Vascular Flashcards
What terminology is used to describe amputations?
Amputations can be classified based on location (upper limb, below above knee).
- Those above the ankle are termed major amputations, and those below the ankle “foot amputations”.
- A primary amputation refers to those without attempt at limb salvage (such as revascularisation, bony repair, soft tissue coverage), whereas those following a failed attempt at revascularisation are termed secondary.
What are the indications of amputations?
Peripheral artery disease, alone or in combination with diabetes mellitus, is responsible for more than 50% of all amputations.
Ischaemic (aka. Gangrene, tissue death due to ↓ blood supply to tissues):
- Peripheral artery disease (refers to atheroma outside of heart and brain). Strongest risk factors are smoking and diabetes (hyperglycaemia and dyslipidaemia lead to endothelial and smooth muscle cell dysfunction)
- Acute thrombosis/thromboembolism
- Frostbite gangrene
Infective: severe soft tissue infections or osteomyelitis can sometimes only be managed by removing the affected part.
Malignancy: some locally unresectable tumours of the musculoskeletal system may warrant amputation.
What are the complications of amputations?
Many patients that require amputation have pre-existing cardiovascular disease. Cardiopulmonary complications include:
- Myocardial infarction
- Arrhythmias
- Heart failure
- Atelectasis
- Pneumonia
Postoperative bleeding (often requiring reoperation for wound haematoma) can occur. These are more common in patients on DVT prophylaxis.
DVT occurs on up to 50% of patients without prophylaxis, so it is essential to provide prophylaxis.
Need for re-amputation is common - 25-50% of above-knee-amputations eventually undergo additional amputations.
Pain, including phantom limb pain, are a common complication of the procedure. Adequate control of intra- and post-operative pain appear to reduce incidence.
Overall mortality for major amputations are 3-18 % (30-days). 1-year survival is 50-80%, depending on level of amputation.
What is the definition and epidemiology of Peripheral Arterial Disease?
Peripheral vascular disease includes a range of arterial symptoms that are caused by atherosclerotic obstruction of the lower-extremity arteries. The prevalence of PVD increases with age and It is fairly common:
- 4-12% of 55-70 year olds are affected
- 15-20% of >70 year olds are affected
What are the stages of peripheral arterial disease?
And what is acute limb ischaemia?
There are four general stages of severity of PAD, based on severity of blood flow reduction:
- Asymptomatic PAD
- Intermittent Claudication - pain is only on movement and subsides at rest.
- Ischaemic Rest Pain (also called Critical Limb Ischaemia)
- Ulceration or Gangrene (also Critical Limb Ischaemia).
Acute‘limb-threatening’ischaemia is a vascular emergency in which the arterial blood supply to one or more extremities is critically reduced. Arterial thrombosis and cardiac emboli are responsible for the majority of cases.
What are the risk factors for peripheral arterial disease?
Risk factors are the same (mostly) as any atherosclerotic disease:
- Smoking (biggest risk factor)
- Diabetes
- Hyperlipidaemia
- Hypertention
- Hyperhomocysteinaemia
- Low levels of exercise
- History of coronary artery disease or cerebrovascular disease
- Age >40
Why are most patients with peripheral arterial disease asymptomatic?
Most patients are asymptomatic (2/3) and diagnosis is prompted on risk factors. Symptoms usually only occur when >70% of the lumen is occluded.
What are the symptoms of Intermittent Limb Claudication?
What is Leriche Syndrome?
-
Lower aorta and Iliac artery disease causes symptoms in the hips and buttocks. This can also produce aortoiliac occlusive disease (a.k.a Leriche Syndrome) which is characterised by:
- Buttock pain
- Erectile dysfunction
- Absent/diminished femoral pulses
- Atrophy of the musculature of the legs
What are the examination features of peripheral arterial disease?
- Diminished pulse or even absent pulse in lower extremity
- Pallor when elevated, and following rubor when gravity pulls down blood. Doing this is called Buerger’s test.
- Signs of limb ischemia include: pale extremity, loss of hair on legs, thickened toenails, shiny/scaly skin, and nerve loss.
- Ulcers at sites of pressure and distal extremities.
What are the clinical features of Critical Limb Ischaemia?
- The defining feature here is pain at rest for more than 2 weeks
- This is typically worse at night (as gravity doesn’t help when lying down), and improves when the person hangs their leg/feet over the edge of the bed.
- Patient may also complain of paraesthesia
- Non-healing wound/ulceration and gangrene are late stages of Critical Limb Ischaemia, and are uncommon.
What are the clinical features of Acute Limb Ischaemia?
6 P’s of Critical Limb Ischaemia:
- Pain
- Pallor
- Paraesthesia
- Poikilothermia
- Paralysis
- Pulseless
This usually happens when there is thrombosis (e.g. plaque rupture - this is usually acute-on-chronic) or an embolism (this is usually acute).
The clinical significance between these two aetiologies is that in acute-on-chronic there are likely collaterals that have developed, whilst in acute there are no collaterals, making the situation even more dangerous.
What are the investigations for Peripheral Arterial Disease?
Bedside: ankle-brachial pressure index (ABPI). This is when an ultrasound Doppler determines the ratio between the systolic blood pressure of the ankle and the brachial artery. A ratio of <0.9 is suggestive of PVD. The lower the value, the greater the extent of atherosclerosis and thus disease.
- >1.2 = medial sclerosis, i.e. the vascular walls are incompressible (calcified). This is commonly due to diabetes mellitus.
- 1.0-1.2 = normal value
- < 0.9 = likely PAD
- < 0.5 = severe PVD - should be referred immediately
Compression bandaging is not considered acceptable if the ABPI < 0.8.
Bloods*:***
- FBC - anaemia will worsen ischaemia
- U&Es to assess renal function
- Lipids, glucose to look at presence of cardiovascular risk factors.
A duplex ultrasound is the first-line investigation to confirm diagnosis, and assess the extent degree of stenosis.
- Triphasic: normal
- Biphasic: Mild stenosis
- Monphasic: Severe stenosis
CT or MR angiography can also be used to assess extent and location of stenoses.
How can you intepret the ankle-brachial pressure index (ABPI)
- >1.2 = medial sclerosis, i.e. the vascular walls are incompressible (calcified). This is commonly due to diabetes mellitus.
- 1.0-1.2 = normal value
- < 0.9 = likely PAD
- < 0.5 = severe PVD - should be referred immediately
- < 0.4 usually indicates critical limb Ischaemia
Describe the management of Acute Limb Ischaemia
If acute limb ischaemia is suspected, start appropriate analgesia (paracetamol +/- opioid) and give LMWH to prevent extension. Refer urgently to vascular surgeons who can perform:
-
Endovascular therapies, for example:
- Percutaneous catheter-directed thrombolytic therapy.
- Percutaneous mechanical thrombus extraction.
-
Surgical interventions, for example:
- Surgical thromboembolectomy.
- Endarterectomy.
- Bypass surgery.
- Amputation if the limb is unsalvageable.
Surgical intervention aimed before 4-6 hours - if not re-perfused within 6 hours, limb is usually lost.
Beware of post-operative reperfusion injury and subsequent compartment syndrome.
What are the clinical features of venous ulcers?
- They happen between the mid-calf and the medial malleolus.
- There is often peripheral oedema.
- They tend to have irregular shapes and sloping edges.
- They are larger but shallower than other ulcers.
- They can ooze venous blood when handled.
- They are painful unlike arterial ulcers.
What are the signs of chronic venous insufficiency?
There may be signs of chronic venous insufficiency:
- There may be varicose veins and varicose eczema.
- Hyperpigmentation is due to heamosiderin deposition in the skin.
- There may also be atrophie blanche (smooth, ivory-white plaques surrounded by hyperpigmentation).
- Lipodermatosclerosis
