14. Aortic Dissection

Question 1

What is an aortic dissection?

Answer 1

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

Question 2

Explain the pathophysiology of an aortic dissection.

Answer 2

• A medical emergency that can lead to death.

1. Aortic dissection begins with a tear in the intimal lining of the aorta.
2. The tear allows a column of blood under pressure to enter the aortic wall
3. This forms a haemotoma, which separates the intima from the adventitia and creates a false lumen.
4. The false lumen extends for a variable distance in either direction:
   - Anterograde (towards bifurcations)
   - Retrograde (towards the aortic root)

Question 3

Where is the blood in aortic dissection?

Answer 3

Between tunica media and intima.

Question 4

What are the different classifications according to the timing of diagnosis from the origin of symptoms?

Answer 4

• Acute - less than 2 weeks
• Subacute - 2-8 weeks
• Chronic - more than 8 weeks

Question 5

What is the Standford system of classification for aortic dissection?

Answer 5

The Stanford system:

1. Type A – affects the ascending aorta, before the brachiocephalic artery
2. Type B – affects the descending aorta, after the left subclavian artery

Question 6

What is the DeBakey system of classification for aortic dissection?

Answer 6

The DeBakey system:

1. Type I – begins in the ascending aorta and involves at least the aortic arch, if not the whole aorta
2. Type II – isolated to the ascending aorta
3. Type IIIa – begins in the descending aorta and involves only the section above the diaphragm
4. Type IIIb – begins in the descending aorta and involves the aorta below the diaphragm

Question 7

Give 5 risk factors for aortic dissection.

Answer 7

Hypertension
Connective tissue disorder
Smoking
Family history
Co-arctation of aorta
Bicuspid aortic valve
Pregnancy
Syphilis
Trauma
Turner/Noonan syndrome

Question 8

Give 2 connective tissue disorders that increase the risk of an aortic dissection.

Answer 8

1. Ehlers-Danlos Syndrome
2. Marfan’s Syndrome

Question 9

Signs on examination of aortic dissection?

Answer 9

1. Sudden onset, severe/maximal, “ripping” or “tearing” chest pain
   - might be migratory
2. Hypertension
3. Weak radial pulse - pulse deficit
   - Radial pulse in 1 arm is decreased or absent and does not match the apex beat
4. Difference in BP between the arms (>20 mmHg)
5. Diastolic murmur

Question 10

Investigations for aortic dissection.

Answer 10

1. ECG + CXR
   - To exclude other causes
   - CXR shows widened mediastinum
2. Urgent CT angiogram with contrast
   - The initial investigation to confirm the diagnosis
3. MRI angiogram / TEE echo.
   - Provides greater detail + can help plan management
   - Often takes longer to get

Question 11

Management of an aortic dissection.

Answer 11

1. Urgent antihypertensives
   - IV Beta blocker e.g. IV metorpolol
   - Vasodilators e.g. IV GTN
2. Adequate analgesia e.g. morphine
3. Surgery to replace aortic arch
4. Endovascular intervention with stents

Question 12

Give 3 key complications of an aortic dissection.

Answer 12

Myocardial infarction.
Stroke.
Paraplegia (motor or sensory impairment in the legs).
Cardiac tamponade.
Aortic valve regurgitation.
Death.

Question 13

A lady presents with a tearing pain and is found to have hypertension. A CT scan is done and a ‘tennis ball sign’ is observed. What is the likely pathology behind the patient’s pain?

Answer 13

Aortic dissection!