PSI - Issue 49

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Kevin Bates / Structural Integrity Procedia 00 (2023) 000 – 000

Kevin Bates et al. / Procedia Structural Integrity 49 (2023) 23–29

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3.2. 3D printing clinical evaluation and virtual stent positioning Confirmation of the section plane led to the printing of a physical model for the clinical team. Using our lab’s Objet 500 Connex 3 Polyjet printer, the model was printed in Tango Plus, a soft and flexible material. The large septal defect is clearly visible in the printed model, shown in Figure 3 (c). The inclusion of incoming and outgoing blood vessels provided a detailed view of the anatomy of the patient’s heart .

Figure 3. 3D printed heart. (a) view facing the section cut; (b) external view of the right side of the heart; (c) closeup showing the defect, with the missing septal wall highlighted by the red arrow. a b c

After printing and initial evaluation, the main clinical concern was assessing how the covered stent would interact with the anatomy. Analyzing the recent studies by Hansen et al. (Brancato et al. 2021) it was determined that an anchoring stent (bare metal, uncovered) would be used to keep the stent in place distally, in the SVC. The SVC being narrower than the right atrium also meant that to anchor the proximal end of the covered stent, it would have to flare outwards. From measurements done on the solid model and confirmed on medical imaging, this stent would need to be expanded to 18 mm in the SVC and up to 25 mm in the right atrium. A custom-made 8 cm long covered stent (NuMED Inc, Hopkinton, New York, USA) was chosen for the task as it would be capable of sustaining flaring on

Figure 4. Simplified stent geometry in 3D heart model. In grey, the crimped stent; in orange, the flared deployed stent, with diameters specified on the left.