CR - Arteritis
intro
endothelial damage -> atheroma
media maintains tone (surrounded by int + ext elastic lamina
adventitia
outer soft tissue
contains vessels that supply blood vessel wall
arts: thicker wall, muscular, narrow lumen
veins: thinner wall, larger diameter, wider lumen
Art types
large elastic (aorta, carotids, iliacs)
medium muscular (coronaries, renals)
small (<2mm) - within tissues + organs
Arterioles
smallest art branches (20-100 micrometres)
small change in lumen size -> profound flow limiting effect
principal area of physiologic resistance to blood flow (bear the brunt effects of hypertension)
Capills
ideal conditions for diffusion between blood + tissue
walls 1 cell thick
bed has large cross-sectional area
slow flow
Veins
large calibre (int diameter)
2/3 of systemic blood in venous circulation
poor support, hence susceptible to...
irregular dilation (results in pooling, hypotension, diminished venous return)
compression
penetration by tumours
inflamm
have valves to prevent reverse flow
lymphatics
thin-walled endothelium lined channels
no blood cells
drainage system for returning interstitial fluid to blood
pathway for disease dissemination
main disease processes of arts
inflamm (vasculitis)
dilation (atherosclerosis - also causes stiffening+fibrosis)
dissection
occlusive (PAD
Vasculitis causes
direct inflamm
Neisseria
syphilis
herpes
aspergiius
mucor (mould)
rocky mountain spotted fever (rickettsia rickettsii)
immunologic
ICD (type 3 hypersensitivity - activates complement)
RA
SLE
Henoch schonlein purpura (HSP - mainly in children)
type 2 hypersensitivity
ANCA - Granulomatosis with Polyangitis (GPA, formerly known as Wegener's granulomatosis) (Dx with blood test)
anti-GBM Igs - Goodpastures (small vessel - young adult men - haematuria + haemoptysis)
type 4 (cell-mediated) - allograft organ rejection
IBD
paraneoplastic
unknown
giant cell vasculitis
takayasu vasculitis (rare, systemic, large arts)
polyarteritis nodosa (PAN - systemic necrotising medium arts)
Non-infectious Vasculitis
large vessel
medium vessel
small vessel
giant cell (temporal) arteritis
long-standing/healed arteritis: intimal thickening
active arteritis: degenerated int elastic membrane (elastic membrane appears as a black wavy line under H&E)
granulomatous
affects aorta + major branches + extracranial branches of carotid
over 50s
emergency - blindness risk - give high dose steroids straight away
Takayasu arteritis
granulomatous
affects aorta + major branches
marked intimal thickening - min residual lumen
under 50s
hard to Dx - do aortic arch angiogram
destruction of media by mononuclear inflamm + giant cells
PAN
affects renal + systemic vessels
spares pul circulation
no vasculitis in arterioles, capills or venules
thromboangitis obliterans (Buerger disease)
lumen occluded by thrombus (may contain abscesses) + inflamm
vessel wall infiltrated with lymphocytes
ischaemia of tissue supplied by affected art
GPA
necrotising vasculitis + granulomatous inflamm of resp tract
large nodular lung lesions
necrotising glomerulonephritis
eosinophilic GPA (Churg-Strauss syndrome)
necrotising vasculitis
esp in asthmatics
granulomatous inflamm of resp tract
blood eosinophilia
HSP
systemic ICD
rash on legs + buttock
sometimes kidney involvement
infectious arteritis
localised
due to direct invasion of infectious agents
weakened art wall may lead to mycotic aneurysm
induces thrombosis -> tissue infarcts -> spread of infection
joint pain (sore knees)