3D-Printed Heart Valve Models Mimic Physiology

Investigators at the Georgia Institute of Technology (Atlanta, USA) had shown previously that a metamaterial three-dimensional printing technique could be used to create patient-specific phantoms that mimicked the mechanical properties of biological tissue. In the current study, they aimed to use this methodology to develop a procedure simulation platform for in vitro transcatheter aortic valve replacement (TAVR). In addition, they evaluated the feasibility of using these three-dimensional printed mimics to quantitatively predict the occurrence, severity, and location of any degree of post-TAVR paravalvular leaks (PVL).

In conducting this retrospective study involving 18 patients who had undergone TAVR, patient-specific aortic root mimics were created using the three-dimensional printing technique combined with pre-TAVR computed tomography. CoreValve (self-expanding valve) prostheses were deployed in the mimics to simulate the TAVR procedure, from which post-TAVR aortic root strain was quantified in vitro. A novel index, the annular bulge index, was measured to assess the post-TAVR annular strain unevenness in the mimics.

Results published in the July 7, 2017, online edition of the journal JACC: Cardiovascular Imaging revealed that the maximum annular bulge index was significantly different among patient subgroups that had no PVL, trace-to-mild PVL, and moderate-to-severe PVL. Compared with other known PVL predictors, bulge index was the only significant predictor of moderate-severe PVL. Thus, in this proof-of-concept study, the investigators demonstrated the feasibility of using three-dimensional printed tissue-mimics to quantitatively assess post-TAVR aortic root strain in vitro.

"These three-dimensional printed valves have the potential to make a huge impact on patient care going forward," said contributing author Dr. Chuck Zhang, professor of industrial and systems engineering at the Georgia Institute of Technology. "Previous methods of using three-dimensional printers and a single material to create human organ models were limited to the physiological properties of the material used. Our method of creating these models using metamaterial design and multi-material three-dimensional printing takes into account the mechanical behavior of the heart valves, mimicking the natural strain-stiffening behavior of soft tissues that comes from the interaction between elastin and collagen, two proteins found in heart valves."

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Georgia Institute of Technology