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Groundbreaking heart valve that grows in the body can transform the lives of children with defects

A groundbreaking heart valve replacement that grows at the same rate as the organ could transform the lives of children with defects, scientists say.

The prosthesis can eliminate the need for patients to undergo multiple risky heart surgeries during childhood and provide a longer-term solution for weak hearts.

The inventors say it can “transform the field” if it is completely safe and they hope it can be tested in humans within two years.

Replacement heart valves are used when a person’s natural valve is sick or damaged, causing the heart to malfunction.

Children with congenital heart disease are forced to undergo repeated open heart surgery during their lifetime to replace the replacement valve with a larger version as their body grows.

But the new valve, made by Boston Children’s Hospital, is intended to offer a more permanent solution.

It has been tested on lambs and has worked safely and effectively for at least 10 weeks.

A groundbreaking heart valve replacement that grows as fast as the organ could change the lives of children with defects. It worked safely when breeding young lambs as they grew in their first weeks of life (pictured, the flap extends to different lengths in sheep)

A groundbreaking heart valve replacement that grows as fast as the organ could change the lives of children with defects. It worked safely when breeding young lambs as they grew in their first weeks of life (pictured, the flap extends to different lengths in sheep)

A groundbreaking heart valve replacement that grows as fast as the organ could change the lives of children with defects. Scientists at Boston Children's Hospital used a computer to model how the valve would expand to cope with the stress of increasing blood flow as a child ages

A groundbreaking heart valve replacement that grows as fast as the organ could change the lives of children with defects. Scientists at Boston Children's Hospital used a computer to model how the valve would expand to cope with the stress of increasing blood flow as a child ages

A groundbreaking heart valve replacement that grows as fast as the organ could change the lives of children with defects. Scientists at Boston Children’s Hospital used a computer to model how the valve would expand to cope with the stress of increasing blood flow as a child ages

More than 1.35 million children are born worldwide with a congenital heart defect.

In the UK, one in 180 babies has potentially fatal heart problems, according to the British Heart Foundation.

These defects account for three to five percent of all deaths in children under the age of five.

WHAT IS HEART REPLACEMENT OPERATION AND WHAT ARE THE OPTIONS?

Heart valve replacement surgery is an operation to repair one or more of the four valves of the heart.

If these are damaged by illness or age, this can reduce how well the vital organ pumps blood through the body.

Valves – where the main arteries and veins connect to the heart – may become less efficient if they do not open or close properly, obstruct blood flow or leak while the heart is pumping.

A valve replacement is a valve in which the damaged valve is replaced by an artificial component or a valve from an animal or human donor.

During surgery, the breast is cut open, the heart stopped and the blood pumped with a bypass machine, then the heart valve is replaced and the breast closed again and the heart restarted.

Patients usually spend a week in the hospital and it may take up to three months for them to fully recover.

The chance of survival of an aortic valve replacement – a common type – is between 97 and 99 percent, according to the NHS.

The risk depends on the age and general health of the patient, but it can cause endocarditis, a heart infection. Blood clots and stroke are also possible complications

WHAT TYPE OF REPLACEMENT VALVES ARE AVAILABLE?

Mechanical valves are made of metal. They can cause blood clots that can be fatal if they cause a heart attack or stroke.

Because the body can see that a mechanical valve is not made from natural tissue, it is more likely that blood clots on the surface of the valve.

The hard surface can also rupture blood cells as they pass through the valve, forming clots.

Tissue valves can be recommended for patients over 70 years of age or for patients who do not want to use blood-thinning drugs.

Tissue valves of an animal are strong and flexible. The advantage of tissue valves is that a patient does not need lifelong blood-thinning drugs such as mechanical valves.

They last 10-20 years, but are expected to wear out faster than a mechanical / artificial valve.

sources: British Heart Foundation and NHS

The number of operations performed for congenital heart disease increased by around 60 percent between 2000 and 2010.

It is thought that most cases occur when something influences the development of the heart during the first six weeks of pregnancy. Maternal diabetes, alcohol and flu are some of the risk factors.

More serious heart defects usually require surgery, of which there are many types. A prosthetic valve replacement can give children the best chance of life without symptoms such as shortness of breath, tiredness and chest pain.

Valve replacements are made of metal – which entails the risk of blood clots – or animal tissue.

Heart valves for animals last 10-20 years, but they are thought to wear out faster than a mechanical valve.

A fake heart valve does not grow as the child grows and must be replaced again. For this reason, it is postponed as long as possible to reduce the number of repeat operations.

The valves are placed in the body by opening the chest and cutting the sternum to reach the heart – which has a total of four valves – in a complex procedure.

Approximately two percent of patients die from an aortic valve replacement, according to the British Heart Foundation, which is much smaller than the risk that serious aortic valve problems remain untreated.

In order to offer a more permanent solution that reduces the surgical burden, Dr. Sophie Hofferberth and colleagues a heart valve that draws inspiration from valves in human veins.

It is composed of two synthetic leaves attached to a stent and can be manually expanded with a balloon catheter for larger amounts of blood moving through the heart.

The valves expand and contract to cope with major changes in blood flow volume, which would be expected as the child ages.

In a new study, published in Science Transitional Medicine, the artificial valve worked safely in seven growing young lambs for a period of up to 10 weeks, without causing injury or inflammation.

When implanted in four young lambs and four adult sheep, the prosthetic valves showed good performance without impeding blood flow.

Researchers say that although studies with longer follow-up times are needed to further validate the design, the device may offer a better alternative to traditional fixed-valve heart valve prostheses.

The valve can also benefit adults with heart valve defects.

Dr. Pedro del Nido, president of cardiovascular surgery at the Boston Children’s Hospital and senior author of the newspaper, said: “We hope to get this new device into clinical testing pretty soon.

“If our pre-clinical results can sustain human testing, this can change the field.”

Dr. Hofferberth said: “A shortcoming of many existing devices is the presence of power failures that lead to blood clot formation and early valve degradation.

“Our design achieves a favorable flow profile that appears to facilitate effective valve flushing and minimizes flow stagnation, which is probably an important determining factor for the durability of the device in the long term.”

The team believes that their data support the start of a clinical study within one to two years.

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