Aortic Dissection

Question 1

What is aortic dissection?

Answer 1

Creation of a “false lumen” due to a tear in the inner and outer tunica media - which allows blood to surge into the aortic wall

Question 2

The aetiology of aortic dissection comes from degenerative changes in the SM of aortic media. Can be exacerbated by hypertension, aortic atherosclerosis, aortic coarctation (congenital), COCAINE etc

Name 2 connective tissue diseases that can contribute to aortic dissection.

Answer 2

Marfan’s, SLE, Ehlers-Danlos

Question 3

Describe the 2 ways in which Aortic dissection can be classified

Answer 3

1. Stanford classification -
   Type A = ascending aorta tear
   Type B = descending aorta tear (distal to left subclavian artery)
2. DeBakey classification -
   Type 1 = originates in ascending aorta, involves ascending aorta + aortic arch, also involves variable amounts of descending aorta
   Type 2 = originates and is confined to ascending aorta
   Type 3a/b= Tear originates distal to left subclavian artery. A= extends through thoracic aorta. B = extends beyond visceral segment

Question 4

Describe the epidemiology of aortic dissection

Answer 4

Occurs most commonly in males between 40-60

Question 5

How will someone with aortic dissection present?

Answer 5

Sudden central “tearing” pain in the chest or back.

Aortic dissection can occlude aorta and its branches which may cause the following symptoms:

Carotid obstruction - hemiparesis, dysphasia, blackout
Coronary artery obstruction - chest pain (angina/MI)
Subclavian obstruction - ataxia, loss of consciousness
Anterior spinal artery obstruction - paraplegia
Coeliac obstruction - severe abdominal pain
Renal artery obstruction - anuria, renal failure

Question 6

Upon examination, what signs may be present in someone with aortic dissection?

Answer 6

1. Blood pressure discrepancy of 20mmHg or more between each arm (HALLMARK), wide pulse pressure.
2. Aortic insufficiency - collapsing pulse, early diastolic murmur over aortic area. May be a palpable abdominal mass.

Question 7

What investigations should be done in someone with aortic dissection suspected?

Answer 7

1. Bloods - FBC, U&E, clotting. Cross match 10 units blood
2. CXR - widened mediastinum, localised bulge in aortic arch
3. ECG - may be normal, ST segment depression may occur if acute dissection. ST elevation rarely
4. Cardiac enzymes, lactate + LFTs
5. Transoesophageal echocardiography is highly specific (not 1st line investigation always though)

Question 8

If liver function is compromised, which 2 enzymes go up?

Answer 8

ALT and AST

Question 9

How is acute aortic dissection managed?

Answer 9

CT-thorax immediately, and at the same time resuscitate and restore blood volume. Pulse/BP monitored in both arms, urinary catheter.

Question 10

How is a type A dissection managed?

Answer 10

Surgical treatment - emergency surgery due to risk of cardiac tamponade. Affected aorta replaced by tube graft, and aortic valve may also be replaced.

Question 11

How is a Type B dissection managed?

Answer 11

Control BP, prevent further dissection with nitroprusside/ IV labetolol.
If intractable/recurrent pain/end organ ischaemia, consider surgery or endovascular repair grafts.

Question 12

What are the complications of aortic dissection

Answer 12

aortic rupture, cardiac tamponade, pulmonary oedema, MI, syncope, ischaemias

Question 13

Describe the prognosis

Answer 13

If untreated, 75% at 2 weeks mortality
If treated, 5-10%. A further 10% have neurological sequelae.

Type B has better prognosis than type A