They slowly released a growth-promoting substance over several weeks. It improved the flow of blood to the heart and made the patients feel better. Scientists said the clinical trial involved only 24 patients and that more studies on hundreds of volunteers will be needed before the approach could be proved to be an acceptable alternative to bypass surgery.
Instead of grafting arteries or veins from other parts of the body to bypass a clogged vessel, the scientists used the slow release of the growth factor to stimulate the regrowth of existing vessels.
Michael Simons, associate professor of medicine at Harvard Medical School and a member of the research team, said the technique produced demonstrable improvements. "Patients receiving the highest dose of the growth factor showed an improvement in blood supply and heart function, while the patients receiving the much lower doses of the growth factor or those not receiving the treatment had no increase in blood flow or heart function."
Over the past 20 years bypass operations in Britain have increased 20- fold, with 23,000 being done a year at a cost of pounds 4,000 each. Many are the result of a constriction of the flow of blood to the heart that results in a lack of oxygen and, eventually, to the development of heart disease.
The team of doctors took 24 patients who were unable to have coronary bypass operations for a variety of reasons and who therefore had a portion of their hearts that were inadequately oxygenated. Eight of the patients had 10 capsules with full-strength growth factor inserted into the fatty deposits next to the inoperable artery, eight received capsules loaded with lower doses and the final eight "controls" received capsules with no growth factor at all. After several weeks all the patients on the full- dose capsules said they had no angina (chest pain associated with badly oxygenated heart muscle), whereas one of the lower- dose groups and three of the eight controls complained of chest pains.
More tests showed that the high-dose capsules had also significantly improved the flow of blood to the heart and substantially reduced the area of heart tissue with inadequate blood flow - from about 19 per cent before the therapy to 9 per cent.
The British Heart Foundation said the concept of using growth factors to repair the heart's arteries was "conceptually exciting" but there was still much work to be done before it could be offered as an alternative to surgery. Professor Simons said that a second trial involving 120 patients who cannot have conventional bypass surgery is under way.
Details of the first clinical study are published in the current issue of Circulation: Journal of the American Heart Association.