Breakthrough 3D Printing Of Heart For Treating Aortic Stenosis

When a narrowed aortic valve fails to open properly and thereby the pumping of blood from the heart to the aorta is obstructed, this might result in a condition called aortic valve stenosis. Aortic stenosis is one of the most common cardiovascular conditions in the elderly and affects about 2.7 million adults over the age of 75 in North America. If the doctors decide that the condition is severe, they may carry out a minimally invasive heart procedure to replace the valve. This procedure is called transcatheter aortic valve replacement (TAVR). But this catheterization procedure is not without some risks which might include bleeding, stroke, heart attack or even death. That is why it is important that the doctors take all care to reduce the risks. The TAVR procedure is less invasive than open heart surgery to repair the damaged valves,

In a new paper published in Science Advances, a peer-reviewed scientific journal published by the American Association for the Advancement of Science (AAAS), some researchers from the University of Minnesota along with their collaborators have been able to produce a new technique that involves 3D printing of the aortic valve along with creating lifelike models of the aortic valve and surrounding structures which models mimic the look and feel of the valve. These 3D printing would possibly help reduce the risks for doctors who want to carry out a TAVR procedure on a patient.

Precisely, they 3D printed a model of the aortic root. The aortic root is a section of the aorta that is closest to the heart and attached to the heart. Some of the components of the aortic root include the aortic valve, which is prone to aortic stenosis in the elderly, along with the openings of the coronary artery. The left ventricle muscle and the ascending aorta which are close to the aortic root are also not left out in the model.

The models include specialized 3D printing soft sensor arrays built into the structure that prints the organs for each patient. The 3D printing process is also customized. The authors believe that this organ model will be used by doctors all over the world to improve the outcomes for patients who will be subject to invasive procedures when treating aortic stenosis.

Before the models are produced CT scans of the patient’s aortic root are made so that the printing will mimic the exact shape of the patient's organ. Then specialized silicone-based inks are used to do the actual printing in order to match the exact feel of the patient's heart. These inks were specially built for this process because commercial printers in the market can print 3D shapes but they cannot be able to reflect the real feel of the heart’s organs which are soft tissues. The initial heart tissue that were used for the test of the 3D printers were obtained from the University of Minnesota's Visible Heart Laboratory. The researchers found that the specialized 3D printers produced models that they wanted, models that mimic the shape and the feel of the aortic valve at the heart.

To watch a video of how the 3D printers work, I encourage you to play the video below. You would find it interesting.

The researchers are happy with what they have achieved.

“Our goal with these 3D-printed models is to reduce medical risks and complications by providing patient-specific tools to help doctors understand the exact anatomical structure and mechanical properties of the specific patient’s heart,” said Michael McAlpine, a University of Minnesota mechanical engineering professor and senior researcher on the study. “Physicians can test and try the valve implants before the actual procedure. The models can also help patients better understand their own anatomy and the procedure itself.”

These models will surely be of help to physicians who will use them to practice on how they will carry out their catheterization procedures on the real heart. Physicians will soon have the ability to practice beforehand on the size and placement of the catheter device on patients before carrying out the real procedure thereby reducing the risks involved. One good thing about the integrated sensors that are fitted into the 3D models is that they will provide physicians with electronic pressure feedback which will guide them in determining and selecting the optimal position of the catheter when being placed into the aorta of a patient.

But the researchers do not think these are the only use cases for their findings or the models. They aim to go beyond that.

“As our 3D-printing techniques continue to improve and we discover new ways to integrate electronics to mimic organ function, the models themselves may be used as artificial replacement organs,” said McAlpine, who holds the Kuhrmeyer Family Chair Professorship in the University of Minnesota Department of Mechanical Engineering. “Someday maybe these ‘bionic’ organs can be as good as or better than their biological counterparts.”

I think these are laudable futuristic goals. If they could achieve their ambition, then McAlpine would be solving a problem that gives sleepless nights to many physicians who have to operate on elderly patients with weak aortic valves.

Because this is a problem-solving innovative solution to a challenging problem, I decided to include it in my blog. I hope you enjoyed reading about the achievements of McAlpine and his colleagues. I wish that they go further than just helping physicians have 3D models but be able to make those models replace weak natural organs.

In addition to McAlpine, the team included University of Minnesota researchers Ghazaleh Haghiashtiani, co-first author and a recent mechanical engineering Ph.D. graduate who now works at Seagate; Kaiyan Qiu, another co-first author and a former mechanical engineering postdoctoral researcher who is now an assistant professor at Washington State University; Jorge D. Zhingre Sanchez, a former biomedical engineering Ph.D. student who worked in the University of Minnesota’s Visible Heart Laboratories who is now a senior R&D engineer at Medtronic; Zachary J. Fuenning, a mechanical engineering graduate student; Paul A. Iaizzo, a professor of surgery in the Medical School and founding director of the U of M Visible Heart Laboratories; Priya Nair, senior scientist at Medtronic; and Sarah E. Ahlberg, director of research & technology at Medtronic.

This research was funded by Medtronic, the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health, and the Minnesota Discovery, Research, and InnoVation Economy (MnDRIVE) Initiative through the State of Minnesota. Additional support was provided by University of Minnesota Interdisciplinary Doctoral Fellowship and Doctoral Dissertation Fellowship awarded to Ghazaleh Haghiashtiani.

You can read the full research paper, entitled "3D printed patient-specific aortic root models with internal sensors for minimally invasive applications," at the Science Advances website.