Aortic dissection

Question 1

What is an aortic dissection?

Answer 1

A tear in the tunica intima (innermost layer of the aorta) causing blood to flow between and split apart the tunica intima and media

Question 2

How long should a dissection occur for it to be classified as acute?

Answer 2

diagnosed ≤14 days

Question 3

How long should a dissection occur for it to be classified as chronic?

Answer 3

diagnosed >14 days

Question 4

Where can aortic dissections from the initial intimal tear progress?

Answer 4

Either:
Distally

Proximally

Both directions from site of origin

Question 5

What are anterograde dissections?

Answer 5

Propagate towards the iliac arteries

Question 6

What are retrograde dissections?

Answer 6

Propagate towards the aortic valve (at the root of the aorta)

Question 7

What can retrograde dissections result in?

Answer 7

Prolapse of the aortic valve

Bleeding into the pericardium, and cardiac tamponade

Question 8

What two systems are used in the classification of aortic dissections?

Answer 8

DeBakey

Stanford

Question 9

Describe the Stanford classification of aortic dissections

Answer 9

Two groups: Type A & B

Type A : involves the ascending aorta and can propagate to the aortic arch and descending aorta (i.e., DeBakey types I and II); the tear can originate anywhere along this path

Type B : does not involve the ascending aorta. Occurs in any other part of aortic arch and descending aorta (i.e., DeBakey Type III)

Question 10

Describe the DeBakey classification of aortic dissections

Answer 10

Groups aortic dissections anatomically

Type I - originates in the ascending aorta and propagates to at least the aortic arch

Type II - confined to the ascending aorta

Type III - originates distal to the subclavian artery in the descending aorta

Question 11

In which group of patients is DeBakey Type I usually seen?

Answer 11

Patients under 65yrs

Carry the highest mortality, quoted at 1% per hour in the acute setting

Question 12

In which group of patients is DeBakey Type II usually seen?

Answer 12

Elderly patients with atherosclerotic disease and hypertension

Question 13

What is DeBakey Type III further subdivided into?

Answer 13

IIIa - extends distally to the diaphragm

IIIb - extends beyond the diaphragm into the abdominal aorta

Question 14

What are the risk factors for aortic dissections?

Answer 14

HTN

Atherosclerotic disease

Male

Bicuspid aortic valve

Question 15

What are younger cases of aortic dissection typically associated with?

Answer 15

CTDs - e.g., Marfan, Ehlers-Danlos

Question 16

What is the characteristic presentation and common signs of aortic dissection?

Answer 16

Tearing chest pain, classically radiating through to the back

Common signs
- tachycardia

• hypotension*
• new aortic regurgitation murmur
• signs of end-organ hypoperfusion (such as reduced urine output, paraplegia, lower limb ischaemia, abdominal pain secondary to ischaemia, or deteriorating conscious level)

Question 17

What causes hypotension in aortic dissection?

Answer 17

Hypovolaemia (from blood loss into the dissection)

Cardiogenic (from severe aortic regurgitation or pericardial tamponade)

Question 18

List some DDx for aortic dissections

Answer 18

MI

PE

Pericarditis

Musculocutaneous pain

Question 19

What investigations should you do?

Answer 19

Bedside
- ECG

Bloods
- FBCs
- U&Es
- LFTs
- crossmatch (at least 4 units)

Imaging
- CT angiogram
- transoesophogeal ECHO (operator dependent)

Question 20

How would you manage someone with aortic dissection?

Answer 20

A-E assessment

Stanford type A = surgical Mx (high mortality if left untreated and should be discussed urgently with cardiac or vascular surgeon)

Uncomplicated Stanford type B = medical Mx with IV labetalol (1st line) or CCBs (2nd line)

Question 21

What does the surgery for a Stanford Type A dissection involve?

Answer 21

Removal of ascending aorta (with or without arch)

Replacement with synthetic graft

Any additional branches of the aortic arch that are involved will require reimplantation into the graft (i.e. brachiocephalic artery, left common carotid artery, left subclavian artery)

Question 22

Why is endovascular repair acutely not recommended for type B dissections?

Answer 22

Risk of retrograde dissection

Question 23

When is surgical intervention in Type B dissections warranted?

Answer 23

Only for certain complications, such as:
- rupture
- renal, visceral or limb ischaemia
- refectory pain
- uncontrollable HTN

Question 24

Which Stanford type can be chronic and what is its most common complication?

Answer 24

Type B

Aneurysm

Question 25

What is the best way to treat aneurysm resulting from a particular Stanford type?

Answer 25

Particular Stanford type = type B

Endovascular repair

Offers a better survival chance

Question 26

What complications can arise for aortic dissections?

Answer 26

Aortic rupture

Aortic regurgitation

Myocardial ischaemia - secondary to coronary artery dissection

Cardiac tamponade

Stroke or paraplegia - secondary to cerebral artery or spinal artery involvement

N.B. Mortality remains high, with over 20% of cases dying before reaching hospital, however early diagnosis, intervention, and blood pressure control significantly improves prognosis.

Question 27

Sources

Answer 27

https://teachmesurgery.com/vascular/arterial/aortic-dissection/