Biotech solution to heart surgery for kids


A prototype valve grows with the patient, so doesn’t need replacing. Andrew Masterson reports.


The Chinese Finger Trap, the inspiration for potentially life-saving heart valve replacements.
The Chinese Finger Trap, the inspiration for potentially life-saving heart valve replacements.
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The Chinese Finger Trap – a tubular braided novelty beloved by kids and pranksters around the world – provided the inspiration for a nifty bit of biotech that looks set to save sick kids a whole lot of heartache. Literally.

Pedro del Nido from Boston Children’s Hospital in the US heads a team that has designed a proof-of-concept device that promises to dramatically cut down on surgery for children with certain types of heart defects.

At present, kids with defective mitral and tricuspid heart valves must undergo surgery in which a corrective implant is installed. The problem, however, is that children grow: the heart increases in size, and requires at least one, and often several, further surgical interventions so that a correspondingly larger implant can be installed.

Needless to say, these repeated bouts of open-heart surgery are extremely traumatic and disruptive.

Now, however, Nido and Karp may have come up with an elegant and clever solution: an implant that grows with the organ.

In a paper published in the journal Nature Biomedical Engineering the pair describe a prototype for a tubular expanding implant known as a tricuspid valve annuloplasty ring.

"The implant design consists of two components: a degrading, biopolymer core and a braided, tubular sleeve that elongates over time in response to the tensile forces exerted by the surrounding growing tissue," says team member Eric Feins.

“As the inner biopolymer degrades, the tubular sleeve becomes thinner and elongates in response to native tissue growth.”

Just like the expanding properties of the Chinese Finger Trap, the sleeve gradually stretches out, becoming thinner but keeping the valve leaks sealed as the heart grows larger.

By adjusting the composition of the polymer, the rate of degradation – and therefore the rate at which the tube stretches – can be precisely engineered.

So far the team have only tested the implant in the lab, but they are hopeful that further research will eventually produce a version suitable for real-world uses.

They are hopeful, too, that kids with heart problems won’t be the only beneficiaries.

“In combination with the braided sleeve exterior, this two-part implant concept could have many medical applications beyond the most obvious ones to enhance cardiac valve surgery in children," says del Nido.

  1. https://www.nature.com/articles/s41551-017-0142-5
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