Aortic dissection (CV) Flashcards
Define aortic dissection.
- tear in aortic wall intima causing blood to flow into a new false lumen in the intima-media space
- this can cause a haematoma to form and rupture –> occlusion of vessels
Which groups does aortic dissection usually affect? (3)
- M>F
- 60-80 years old
- patients with Marfan syndrome (or other CTDs) are 30-50y/o and predisposed to aortic dissection and aneurysms
Which part of the aorta is usually affected in aortic dissection?
Most commonly the ascending aorta (Stanford type A)
What is aortic dissection usually preceded by?
Degenerative changes in smooth muscle of aortic media
What can expansion of the false lumen in aortic dissection lead to?
Obstruction of branches of aorta (subclavian, carotid, coeliac, renal arteries) –> hypoperfusion of the target organs of these major arteries –> other symptoms
What are the two classification methods used for aortic dissection?
- Stanford classification
- DeBakey classification
Describe the Stanford classification for aortic dissection.
- Stanford type A (2/3) - dissection involving the ascending aorta (with/without involvement of arch and descending aorta)
- Stanford type B (1/3) - dissection involving the descending aorta only (distal to left subclavian artery)
Describe the DeBakey classification for aortic dissection.
- type I - involves ascending and descending aorta (originates ascending –> at least aortic arch and possibly beyond distally)
- type II - only ascending aorta up to brachiocephalic artery (originates in and confined to ascending)
- type III - only descending aorta distal to left subclavian artery (originates descending, rarely extends proximally but will extend distally)
What are some clinical features of aortic dissection? (5)
- sudden and severe, sharp tearing chest pain
- intercapsular pain radiating to the back (back/abdominal pain may be type B)
- asymmetrical BP and pulse between limbs (mostly arms)
- early diastolic murmur (aortic regurgitation) in ascending aortic dissection (severe AR = Austin flint murmur which is mid-diastolic best heard at apex)
- focal neurological deficits (Horner’s syndrome in carotid dissection)
What are some specific features of asymmetrical BP and pulse between limbs in aortic dissection? (3)
- weak or absent carotid, brachial or femoral pulse
- radio-radial delay
- radio-femoral delay
What specific symptoms are caused by obstruction of aorta branches in aortic dissection? (6)
- carotid artery - hemiparesis, dysphasia, blackout
- coronary artery - chest pain (angina/MI)
- subclavian artery - ataxia, loss of consciousness
- anterior spinal injury - paraplegia
- coeliac axis - severe abdominal pain due to ischaemic bowel
- renal artery - anuria, renal failure
What is an Austin flint murmur?
Mid-diastolic murmur best heard at apex, sign of severe aortic regurgitation
What focal neurological deficit is seen in carotid dissection?
Horner’s syndrome - due to compression of the sympathetic trunk by expanding aortic dissection
What might you see on examination of aortic dissection? (9)
- murmur on back (below left scapula) descending to abdomen
- Horner’s syndrome
- hypertension
- BP difference >20mmHg between two arms
- unequal arm pulses
- wide pulse pressure
- signs of aortic regurgitation - high volume collapsing pulse, early diastolic murmur over aortic area
- palpable abdominal mass
- pulsus paradoxus - abnormally large decrease in systolic BP and pulse wave amplitude during inspiration
What might pulsus paradoxus indicate? (4)
- tamponade (hypotension)
- pericarditis
- chronic sleep apnoea
- obstructive lung disease
What is the most important risk factor for aortic dissection?
Hypertension
What are some risk factors for aortic dissection?
- hypertension
- trauma
- CTDs e.g. Marfan’s syndrome, Ehlers-Danlos, SLE
- smoking
- aortic atherosclerosis
- congenital cardiac abnormalities (e.g. coarctation of aorta)
- aortitis
- iatrogenic (e.g. during angioplasty/angiography)
- vasculitis
- pregnancy
- crack cocaine
What are some features of Marfan syndrome (risk factor for aortic dissection)? (4)
- tall and high arched palate
- pectus excavatum
- joint hypermobility
- autosomal dominant condition
What are the first-line investigations for aortic dissection? (4)
- CT angiogram (chest, abdomen and pelvis) - 1st line for definitive diagnosis
- transoesophageal echocardiography
- CXR
- ECG
What is the 1st-line imaging for definitive diagnosis of aortic dissection?
CT angiogram of chest, abdomen and pelvis - can see false lumen
What imaging can be done for patients with aortic dissection that are too haemodynamically unstable to be taken to CT?
Transoesophageal echocardiography
What would a CXR show in aortic dissection?
- widened mediastinum (>8-8.8cm at the level of the aortic knob on portable anteroposterior chest films)
- double aortic contour
- irregular aortic contour
- inward displacement of atherosclerotic calcification (>1cm from aortic margin)
What must you always perform in patients with suspected aortic dissection and why?
- ECG to rule out STEMI
- inferior STEMI if RCA occluded with LVH
- survivor bias for those with LCA affected as it is fatal
What are some differential diagnoses for aortic dissection? (6)
- ACS
- pericarditis (pleuritic chest pain, diffuse STE)
- aortic aneurysm
- MSK pain
- pulmonary embolism
- mediastinal tumour
