Cardiology: Peripheral Vascular Disease (PVD)
Peripheral vascular disease (PVD) is due to atherosclerosis of arteries in the limbs. The level of arterial occlusion present is proportional to the symptoms. The pathogenesis and risk factors are the same as for coronary artery disease (CAD), and include:
- Hypertension
- Dyslipidaemia
- High LDL and low LDL levels
- Diabetes
- Obesity
- FH of arterial disease
- Smoking
- Age
- Male gender
Epidemiology
- Affects about 10% of the population
- Usually CAD (coronary artery disease) is also present. About 75% of patients will have symptomatic CAD. In the other group of patients it is believed the CAD is masked by PVD, as the PVD prevents patients from exerting themselves to a degree which would initiate symptoms of CAD.
Classification
Mild PVD
- Claudication – this is limb pain (inc aching, cramping and tired feeling of the legs) upon exertion. It most commonly occurs in the calves, but may also be present in the thighs, buttocks and even arms. The distance a patient can walk before they experience symptoms is known as the claudication distance.
o Claudication could be thought of ‘angina’ of the limbs
o Pain is usually relieved by rest
o As claudication progresses, the distance that a patient can walk reduces.
Severe PVD
- Can cause claudication / buttock pain at rest
- Burning pain at night, due to elevation (which reduces limb perfusion), and is relieved by hanging the legs over the side of the bed (very bad sign!)
- Patients may have:
o ‘Punched out’ ischaemic ulcers – usually on the toes and heels, rarely higher up the limb. These tend to occur after a localised traumatic event. They are often painful, but diabetic and alcoholic patients may not notice.
o Gangrene – often black necrotic gangrenous tissue surrounds the punched out ulcer lesions. Infection of this areas can occur (wet gangrene).
o Reduced / absent peripheral pulses – start distally, and work your way up until you find the pulse
o Skin atrophy – in chronic disease
o Hair loss - in chronic disease
o Cyanosis
o Excessive sweating – due to overactivity of the sympathetic nerves
o Erectile Dysfunction – Leriche syndrome – the result of distal aortic disease. Other features of the syndrome are buttock pain, and pale, cold legs. Surgery may be useful to reduce symptoms in these patients
o Amputation –may be necessary in patients with very severe disease. Usually only performed in patients with severe unremitting leg pain + gangrene, to prevent sepsis. Amputation should be performed as distally as possible, hopefully below the knee, as this provides the greatest flexibility with prosthetic replacement limbs, but must be high enough to provide sufficient perfusion to allow healing of the stump. Thus above the knee amputation is likely to heal better.
§ Phantom limb pain is common, and usually treated with gabapentin. This is often used prophylactically, as this improves efficacy.
Investigations
- Examination
o Elevating the leg may cause it to go pale and cold, as well as causing pain.
o Increased vascular filling time - Upon lowering, the leg may become hot and red as reperfusion occurs. Perfusion time tends to be reduced (>15s)
o Beuger’s angle <20’ – the leg will go pale and cold upon raising it 20’ off the couch.
o Oedema is not usually present
- ABPI – Ankle-Brachial pressure index
o This is usually diagnostic
§ Measure the blood pressure in both arms and take the highest value
§ Measure the blood pressure in both ankles and take the highest value
· Instead of the stethoscope, use a Doppler ultrasound probe to measure the pressure over the posterior tibial artery – record the pressure when your hear the first ‘whoosh’
§ Using only systolic values, divide the ankle pressure by the brachial pressure
§ A normal value is >1
§ A value of <0.9 is pathological for limb ischaemia (PVD). The lower the number, the greater the degree of PVD
§ Pain at rest – ABPI = <0.6
§ High Risk of gangrene – ABPI - <0.3, or ankle systolic pressure <55mmHg
§ CAUTION – in very severe arteriosclerosis the vessels are incompressible, and thus falsely high readings may be obtained (e.g. an ABPI >1.3)
- Investigate for Diabetes
- Bloods
o Lipids
o U+E’s
o ESR/CRP – to exclude arteritis
o ECG – to check for cardiac involvement
o Platelets and clotting
- Arterial imaging
o Should be performed to assess the extent of the disease
o E.g. contrast arteriography, DSA (digital subtraction arteriography), colour duplex imaging
o Stop METFORMIN before arterial imaging – as it increases the risk of metabolic acidosis
Management
- Conservative
o Stop smoking
o Lose weight
o Increase exercise – e.g. 30-60 mins, 4x week – often undervalued as a treatment. May increase the claudication distance, and improve QoL. Thought to be beneficial by increasing collateral circulation, improved endothelial compliance (eg. Better vasodilation), decreased blood viscosity.
§ 1/3 of patients will improve
§ 1/3/ will stay the same
§ 1/3/ will get worse
o Symptom management
§ Raising the pillow 4-6 inches can help keep the legs below heart level and reduce leg pain at night
§ Avoid cold weather if possible
§ Foot care – inspection every day for lesions, with prompt treatment. Careful washing of the feet everyday with thorough drying
- Control of risk factors
o Diabetes
o Dyslpidaemia
o Hypertension – β-blockers are often advised to be avoided, but are safe unless PAD is very severe
o Antiplatelet agent – usually aspirin – can improve claudication distance and reduce other symptoms.
- Other Interventions
o Percutaneous Transluminal angioplasty - PTA – is useful for short lesions (usually <5cm) in big arteries. A balloon is used to widen the artery, which in some cases, may be enough on its own. In many cases, a stet is also placed. Particularly useful in iliac artery disease (successful in 75-90% of patients), and also successful in 50-70% of thigh and calf disease patients.
§ PTA is not good for long lesions. These are more likely to occur in diabetic patients. Selection of patients is usually based on arterial imaging.
§ PTA can result in thrombus formation and subsequent embolisation
§ Reccurrence is about 30% at 3 years
o Surgery - thromboendarterectomy
§ is suitable for some patients. These are usually those with an obvious blockage, where the distal vessel is filled well by collateral vessels (indicating that the distal vessel is still in good shape) – similar to the indications for PTA – however patients must be able to tolerate surgery. May be used in those in whom PTA was not successful.
§ These patients may receive a bypass graft. These are usually made from venous tissue, but prosthetic structures are also used.
· Aspirin improves the longeveitiy / patency of prosthetic grafts
· Warfarin may be required after graft surgery in venous grafts
§ Sympathectomy may be used to relieve pain. This can be chemical or surgical, but as they are equally effective, and generally used in those who can’t tolerate other surgery, chemical sympathectomy is much more widely performed. Particularly useful in diabetic patients.
o Limb Compression
§ May help those with severe disease who are not candidates for surgery.
§ Inflatable cuffs are placed over the limb and inflated rhythmically for a period of 1-2 hours, several days per week
§ This is thought to improve both venous and arterial flow, thus reducing symptoms, but evidence is poor
Notes by Tom Leach
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