Scientists' long search for heart transplant alternative

THE battery-powered portable heart pump implanted into a British man on Thursday, as reported on page 1, is the result of a 25-year search by scientists for a viable alternative to heart transplantation.

In 1991, a patient at the Texas Heart Institute in Houston became the first patient worldwide to receive a pump implant, similar to that used at Papworth Hospital in Cambridgeshire this week. This was a 'bridging' device to support his own heart until a donor became available. The man died after 16 months from unrelated causes. But hundreds of other patients have been given the implant since; some have lived at home for more than a year.

The Papworth operation announced yesterday is significant because it marks the final stage of the development of such pumps, from use as stop-gaps in patients waiting for a donor heart, to a possible permanent treatment for heart failure.

Up to 10,000 people in Britain could benefit from a heart-assist device such as the pump. Drug therapy can help their hearts, but for many the only solution is a heart transplant. Donor organs are in short supply and the waiting list long; as of 31 July there were 285 people waiting for a heart and 170 needing a heart- lung transplant. Many others with heart failure are not suitable for transplant.

The electromechanical pump, known as a left ventricular assist system (LVAS), used at Papworth is made of metal and plastic, measuring 6in by 2in, and weighs about 2lb. It was implanted in the lower abdomen of a man of a 62-year-old man, who was suffering from end-stage heart failure, beneath the skin and subcutaneous layers of muscle and fat.

The LVAS consists of a cannula - a hollow tube - connected to the left ventricle. This is the thick, muscular, lower chamber of the heart which is responsible for pumping oxygen-rich blood to the rest of the body. It does about 80 per cent of the heart's work and a damaged or weakened left ventricle is implicated in virtually all cases of heart failure.

An 'inflow conduit' in the cannula drains blood from the left ventricle and directs it to the pump. The pump ejects the blood out and up through another cannula which has been connected to the aorta and main arteries leading from the heart to the rest of the body.

The pump synchronises with the patient's heartbeat and takes over its workload. It is powered by batteries carried in a belt-pack or worn in a holster-like arrangement.