New implant will help patients regenerate their own heart valves

Every year, more than 5 million people in the U.S. are diagnosed with heart valve disease, but this condition has no effective long-term treatment. When a person’s heart valve is severely damaged by a birth defect, lifestyle, or aging, blood flow is disrupted. If left untreated, there can be fatal complications.

Valve replacement and repair are the only methods of managing severe valvular heart disease, but both often require repeated surgeries that are expensive, disruptive, and life-threatening. Most replacement valves are made of animal tissue and last up to 10 or 15 years before they must be replaced. For pediatric patients, solutions are extremely limited and can require multiple reinterventions.

Now, Georgia Tech researchers have created a 3D-printed heart valve made of bioresorbable materials and designed to fit an individual patient’s unique anatomy. Once implanted, the valves will be absorbed by the body and replaced by new tissue that will perform the function that the device once served.

The invention comes out of the labs of faculty members Lakshmi Prasad Dasi and Scott Hollister in the Wallace H. Coulter Department of Biomedical Engineering (BME) at Georgia Tech and Emory.

“This technology is very different from most existing heart valves, and we believe it represents a paradigm shift,” said Dasi, the Rozelle Vanda Wesley Professor in BME. “We are moving away from using animal tissue devices that don’t last and aren’t sustainable, and into a new era where a heart valve can regenerate inside the patient.”

Dasi is a leading researcher in heart valve function and mechanics, while Hollister is a top expert in tissue engineering and 3D printing for pediatric medical devices. They brought their teams together to create a first-of-its-kind technology.

“In pediatrics, one of the biggest challenges is that kids grow, and their heart valves change size over time,” said Hollister, who is professor and Patsy and Alan Dorris Chair in Pediatric Technology and associate chair for Translational Research. “Because of this, children must undergo multiple surgeries to repair their valves as they grow. With this new technology, the patient can potentially grow new valve tissue and not have to worry about multiple valve replacements in the future.”

Growing into the Heart

Although 3D-printed heart valves currently exist and bioresorbable materials have been used for implants before, this is the first time the two technologies have been combined to create one device with a resorbable, shape memory material.

“From the start, the vision for the project was to move away from the one-size-fits-most approach that has been the status quo for heart valve design and manufacturing, and toward a patient-specific implant that can outlast current devices,” explained Sanchita Bhat, a research scientist in Dasi’s lab who first became involved in the project as a Ph.D. student.

The initial research involved finding the right material and testing different prototypes. The team’s heart valve is 3D-printed using a biocompatible material called poly(glycerol dodecanedioate).

The valve has shape memory, so it can be folded and delivered via a catheter, rather than open heart surgery. Once it is implanted and reaches body temperature, the device will refold into its original shape. The material will then signal to the body to make its own new tissue to replace the device. The original device will absorb completely in a few months. 

Srujana Joshi, a fourth-year Ph.D. student in Dasi’s lab, has played a major role in testing and analyzing the heart valve’s design and performance.

“Once you have an idea for an implant, it takes a lot of fine-tuning and optimization to arrive at the right design, material, and manufacturing parameters that work,” Joshi said. “It is an iterative process, and we’ve been testing these aspects in our systems to make sure the valves are doing what they're supposed to do.”

Bhat and Joshi are currently testing the heart valve’s physical durability with both computational models and benchtop studies. Dasi’s lab has a heart simulation setup that matches a real heart’s physiological conditions and can mimic the pressure and flow conditions of an individual patient's heart. An additional machine tests the valve’s mechanical durability by putting it through millions of heart cycles in a short time.

A Paradigm Shifting Technology

According to the researchers, it is an enormous challenge to create a material that can carry out a heart valve’s rigorous function, while also encouraging new tissue to develop and take over. Also, new medical devices undergo a long journey from bench to bedside, and several key milestones must be met.

The researchers hope their technology can revolutionize treatment for heart valve patients — and that it will usher in a new era of more tissue-engineered devices.

According to Dasi and Hollister, implants aren’t developed for pediatric populations as often as they are for adults. This is due to child diseases being rarer, along with the high cost of manufacturing. The researchers think that combining bioresorbable materials with 3D printing and manufacturing could be the key to developing better pediatric devices.

“The hope is that we will start with the pediatric patients who can benefit from this technology when there is no other treatment available to them,” Dasi said. “Then we hope to show, over time, that there’s no reason why all valves shouldn’t be made this way.”

Note: Harsha Ramaraju (research scientist), Ryan Akman (research scientist), Adam Verga (Ph.D. candidate), David Rozen (undergraduate student), Satheesh Kumar Harikrishnan (former research engineer), and Hieu Bui (former postdoctoral fellow) also played a major role in developing this technology.

Funding: Development of the bioresorbable material was supported by the National Institutes of Health grant number NIH/NHLBI R21-126004.