Aortic dissection

Aetiology

Dissection results from a tear in the aortic intima, which cleaves a plane in the media and allows blood to enter the false lumen. Arterial pressure extends the dissection for a variable distance distally and sometimes proximally.

M:F = 3:1. Peak 50-70yo
Mortality is about 1% per hour for the first 48 hours
Aetiolog often unknown but associated with:
- Hypertension
- Marfan’s syndrome
- Ehlers-Danlos syndrome
- Aortic coarctation
- Aortitis
- Trauma
- Pregnancy
- Cocaine use

Presentation

Chest pain (sudden onset, "ripping"). May also have myocardial ischaemia pain if involving coronaries. May radiate to back
Painless in 10%
Neurological symptoms (radicular pain / stroke), syncope, limb pain, dysphagia
Symptoms of organ / limb ischaemia

Aortic Dissection 9 Months Earlier - Normal

Dissection Stanford B. Three dimensional reconstruction from the computed tomography angiogram showing the aortic arch and the iliac bifurcation. The left arrow shows the intimal flap and the right arrow indicates the occluded left commom iliac artery

Classification

Stanford type A dissection

Involves the ascending aorta
75% of all cases of dissection
Presents with anterior chest pain
Treatment = emergency cardiothoracic surgery
- Mortality 50% if no treatment
- Cardiac tamponade
- Aortic rupture
- AMI, aortic regurgitation if involves aortic root

Stanford type B dissection

Starts distal to the left subclavian artery
Presents with inter-scapular back pain (ripping)
Divided clinically into uncomplicated and complicated (20%)
Complications:
- Organ ischaemia (flap occluding vessel)
  - Renal, splenic, mesenteric, spinal infarction
- Later aneurysmal dilatation of the aorta (20%

Treatment type A

Surgery - open resection & replacement aortic segment
Surgical mortality 30%
High rate complications (organ/limb/spinal/brain ischaemia)

Treatment type B

Uncomplicated dissections treated medically
Control hypertension - analgesia, β block ±nitrates
Complicated dissections require surgery

Summary of Systematic Review

A normal D-dimer excludes acute aortic dissection.[Eur Heart J. 2007 Dec;28(24):3067-75]. PMID: 17986466.

16 studies (437 patients), >D-dimer:
- High sensitivity (0.97 95% CI 0.94-0.98)
- High neg LR (0.06 95% CI 0.02-0.13)
A negative D-dimer will exclude AAD

Aortic Dissection