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The guessing game of where to put a stent as patients undergo heart surgery may soon be over.

Researchers from the Georgia Institute of Technology and the Piedmont Heart Institute have discovered a new way to develop heart valve models, by using a 3D printer to make models specifically for each patient undergoing valve replacement surgery.

Doctors currently take a CT image to see the condition of the heart, and then select the stent and location they feel is best. However, they have to select from several options of sizes and brands, which can lead to fitting problems.

By creating custom models, doctors will be able to select the best size and model stent for a given patient, cutting down the risk of side effects, said Chuck Zhang, a professor in the Stewart School of Industrial and Systems Engineering at Georgia Tech, in an interview with R&D Magazine.

“They have to make a lot of decisions and right now they are doing the decision-making based on the doctor’s experience,” Zhang said.

New 3D printing technologies allow researchers to create patient-specific heart valve models that mimic the physiological qualities of the real valves. This image shows the submerged valve during flow testing. Credit: Rob Felt

The aim of the new method is to improve the success rate of transcatheter aortic valve replacements (TAVR) by selecting the right prosthetic and avoiding paravalvular leakage—a common complication with heart valve surgery.

According to the researchers, tens of thousands of patients are diagnosed each year with heart valve disease, and TAVR is often considered for patients who are at high risk for complications with an open-heart surgery to replace the valve. Leakage occurs when the new valve doesn’t have a precise fit and blood flows around the prosthetic instead of through it.

 “What we are doing is we print the patient specific picture imaging of the valve, a physical model so the doctor can try on the stent and test which size or which model or brand and also the location that will fit the best,” Zhang said. “In doing that they will have a much better chance to reduce the side effects of that surgery—the leakage basically.”

Zhang explained how they used a 3D printing method specifically to create realistic heart valve models.

“We actually did some research and used a special mechanical material design approach, so we design and print microstructures inside the 3D printed body of the valve,” he said. “That microstructure actually gave the tissue mimicking mechanical properties.”

During the study the researchers made heart valve models from medical images of 18 patients who had undergone a valve replacement surgery. The models were outfitted with dozens of radiopaque beads to help measure the displacement of the tissue-mimicking material.

The researchers then paired the models with the same type and size prosthetic valves that interventional cardiologists had used during each of the surgery. 

Zhang said the researchers now plan on commercializing the process.

“Our goal is to commercialize it and we are in the process of talking to one company who is interested in commercializing it,” he said.

Zhang said the model they created was specifically for the aortic valve but it can be used for other valves and even to help train surgeons.

     

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