New type of heart valve may be the only replacement a child needs

February 19, 2020

Current prosthetic heart valves for children with congenital heart disease are fixed in size, requiring repeated open-heart surgeries during childhood to replace the valve with a larger version. But a surprising new design created at Boston Children's Hospital could allow children to keep the same prosthetic valve until adulthood, and could also benefit adults with heart valve defects. The new device is described in Science Translational Medicine, published online February 19.

Benchtop studies, computer simulations and extensive testing in large animal models demonstrate that the new prosthetic valve design works across a wide range of sizes, and that the valve retains its functionality when expanded via a minimally invasive balloon catheter procedure.

"We hope to bring this new device into clinical testing fairly rapidly," says Pedro J. del Nido, MD, Chairman of Cardiovascular Surgery at Boston Children's Hospital and senior author on the paper. "If our preclinical results hold up in human testing, this could transform the field."

Less is more: Two valve leaflets versus three

More than 330,000 children worldwide are born with a heart valve defect, and millions of others develop rheumatic heart disease requiring early valve replacement. Current prosthetic heart valves are fixed in diameter, so typically need to be replaced every few years; children receiving their first replacement before age 2 will need as many as five high-risk open-heart operations before reaching adulthood.

Commercially available prosthetic heart valves have three leaflets, tiny flaps that provide a one-way inlet or outlet for blood to keep it flowing in the right direction. The new design was inspired by human venous valves, located in the deep veins of the leg. Unlike our hearts' native outflow valves, our venous valves have just two leaflets, and a geometry that is optimized to maintain closure and one-way flow even when the veins expand in diameter to accommodate larger volumes of blood passing through.

"Veins carry approximately 70 percent of our blood volume," says Sophie C. Hofferberth, MD, a surgical resident at Brigham and Women's Hospital who led the research in del Nido's lab at Boston Children's. "The vein dimensions can change dramatically depending on body position, yet the valves must remain functional. We mimicked the geometric profile of the human venous valve to design a bileaflet valve of programmed dimensions that is adaptable to growth without loss of one-way flow control."

In multiple rounds of testing, in both benchtop and large animal models, valve prototypes with the biomimetic two-leaflet design were able to expand to accommodate growth and structural asymmetries within the heart. The valves remained fully functional across a wide range of dimensions, at a range of pressure and flow rates.

Because the valve is designed to expand without requiring the frame and leaflet to stretch or enlarge, it is compatible with a range of off-the-shelf materials, the researchers say. The study showed the device could be effectively expanded at multiple timepoints in a growing animal model, using a minimally invasive balloon catheter approach.

Potential for fewer blood clots

The researchers also observed that their "geometrically adaptable" design encourages a favorable blood flow profile through the valve, potentially reducing the risk for blood clot formation often seen with existing valve replacement devices. In the growing sheep model, there was no evidence of blood clot formation over 10 weeks of observation, even without the use of blood-thinning medication typically given to prosthetic valve recipients.

"A shortcoming of many existing devices is the presence of flow disruptions that lead to blood clot formation and early valve deterioration," says Hofferberth, who is first author on the paper. "Our design achieves a favorable flow profile that seems to facilitate effective valve washout and minimize flow stagnation, which is likely to be an important determinant of long-term device durability."

The research team believes their data support initiation of a clinical study within one to two years.
-end-
Mossab Saeed, Christopher Payne, Karl Price, and Peter Hammer of Boston Children's Department of Cardiac Surgery were coauthors on the paper, together with Lara Tomholt, Matheus Fernandes, and James Weaver of the Wyss Institute for Biologically Inspired Engineering; Gerald Marx, Jesse Esch, and David Brown of Boston Children's Department of Cardiology; Jonathan Brown and Elazer Edelman of MIT; and Richard W. Bianco of the University of Minnesota. The study was supported by a NIH-NRSA postdoctoral fellowship grant (1F32HL138993-01), an Early Career Award from the Thrasher Research Fund, and the Oakwood Foundation. A provisional patent has been filed naming several of the authors.

About Boston Children's Hospital

Boston Children's Hospital is ranked the #1 children's hospital in the nation by U.S. News & World Report and is the primary pediatric teaching affiliate of Harvard Medical School. Home to the world's largest research enterprise based at a pediatric medical center, its discoveries have benefited both children and adults since 1869. Today, 3,000 researchers and scientific staff, including 8 members of the National Academy of Sciences, 21 members of the National Academy of Medicine and 12 Howard Hughes Medical Investigators comprise Boston Children's research community. Founded as a 20-bed hospital for children, Boston Children's is now a 415-bed comprehensive center for pediatric and adolescent health care. For more, visit our Discoveries blog and follow us on social media @BostonChildrens, @BCH_Innovation, Facebook and YouTube.

Boston Children's Hospital

Related Congenital Heart Disease Articles from Brightsurf:

Low risk of COVID-19 infection found among people with congenital heart disease
Results of a retrospective analysis suggest that people born with a heart defect who developed COVID-19 symptoms had a low risk of moderate or severe COVID-19 infection, according to a new article published today in the Journal of the American Heart Association, an open access journal of the American Heart Association.

New method for in utero 4D imaging of baby hearts may aid diagnosis of congenital heart disease
Researchers at King's College London have developed a new method for helping detect congenital heart disease of a baby in pregnant mothers using MRI.

Gout treatment may aid patients with congenital heart disease
A drug used to treat gout, probenecid, may improve heart function in individuals with a particular heart defect, according to results from a small pilot study run by a University of Cincinnati researcher.

Stakeholders update newborn screening guidelines for critical congenital heart disease
A distinguished panel of medical experts, state and federal health officials, and congenital heart disease parent advocates published recommended updates to the current American Academy of Pediatrics' protocol for detecting critical congenital heart disease (CCHD) in newborn babies using pulse oximetry.

Congenital heart disease more deadly in low-income countries
Even though mortality from congenital heart disease (CHD) has declined over the last three decades as diagnosis and treatments have advanced, a new study shows that the chances for a child to survive a CHD diagnosis significantly differs based on the country where he or she is born.

Telehealth effectively diagnoses/manages fetal congenital heart disease in rural patients
A recent study of 368 pregnant mothers, led by Bettina Cuneo, MD, director of perinatal cardiology and fetal cardiac telemedicine at Children's Hospital Colorado, found that fetal congenital heart disease (CHD) was correctly identified and successfully managed according to evidence-based risk stratification.

Uncorrected congenital heart disease may lead to increased risks in pregnant women
Pregnant women with congenital heart disease (CHD) who have not had surgery to repair their cardiac condition are more likely to experience cardiac events or maternal death, especially those with certain conditions in emerging countries, according to a study published Oct.

A new framework to study congenital heart defects
In a new study published in the scientific journal Nature, a team of researchers at the Gladstone Institutes, in collaboration with the University of Luxembourg, reveal for the first time the full spectrum of cells that come together to make a heart at the earliest stages of embryo formation.

Risk of cancer among children, young adults with congenital heart disease
National registry data in Sweden were used in this study that assessed the risk of developing cancer in children and young adults with congenital heart disease compared with healthy people in the general population from birth to age 41.

Congenital heart defects vastly increase risk of heart problems later in life
An infant born with a relatively simple heart defect is far more likely to develop heart problems as an adult, researchers at the Stanford University School of Medicine have discovered.

Read More: Congenital Heart Disease News and Congenital Heart Disease Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.