Peripheral Vascular Disease

What is peripheral vascular disease? What is a vascular ulcer and how do you treat it ?

What is peripheral vascular disease ?

Peripheral vascular disease means narrowing of the lumen of arteries in the legs, causing a reduction in circulation. It can occur in individuals without diabetes but is more common and more severe in people with diabetes. Why this is the case is not clear, but it is well established that smoking makes peripheral vascular disease much worse.

Although both big and small blood vessels can be affected by diabetes (known as macrovascular and microvascular disease respectively), in diabetic peripheral vascular disease it is blockage of the larger arteries in the thigh and leg which causes most of the clinical problems. Peripheral vascular disease can affect both legs but is often more severe on one side (contrast with peripheral neuropathy which affects both feet symmetrically).

The large arteries are blocked, causing problems. Here are the typical sites of blockages of the arteries (shown in green)

What problems can be caused by peripheral vascular disease?

If it is mild, peripheral vascular disease can be completely without symptoms. However, as blood supply becomes progressively inadequate, it can cause claudication, rest pain or vascular ulceration:

Claudication is development of pain in the calf after walking for a distance or up an incline or stairs. The distance a person can walk before such pain occurs is referred to as claudication distance. The leg and foot look and feel normal as long as the person is resting. As claudication distance becomes shorter and shorter, physical activities become more and more restricted. Cessation of smoking is most important before one gets to this stage. Regular exercise by walking through the pain threshold can sometimes increase the claudication distance. In many cases to relieve the symptom it is necessary to have either an angioplasty (an instrument is threaded down the artery to widen the blocked area) or by-pass surgery (a vein from other part of the body or an artificial tubing is used to by pass the blockage, allowing blood to flow through).

Three examples of typical bypass surgey.

The blockages are shown in green and the bypasses are shown in red.

  Rest pain is pain in the foot even when not walking. This is distressing and difficult to obtain respite. It is therefore important not to get to this stage by refraining from smoking. It is a more severe stage of peripheral vascular disease than claudication. The affected foot looks purplish in colour and feels cold to touch. The foot pulses are not palpable. Angioplasty and by-pass surgery are the only available treatment. Sometimes, amputation is required as the last resort to relieve pain.

An ischaemic foot which is purplish, cold and painful

The wounds of patients with severe vascular disease heal poorly because of inadequate blood supply. Therefore minor trauma or pressure often leads to ulceration. This is called a vascular ulcer (sometimes also known as arterial ulcer or ischaemic ulcer). It tends to be situated on the edge of the foot or toes because blood supply is the poorest at these sites. A typical vascular ulcer is shown below. In a purely vascular ulcer, nerve function is normal and sensation is intact, hence vascular ulcers are usually painful.

A typical vascular ulcer

Therefore, a typical vascular ulcer is :

  • painful
  • not surrounded by callus
  • associated with absent or poor foot pulses
  • associated with a foot that is cold to touch
  • at the edge of the foot or toes

A vascular ulcer should not be confused with a venous ulcer which is due to varicose veins. Varicose ulcers are situated on the leg (rather than in the foot), associated with varicose veins and often accompanied by swelling and a brownish discoloration of the leg. A typical varicose ulcer is shown bellow.

A typical varicose ulcer

Are you are at high risk of developing a vascular ulcer ?

This is dealt with more thoroughly in the section on Foot Examination.

Briefly, you are at risk if :

  • you have had a foot ulcer before
  • you have poor circulation in the feet when you doctor tested it
  • you have mishaped feet eg:clawed toes or bunions
  • you have claudication or rest pain
  • you do not follow advice to protect your feet with good footwear and hygiene

What sort of treatment is required for a vascular ulcer ?

Greater detail regarding these ulcers is found at Peripheral Vascular Disease Appendix. In principle, these are the important measures :

  • Remove the precipitating cause eg. get rid of the shoes that are too tight
  • Clean and dress the wound with non-caustic materials. In contrast to the treatment of neuropathic ulcers, do not debride aggressively. In the presence of vascular disease debridement could make the ulcer worse.
  • Taking antibiotics if the ulcer is infected. Remember that signs of infection such as local redness, heat and swelling are often masked by vascular disease.
  • Rest the feet as much as possible because this helps to minimize trauma to the ulcer. Walking is not a good exercise for someone who has a vascular ulcer (or someone at great risk of developing one).

If you suspect an ulcer is vascular it is necessary to assess the severity of vascular blockage to see if it can be treated by angioplasty or by-pass surgery. Briefly, the steps to be taken are:

Measure the blood pressure at the ankle and compare it with the pressure in the arm to determine if there is enough blood supply to the foot. This measurement is called the Ankle-Brachial Index and is done with a Doppler machine.

Because the arteries in the ankle may be calcified in diabetes, blood pressure readings at this site is often unreliable. In this situation it is more accurate to measure pressure at the toe.

Once a Doppler test has established that circulation is poor in the leg, further tests such as a Duplex scan or angiogram can be done to evaluate the obstruction of arteries more accurately to determine if surgery is needed to help the vascular ulcer to heal.

Page revised on 16th May 2007