Updated:02/19/2020 8:00 p.m.
The current heart valves that are implanted in children with congenital heart disease present a serious problem: they are of a single size and, therefore, as the child grows, I know makes replacement necessary, which translates into new surgical interventions, with the inconvenience and risks that this entails. But now, it is possible that this situation change completely.
A surprising new design, created in the Boston Children’s Hospital (USA) could allow children to maintain the same prosthetic valve until adulthood and, also, could benefit adults whose heart valves are defective. The new device is described today in “Science Translational Medicine.”
Both the tests carried out in the laboratory, the computer simulations and the tests carried out in large animal models demonstrate that The new design works in a wide range of sizes and that the valve retains its functionality when expanded by a minimally invasive balloon catheter procedure.
“We hope to start the human analysis shortly,” says Pedro J. del Nido, from Boston Children’s Hospital, lead author of the article and one of the eminences in childhood cardiac surgery. “If our preclinical results remain in humans, this could transform this medical field.”
More of 330,000 children worldwide They are born with a heart valve defect, and millions develop heart disease that requires early valve replacement. Current prosthetic heart valves have a fixed diameter, so they generally need to be replaced every few years; Children who receive their first replacement before age 2 will need up to five high-risk open heart operations before reaching adulthood.
Commercially available prosthetic heart valves have three leaflets, small fins that provide a unidirectional inlet or outlet for blood to continue flowing in the right direction. The new design was inspired by human venous valves, located in the deep veins of the leg. Unlike the native outflow valves of our hearts, our venous valves have only two leaflets and a geometry that is optimized to maintain the closure and unidirectional flow, even when the veins expand in diameter to accommodate large volumes of blood that pass.
“Veins carry about 70 percent of our blood volume,” says Sophie C. Hofferberth, who led the research in the Nest laboratory. “The dimensions of the veins can change dramatically depending on the position of the body, but the valves must remain functional. We imitate el geometric profile of the human venous valve to design a two-way valve of programmed dimensions that adapts to growth without loss of unidirectional flow control ».
In multiple tests, both in desktop models and in large animals, the valve prototypes with the biomimetic two-leaf design they could expand to accommodate growth and structural asymmetries within the heart. The valves remained fully functional in a wide range of dimensions, in a range of pressure and flow.
Because the valve is designed to expand without requiring that the frame and the booklet are stretched or enlarged, is compatible with a range of materials available in the market, say the researchers.
In addition, the study showed that the device could effectively expand in multiple stages in a growing animal model, using an approach catheter with balloon minimally invasive
The researchers also noted that their design «Geometrically adaptable» encourages a favorable blood flow profile through the valve, potentially reducing the risk of blood clot formation that is often seen with existing valve replacement devices. In the growing sheep model, there was no evidence of blood clot formation during 10 weeks of observation, even without the use of anticoagulant medications that are typically administered to prosthetic valve recipients.
“A deficiency of many existing devices is the presence of flow interruptions that lead to the formation of blood clots and the early deterioration of the valve,” says Hofferberth. «Our design achieves a favorable flow profile that seems to facilitate the effective washing of the valve and minimize the stagnation of the flow, which is probably an important determinant of the long-term durability of the device ».
Experts believe that their data support the start of a clinical study within one or two years.