Peripheral Vascular Occlusive disease Flashcards
Fontaine Classification for PAD
Stage 1- Asymptomatic
Stage 2- IC
Stage 3- Rest pain
Stage 4- Ulceration/gangrene
Sunset foot
Sign of very severe critical limb ischaemia
Poor condition of toe nails
Colour due to small arteriole vasodilation as a response to chronic lactic acidosis built up in the foot
What happens when a main artery is slowly stenosed then occlused because of atherosclerosis
Collateral vessels form
Stimulated by multiple episodes of ischemic pain (lactic acidosis)
Ask patients to walk until limit of their pain- encourages formation of these collaterals
Commonest cause of foot neuropathy
Diabetes
Diabetic neuropathy is also associated with
Fibrosis of the plantar fascia of the foot
Fibrosis of the plantar fascia of the foot
Results in the metatarsal heads pushing down into the sole and a hammering of the toes
Problems of the concept of critical limb ischaemia in diabetic patients
Rest pain is not a reliable sign in diabetic neuropathy
Severely calcified blood vessels in diabetes can allow for high ankle pressures which can appear falsely reassuring
Acutely ischaemic Limb 6 Ps
Pain Pallor Perishingly Cold Pulseless Paraesthesia Paralysis
Acutely Ischaemic limb
Rest pain for less than 2 weeks requiring analgesia And/or ulceration And/or gangrene Ankle pressure <50mmHg Toe pressure (in diabetics)<30 mmHg
Acute limb ischaemia progression 0-6hrs
Marble white leg
Intense vasospasm of distal arterial tree
Emptying of veins
Acute limb ischaemia progression 6-12 hours
Mottled leg
Vasodilation in response to smooth muscle hypoxia
Fills with deoxygenated blood
Still blanches
Acute limb ischaemia progression 12 hours +
Irreversible ischaemia Stagnant blood coagulates and thrombus propagates Capillary rupture causing fixed staining Tense muscles Blistering
Acute limb ischaemia Category I
Not immediately threatened No sensory loss No muscle weakness Audible arterial doppler Audible venous doppler
Acute limb ischaemia Category IIa
Salvable if prompt treatment Minimal sensory loss in toes No muscle weakness Inaudible Arterial doppler Audible venous doppler
Acute limb ischaemia category IIb
Salvable if immediate treatment Moderate sensory loss plus pain Mild/moderate muscle weakness Inaudible arterial doppler Audible venous doppler
Acute limb ischaemia category III
Major tissue loss of permanent nerve damage inevitable Profound or anaesthetic sensory loss Profound muscle weakness/paralysis Inaudible arterial doppler Inaudible venous doppler
Causes of acute limb ischaemia
Thrombosis (60%)
Embolism (30%)
Rare
Causes of acute limb ischaemia- Thrombosis “Acute on chronic”
60% Atherosclerosis Popliteal aneurysm Graft occlusion Thrombotic conditions
Causes of acute limb ischaemia- Embolism “true acute”
30% Atrial fibrillation (80%) Mural thrombosis (thrombus in the wall of a vessel higher up dislodging and travelling distally to block the vessel further downstream) Vegetations Proximal aneurysms and plaques
Causes of acute limb ischaemia- rare
Trauma
Causes of acute limb ischaemia- AF
If the heart is not beating in coordinated fashion, there will be areas where the blood flow is slower than normal. This will lead to stasis of blood and hence clots. These clots can be dislodged from the heart and fly round the circulation causing end organ ischaemia - brain (ischaemic stroke); limbs; visceral ischaemia eg. mesenteric ischaemia.
Causes of acute limb ischaemia- vegetations
Infected vegetations (endocarditis) on heart valves can similarly dislodge and embolise into the vasculature
Immediate management of Acute limb ischaemia
Blood ECG CXR Echo Imaging of arterial tree TREAT
Acute ischaemia non-viable limb
Fixed motting (pressing on the purpuric areas) will not cause them to blanche- this signifies the arterioles and end capillaries have ruptured in the effort to open up as much as possible
Acutely ischaemic limb- all require
oxygen
IV fluids
Analgesia
IV heparin
Ischaemic limb can lead to
Primary Amputation
Angiogram
Embolectomy
Embolectomy
Fogarty catheter inserted into artery with thrombus
Inflated Fogarty balloon
Remove thrombus
Reperfusion injury
Once you return oxygen to muscle that has been starved of oxygen for more than 4 hours, some degree of reperfusion injury will occur
Reperfusion injury causes
Free oxygen radicals
Activation of coagulation
Mitochondrial dysfunction
Myocyte hypercontracture
Free oxygen radicals
Alters membrane proteins and phospholipids
Increased oxidative stress
Increased inflammation
Leukocyte activation and aggregation
Activation of coagulation
Platelet activation
Compliment activation leading to microvascular and endothelial dysfunction
Mitochondrial dysfunction
Decreased mitochondrial calcium concentration
Decreased ATP and apoptosis
Myocyte hypercontracture
Increased intracellular calcium
Reoxygenation of myocytes
Reperfusion swelling
Reperfusion associated with extensive swelling of the muscles (typically the calf)
The calf muscles are constrained within the fascial envelopes of the leg (there are 4 of these)
If these envelopes are not released with fasciotomies then compartment syndrome will result with rhabdomyolysis and kidney failure
