Aortic Dissection

Quiz

Identify the type of aortic dissection

Stanford Type A

Stanford Type B

Stanford Type C

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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.

	True Lumen	False Lumen
Size	Usually smaller (compressed by false lumen)	Usually larger due to higher pressure and lesser resistance
Shape	Round	Cresenteric
Contrast density	Similar to other arteries	Less dense contrast due to delayed opacification.
Thrombosis	Less likely	Common
Configuration	No beak or cobweb sign	Beak Sign. Cobweb sign

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

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