Hospital – Health Care
Tag

Hospital

Browsing

A breakthrough medical technology can save the lives of children with heart defects. Scientists have developed the first-ever heart valve that grows with the child, reducing the need for risky heart surgeries in the future.

Children with congenital heart disease who need valve replacement often undergo multiple surgeries because the valve cannot grow as the child's heart grows. They need multiple heart surgeries to change the heart valve to accommodate the growing size of the heart. However, these surgeries are risky and pose a threat to the child's health.

To solve this problem, a team of scientists from Boston Children's Hospital developed a prosthetic valve that mimics the geometry of the human venous valve. Composed of polymeric leaflets attached to a stainless-steel stent, the valve can be expanded by a minimally invasive balloon catheter procedure, reducing invasive open-heart surgeries.

The doctors can use keyhole surgery to insert a rubber tube attached to a deflated balloon in the valve. They can inflate it depending on the child's heart size.

The valve replacement expanding to accommodate different lengths in implanted sheep. This material relates to a paper that appeared in the Feb. 19, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by S.C. Hofferberth at Boston Children's Hospital in Boston, MA; and colleagues was titled, "A geometrically adaptable heart valve replacement." Image Credit: S.C. Hofferberth et al., Science Translational Medicine (2020)

Multiple heart surgeries

Congenital heart valve disease is life-threatening, and children with this condition may need valve replacement early in their lives. However, children grow, and the artificial heart valve may not be able to accommodate the heart's increasing size.

Many children with this condition face high-risk and multiple open-heart surgeries to remove the valves and replace then with bigger ones.

The scientists used computational modeling to predict how their valve replacement expanded to deal with the stress of blood flow. This material relates to a paper that appeared in the Feb. 19, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by S.C. Hofferberth at Boston Children's Hospital in Boston, MA; and colleagues was titled, "A geometrically adaptable heart valve replacement." Credit: S.C. Hofferberth et al., Science Translational Medicine (2020)

For the first time, the new valve, a biomimetic prosthetic valve, adapts to accommodate growth and structural asymmetries within the heart. In previous heart valve models, they contain three leaflet-like flaps providing a one-way inlet or outlet for blood flow. However, in the new heart valve, it only has two flaps, with a geometry designed to maintain closure, and a one-way flow even when the veins expand in diameter.

"Veins carry approximately 70 percent of our blood volume. 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 bi-leaflet valve of programmed dimensions that is adaptable to growth without loss of one-way flow control," Dr.  Sophie C. Hofferberth, a surgical resident at Brigham and Women's Hospital and lead researcher at Boston Children's Hospital, said.

New artificial heart valve on the way

Related Stories

  • Poor sleep in women linked to raised risk of heart disease
  • Plant-based diets improve heart health via the gut microbiome
  • Switching what heart cells consume could help them regenerate

The new heart valve has been tested in large animal models, computer simulations, and benchtop studies, demonstrating that it works across a broad range of sizes. What is more, it retains functionality and efficacy when it is expanded through a balloon catheter procedure.

The team tested the prosthetic heart valve in growing young lambs. When implanted on the animals, it exhibited good performance without the blockage of blood flow. In another test in other lambs, the valves stayed functional for ten weeks without causing inflammation or injury to the heart tissues.

Though the study requires human testing and longer-follow up times, there is more work needed to validate the design. If it passes through rigorous testing, it can help more than 1.35 million children across the globe who were born with a congenital heart valve disorder.

The researchers also found that the new prosthetic valve promotes favorable blood flow through the valve, reducing the risk for blood clot formation, which is often observed in existing valve replacement devices. With the invasive heart valve device, there are fewer complications that may endanger the life of the child.

The study was published in the journal Science Translational Medicine.

What is congenital heart valve disease?

The heart pumps blood throughout the body throughout the day, and it contains valves that are responsible for keeping the blood from flowing backward. As a result, the blood flow is controlled, and the oxygenated and non-oxygenated blood will not mix.

A congenital heart valve disease happens if one or more of the valves in the heart do not work well, leading to problems such as regurgitation, stenosis, and atresia. Usually, this occurs when a heart's valves do not develop before birth, causing a defect that keeps the valve from closing completely.

Regurgitations happen when the blood backflows because the valve does not close tightly or adequately. The most common cause of blood backflow is a valve prolapse.

Stenosis happens when the flaps become thick, stiff, or fuse, resulting in the inability of the valve to open fully. Stenosis leads to blockage of blood flow. Atresia pertains to a condition when the valve does not have an opening for the blood to pass through.

All these conditions lead to a wide range of heart problems and can endanger the life of the child. Over time, these problems can strain the heart because it works double-time to compensate for the valve defect. It can cause serious problems such as aortic aneurysm, dilated cardiomyopathy, and heart failure.

Source:

National Heart, Lung, and Blood Institute. (2020). Heart Valve Disease. https://www.nhlbi.nih.gov/health-topics/heart-valve-disease.

Journal reference:

Hofferberth, S., Saeed, M., Tomholt, Fernandes, M., Payne, C., Price, K., Marx, G., Esch, J., Brown, J. et al. (2020). A geometrically adaptable heart valve replacement. Science Translational Medicine. https://stm.sciencemag.org/content/12/531/eaay4006?rss=1.

Using cutting-edge imaging technology, researchers at Massachusetts General Hospital (MGH) have shown that the brains of young men with autism spectrum disorder (ASD) have low levels of a protein that appears to play a role in inflammation and metabolism. This surprising discovery, which published online today in the journal Molecular Psychiatry provides an important new insight into the possible origins of ASD, which affects one in 59 children.

ASD is a developmental disorder that emerges in early childhood and is characterized by difficulty communicating and interacting with others. While the cause is unknown, growing evidence has linked ASD to inflammation of brain tissue, or neuroinflammation. One sign of neuroinflammation is elevated levels of a substance called translocator protein (TSPO), which can be measured and located in the brain using positron-emission tomography (PET) and anatomical magnetic resonance imaging (MRI). The MGH study, led by Nicole Zurcher, PhD, an investigator in MGH's Athinoula A. Martinos Center for Biomedical Imaging, was the first to use a new generation of PET "tracers," which more accurately detect TSPO, to examine the brains of people with ASD.

In the study, Zurcher and her colleagues scanned the brains of 15 young adult males (average age, 24) with ASD. The group included both high- and low-functioning subjects with varying degrees of intellectual abilities. For comparison, Zurcher's team scanned the brains of 18 healthy control subjects who were similar in age. The investigators hypothesized that the scans would show increased levels, or expression, of TSPO in subjects who have ASD.

"To our surprise, that's not what we saw," says Zurcher. Instead, the scans showed that the brains of males with ASD had lower levels of TSPO than those of the healthy subjects. In fact, the men with the most severe symptoms of ASD tended to have the lowest expression of TSPO. When the tests were repeated several months later, the pattern persisted. The brain regions found to have low expression of TSPO have previously been linked to ASD in earlier studies, and are believed to govern social and cognitive capacities such as processing of emotions, interpreting facial expressions, empathy, and relating to others. "We know these brain regions are involved in autism," says Zurcher.

Related Stories

  • Research reveals new pathogenic mechanism for influenza NS1 protein
  • Light-activated protein restores mitochondrion function in fruit fly model of Parkinson’s disease
  • Improving ability to predict autism risk with few drops of blood

To understand this unexpected finding, Zurcher notes that TSPO does more than serve as a marker of inflammation. "It has multiple complex roles," she says, and some actually promote brain health. For example, adequate TSPO is necessary for normal functioning of mitochondria, which are the "power houses" in cells that produce energy. Earlier research has linked malfunctioning mitochondria in brain cells to ASD.

Zurcher and her colleagues next plan to study brains from deceased donors with the goal of determining which brain cells in people with ASD might experience mitochondrial dysfunction, which she says may well be occurring alongside neuroinflammation and other mechanisms to cause ASD.

Our study has generated new hypotheses that now need to be investigated. There's more work to be done."

Nicole Zurcher, PhD, investigator, MGH's Athinoula A. Martinos Center for Biomedical Imaging

Source:

Massachusetts General Hospital

Journal reference:

Zürcher, N.R., et al. (2020) [11C]PBR28 MR–PET imaging reveals lower regional brain expression of translocator protein (TSPO) in young adult males with autism spectrum disorder. Molecular Psychiatry. doi.org/10.1038/s41380-020-0682-z.