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)