The quest for perfect replacement heart valves

Heart valve disease is a common heart problem, meaning that blood can’t flow through your heart as well as it should. Thousands of people need valve replacement surgery in the UK each year.

Early valve replacement surgery

One of the first BHF research grants in the early 1960s was awarded to a pioneer in heart valve replacement surgery, Professor Donald Ross. The grant was to fund his efforts to improve the safety of an innovative operation using human heart valves to replace diseased valves.

In 1967, Ross performed a world-first operation that would come to bear his name, to treat people with a faulty aortic valve. The aortic valve is one of the four valves in your heart, and the one which blood has to pass through when pumped out of the heart into the body. The Ross procedure involved not one but two valve replacements. First the faulty aortic valve was removed and the patient’s own healthy pulmonary valve was used to replace it. A preserved valve taken from a corpse was placed in the position originally occupied by the patient’s pulmonary valve. The thinking at the time was that the original healthy pulmonary valve would have the best chance of withstanding the high-pressure battering that the aortic valve faces with each heartbeat. This procedure was a revolution in heart valve surgery, and many patients went on to live for 20 years or more. The procedure is still used by some surgeons today, especially for treating infants and children born with heart defects.

What valve to use when?

The 1960s and 1970s were a time of innovation for heart valve replacement technology. The first successful artificial valve was inserted in 1960, and valves with similar designs have now been in use for over 40 years. Throughout this period new types of artificial valves and biological valves (using human, pig or cow tissue) have been developed and trialled in humans.

But faced with these growing options, how could doctors decide what type of valve to offer a patient? The Edinburgh Heart Valve study, set up in the 1970s by BHF Professor David Wheatley, and the UK Valve Registry, started in the 1980s by BHF Professor Ken Taylor, collected information on how many patients were having valve surgery, what type of valve was being used (artificial or biological valve), and how successful the procedures were. These studies provided vital information to help surgeons and patients make informed treatment decisions, like for example to choose between biological and artificial valves. Another important finding was that older patients, in their 80s or even early 90s, could still benefit from valve replacement surgery.

The quest for the perfect heart valve

Currently faulty heart valves are replaced with either an artificial valve or a biological valve. Both types have pros and cons. An artificial valve is long-lasting but comes with a higher risk of blood clots forming on the valve surface, which means the patient must take lifelong blood-thinning drugs. This medication prevents clots forming on the valve, but also increases the risk of serious bleeding. Biological valves are made from pig or cow tissue, and usually mean that blood-thinning drugs are not needed. But these valves don’t last as long, and the patient may face further surgery years later.

To solve these problems, BHF-funded researchers are developing what they hope will be the perfect material for the next generation of heart valve replacements. In 2020, Professor Geoff Moggridge at the University of Cambridge, Professor Raimondo Ascione at the University of Bristol and colleagues revealed their work on a new artificial valve – called the PoliValve – which is designed to closely resemble a natural heart valve. It combines strength with flexibility, and its use would not require blood-thinning drugs.

While further refinement and testing is needed before this valve can be used in patients, the PoliValve has the potential to be a big step forward for the thousands of patients who require valve replacement surgery.

First published 1st June 2021