aortic dissections

Question 1

what are the layers of the artery wall?

Answer 1

tunica intima (innermost layer),

tunica media (middle layer), and

tunica adventitia (outermost layer)

Question 2

what is an aortic dissection?

Answer 2

a tear in the intimal layer of the aortic wall, causing blood to flow between and splitting apart the tunica intima and media

can progress distally, proximally or in both directions from point of origin

Question 3

when is an aortic dissection acute?

Answer 3

when diagnosed in =14 days

Question 4

when is an aortic dissection chronic?

Answer 4

when diagnosed at >14 days

Question 5

what is the difference between anterograde dissections and retrograde dissections?

Answer 5

Anterograde dissections propagate towards the iliac arteries and retrograde dissections propagate towards the aortic valve (at the root of the aorta)

Question 6

what are some consequences of retrograde dissections?

Answer 6

Retrograde dissections can result in prolapse of the aortic valve, bleeding into the pericardium, and cardiac tamponade

Question 7

how are aortic dissections classified using the DeBakey classification?

Answer 7

using DeBakey classification

groups them anatomically

type 1 = originates in ascending aorta and propagates to at least the aortic arch

type 2 = confined to ascending aorta

type 3 = originates distal to subclavian artery in the descending aorta

Question 8

how are aortic dissections classified using the Stanford classification?

Answer 8

group a = Includes DeBakey types 1 and 2 and involves ascending aorta. Can propagate to aortic arch and descending aorta. Tear can originate anything along this path

group b = dissections the don’t involve the ascending aorta. Include DeBakey type 3.

Question 9

what are the risk factors for an aortic dissection?

Answer 9

• hypertension
• atherosclerotic disease
• male gender
• CT disorder e.g marfans or Ehlers danlos
• bicuspid aortic valve
• male

Question 10

what are the clinical features of aortic dissections?

Answer 10

• tearing chest pain, radiating through to the back
• tachycardia
• hypotension
• new aortic regurgitation murmum
• signs of end organ hypo perfusion e.g reduced urine output, lower limb ischarmia, abdominal pain secondary to ischaemia, deteriorating conscience level and paraplegia

Question 11

why may a patient with an aortic dissection be hypotensive?

Answer 11

hypotension secondary to hypovolaemia from blood loss to dissection, or cariogenic from severe aortic regurgitation or pericardiac tamponade

Question 12

what are the differentials for an aortic dissection?

Answer 12

• MI
• PE
• pericarditis
• MSK back pain

Question 13

what investigations are done into an aortic dissection?

Answer 13

• Baseline bloods (FBC, U&Es, LFTs, troponin, coagulation) with a crossmatch
• ECG to exclude cardiac pathology
• CT angiogram is first line imaging to classify and diagnose.
• Transoesophageal ECHO can also be useful but is operator dependant.

Question 14

how should aortic dissections be treated initially?

Answer 14

• urgent initial assesment
• high flow oxygen
• 2x large bore cannulas for IV access
• cautious fluid resuscitation

If a rupture, then the target pressure should be sufficient for cerebral perfusion only. In the setting of an uncomplicated dissection then the target systolic pressure should be kept below 110mmHg systolic.

after, need antihypertensive therapy and surveillance imaging due to risk of developing further dissections and other complications.

Question 15

how is a type A aortic dissection treated?

Answer 15

• manage surgically in first instance
• involves removal of ascending aorta and replacement with a synthetic grade
• any additional branches of the aortic arch that are involved will need reimplantation into the graft
• have the worst prognosis

Question 16

how are type B dissections treated?

Answer 16

• uncomplicated = managed medically
• first line = manage hypertension with IV beta blockers or CCB as second line therapy. Aim is to lower systolic BP, pulse pressure, pulse rate and minimise dissection stress and further propagation.
• surgery if complications present e.g rupture, renal/visceral/limb ischaemia, refectory pain, uncontrollable hypertension
• can become chronic with continued leakage into dissection even if stunted
• most common complication = aneurysm formation
• these present further surgical problems = endovascular repair can offer a better survival chance

Question 17

what are the complications of an aortic dissection?

Answer 17

• Aortic rupture
• Aortic regurgitation
• Myocardial ischaemia secondary to coronary artery dissection
• Cardiac tamponade
• Stroke or paraplegia secondary to cerebral artery or spinal artery involvement