Dissection

Question 1

What is aortic dissection?

Answer 1

when a break or tear forms in the inner layer of the aorta, allowing blood to flow between the intima and media layers of the wall of the aorta

Question 2

What is the most common site of a tear for aortic dissection?

Answer 2

right lateral area of the ascending aorta

Question 3

What are the 2 classification systems for aortic dissections?

Answer 3

The Stanford system:
- Type A – affects the ascending aorta, before the brachiocephalic artery
- Type B – affects the descending aorta, after the left subclavian artery

The DeBakey system:
- Type I – begins in the ascending aorta and involves at least the aortic arch, if not the whole aorta
- Type II – isolated to the ascending aorta
- Type IIIa – begins in the descending aorta and involves only the section above the diaphragm
- Type IIIb – begins in the descending aorta and involves the aorta below the diaphragm

Question 4

Conditions or procedures that affect the aorta increase the risk of a dissection, such as:

Answer 4

Bicuspid aortic valve
Coarctation of the aorta
Aortic valve replacement
Coronary artery bypass graft (CABG)

Conditions that affect the connective tissues can also increase the risk of a dissection, notably:
- Ehlers-Danlos Syndrome
- Marfan’s Syndrome

Question 5

Signs and Sx of aortic dissection

Answer 5

• sudden onset, severe, “ripping” or “tearing” chest pain
• Hypertension
• Differences in blood pressure between the arms (more than a 20mmHg difference is significant)
• Chest and abdominal pain
• Collapse (syncope)

Question 6

Ix for aortic dissection

Answer 6

CT angiogram is usually the initial investigation to confirm the diagnosis and can generally be performed very quickly.

MRI angiogram provides greater detail and can help plan management but often takes longer to get.

Question 7

Mx for aortic dissection

Answer 7

Analgesia (e.g., morphine) is required to manage the pain.

beta-blockers

Surgical intervention from the vascular team will depend on the type of aortic dissection.

Type A may be treated with open surgery (midline sternotomy) to remove the section of the aorta with the defect in the wall and replace it with a synthetic graft. The aortic valve may need to be replaced during the procedure. Keep BP around 100 systolic.

Type B may be treated conservatively with IV labetalol, or with thoracic endovascular aortic repair (TEVAR), with a catheter inserted via the femoral artery inserting a stent graft into the affected section of the descending aorta. Complicated cases may require open surgery.