Aortic dissection

Question 1

What is aortic dissection?

Answer 1

A tear in the intimal layer of the aorta causes bleeding into the intimacy-media space.

Question 2

How is aortic dissection classified?

Answer 2

Stanford classification:
Type A - involves the ascending aorta
Type B - Involves only the descending aorta (distal to the left subclavian artery).

DeBakey classification:
Type I (Stanford A)- originates in the ascending aorta and propagates to at least the arch
Type II - Involves the ascending aorta only
Type III A - descending aorta only and above the diaphragm
Type III B (Stanford B) - descending aorta only and descends below the diaphragm.

Question 3

What are the risk factors for aortic dissection?

Answer 3

• hypertension
• smoking
• advanced age
• male
• family history
• pregnancy
• trauma (tear at the aortic isthmus in deceleration injuries)
• connective tissue disorders and congenital aortic disorders.

Question 4

What are the presenting symptoms/signs of aortic dissection?

Answer 4

Pain - classically tearing chest pain radiating to the back.
Absent pulses distal to the dissection/limb ischaemia
Syncope or collapse
Stroke
Myocardial infarction

Question 5

What are the complications associated with aortic dissection?

Answer 5

Cardiac - myocardial infarction, aortic regurgitation, tamponade
Neurological - stroke, paraplegia from spinal cord ischaemia
Renal - AKI
Vascular - distal limb ischaemia and compartment syndrome
Gastro - mesenteric ischaemia
Haematological - major transfusion, coagulopathy

Question 6

What imaging can be used for aortic dissection?

Answer 6

Most commonly - CT aorta
Gold standard - aortography
Other useful modalities:
- echo (TTE/TOE) - dissection flap, pericardial effusion/tamponade, regurgitation
CXR - widened mediastinum, loss of aortic knuckle
MRI - can visualise dissection but not really appropriate in unstable patients and CT can do the same.

Question 7

What are the principles of management of aortic dissection?

Answer 7

• Resuscitate and stabilise the patient in an A-E manner:
• (paying attention to neurology, limb pulses, cardiac function (ECG, echo, trop), renal function (catheter, U&Es) and invasive blood pressure monitoring and analgesia).
• Establish diagnosis with urgent CT aorta
• differentiate between type A and B.
• Discuss with cardiothoracic/aortic surgical team
• For type B, often 1st line is BP control and heart rate control (beta blockers (1), CCBs (2), SNP, hydralazine, GTN (3)) - aiming for systolic 100- 120mmHg but adequate organ/limb perfusion.
• For complicated type B or type A - surgery.

Question 8

What is an acute aortic syndrome?

Answer 8

Constellation of life-threatening aortic conditions with a similar presentation. All involve an injury to the wall of the aorta, but have distinct survival characteristics:

European society cardiology classification:

• class 1: Classic dissection
• class 2: Intramural haemorrhage/haematoma
• class 3: Subtle-discrete aortic dissection
• class 4: Plaque rupture/ulceration (penetrating ulcer)
• class 5: traumatic/iatrogenic dissection