Vascular Flashcards
Peripheral arterial disease
Peripheral arterial disease (PAD) refers to the narrowing of the arteries supplying the limbs and periphery, reducing the blood supply to these areas. It usually refers to the lower limbs, resulting in symptoms of claudication.
What are the stages of peripheral vascular disease?
Intermittent claudication
Acute limb ischaemia
Critical limb ischaemia
Necrosis and gangrene
Intermittent claudication
Intermittent claudication is a symptom of ischaemia in a limb, occurring during exertion and relieved by rest. It is typically a crampy, achy pain in the calf, thigh or buttock muscles associated with muscle fatigue when walking beyond a certain intensity.
Critical limb ischaemia
Critical limb ischaemia is the end-stage of peripheral arterial disease, where there is an inadequate supply of blood to a limb to allow it to function normally at rest. The features are pain at rest, non-healing ulcers and gangrene. There is a significant risk of losing the limb.
Acute limb ischaemia
Acute limb ischaemia refers to a rapid onset of ischaemia in a limb. Typically, this is due to a thrombus (clot) blocking the arterial supply of a distal limb, similar to a thrombus blocking a coronary artery in myocardial infarction.
What is meant by gangrene compared to necrosis?
Necrosis refers to the death of tissue.
Gangrene refers to the death of the tissue, specifically due to an inadequate blood supply.
What are the features of critical limb ischemia?
The 6 P’s
- Pain
- Pallor
- Pulseless
- Paralysis
- Paraesthesia (abnormal sensation or “pins and needles”)
- Perishing cold
Signs on examination of PAD:
Signs of arterial disease on inspection are:
- Skin pallor
- Cyanosis
- Dependent rubor (a deep red colour when the limb is lower than the rest of the body)
- Muscle wasting
- Hair loss
- Ulcers
- Poor wound healing
- Gangrene (breakdown of skin and a dark red/black change in colouration).
On examination, there may be:
- Reduced skin temperature
- Reduce sensation
- Prolonged capillary refill time (more than 2 seconds)
- Changes during Buerger’s test
Description of arterial ulcers
Arterial ulcers are caused by ischaemia secondary to an inadequate blood supply. Typically, arterial ulcers:
Are smaller than venous ulcers
Are deeper than venous ulcers
Have well defined borders
Have a “punched-out” appearance
Occur peripherally (e.g., on the toes)
Have reduced bleeding
Are painful
Venous ulcers
Venous ulcers are caused by impaired drainage and pooling of blood in the legs. Typically, venous ulcers:
Occur after a minor injury to the leg
Are larger than arterial ulcers
Are more superficial than arterial ulcers
Have irregular, gently sloping borders
Affect the gaiter area of the leg (from the mid-calf down to the ankle)
Are less painful than arterial ulcers
Occur with other signs of chronic venous insufficiency (e.g., haemosiderin staining and venous eczema)
Investigations of PAD
Ankle-brachial pressure index (ABPI)
Duplex ultrasound – ultrasound that shows the speed and volume of blood flow
Angiography (CT or MRI) – using contrast to highlight the arterial circulation
Management of PAD:
Lifestyle and exercise training to push through claudication.
Medication: Atorvastatin, clopidogrel
Surgery:
- Endovascular angioplasty and stenting
- Endarterectomy – cutting the vessel open and removing the atheromatous plaque
- Bypass surgery – using a graft to bypass the blockage
Management of critical limb ischemia
Patients with critical limb ischaemia require urgent referral to the vascular team. They require analgesia to manage the pain.
Urgent revascularisation can be achieved by:
Endovascular angioplasty and stenting
Endarterectomy
Bypass surgery
Amputation of the limb if it is not possible to restore the blood supply
Management options for acute limb ischemia:
- Endovascular thrombolysis – inserting a catheter through the arterial system to apply thrombolysis directly into the clot
- Endovascular thrombectomy – inserting a catheter through the arterial system and removing the thrombus by aspiration or mechanical devices
- Surgical thrombectomy – cutting open the vessel and removing the thrombus
- Endarterectomy
- Bypass surgery
- Amputation of the limb if it is not possible to restore the blood supply
Common DVT risk factors:
- Immobility
- Recent surgery
- Long haul travel
- Pregnancy
- Hormone therapy with oestrogen (combined oral contraceptive pill and hormone replacement therapy)
- Malignancy
- Polycythaemia
- Systemic lupus erythematosus
- Thrombophilia
Top tip:
In your exams, when a patient presents with possible features of a DVT or PE, ask about risk factors such as periods of immobility, surgery and long haul flights to score extra points.
Thrombophilias are what?
- examples of thrombophilias
Thrombophilias are conditions that predispose patients to develop blood clots. There are a large number of these:
- Antiphospholipid syndrome
- Factor V Leiden
- Antithrombin deficiency
- Protein C or S deficiency
- Hyperhomocysteinaemia
- Prothombin gene variant
- Activated protein C resistance
TOP TIP:
What condition can cause recurrent thromboembolism and lead to recurrent miscarriage?
- How do you test to this condition?
If you remember one cause of recurrent venous thromboembolism, remember antiphospholipid syndrome. The common association you may come across in exams is recurrent miscarriage. The diagnosis can be made with a blood test for antiphospholipid antibodies.
VTE prophylaxis - read summary
Every patient admitted to hospital should be assessed for their risk of venous thromboembolism (VTE). If they are at increased risk of VTE, they should receive prophylaxis unless contraindicated. Prophylaxis is usually with low molecular weight heparin, such as enoxaparin. Contraindications include active bleeding or existing anticoagulation with warfarin or a DOAC.
Anti-embolic compression stockings are also used, unless contraindicated. The main contraindication for compression stockings is significant peripheral arterial disease.
How do you examine for calf swelling?
To examine for leg swelling, measure the circumference of the calf 10cm below the tibial tuberosity. More than 3cm difference between calves is significant.
What is Wells score?
The Wells score predicts the risk of a patient presenting with symptoms having a DVT or PE. It includes risk factors such as recent surgery and clinical findings such as unilateral calf swelling 3cm greater than the other leg.
How is DVT diagnosed and what other investigations should be done?
Doppler ultrasound of the leg is required to diagnose deep vein thrombosis. NICE recommends repeating negative ultrasound scans after 6-8 days if a positive D-dimer and the Wells score suggest a DVT is likely.
Pulmonary embolism can be diagnosed with a CT pulmonary angiogram (CTPA) or ventilation-perfusion (VQ) scan. CTPA is usually preferred, unless the patient has significant kidney impairment or a contrast allergy.
Management of DVT/PE
The initial management for a suspected or confirmed DVT or PE is with anticoagulation. In most patients, NICE (2020) recommend treatment dose apixaban or rivaroxaban. It should be started immediately in patients where DVT or PE is suspected, and there is a delay in getting the scan.
The NICE guidelines (2020) recommend considering catheter-directed thrombolysis in patients with a symptomatic iliofemoral DVT and symptoms lasting less than 14 days. This involves inserting a catheter under x-ray guidance through the venous system to apply thrombolysis directly into the clot.
Long term anticoagulation for VTE:
The options for long term anticoagulation in VTE are a DOAC, warfarin, or LMWH.
DOACs are oral anticoagulants that do not require monitoring. They were called “novel oral anticoagulants” (NOACs), but this has been changed to “direct-acting oral anticoagulants” (DOACs). Options are apixaban, rivaroxaban, edoxaban and dabigatran. They are suitable for most patients, including patients with cancer.
Warfarin is a vitamin K antagonist. The target INR for warfarin is between 2 and 3 when treating DVTs and PEs. It is the first-line in patients with antiphospholipid syndrome (who also require initial concurrent treatment with LMWH).
Low molecular weight heparin (LMWH) is the first-line anticoagulant in pregnancy.
How long should a patient stay on anti-coagulation for following VTE?
- 3 months if there is a reversible cause (then review)
- Beyond 3 months if the cause is unclear, there is recurrent VTE, or there is an irreversible underlying cause such as thrombophilia (often 6 months in practice)
- 3-6 months in active cancer (then review)
When are Inferior vena cava filters indicated?
Inferior vena cava filters are devices inserted into the inferior vena cava, designed to filter the blood and catch any blood clots travelling from the venous system, towards the heart and lungs. They act as a sieve, allowing blood to flow through whilst stopping larger blood clots. They are used in unusual cases of patients with recurrent PEs or those that are unsuitable for anticoagulation.
