Aortic dissection Flashcards
What is an aortic dissection?
A tear in the tunica intima (innermost layer of the aorta) causing blood to flow between and split apart the tunica intima and media
How long should a dissection occur for it to be classified as acute?
diagnosed ≤14 days
How long should a dissection occur for it to be classified as chronic?
diagnosed >14 days
Where can aortic dissections from the initial intimal tear progress?
Either:
Distally
Proximally
Both directions from site of origin
What are anterograde dissections?
Propagate towards the iliac arteries
What are retrograde dissections?
Propagate towards the aortic valve (at the root of the aorta)
What can retrograde dissections result in?
Prolapse of the aortic valve
Bleeding into the pericardium, and cardiac tamponade
What two systems are used in the classification of aortic dissections?
DeBakey
Stanford
Describe the Stanford classification of aortic dissections
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)
Describe the DeBakey classification of aortic dissections
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
In which group of patients is DeBakey Type I usually seen?
Patients under 65yrs
Carry the highest mortality, quoted at 1% per hour in the acute setting
In which group of patients is DeBakey Type II usually seen?
Elderly patients with atherosclerotic disease and hypertension
What is DeBakey Type III further subdivided into?
IIIa - extends distally to the diaphragm
IIIb - extends beyond the diaphragm into the abdominal aorta
What are the risk factors for aortic dissections?
HTN
Atherosclerotic disease
Male
Bicuspid aortic valve
What are younger cases of aortic dissection typically associated with?
CTDs - e.g., Marfan, Ehlers-Danlos
What is the characteristic presentation and common signs of aortic dissection?
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)
What causes hypotension in aortic dissection?
Hypovolaemia (from blood loss into the dissection)
Cardiogenic (from severe aortic regurgitation or pericardial tamponade)
List some DDx for aortic dissections
MI
PE
Pericarditis
Musculocutaneous pain
What investigations should you do?
Bedside
- ECG
Bloods
- FBCs
- U&Es
- LFTs
- crossmatch (at least 4 units)
Imaging
- CT angiogram
- transoesophogeal ECHO (operator dependent)
How would you manage someone with aortic dissection?
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)
What does the surgery for a Stanford Type A dissection involve?
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)
Why is endovascular repair acutely not recommended for type B dissections?
Risk of retrograde dissection
When is surgical intervention in Type B dissections warranted?
Only for certain complications, such as:
- rupture
- renal, visceral or limb ischaemia
- refectory pain
- uncontrollable HTN
Which Stanford type can be chronic and what is its most common complication?
Type B
Aneurysm
What is the best way to treat aneurysm resulting from a particular Stanford type?
Particular Stanford type = type B
Endovascular repair
Offers a better survival chance
What complications can arise for aortic dissections?
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.
Sources
https://teachmesurgery.com/vascular/arterial/aortic-dissection/
