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Path + CR: Atherosclerosis (ii) (thoracic aorta dissection (most serious…
Path + CR: Atherosclerosis (ii)
Aneurysm
localised abnormal dilation of a blood vessel
can be true (bounded by arterial/heart wall) or false/pseudo (breach in vasc wall, e.g. due to trauma - extravasc haemotoma that freely communicates with intravasc space)
causes
atherosclerosis (esp AAA)
congenital defects (e.g. berry aneurysms in circle of Willis)
trauma
systemic diseases (e.g. vasculitis)
cystic medial necrosis
disorder of large arts, esp aorta
accumulation of basophilic ground substance in media with cyst like lesions
hallmark histologic change associated with dissection in Marfan syndrome
syphilitic / luetic aneurysm
secondary to syphilitic aortitis
AAA
below renal arts + above bifurcation
can be fusiform (balloons out on all sides) or saccular (only bulges on 1 side)
max diameter = 15cm, length can be variable
rupture risk is directly prop to size (>5cm = high risk)
growth rate correlates with BP
expansile pulsatile mass in abdomen
severe abdominal pain, +/- shock
if back pain it's dissecting
clinical consequences
rupture into peritoneal cavity/retroperitoneal tissues
massive/fatal haemorrhage
art obstruction (iliac/mesenteric/vertebral)
ischaemic tissue injury
embolism
impingement on an adjacent structure (e.g. ureter/vertebrae)
thoracic aorta dissection
NOT related to atheroma
tear in intima, blood flows inside media
blood-filled channel in wall
can rupture outward, causing massive often fatal haemorrhage
sometimes due to an aneurysm
over 90% occur in men aged 40-60 with antecedent (genetic) hypertension
can be due to abnormality in connective tissue (e.g. Marfan)
can be iatrogenic (e.g. complication of arterial cannulation)
symptoms
sudden onset of excruciating pain beginning in ant chest + radiating to back + down as dissection progresses
most serious complications occur between aortic valve + arch
still in pericardium
haemopericardium (aka cardiac tampondae)
blood pushes against heart + prevents pumping