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Page 2 of 17 Hong et al. Vessel Plus 2022;6:4 https://dx.doi.org/10.20517/2574-1209.2021.88

aortic dissection is typically considered chronic and is susceptible to aneurysm formation induced by a
pressurized false lumen and other factors; subsequently, although most patients with chronic aortic
[1,2]
dissection are initially managed medically, surgical intervention may become necessary .

In this manuscript, we describe the classification of aortic dissection, along with indications for repair, and
highlight operative techniques for open repair of aneurysms related to chronic dissection of the
thoracoabdominal aorta.

Classification
Aortic dissection is classified by the anatomical distribution and time from onset, which guide treatment
strategy. The most commonly used anatomical classification systems include the Stanford classification, the
DeBakey classification, and the Society of Thoracic Surgeons/Society of Vascular Surgery (STS/SVS) system
[Figure 1].

The Stanford classification characterizes the dissection on the basis of its location: dissection involving the
ascending aorta is defined as type A, and dissection involving the descending thoracic or thoracoabdominal
[3]
aorta only is defined as type B . The DeBakey classification further characterizes an aortic dissection on the
[4]
basis of its distal extent : DeBakey type I aortic dissection is extensive, involving both the ascending aorta
and the descending thoracic or thoracoabdominal aorta, whereas type II is strictly limited to the ascending
aorta; DeBakey type III dissection originates distal to the left subclavian artery and is further subdivided into
type IIIA, which is limited to the descending thoracic aorta, and type IIIB, which extends below the
diaphragm .
[4]
The STS/SVS classification was designed to characterize dissections of the aortic arch better and is based on
the location of the originating tear. The aorta is divided into several zones (0 to 9); a type B dissection has an
entry tear originating in zones 1 to 9 (distal to the innominate artery). The entry tear and distal extent of
dissection zones are denoted by a subscripted zone number. Thus, extensive aortic dissection limited to
thoracoabdominal aorta would be described as type B 3,9 [5] . The STS/SVS system also classifies aortic
dissection by the time from the initial insult: Hyperacute is defined as < 24 h; acute, 1-14 days; subacute, 15-
90 days; and chronic, > 90 days .
[5]

Thoracoabdominal aortic aneurysms (TAAAs) are classified by the extent of repair, according to the E.
Stanley Crawford classification system [Figure 2] . A Crawford extent I TAAA involves the descending
[6]
thoracic aorta to the suprarenal aorta. An extent II TAAA involves the descending thoracic aorta to the
aortoiliac bifurcation. An extent III TAAA involves the distal descending thoracic aorta (T6 aorta) to the
aortoiliac bifurcation. Finally, an extent IV TAAA involves the aorta from the diaphragm to the aortoiliac
bifurcation.

Acute aortic dissection
The initial management for acute aortic dissection is anti-impulse therapy (e.g., beta-blockers) to limit
hemodynamic stress on the aortic wall and minimize propagation of the dissection by reducing heart rate,
blood pressure, and the velocity of left ventricular contraction . Our hemodynamic targets are a heart rate <
[7]
70 beats per minute and systolic blood pressure of 100-120 mmHg. If the patient continues to be
hypertensive with adequate heart rate control, vasodilator therapy is indicated.

Acute DeBakey type I or type II aortic dissection is a surgical emergency and requires the replacement of the
dissected ascending aorta. Arch replacement with an elephant trunk may be indicated when the aortic arch