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3D printing may be used for fit-testing valves before TAVR
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Researchers developed a novel workflow using 3D printing to help clinicians determine what valve size to use before performing transcatheter aortic valve replacement on patients, according to a study published in the Journal of Cardiovascular Computed Tomography.
“Being able to identify intermediate- and low-risk patients whose heart valve anatomy gives them a higher probability of complications from TAVR is critical, and we’ve never had a noninvasive way to accurately determine that before,” Beth Ripley, MD, PhD, a cardiovascular imaging fellow at Brigham and Women’s Hospital at the time of the study and now an assistant professor in the department of radiology at the University of Washington in Seattle, said in a press release. “Those patients might be better served by surgery, as the risks of an imperfect TAVR result might outweigh its benefits.”
Ripley, along with Ahmed Hosny, research fellow at the Wyss Institute for Biologically Inspired Engineering at Harvard University at the time of the study and currently a PhD candidate at the Computational Imaging and Bioinformatics Laboratory at Dana-Farber Cancer Institute and at Maastricht University in the Netherlands, and colleagues analyzed data from 30 patients who underwent TAVR between 2013 and 2016.
Patients were categorized by the presence (n = 15; mean age, 84 years; nine women) or absence (n = 15; mean age, 85 years; eight women) of paravalvular leaks. Those with paravalvular leaks had mild, moderate or severe leaks within 30 days after TAVR.
Patients underwent cardiac CT scans as per standard department protocol. Researchers used the best motion-free dataset in diastole for aortic leaflet coordinate measurements and for creation of the 3D model. Thresholding strategies were used to segment calcified portions of the annulus, valves and left ventricular outflow tract. Leaflets were then generated through web-based open-source software, and aortic root and LV outflow tract models were printed on a 3D printer. Printed models were twice the size of the original to avoid any technical difficulties while printing thin leaflets and to aid in more accurate sizing estimates. A single observer used the valve sizer to determine whether the benchtop-predicted valve size was appropriate for the patients in this study.
There was a statistically significant correlation between the benchtop-predicted valve size and gold standard CT measurements of the average annulus diameter (P < .0001 Wilcoxon matched-pairs signed rank test; Spearman rank sum = 0.877; P < .0001).
Seal adequacy was accurately predicted in 73.3% of patients who received a balloon-expandable valve and in 60% of those who received a self-expanding valve.
Pressure testing was used to create a physical map of areas where the seal was inadequate. Results shown on the map corresponded to areas of paravalvular leak that were shown in transthoracic echocardiography performed after the procedure.
“This workflow may be a useful complement to current clinical sizing strategies and may also help anticipate the most likely complications for an individual’s unique anatomy and pathology,” Hosny and colleagues wrote. “In addition, by its very design, our benchtop workflow involves the direct, hands-on interaction between the physician, the 3D-printed valve analogue and a patient’s unique anatomy, allowing for a much more intuitive interaction as well as haptic feedback to the physician during simulated valve deployment.” – by Darlene Dobkowski
Disclosures: The research was supported by the Human Frontier Science Program. The authors report no relevant financial disclosures.
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