Peripheral Vascular Disease Flashcards
what is an aneurysm
dilatation of a vessel by more than 50% of its normal (AP) diameter
what is the normal aortic diamter
1-2 cm
describe a true aneurysm
all three layers of vessels are in tact, blood is contained (usually abdominal aortic)
describe a false aneurysm
when there is a breach in vessel wall and surrounding structures are acting as vessel- usually caused by trauma
name three morphology of aneurysms
saccular, fusiform, mycotic
describe what gives rise to mycotic aneurysms
secondary to and infectious process that weakens the artery wall, involves all three layers of the artery
which aneurysms have highest risk of rupturing
any can but saccular and mycotic more than fusiform
does atherosclerosis cause aortic aneurysms
no
what causes aortic aneurysms
medial degeneration
- middle layer of vessel wall
- imbalance between elastin and collagen in aortic wall
- this leads to weakening of the wall
- which leads to aneurysmal dilatation
- increase in aortic wall stress
- progressive dilatation
related to age, gender, smoking, hypertension
a quarter of AAA patients will have what
popliteal aneurysm
how do asymptomatic aneurysm present (vast majority)
no symptoms, identified om imaging/ surveillance
how do symptomatic aneurysm present
- pain (renal colic)
- trashing- thrombus in aneurysm due to turbulent blood flow breaks off and enters peripheral circulation, damaging distal arteries
- rupture
how does a ruptured AAA present
sudden onset epigastric/ central pain
-may radiate through to back
-may mimic colic
collapse
what is found on examination of a ruptured AAA
may look well
hypo/hypertensive due to pain
pulsatile, expansile mass +/- tender
pulse transmitted from mass to flanks
hard to palpate due to obesity
describe the small amount of ruptured AAAs that make it to hospital
retroperitoneal usually, rupture contained by retroperitonium- tamponades itself
how severe are free intra-peritoneal rupture
rapidly fatal
when should intervention be taken for an AAA
balance fitness of patient and risk of rupture
if symptomatic or when asymptomatic and;
-size > 5.5cm AP diameter
or
-expanding >0.5cm/6 months or >1cm/ year
what does duplex ultrasound shows, its pros and cons
no radiation or contrast
only shows AP diameter and involvement of (iliac) arteries
describe a CT scan- aterial phase
IV contrast in aterial system shows aneurysm morphology, shape, size, iliac involvement. AND only one to show if ruptured
allows management planning
describe open repair of an aneurysm
laparotomoy to access it
clamp aorta and iliacs (for bloodless field)
dacron (polyester) graft (tube and bifurcated) anatstomosed onto artery
essential to close aneurysm sac over graft as bowl will stick to it
describe Endovascular Aneurysm Repair (EVAR)
exclude the aneurysm from within the vessel, graft inserted via peripheral artery, guided via x-ray. seal needed between tops of stent graft and vessel to prevent blood escaping into the sac
what is acute limb threat
- acute limb ischaemia
- acute on chronic limb ischaemia
- diabetic foot sepsis
what is acute limb ischaemia
sudden loss of blood supply to a limb
what causes acute limb ischaemia
occlusion of native artery or bypass graft
what can cause a sudden occulsion of an artery
Embolism Atheroembolism- narrowing, bits break off Arterial dissection Trauma e.g. dislocating knee Extrinsic compression- tumours
what are the clincal features of acute limb ischaemia
6 P's Pain- excruciating Pallor Pulseless (arteries distal to blockage) Perishingly cold Paraesthesia- nerve begins to die, what makes it so painful Paralysis
what are the aspects of acute limb ischaemia given in a history
No prior history of claudication- cramping
Known cause for embolism
Full complement of contra-lateral pulses (all pulses on other side)
describe the pain of acute limb ischaemia
Severe, sudden onset, resistant to analgesia
Calf/muscle tenderness with tight (‘woody’) compartment indicates muscle necrosis
Often irreversible ischaemia
why is pallor a symptom of acute limb ischaemia
Limb initially white with empty veins
why does the limb appear mottled as the acute limb ischaemia progresses
capillaries fill with stagnated de-oxygenated blood giving a mottled appearance
what does blanching mottling mean
salvageable if prompt revascularisation
what does non blanching mottling suggest
irreversible ischaemia as artiers distal to the occlusion fill with propagated thrombus with rupture of capillaries
why does ALI cause paralysis
as sensorimotor deficit indicative of muscle and nerve ischaemia
what happens after 12 hours of ALI
fixed mottling, paralysis, non salvageable
why do you never perfuse a non salvageable leg
as will release noxious chemical from dead muscle, killing the patient
why are anticoagulants given in ALI
stops propagation of thrombus, may improve perfusion (careful as surgery may be needed)
what tests are given on a patient presenting with an ALI
ABC, bloods, troponin, ECG (MI, dysrhythmia), CXR (underlying malignancy), arterial imaging (to plan appropriate management- CT angiogram/ catheter angiogram)
what are the managements for ALI if the limb is salvageable
Embolectomy (balloon catherter) +/-fasciotomies +/- thrombolysis
what are the managements for ALI if the limb is not salvageable
palliation or amputation
what do diabetic foot problems include
diabetic neuropathy, peripheral vascular disease, infection
what can combinations of diabetic foot problems lead to
tissue loss; ulceration, necrosis and gangrene = may result in amputation
what is the source of sepsis
break in skin (don’t notice because of neuropathy), infection from nail plate or inter-digital space, neuro-ischaemic ulcer (secondary to neuropathy and repetitive trauma- increased pressure in feet)
why is infection in the foot such a big problem
as muscles confined in rigid compartment which does not allow pus to escape, causing a build up of pressure which impairs capillary blood flow and further ischaemia and tissue damage. Can rapidly progress to sepsis and limb loss
what are the systemic finding in diabetic foot sepsis
Pyrexia Tachycardic Tachypnoeic Confused Kussmauls breathing (deep sighs- sepsis causes shock, hyper perfusion of distal organs and build up of lactic acid and CO2, trying to ventilate this acid out and raise pH)
what are the local finding of diabetic foot sepsis
Swollen affected digit (‘sausage’ like)
Swollen forefoot (‘boggy’ feeling to swelling)
Tenderness
Ulcer with pus extruding
Erythema (redness of the skin), may track up the limb
Patches of rapidly developing necrosis
Crepitus in the soft tissues of the foot (Gas from gas forming organisms in soft tissues)
Pedal pulses may or may not be present
local findings may be tip of iceberg
how is diabetic foot sepsis considered
vascular surgical emergency
how is diabetic foot sepsis treated
antibiotics (got to cover gram +ve cocci, gram -ve bacilli and anaerobes)
rapid surgical debridement of infected tissue, wound open to encourage drainage
when is a guillotine amputation done
to break cycle of infection, not neat stump, just clean above the ankle
what forms plaques in atherosclerosis
activated platelets, LDL cholesterol, inflammatory cells (WBD->macrophages->foam cells)
what is the role of collateral vessels in intermittent claudications
find way around blockage
what are the non invasive investigations of lower limb ischaemia
measurement of ABPI, duplex ultrasound scanning
what are the invasive investigations of lower limb ischaemia
magnetic resonance angiography, CT angiography, catheter angiography
what is ABPI
ankle brachial pressure index (ankle pressure over brachial pressure)
is it when ABPI is increased or decreased that there is a problem
drops
how does narrowing of artery affect blood flow
turbulent flow
how is progression of lower limb ischaemia slowed
stop smoking, lipid lowering, antiplatelets, hypertension Rx, diabetes Rx, life style issues
how are claudication symptoms treated
exercise training, drugs, angioplasty/stenting, surgery
what inflow surgery can treat lower limb ischaemia
endarterectomy, bypass,
what outflow surgery can treat lower limb ischaemia
bypass
describe the symptoms of critical limb ischaemia
rest pain- toe/foot ischaemia (when lying/sleeping)
ulcers/gangrene- severe ischaemia +damage (trauma + footwear)
worse at night
helped by sitting putting the leg in a dependent position and walking
what are the clinical features of critical limb ischaemia
cool to touch absence of peripheral pulses colour change hair loss thick nails shiny skin venous guttering ulcers gangrene
what are the risk factors for critical limb ischaemia
smokin, diabetes, hypertension, raised cholesterol
how is critical lower limb ischaemia treated
analgesia, angioplasty/ stenting, surgery/ amputation (depends on function and patients chance of recovery)
