Although fully-functional 3D printed organs might still be a ways down the track, the technology has been saving lives for years by creating tissue, lifelike training models and external devices that mimic organ function. Now a team at Georgia Tech is 3D printing exact replicas of patients' heart valves, based on details pulled from CT scans, to help pick out the perfect prosthetic.
While similar systems could help with a range of illnesses, the study has been focused on helping surgeons treat aortic stenosis, a condition where the left ventricle constricts and causes the heart to work harder to pump blood through. If left untreated, it can eventually lead to complications as severe as heart failure.
One alternative to open-heart surgery is a procedure known as transcatheter aortic valve replacement (TAVR), which allows the surgeon to repair the valve without actually removing it. Since it can be performed through smaller openings that don't require separation of the ribs, it's far less invasive and is a preferred option for patients, particularly the elderly, who may be vulnerable to complications from the more extreme procedure.
To account for the natural variations in patients of different body types, sexes and ages, the prosthetic valves are available in a range of types and sizes, and finding one that's a perfect match for a patient is extremely important to keep blood from leaking around the implant. Enter Georgia Tech's 3D printed model. Created using data from a CT scan of the person's own valve, doctors can inspect the model freely and match up the right prosthetic before they ever pick up a scalpel.
"The issue is, everybody is different," says Chuck Zhang, a Georgia Tech professor. "A male will be different than a female. It's a big challenge for the doctors to select the right type of that prosthesis for a specific patient."
Using a multi-material 3D printer, the researchers can tweak details to create an exact copy of the natural valve that moves, feels and stretches like the real thing. It's even able to recreate related conditions specific to a patient, like deposits of calcium that may be present, to aid in deciding which implant is the best fit.
"The results are quite encouraging," says Zhen Qian, of the Piedmont Heart Institute, a partner on the project. "Our printed model is able to tell you before the procedure how much paravalvular leakage there will be and where it is, a good indicator for short- and long-term mortality."
So far, the team has printed heart models based on data from more than 20 patients, but has yet to begin using them for pre-surgery planning. That's the next step, along with imaging patients that have already undergone a TAVR procedure to help determine just how effective their models are at matching patients with prosthetics.
"There is big potential for these models," says Zhang. "We're thinking in the future, this may be a standard tool for pre-surgery planning and for training new surgeons."
Eventually, the models could be made with embedded sensors in the valve walls, to better monitor the effects of a prosthetic on the surrounding tissue.
Source: Georgia Tech
