TINY, targeted doses of radiation could spare thousands of patients with
heart disease unpleasant and costly returns to hospital. The novel treatment
uses beta particles to halt the abnormal growth of cells that line arteries
where a blockage has already been removed.
Researchers led by cardiologist Martin Rothman and radiation oncologist
Melanie Powell at the London Chest Hospital have had promising results with all
five patients who have so far received the treatment, developed by the US firm
Guidant based in Santa Clara, California.
Surgeons usually treat blocked coronary arteries with balloon angioplasty.
This involves feeding a catheter containing a tiny balloon into the coronary
artery via an artery in the groin. The balloon is then inflated to clear the
blockage. Surgeons will normally then position a 鈥渟tent鈥濃�攁 tiny
stainless-steel tubular lattice鈥攊n the artery, to keep it clear. In
Britain alone, about 30,000 people undergo balloon angioplasty each
year鈥攁nd in most patients the artery heals nicely.
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But a significant minority鈥攁round 10 per cent鈥攄evelop restenosis,
a process where healing gets out of hand. The cells lining the artery divide too
rapidly and cause a new blockage. These patients have to undergo repeated
surgery.
The new treatment exploits the fact that these rapidly dividing cells are
unusually sensitive to radiation. The surgeon performs a normal balloon
angioplasty, but then inserts a fine wire containing phosphorus-32, a
beta-emitting isotope, at the site of the blockage.
Previous teams have attempted a similar technique using gamma radiation.
Jonathan Clague, a consultant cardiologist at the Royal Brompton Hospital in
London, says of radiation therapy: 鈥淧robably, it鈥檚 the best tool we have at the
moment for dealing with in-stent restenosis.鈥�
However, compared with phosphorus-32, gamma ray sources are more dangerous
to handle and require longer exposure times.