Peripheral Arterial Disease

Overview

Definitions

Lower limb peripheral arterial disease (PAD) may present symptomatically either with pain on exercise (intermittent claudication) or with signs/symptoms at rest (previously “critical limb ischaemia” – this term has now been replaced by “chronic limb threatening ischaemia” (CLTI)).

Patients with CLTI typically have pain in the most distal part of the limb (toes) that is worse when the leg is elevated (e.g. at night), then relieved by hanging the leg down/sleep in a chair and/or a wound or lesion (tissue loss), usually below the ankle, that is painful or non-healing.

Patients with tissue loss who have diabetes and reduced perfusion often present without pain.

The pathway for people with diabetes and a new active foot problem is on REMEDY:
Diabetes Foot Care (Remedy BNSSG ICB)  

Intermittent Claudication

This is the most common way in which people present with symptomatic PAD. Pain is felt in the large muscle groups when demand for oxygen increases during exertion and the delivery of oxygen (due to PAD) cannot keep up (anaerobic metabolism and lactic acid build up). Pain in the calf, thigh or buttock will occur usually after a predictable distance, be worse on hills and will disappear after a reproducible period of rest.

Cramping in these muscle groups at night is common and is not a sign of CLTI.

Intermittent claudication has a benign prognosis relating to the limb.

• 50% of patients will improve with lifestyle changes and exercise;
• 30% will stay around the same;
• Only 20% will have progressive symptoms.

Very few go on to develop CLTI and less than 1/100 patients who present initially with claudication will progress to major lower limb amputation.

However, a diagnosis of symptomatic peripheral arterial disease is associated with a higher risk of heart attack or stroke (2-6x fold increase) and cardiovascular death. The management of the patient’s cardiovascular risk is the priority.

Assessment

History and Examination

Assessment of the patient presenting with leg pain on exertion should include direct questioning and examination for potential red flag symptoms/signs that may warrant urgent referral to secondary care (see below).

The presence or absence of a peripheral pulses is not objective and does not rule out PAD.

Investigations

Ankle brachial pressure index (ABPI) measurements at rest can be useful. The normal range for ABPI is 0.9-1.3.

An ABPI < 0.9 confirms the diagnosis PAD. However, a normal ABPI does not fully exclude the diagnosis.

An ABPI of >1.3 may be due to arterial calcification (PAD) but is most commonly simply due to swelling in the limb falsely elevating the pressure needed to compress the artery. Patients who have ABPI >1.3 can have toe pressure assessment by Vascular Studies as this is less likely to be affected by swelling or calcification.

Toe pressure brachial index (TBPI) of >0.7 usually excludes PAD, whilst a TBPI <0.7 is suggestive of PAD. This test can be performed by community teams or Vascular studies at BRI, Weston or NBT by ICE request directly from primary care (see below)

Asymptomatic patients with low or high/incompressible ABPI do not need referral to a specialist.

The most accurate way of making the diagnosis of intermittent claudication is an exercise ABPI conducted by Vascular Studies. This can be requested directly from primary care (via ICE – see referral section below). This involves measuring the ABPI at rest then performing a standardised treadmill test or tip toe exercise then reassessing the ABPI. If the ABPI drops by more than 20% after exercise the test confirms the diagnosis of symptomatic PAD.

Who to Refer

Most patients with intermittent claudication can be managed in primary care (see management section below)

Referral of patients with intermittent claudication should be considered when:

1. The diagnosis is unclear (for example patient with multiple pathologies (e.g. spinal stenosis or diabetes) and abnormal or normal ABPI or equivocal exercise test)
2. There is any history of previous peripheral vascular intervention (angioplasty/stent/bypass/aneurysm repair)
3. Patients with very short distance claudication who struggle to work or carry out activities of daily living
4. Patients who you feel would benefit from the reassurance of specialist assessment (that exercise is the safest and most durable treatment)
5. There has been no improvement with exercise
6. There has been a stepwise or sudden deterioration in previously stable symptoms (but without signs of acute limb ischaemia).

Patients referred without red flag symptoms who do not already have a confirmed diagnosis of symptomatic arterial disease will be triaged “straight to test” (exercise ABPI).

Secondary Care Management - what to expect

The majority of patients who have a positive exercise test or with previously proven symptomatic/treated PAD will see a member of the specialist vascular nursing team. We will

1. Confirm of the diagnosis
2. Provide structured exercise advice
3. Review medication (although we will mainly re-direct to https://remedy.bnssg.icb.nhs.uk/formulary-adult/local-guidelines/2-cardiovascular-system-guidelines/)
4. Consider referral to supervised exercise class

Most patients will be discharged back to primary care after review. A small proportion of patients with severely lifestyle limiting claudication will go on to have arterial imaging (duplex ultrasound) and follow-up. Intervention is unusual.

Vasodilator therapy

Naftidrofuryl Oxalate can be used in patients who do not improve with exercise (Naftidrofuryl oxalate | Prescribing information | Peripheral arterial disease | CKS | NICE) however it is not widely used in current vascular practice.

Management in Primary Care

If referral is not indicated then the management of the patient with intermittent claudication is usually safely done in primary care. The key aspects of management are:

Establish the diagnosis

Perform ABPI in the practice or referral to Vascular Studies for gold standard test– see referral section below.

Modify cardiovascular risk

1. Smoking Cessation
2. Antiplatelet drugs -clopidogrel is advised first line by NICE or aspirin as an alternative. See Antiplatelets for the prevention of CVD | CKS
3. Aggressive Lipid management (secondary prevention)- see Hyperlipidaemia page.
4. Hypertension screening/control - see Hypertension page. Target BP <130/80.

See also the BNSSG Formulary Cardiovascular System Guidelines

Exercise

There is no standardised agreed exercise programme for patients with intermittent claudication. However, a patient information leaflet in available from the NHS on lifestyle changes including exercise:

• Peripheral arterial disease (PAD) - Treatment - NHS

Most studies have demonstrated that supervised exercise classes achieve better results than unsupervised exercise, and that 30 minutes, at least 3 times per week is optimal. Furthermore, patients need to exercise up to the point of discomfort to gain benefit; however, it is usually unhelpful to suggest that patients should “walk through the pain”.

The vascular team recommend that patients are encouraged to exercise for half an hour, three times a week in the form of a “training programme” (going for a walk with the purpose of trying to improve walking, rather than simply walking to the shops etc). They should exercise up to the point of discomfort, then rest until the pain subsides, then exercise again, repeating for the half an hour period.

Most initial benefit from exercise is derived from adaptation in the muscle (training effect – more efficient muscle able to do more with less oxygen need) rather than development of “new blood vessels”.

The availability/capacity of supervised exercise classes in BNSSG is limited. A programme is run through Physiotherapy at Bristol Royal Infirmary with exercise class once per week for 12 weeks. This is not available directly from a GP referral and access to this service remains via referral from vascular surgery.

Vascular Intervention

Modern vascular practice has moved away from invasive treatment for claudication (e.g. angioplasty/stenting or surgery) as this is associated with worse long-term outcomes, with high rates of re-intervention and higher rate of major amputation than exercise. Patients referred to vascular surgery for assessment and management advice should not be given the expectation that intervention will follow.

Chronic Limb Threatening Ischaemia (CLTI)

Patients who present with the following symptoms should be referred urgently to the vascular surgery triage service via eRS.

Symptoms suggestive of CLTI

1. Pain at night in the foot

The pain is usually felt in the toes (further distance from the heart) and is made better by dangling the limb out of bed, or most commonly sleeping in the chair. The pain is often described as relentless, unbearable or burning. Feeling of numbness (in non-diabetic patients) at night may precede ischaemic rest pain but it is not a reliable indicator of reduced perfusion.

Signs suggestive of CLTI

1. Tissue loss in the foot (usually associated with the pain) that is non-healing or progressive. This is often on the end of a digit, on the heel or on another area of pressure.
2. Redness in the foot that disappears when the foot is elevated – this “sunset appearance” is typical of CLTI

The presence or absence of a foot pulse is not necessarily relevant. We would expect a present with CLTI to have an ABI<0.4 or absolute pressure at the ankle of <50mmHg. A patient with low ABI/toe pressure with no symptoms/signs does not have CLTI.

People with tissue loss in the foot who have associated signs or systemic symptoms of infection should be referred as as an emergency (see below).

Acute Limb Ischaemia

If Acute Limb Ischaemia is suspected then arrange emergency admission (see below). Features include:

• Pain — constantly present and persistent.
• Pulseless — ankle pulses are always absent.
• Pallor (or cyanosis or mottling).
• Power loss or paralysis.
• Paraesthesia or reduced sensation or numbness.
• Perishing with cold.

Emergency Admission

Emergency referrals can be made to the vascular network in 2 ways

1. Contact the vascular registrar on call via NBT Switchboard (0117 9505050)
2. Electronic referral via referapatient.org

Referral

Vascular Studies

Vascular studies can be requested directly in the following ways:

• NBT ICE - search for ABPI and tick the US ABPI box (also listed under the Vascular tab). In the clinical request free text simply state the clinical issue and whether you want the patient to have toe pressures or exercise ABPI.
• UHBW ICE - search for ABPI and tick the APBI +- exercise testing box.

Vascular Outpatient Referral (including urgent referrals)

All vascular referrals should be sent via eRS to the Vascular Surgery Triage Service (RAS). Referrals will be triaged on a daily basis by the vascular team and booked into appropriate clinics. Please include all relevant clinical and contact details in referrals to help facilitate the triage process.

This is also the way to access the Vascular Hot Clinic at Southmead Hospital for patients requiring urgent review but not necessarily admission.

Resources

NICE CKS - Diagnosis of Peripheral Arterial Disease on management of PAD 

Patient information: Lifestyle and Medical Management of PAD - Circulation Foundation

Patient information: Exercise for Intermittent Claudication - Circulation Foundation

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