Chelation therapy was first developed in the US in the early 1950s. It has been approved by the US Food and Drug Administration as a way of removing toxic metals (such as lead and mercury) from the bloodstream but no such approval has yet been granted for its use in unclogging the arteries of heart patients. Its use in this area remains controversial.

Chelation involves up to 30 intravenous infusions of an amino acid, EDTA (ethylene diamine tetra acetic acid), usually given twice a week. As EDTA travels through the patient's blood system, it binds with artery clogging calcium deposits, and as the acid passes out of the body, so the deposits are excreted. The treatment should be accompanied by an extensive change of lifestyle, including optimum diet, exercise and stress reducing techniques."Chelation is only part of the answer," says Richard Brown, head of the Arterial Disease Clinic in Lancashire.

In the UK, chelation is theoretically available on the National Health Service we are aware of two cases at the moment but health minister Virginia Bottomley says it is not an accepted procedure as it has never gone through a double blind study.

However, several small scale studies have been carried out. In an unpublished review of more than 40 published reports into chelation therapy, Dr Terry Chappell, assistant professor of family practice at Wright State School in the US, concludes that 87 per cent of the 22,502 patients covered had favourable outcomes.

Chelation therapy has been available in the UK for nine years, including five at the Arterial Disease Clinic. In that time, the clinic has treated around 5,000 patients, and claims about an 85 per cent success rate. It will accept all victims, in any condition, be they gangrene sufferers, stroke victims or bypass and angioplasty failures. While it does carry out a before and after study of the patient, including magnesium tests, the clinic has failed to conduct a long term follow up study.

There are, however, serious concerns about the safety of chelation. In high doses, EDTA can cause renal failure. During the mid 1970s, the deaths of 13 heart patients at a US hospital were linked with this therapy. Defenders of chelation point out that some of these were already terribly ill (and had been sent home to die by their conventional doctors) and claim that the hospital failed to follow the protocol developed by the American College of Advancement in Medicine which, it claims, makes the technique safe and effective.

Another worrying aspect of chelation is the tendency to promote it almost as a "feel good" treatment: the Arterial Disease Clinic's promotional literature cites one case study that gives the impression that a young man had chelation therapy simply to allow him to run faster. Other doctors are beginning to talk about chelation as a just in case treatment for those with a family history of heart disease.

Chelation therapy is also very expensive. A 30 infusion treatment will cost around £3,000.

If you are considering chelation therapy, Dr Wayne Perry of London's Wimpole Street, advises:

Check that the doctor is experienced in the practice and will be following the ACAM protocol. (The drugs used in chelation therapy are widely available, and there is nothing to stop any doctor offering this treatment.)

Check that he will be monitoring your renal function before and after chelation.

Find out in advance exactly what drugs you will be receiving and do your own research to make sure you are happy about the proposed treatment.

For information, the Arterial Disease Clinic can be contacted on 0942 676617; Dr Perry is on 071 486 1095.