Type A dissection = surgical emergency. Any dissection involving the ascending aorta requires immediate OR regardless of how it originated or how far it extends distally.
Stanford Classification
| Type | Involvement | Management |
|---|---|---|
| Type A | Ascending aorta (± arch, ± descending) — any dissection involving the ascending aorta | Surgical emergency — immediate OR |
| Type B | Descending aorta only — distal to origin of left subclavian artery | Medical management (BP and HR control); TEVAR if complicated |
Complicated Type B — Indications for TEVAR
Type B dissection is managed medically unless one or more of the following are present:
- Malperfusion — visceral (bowel ischemia), renal, or limb
- Rupture or impending rupture — periaortic hematoma, hemothorax, rapidly expanding false lumen
- Refractory hypertension or pain despite maximal medical therapy
DeBakey Classification
| Type | Involvement | Stanford Equivalent | Management |
|---|---|---|---|
| I | Ascending aorta + arch + descending (entire aorta) | Type A | Surgical |
| II | Ascending aorta only (stops at arch) | Type A | Surgical |
| IIIa | Descending only, above diaphragm | Type B | Medical / TEVAR |
| IIIb | Descending, extends below diaphragm | Type B | Medical / TEVAR |
True vs False Lumen — Imaging Differentiation
| Feature | True Lumen | False Lumen |
|---|---|---|
| Size | Smaller (compressed) | Larger |
| Density | Enhances early (arterial phase) | May enhance later or thrombose |
| Calcification | Intimal calcification displaced inward | Outer wall (no calcification) |
| Beak sign | Absent | Present — acute angle at dissection flap origin |
| Cobweb sign | Absent | Present — thin strand remnants of media |
| Flow | Faster; systolic expansion | Slower; may thrombose |
The false lumen is typically the larger, outer lumen in the descending aorta. Identify the intimal flap and trace it to determine which lumen feeds each branch vessel — this determines malperfusion territory.
Reporting Checklist — Aortic Dissection
- Stanford type: A (involves ascending) / B (descending only); DeBakey I / II / IIIa / IIIb
- Intimal flap: location (ascending / arch / descending) and longitudinal extent (cm)
- Entry tear: most proximal location (cm from aortic valve / sinotubular junction)
- Aortic root / annulus involvement (Type A): yes / no
- Pericardial effusion / hemopericardium: present / absent; size if present
- Coronary ostia involvement (Type A): right / left / both / none
- Branch vessel involvement: celiac / SMA / renal arteries / iliac arteries — true vs false lumen supply
- True vs false lumen: identify dominant flow lumen; false lumen thrombosis extent
- End-organ malperfusion: bowel ischemia / renal infarct / spinal cord ischemia
- Maximum aortic diameter and location; comparison to prior if available
- Complicated Type B criteria: malperfusion / rupture / refractory HTN — present / absent