Restriction of blood supply >> decreased oxygen and glucose. - perfusion fails to meet demands - leads to tissue death

Vascular Disease in the Lower Limb Flashcards by Eleanor Barnard

What is ischaemia?

Restriction of blood supply&raquo_space; decreased oxygen and glucose.

perfusion fails to meet demands
leads to tissue death

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What is the most common cause of lower limb disease?

Atherosclerotic plaque.

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What are other causes of lower leg ischaemia?

Emboli

- Trauma

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What are the main classifications of lower limb ischaemia? (2)

Acute

- Chronic

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What is acute ischaemia?

Sudden loss of perfusion.

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What normally cause acute ischaemia? (3)

Thrombus (atherosclerosis)
Embolus
2* to trauma

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What is chronic ischaemia?

Gradual loss of perfusion.

-caused by atherosclerosis

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What is the general process of atherosclerosis formation?

Endothelial damage&raquo_space; lipid plaques in artery walls.

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What do adhesion molecules released by endothelial damage attract?

Monocytes

- Platelets

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What happens to monocytes attracted to endothelial damage?

They infiltrate the endothelium and differentiated into macrophages.

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What happens to platelets attracted to endothelial damage?

They adhere to endothelium and release pro-inflammatory mediators.

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What happens to circulating LDL when endothelial damage occurs?

It is oxidised and scavenged by macrophages&raquo_space; foam cells.

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What happens to plaque if inflammation resolves?

It remains stable.

-may occlude artery lumen

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What happens to plaque if inflammation continues?

It becomes unstable.

-liable to rupture

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What happens when a plaque ruptures?

Platelet aggregation and coagulation cascade&raquo_space; thrombus.

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What are the main risk factors for atherosclerosis?

Smoking
Hypertension
Hyperlipidaemia
Diabetes
Genetics
Male

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What sort of arteries do atheromas tend to form in?

Medium-large conduit arteries, especially at birfurcations (turbulence).

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What are the main benefits of taking statins for atherosclerosis? (3)

Decreases lipids
Antiplatelet activity
Stabilises plaque

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Describe the general path of arteries in the leg.

Abdominal aorta&raquo_space; common iliac&raquo_space; internal and external iliacs.

External iliac&raquo_space; femoral artery.

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What is the Fontaine classfication?

Severity of peripheral vascular disease, based on symptoms.

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What are the stages of the Fontaine classification? (4)

1 - Asymptomatic
2 - Intermittent claudication
3 - Ischaemic rest pain
4 - Ulceration / gangrene (CRITICAL)

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Why is acute ischaemia a surgical emergency?

Must be re-vascularised within an hour to preserve limb.

-significant mortality

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What is the most common cause of acute ischaemia?

Atherosclerotic plaque rupture&raquo_space; thrombus/embolus causing complete occlusion.

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Why does acute ischaemia present so suddenly?

Perfusion suddenly decreases, and no time for collateral circulation to develop.
-unlike chronic ischaemia

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Is acute ischaemia painful?

Yes, can be very painful.

How are the signs/symptoms of acute ischaemia remembered?

6P's.

What are the 6 P's?

- Pain - Pulseless - Perishingly cold - Pallor - Paraesthesia - Paralysis

How does the leg normally appear in acute ischaemia?

Markedly abnormal looking and pale. | -NB may appear red if hanging down

When may the affected leg not look as abnormal in acute ischaemia?

If the patient already has vascular disease or chronic ischaemia. -collateral circulation

How is acute ischaemia treated?

- Urgent re-vascularisation | - Treat risk factors (e.g. diabetes)

What investigations are carried out in acute ischaemia?

Investigation of the cause. | -e.g. blood tests, ECG, echocardiogram

What is chronic ischaemia?

Gradual decreased perfusion, 2* to atherosclerotic disease. | -often bilateral

How does the limb remain perfused in chronic ischaemia?

Collateral circulation develops. | -limb poorly perfused

What happens to a chronic ischaemic limb eventually?

EITHER: - limb eventually becomes critically ischaemic - plaque suddenly ruptures >> ACUTE ON CHRONIC ischaemia

What is the general development of chronic ischaemia?

Atheroma plaque grows >> increased obstruction. - initially only painful when active (INTERMITTENT CLAUDICATION) - eventually painful at rest (CRITICAL ISCHAEMIA; ulceration and gangrene)

What is intermittent claudication?

Cramping pain in the leg induced by exercise. | -usually due to arterial occlusion

What is critical ischaemia?

Severe artery obstruction progresses >> pain, ulceration and gangrene.

When does chronic gangrene present?

EITHER: - at intermittent claudication (pain when walking) - at critical ischaemia (resting pain, ulceration, gangrene)

How is chronic ischaemia investigated?

- Blood tests - ECG - Vascular imaging - Ankle brachial pressure index

How is chronic ischaemia managed?

- Smoking cessation - Exercise - Antiplatelet drugs (e.g. aspirin)

What type of gangrene normally develops due to chronic ischaemia?

Dry gangrene. - tissue necrosis without infection - black, shrunken toes

Why does dry gangrene normally develop instead of wet gangrene?

Decreased blood supply >> decreased O2 and glucose to drive bacterial infection.

What is usually the 1st sign of decreased blood flow to the leg?

Claudication. | -then resting pain

What is a non-invasive procedure?

Doesn't require incision into the body / removal of tissue.

What are the main non-invasive techniques used to view lower limb vasculature? (3)

- Duplex scanning - MR angiography - CT angiography

What is the main invasive techniques used to view lower limb vasculature?

Catheter/contrast angiography.

What is duplex scanning?

Vasculature ultrasound. | -no ionising radiation

What effect is used in duplex scanning?

Doppler effect. | -change in wave frequency

What measurements can be obtained from duplex scanning? (2)

- Volume | - Velocity

What does 'operator dependent' mean in terms of duplex scanning?

Only person doing the scan can interpret the results.

What is CT angiography?

Combination of cross-sectional x-rays.

What is CT angiography useful to assess? (3)

- Aneurysms - Bleeding - Peripheral vessels

What is MR angiography (MRA)?

Magnetic resonance. | -no ionisation

When is MR angioplasty not suitable?

- Pacemaker - Prostheses - Claustrophobia

What effect does MR angiography have on stenosis?

Overestimates stenosis.

Which non-invasive techniques have no ionisation? (2)

- Duplex scanning | - MR angiography

Which non-invasive technique has ionisation?

CT angiography.

NB. what is angiography?

Imaging technique used to visualize the inside / lumen, of blood vessels and organs.

What is the main invasive techniques used to view lower limb vasculature?

Catheter/contrast angiography.

What type of procedure is catheter angiography; invasive or non-invasive?

Invasive. | -contrast is injected

What is the access point for catheter angiography in the leg?

Femoral artery over the femoral head. | -superficial and compressible

What is the access point for catheter angiography for the heart or kidneys?

Radial artery.

What are the 2 main types of contrast used?

- Iodine (iodinated) | - CO2

What is interventional radiology?

Use of imaging to affect treatment, rather than just diagnosis. -e.g. x-ray, CT, ultrasound

What are the main advantages of interventional radiology?

- Minimally invasive alternative to surgery (imaging guide treatment) - Allows novel treatment (thermal tumour ablation, chemoembolisation) - Can be live-saving

What is the 1st line procedure for haemoptysis (coughing up blood)?

Endoscopy (camera), then embolisation.

What are the main uses of non-haemorrhagic embolisation? (3)

- Chemo-embolisation (tumour) - Selective internal radiotherapy (SIRT) - Uterine artery embolisation (fibroids)

What is therapeutic embolisation?

Therapeutic introduction of a substance into a vessel. | -prevents haemorrhage / breaks down tumour / decreases blood flow

What are the main uses of interventional radiology? (2)

- Vascular radiology (close/open arteries) | - Oncology (chemoembolisation, thermal ablation)

What are the main vascular diseases in the legs? (2)

- Peripheral vascular disease (>> ischaemia) | - Aneurysmal disease

What are the main causes of ischaemia? (3)

- Thrombus - Embolus - Other (e.g. intrinsic clotting abnormality, surgery)

What are the main signs of acute ischaemia?

Initially pale leg >> mottled (patchy) leg; 6-12 hours >> irreversible (fixed blue) ischaemia

What are the main stages of ischaemia?

I - viable IIa - marginally threatened IIb - immediately threatened III - irreversible injury

If someone presents with suspected stage I-IIa ischaemia, how is it dealt with?

Imaging.

If someone presents with suspected stage IIb-III ischaemia, how is it dealt with?

Immediate treatment.

What is CT angiography good for?

Aneurysm and dissection. | -rapid scan times

What are the key treatment principles of ischaemia?

- Clear clot - Treat underlying lesions - Revascularise

What are the main endovascular treatment options? (3)

- Thombolysis - Aspiration - Stent

What are the main surgical treatment options? (2)

- Thrombectomy | - Bypass

What is thrombolysis?

Breakdown of blood clots by pharmacological means. | -infusion of tissue plasminogen activator (tPA) to activate plasminogen to plasmin

What is aneurysmal disease?

>50% expansion of an artery.

Who is screened for aneurysmal disease?

Males, >60 years.

What size aneurysm needs treatment?

>5.5 cm. - surgery/endovascular - emergency for rupture

Vascular Disease in the Lower Limb Flashcards

(83 cards)