- This Pocket Guide summarizes a new classification system for practical use and reporting of type B aortic dissection including the aortic arch.
- In addition, the Society for Vascular Surgery and the Society of Thoracic Surgeons (SVS/STS) has provided improved standards for reporting type B aortic dissection (TBAD), with particular attention to those attributes of TBAD that would appear to have an impact on outcomes.
- Management of aortic dissection has evolved over time and now includes medical, surgical, and endovascular therapies performed by several specialties, including vascular surgery, cardiothoracic surgery, interventional radiology, and cardiology. There has been an explosion of literature in multiple specialty journals regarding presentation, treatment, and outcomes. Consequently, SVS/STS has responded to the need for a common, updated, inclusive and systematized structure for the reporting of TBAD and, by extension, management of aortic dissection in general. Particular attention has been paid to those attributes of management that would appear to have an impact on outcomes and therefore augment improvements through a common, comprehensive database.
Anatomic Classification of Thoracic Aortic Dissection
- Although generally adequate for everyday clinical use, existing classification systems for aortic dissection are imprecise in localizing both the origin and the extent, proximal as well as distal, of the pathology and the presence of an intramural hematoma (IMH) (Figures #1–4).
- The SVS/STS system (Figures #5–9), which is intended primarily for research reporting, improves the precision (Figure #7) and can accommodate further information such as aortic ulcers (Figure #10), acuity and chronicity (Figure #11, 12, Tables I & II). It also allows ready comparison of subsequent episodes of aortic dissection with the original.
Table I. SVS/STS chronicity classification of aortic dissection
|Chronicity||Time from onset of symptoms|
Figure 1. Aortic Dissection
A, Three-dimensional computed tomography angiography (CTA) reconstruction of an aortic dissection (arrow) involving the aortic arch. B, Coronal CTA image of this same aortic dissection clearly demonstrating the location of the primary tear in the arch (arrow).
Neither the DeBakey nor the Stanford system classification scheme addresses aortic dissections that originate in the arch. In arch dissections, the dissection flap or intramural hematoma (IMH) typically involves the transverse arch and often spares the proximal ascending aorta.
Figure 2. Type B aortic dissection
Type B aortic dissection (TBAD) with visualization of entry tear (arrow) in the descending thoracic aorta.
Figure 3. Intramural Hematoma, descending aorta
Noncontrast-enhanced computed tomography (CT) scan demonstrating intramural hematoma (IMH) of the descending thoracic aorta. Note that the IMH appears bright on nonenhanced imaging.
Figure 4. Intramural Hematoma, ascending aorta
Example of the gross pathologic appearance of an intramural hematoma (IMH), in this case of the ascending aorta, as seen during central repair for acute type A IMH.
Figure 5. SVS/STS Classification System
Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) Aortic Dissection Classification System of dissection subtype according to zone location of primary entry tear.
An aortic dissection with an entry tear in zone 0 is classified as type A. In the example illustrated, the dissection process extends distally to zone 9, such that the dissection is fully classified as A9.