Heart valve diseases are among the most common acquired and congenital heart diseases. Every year, around 160,000 children worldwide are born with a defect in the pulmonary valve - the valve between the right ventricle and the pulmonary artery. In Germany, there are approximately 800 newborns per year.
So far, prostheses whose leaflets are made from animal tissue from cattle or pigs have been available to replace this valve. However, these valves are only sustainable for a limited time and have to be replaced after a few years. In children, there is an additional decisive disadvantage: the replacement valves do not grow with the child and have to be replaced with a larger model every five to ten years. Each of these open heart surgeries means a considerable burden and longer hospital stays for the young patients.
Perspectives for children with heart defects
PD Dr Boris Schmitt, paediatrician at Charité's German Heart Centre (DHZC), and his team have been researching a solution to these problems since 2010: ‘The decisive advantage of our innovation lies in the use of the body's own tissue,’ explains PD Dr Boris Schmitt, paediatrician at Charité's German Heart Centre. "These valves are not recognised as foreign by the immune system. They are initially supplied with nutrients by the bloodstream and, over time, cell layers even form. The leaflets of the heart valve thus remain alive, so to speak, and can regenerate and adapt to the body's needs. We therefore hope that these valves can last significantly longer than the models available to date, ideally for a lifetime."
The use of this technology is particularly promising for children with congenital heart valve malformations. A special stent is developed for this purpose, which dissolves in the body after some time. All that remains is the heart valve made of the body's own tissue, which is no longer limited in size by the wire frame. ‘In this way, we want to create the best possible conditions for the growth of the valve that we hope for in children and adolescents,’ explains Boris Schmitt.
Prof. Dr Felix Berger, Director of the Clinic for Congenital Heart Defects - Paediatric Cardiology at the DHZC, who led the development of the project, emphasises: "With around 160,000 children worldwide being born with a pulmonary valve defect every year, this technology could represent a paradigm shift in the treatment of many of these children. We hope that this method will enable us to significantly reduce the number of open heart operations required."
Durable and gentle
In this method, autologous tissue is removed from the patient's pericardium, from which the leaflets of the new heart valve are moulded and attached to a wire frame (stent). This is then compressed, placed in exactly the right position in the heart via a thin catheter under X-ray control and deployed there. The entire procedure takes just a few hours and is performed without open heart surgery.
From research project to start-up
After years of preparation, the novel method can be tested on humans for the first time. The current GECT-DZHK28 study is testing safety in seven young adults with pulmonary valve defects. A larger follow-up study with adults and children is planned. The technology was transferred to the Berlin start-up GrOwnValve (founded in 2019), which received 7.8 million euros in funding for clinical trials.
First patient already fit for work again
Two patients have already been successfully treated. Marcus L. from Saxony, the first patient, was born with valve stenosis in early 1990 and underwent a so-called Ross operation in 2001, which included replacing his pulmonary valve with a valve made from animal tissue. 24 years later, this valve has to be replaced again. As an ideal candidate for the new procedure, he was informed by Dr Schmitt and his team about the innovative treatment option.
'As a father of three and a self-employed painter and floor installer, I wanted to be fit for work again as quickly as possible, which is why I immediately decided in favour of this new procedure,' explains Marcus L. His plan has paid off so far: He was discharged from hospital just five days after the procedure and returned to work four weeks later. ‘I feel excellent,’ reports the 34-year-old.
Future prospects for the technology
The procedure is currently only approved for the replacement of the pulmonary valve, i.e. the valve between the right ventricle and the pulmonary artery. In future, however, following extensive testing, the technology should also be able to be used for other heart valves such as the aortic valve, which have to withstand higher loads.
