Replicas of the human heart that are made on 3D printers could help save babies' lives, new research suggests.

The heart replicas are designed to match every tiny detail of a baby's heart, so they can help surgeons plan where to cut tissue, reroute piping and patch holes in children with congenital heart defects, researchers said. The new findings were presented today (Nov. 19) at the American Heart Association meeting in Chicago.

Though just a handful of such hearts have been used so far, the replicas have already revealed hidden Swiss cheese-like holes in one child's heart, and in another case, inspired a repair strategy that dramatically extended the baby's projected life span.

"From the first two cases straight out of the gate, we've had this dramatic impact," said study co-author Dr. Matthew Bramlet, a pediatric cardiologist at the University of Illinois College of Medicine and the Children's Hospital of Illinois, both in Peoria.

The early results suggest 3D printing hearts could dramatically improve surgeons' understanding of defects before they go into the operating room, the researchers said. [See Images of the 3D Printed Hearts]

Tiny hearts

Children who have certain congenital heart defects — such as holes in one of the four chambers of the heart or misrouted arteries and vessels — often face years of complex, risky surgeries. When these fragile babies are born, doctors typically do a very quick surgery that improves blood flow just enough for them to grow. Once the little ones have doubled in size (usually when they are 6 to 9 months old), surgeons often perform more complicated repair surgery, Bramlet said.

But even the hearts of bigger babies are tiny, and the magnetic resonance imaging (MRI) scans that are currently done to guide surgical decisions are difficult to interpret. Although researchers have 3D-printed an artificial heart sleeve, an artificial wind pipe and replicas of kidneys and livers to guide surgeries, 3D replicas of the heart were slower to come along, Bramlet said.

Holding the heart

So Bramlet and his colleagues began using detailed MRIs to design anatomically accurate replicas of the heart that were then printed at the Jump Trading Simulation and Education Center, also in Peoria.

Almost immediately, the printed hearts helped guide surgical decisions. In the very first case, doctors  believed that a baby had a single hole in the wall of one of the heart's ventricles, based on the MRI images. This kind of defect, called a ventricular septal defect, is usually patched up with a fairly straightforward technique. But the 3D-printed heart clearly revealed several Swiss-cheese-like holes in the heart that also had to be closed.

The realization helped the surgeon rethink his strategy, which reduced how long the heart had to be stopped during the surgery, Bramlet said.

In the second case, a baby had problems with the major arteries emerging from the heart's right ventricle, as well as several holes in the heart. Normally, with the procedure used to fix these defects, doctors destroy so much heart tissue and reroute blood flow so dramatically that they essentially reduce the heart to two functional chambers. But in this case, by looking at the anatomy in 3D, the team was able to find a better work-around and spare all four of the heart's chambers, which increased the baby's life expectancy from 20 to 30 years  to near-normal, Bramlet said.

"Holding [the heart] in her hand, the surgeon could much, much more easily determine how to appropriately perform that surgery," Bramlet told Live Science.

Since the first repair, the team has gone on to create eight or nine heart replicas, and all of them have improved the surgeon's understanding of the heart anatomy prior to the surgery, he said.

But the total number of hearts they've studied so far is small, so it's too soon to know whether the heart replicas improve surgical outcomes, Bramlet said. Because these complicated heart defects are rare, researchers would need to set up a clinical trial at multiple sites to get enough cases, Bramlet said.

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