Aortic Dissection Classification

Aortic dissection occurs when an intimal tear allows blood to enter the medial layer, creating a false lumen that propagates along the aorta. It represents one of the most lethal cardiovascular emergencies, with untreated Type A dissection mortality approaching 1% per hour early after symptom onset. [@hagan2000] [@erbel2014]

**Stanford Classification**

The Stanford system divides dissections based on involvement of the ascending aorta. [@daily1970]

* **Type A:** Any dissection involving the ascending aorta, regardless of the site of primary intimal tear. Requires emergent surgical intervention due to high risk of rupture, tamponade, aortic regurgitation, and coronary malperfusion.
* **Type B:** Dissection confined to the descending aorta (distal to the left subclavian artery). Management depends on presence of complications.

Modern classification frameworks from the American Heart Association (AHA), American College of Cardiology (ACC), and the European Society for Vascular Surgery (ESVS) also recognize "Non-A Non-B" dissections, which involve the aortic arch but spare the ascending aorta [@isselbacher2022] [@esvs2025].[@esvs2025] [@aha2022-c] [@esvs2025-c].

**DeBakey Classification**

The DeBakey system provides anatomic detail based on origin and extent. [@debakey1965]

* **Type I:** Originates in ascending aorta and extends to at least the aortic arch, often to the descending aorta or beyond.
* **Type II:** Originates in and is confined to the ascending aorta.
* **Type IIIa:** Originates in descending thoracic aorta and extends distally but remains above the diaphragm.
* **Type IIIb:** Originates in descending thoracic aorta and extends below the diaphragm.

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**Table 6.2. Aortic Dissection Classification Systems**

| **Stanford** | **DeBakey** | **Anatomic Extent** | **Primary Management** |
| --- | --- | --- | --- |
| Type A | Type I | Ascending → arch → descending | Emergent open surgery |
| Type A | Type II | Ascending only | Emergent open surgery |
| Type B | Type IIIa | Descending thoracic only | Medical ± thoracic endovascular aortic repair (TEVAR) |
| Type B | Type IIIb | Descending → abdominal | Medical ± TEVAR |

**Temporal Classification**

Timing from symptom onset influences treatment strategy and aortic wall characteristics. Contemporary guidelines define four distinct phases: hyperacute (<24 hours), acute (1–14 days), subacute (15–90 days), and chronic (>90 days) [@isselbacher2022] [@esvs2025].[@esvs2025] [@aha2022-c] [@esvs2025-c]. This classification is critical because the aortic wall's friability and the potential for favorable remodeling after thoracic endovascular aortic repair (TEVAR) vary substantially across these timeframes [@erbel2014] [@esvs2025].[@esvs2025] [@esvs2025-c].