Arterial occlusive disease Flashcards
What is peripheral arterial disease
narrowing or occlusion of peripheral arteries, affecting the blood supply to lower limbs
What can chronic limb ischaemia present as
Intermittent claudication
Cirtical limb ischaemia
Chronic limb-threatening ischaemia
What is acute limb ischaemia
– sudden decrease in arterial limb perfusion, due to thrombotic or embolic causes
What is intermittent claudication
diminished circulation leads to pain in the lower limb on walking or exercise that is relieved by rest (‘angina’ of limbs’)
What. is critical limb ischaemia
where circulation is so severely impaired that there is an imminent risk of limb loss
What is chronic limb-threatening ischaemia
represents end stage peripheral arterial disease where there is threatened limb viability relayed to several factors
What is atherosclerosis
Deposition of fatty plaques and thickening of walls in medium to large sized arteries
Process of atherosclerosis
1) Endothelial dysfunction
2) Causes inflammation of artery wall and platelet adhesion to wall
3) Inflammation leads to recruitment of mediating cells
4) Macrophages ingest cholesterol which form foam cells
5) Foam cells then form fatty streak
6) Leads to atheroma plaque formation
7) These atheroma have lipid cores and fibrous caps
8) Over time, weakening of fibrous cap
9) Plaque rupture
10) Thrombus formation
Common sites of atherosclerosis
Where vessels branch, curve or are irregular and where blood undergoes sudden changes in velocity and direction of flow
1) Circle of WIllis
2) Carotid arteries
3) Popliteal arteries
4) Coronary arteries
5) Abdominal aorta
bruce Willis Catches a Perceptive Criminal named hAns
Resulting pathology of atherosclerosis
Weakening of vessel wall- arterial aneurysm or dissection
Demand-supply mismatch- coronary heart disease, peripheral arterial disease, vascular dementia
Thrombosis- Acute coronary syndromes, acute ischaemic stroke, acute limb ischaemia
Atherosclerosis of renal artery can lead to renovascular hypertension
Risk factors for atherosclerosis and chronic peripheral arterial disease
Obesity Physical inactivity Hypertension Smoking Hypercholesterolaemia Diabetes mellitus Old age
Clinical signs of atherosclerosis
Xanthelasma
Bruits (carotid or abdo)
Aortic aneurysm on palpation
Poor peripheral pulses
What is chronic peripheral arterial disease associated with
Coronary heart disease
Cerebrovascular disease
Diabetes
Causes of chronic peripheral arterial disease
Atherosclerosis (most common cause)
Vasculitis (inflammation of vessel or artery)
Fibromuscular dysplasia
Why does intermittent claudication lead to pain
Reduced blood flow to limbs
At rest, perfusion is adequate to meet O2 demands of the tissue
During exercise, perfusion is not adequate enough to meet increased O2 demands of the tissue
Classical features of intermittent claudication
Gripping, tight, cramp-like pain (typically in calves)
Induced by exercise
Typically relieved by rest
Predominates in one leg usually
Reproducible
Difference in presentations between arterial insufficiency and cauda equina
arterial insufficiency- Fixed claudication distance
Pain exacerbated by walking uphill, better downhill
Pain disappears after 1-2 mins of rest typically
Examination findings: Absent peripheral pulses and reduced ABPI but no evidence of neurological findings
Cauda equina
Variable claudication distance
Pain often better when walking uphill but worse downhill
Pain disappears after 15-30 mins typically
Examination findings: LMN findings such as reduced reflexes but pulses present as normal
What is the progression of symptoms of peripheral arterial disease
Intermittent claudication
- Claudication distance reducing
- Ischaemic rest pain (worse at night because of reduced nocturnal BP dye to reduced CO and loss of gravity)–> Patients may report improvement of symptoms with legs hanging out of bed or sleeping in chair
- Gangrene
Clinical signs of pts with peripheral arterial disease
Pale, cold hairless legs
- Reduced CRT
- Arterial ulcerations (deep, punched out, painful, small, present over toe joints, heel and lateral aspect of leg)
Arterial bruits
Weak of absent pulses
two main symptoms of critical limb ischaemia
Rest pain due to insufficient blood supply (burning pain)
Tissue loss- Development of necrotic tissue which if infected becomes gangrene
–>Can lead to osteomyelitis so urgent treatment required
Bedside Investigations for peripheral arterial disease
Obs
ECG
Blood investigations for peripheral arterial disease
FBCs ESR (erythrocyte sedimentation rate)- secondary causes such as vasculitis Thrombophilia screen Lipid levels Blood glucose
Scans for peripheral arterial disease
ABPI (ankle brachial pressure index)
Non invasive- Duplex USS (to determine the site of the disease and indicate the degree of stenosis and length of occlusion)
Non invasive- MRI/CT angiography (prior to revascularisation via angioplasty or reconstructive surgery)
What is ABPI (ankle brachial pressure Index)
Method of quantifying severity of arterial disease in legs
Uses a dopplerto measure the blood pressure in the brachial artery and the two arteries in the foot
As arterial disease progresses in the legs, we get reduced flow through the arteries and hence the blood pressure falls
This is commonly measured in patients with ulcers to help differentiate the type of ulcer
What is a normal ABPI
1-1.2
Conservative management of PAD
Peripheral vasodilators
Smoking cessation
Lipid modification and initiation of statin therapy
Antiplatelet therapy
Optimal management of co-morbidities (HTN, T2DM)
Difference between acute limb ischaemia with thrombotic vs embolic causes
Embolic - acute onset. Limb appears white and other leg usually normal. Very severe
thrombotic - Onset more gradual. Leg may not be white and symptoms may be less severe. Presentation is usually with worsening claudication and rest pain.Pulses in other leg may be absent.
Risk factors for acute limb ischaemia between thrombotic and embolic
Embolic- AFEndocarditis Mitral stenosis Aneurysms Atherosclerotic disease Presence of graft
Thrombotic-Peripheral vascular disease Ischaemic heart disease Cardiovascular disease Presence of graft Blood disorders
Classical features of acute limb ischaemia
irreversible limb ischaemia?
6P’s
Pain — constantly present and persistent.
Pulseless — ankle pulses are always absent.
Pallor (or cyanosis or mottling).
Power loss or paralysis due to nerve ischaemia
Paraesthesia or reduced sensation or numbness.
Perishing with cold.
irreversible- hard woody muscles and mottled non-blanching appearance. Urgent amputation required
Differentials for acute limb ischaemia
Chronic peripheral neuropathy (e.g. diabetic neuropathy. However with this, pulses are present and temperature is normal)
Compartment syndrome (muscles are tense. Not main symptom in acute limb ischaemia)
DVT (red hot swollen calf and pulses normally palpable )
Management of acute limb ischaemia
Surgical emergence
If embolus- surgical embolectomy or intra-arterial thrombolysis
If thrombus- angioplasty, bypass or intra-arterial thrombolysis
Complications of acute limb ischaemia
Compartment syndrome — reperfusion of ischaemic muscles can cause oedema and increased compartmental pressure.
Reperfusion injury — products of cell death (for examplepotassium, phosphate and myoglobin) are released when blood flow to the ischaemic limb is restored. This can result in rhabdomyolysis, cardiac dysrhythmia, acute kidney injury, multiorgan failure, and disseminated intravascular coagulation.
If untreated- significant necrosis and probably amputation
What are vasospastic disorders
Atherosclerosis induces increased contraction of the smooth muscle resulting in greater vasospasm
–> In atherosclerosis it does not stimulate as much prostacyclin and NO to induce relaxation on smooth muscle cells. There is not as much inhibition of aggregation of platelets. Greater aggregation of platelets produce ASP, serotonin and thromboxane 2 which cause contraction of smooth muscle
What are the main vasospastic disorders
Raynaud’s syndrome
Acrocyanosis
Livedo reticularis
What is Raynaud’s disease
Charecterised by paroxysmal vasospastic and subsequent vasodilatory chain of events affecting small peripheral arterioles
Usually affects hands and feet. Precipitated by cold and emotion
Colour change of digits
- Pale- ischaemia
- Blue- cyanosis
- Red- hyperaemia
Raynaud’s disease vs phenomenon
Raynaud’s disease more likely to be primary - Such as present in younger, female patients with a genetic component with no features of underlying disease
Phenomenon is secondary. More likely to present as an older patient, with more severe symptoms (digital scars, ulceration or gangrene and nail changes)
Secondary causes of Raynaud’s
autoimmune- Scleroderma, rheumatoid arthritis
Environment- smoking, trauma, chronic vibration, chemical exposure
Endocrine- diabetes, hypothyroidism
Arterial- Buerger’s disease
Blood- lymphoma, polycythaemia
Drugs - B blockers, COC, cytotoxic agents
