Background
The SVS grading system (Society for Vascular Surgery; Azizzadeh et al., 2009) is the standard CT-based classification for blunt thoracic aortic injury (BTAI). It was developed to stratify management — particularly the decision between medical management and endovascular repair (TEVAR) — based on CT morphology alone.
The aortic isthmus, just distal to the left subclavian artery origin, accounts for >90% of injuries due to deceleration shear forces at the relatively fixed ligamentum arteriosum.
Grading System
| Grade | Name | CT Finding | Management |
|---|---|---|---|
| I | Intimal tear | Intimal irregularity or small intraluminal thrombus ≤10 mm; no periaortic hematoma | Medical management; anti-impulse therapy; CTA at 24 h |
| II | Intramural hematoma | Aortic wall thickening; periaortic soft-tissue haziness; no discrete pseudoaneurysm | Medical management; anti-impulse therapy; CTA at 24–48 h |
| III | Pseudoaneurysm | Focal outpouching beyond expected aortic wall contour, contained by adventitia | TEVAR (preferred); open surgery if anatomy prohibitive |
| IV | Rupture | Active contrast extravasation; hemothorax from aortic source; complete transection | Emergent TEVAR or open surgical repair |
Imaging Findings by Grade
Grade I — Intimal Tear
- Subtle intimal irregularity
- Small intraluminal filling defect (thrombus ≤10 mm)
- No periaortic hematoma; mediastinum may be normal
- Can be nearly occult — review sagittal oblique (candy-cane) and coronal reformats carefully
Grade II — Intramural Hematoma
- Concentric or eccentric aortic wall thickening (>3 mm)
- Hyperdense aortic wall crescent on non-contrast CT
- Periaortic soft-tissue stranding without a discrete outpouching
- Mediastinal widening may be present
Grade III — Pseudoaneurysm
- Focal bulge or contour abnormality projecting beyond the outer aortic wall
- Contained by adventitia or periadventitial tissue — no active extravasation
- Most common grade requiring intervention
- Periaortic hematoma and mediastinal widening typically present
Grade IV — Rupture
- Active contrast blush outside the aortic lumen on arterial phase
- Large hemothorax (especially left-sided)
- Free mediastinal blood; complete transection possible
- Usually associated with other life-threatening injuries
Imaging Protocol
CTA chest with IV contrast (arterial phase) is the standard modality. Non-ECG-gated trauma protocols are acceptable — motion artifact at the aortic root is expected and should not be over-interpreted as injury.
- Slice thickness: 1–1.5 mm axial reconstructions
- Reformats: Sagittal oblique (candy-cane view) and coronal reformats are essential for grade assessment — do not grade on axials alone
- MIP: 5–10 mm MIP for vascular survey
- Delayed phase: Not routinely required for isolated aortic injury
Management Overview
| Grade | Primary Treatment | Anti-impulse Therapy | Surveillance Imaging |
|---|---|---|---|
| I | Medical | HR <80 bpm, SBP <100–120 mmHg | CTA at 24 h; repeat at 1 week |
| II | Medical | Same targets | CTA at 24–48 h; repeat at 1 week |
| III | TEVAR | Yes (bridge to procedure) | CTA post-procedure; 1 month; 12 months |
| IV | Emergent TEVAR / Open | If hemodynamically stable | Intraoperative; post-procedure |
Grades I–II progression: Approximately 10% of medically managed injuries progress to pseudoaneurysm — surveillance imaging is mandatory even when initial CTA appears minor.
Anti-impulse therapy: IV beta-blockade (esmolol or labetalol preferred). Goal: heart rate <80 bpm and systolic BP <100–120 mmHg to reduce aortic wall stress until definitive management.
Case Examples
References
- Azizzadeh A, et al. Blunt traumatic aortic injury: Initial experience with endovascular repair. J Vasc Surg. 2009;49(6):1403–1408.
- Lee WA, et al. Endovascular repair of traumatic thoracic aortic injury: Clinical practice guidelines of the Society for Vascular Surgery. J Vasc Surg. 2011;53(1):187–192.
- Rabin J, et al. Contemporary management of blunt thoracic aortic injury. J Trauma Acute Care Surg. 2020;88(6):879–887.