Aortic Dissection

Quiz

Identify the type of aortic dissection

1. Stanford Type A
2. Stanford Type B
3. Stanford Type C

True v/s False Lumen of Aortic Dissection

• Intimal defect – blood enters media of aortic wall – “dissects” the aortic wall longitudinally.
• Two lumens separated by dissection flap: True lumen and False lumen – formed because of the dissection flap.

Beak sign of false lumen: Acute angle commonly formed by the false lumen against the true lumen.

Bird Beak Sign (slide to compare)

CT Angiogram

Cobweb sign of false lumen: Fine strands of dissected media tissue forming a web cluster.
Mercedes Benz Sign : Triple channel dissection due to secondary dissection within one channel

• Widening of superior mediastinum > 8cm and progressive aortic enlargement on radiographs.
• CT is imaging modality of choice in acute cases. MRA is good for follow up.

Key is to report what portion of the aorta is involved.

Ascending aorta : Stanford A – Acute worrisome – Acute management (Surgical).
Beyond ascending aorta – Stanford B – Be calm (Conservative management).

Classification systems for Aortic Dissection

Stanford classification
Type A (60%): Involves ascending aorta, regardless of site of origin
Type B (40%): Does not involve ascending aorta
DeBakey classification
Type I: Originates in ascending aorta, involves at least aortic arch, and may involve descending aorta
Type II: Originates in and confined to ascending aorta
Type III: Originates in descending aorta; IIIa: Limited to descending aorta; IIIb: Extends below diaphragm

Analysis and reporting algorithm for diagnostic CT findings

Remember the mnemonic : DISSECTION –

Dissection or other acute aortic syndrome: Yes/No?
Is ascending aorta involved: Yes/No?
Intimal tear location
Size of the true and false lumen.
Segment(s) of aorta involved
Extent and involvement of aortic branches.
Complications –
Thrombus in the false lumen
Inspect False/True lumen
Other factors to consider : Trauma, age sex
Notify the provider

Source: Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression

Management

• Type A: Surgery due to involvement of aortic root
• Type B: Conservative treatment and Surgery in complicated cases (organ ischemia, rupture, descending aorta > 6cm,hemodynamic instability.)
• Mesenteric, renal, extremity ischemia
• Rupture, aneurysmal enlargement of false lumen; descending aorta > 6 cm
• Hemodynamic instability; pseudocoarctation syndrome; distal embolization.

Access the above case as a full DICOM image set (includes report impression): Aortic Dissection full DICOM set

References and further reading:

• Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression