what are the layers of the artery wall?
tunica intima (innermost layer),
tunica media (middle layer), and
tunica adventitia (outermost layer)
what is an aortic dissection?
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
when is an aortic dissection acute?
when diagnosed in =14 days
when is an aortic dissection chronic?
when diagnosed at >14 days
what is the difference between anterograde dissections and retrograde dissections?
Anterograde dissections propagate towards the iliac arteries and retrograde dissections propagate towards the aortic valve (at the root of the aorta)
what are some consequences of retrograde dissections?
Retrograde dissections can result in prolapse of the aortic valve, bleeding into the pericardium, and cardiac tamponade
how are aortic dissections classified using the DeBakey classification?
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
how are aortic dissections classified using the Stanford classification?
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.
what are the risk factors for an aortic dissection?
- hypertension
- atherosclerotic disease
- male gender
- CT disorder e.g marfans or Ehlers danlos
- bicuspid aortic valve
- male
what are the clinical features of aortic dissections?
- 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
why may a patient with an aortic dissection be hypotensive?
hypotension secondary to hypovolaemia from blood loss to dissection, or cariogenic from severe aortic regurgitation or pericardiac tamponade
what are the differentials for an aortic dissection?
- MI
- PE
- pericarditis
- MSK back pain
what investigations are done into an aortic dissection?
- 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.
how should aortic dissections be treated initially?
- 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.
how is a type A aortic dissection treated?
- 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
how are type B dissections treated?
- 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
what are the complications of an aortic dissection?
- Aortic rupture
- Aortic regurgitation
- Myocardial ischaemia secondary to coronary artery dissection
- Cardiac tamponade
- Stroke or paraplegia secondary to cerebral artery or spinal artery involvement
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the acutely painful limb13
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lower limb ulcers18
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carotid artery disease13
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abdominal aortic aneurysm17
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aortic dissections17
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thoracic aortic aneurysm10
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acute limb ischaemia12
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chronic limb ischaemia17
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acute mesenteric ischaemia11
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chronic mesenteric ischaemia11
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peripheral and visceral artery aneurysms19
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varicose veins17
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deep venous insufficiency11
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subclavian steal syndrome8
