary artery injury. Also the area of dissection is removed and replaced with a Dacron graft to prevent further dissection from occurring. However type B dissections are not improved, from a mortality point of view, by operation, unless there is leaking, rupture or compromise to other organs, e.g. kidneys.