PSI - Issue 49

Kevin Bates et al. / Procedia Structural Integrity 49 (2023) 23–29 Kevin Bates / Structural Integrity Procedia 00 (2023) 000 – 000

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one end. Another concern was to determine whether the stent would occlude the pulmonary vein draining into the left atrium. Due to the highly customized nature of the device, a test stent could not be deployed in the printed model before implanting the real device in the patient. Therefore, CAD software (Autodesk Fusion 360®) and a simplified stent geometry was placed within the 3D heart model to examine potential interactions between device and anatomy. Figure 4 shows the virtual stent placement, with the deployed stent accounting for a 30% predicted foreshortening of the device during deployment. To assess pulmonary vein drainage, the three-dimensional nature of the model was used to rotate, section, annotate and enlarge the views. Two main section views are describe the results. In Figure 5 (a) we are looking from the point of view of inside the left atrium towards the defect. The covered stent, highlighted in orange, reduces the defect significantly when the flaring is done. In (b), a coronal section transects the device at the level of the pulmonary vein. Red arrows indicate the direction of flow for pulmonary vein drainage. According to the clinical team, this flow pattern appears to be minimally affected by the covered stent.

Figure 5. (a) Covered stent showing defect closure; (b) section view showing pulmonary vein drainage.

The clinical team decided to go forward with the procedure following their evaluation of the model. The defect was accessed endovascularly under transesophageal echocardiography and fluoroscopy guidance. A catheter balloon was first inflated to 30 mm where the stent would be placed to verify that the covered stent would indeed seal the ASD without pulmonary vein occlusion. Once this was confirmed, the covered stent was guided into position, expanded with flaring, and securely anchored distally using a bare metal stent. The procedure was successful, with no residual communication between the right and left atria as well as no pulmonary vein obstruction. Short-term follow-up showed no indication of complications and no ventricular failure symptoms. Pre-procedural heart failure symptoms had decreased, and renal function remained the same. 4. Discussion This case study shows the power of a procedural planning approach using solid modeling and 3D printing as an additional tool for clinicians. Using both physical models and versatile virtual models, the medical team was able to make observations that would have been more difficult to determine from standard medical imaging alone. The clinical team had no previous experience with this endovascular procedure and it was the first such procedure attempted in North America. As such, the solid model and 3D printed heart provided valuable insight into the anatomy of the patient. The integration of 3D modeling allowed for anatomical evaluation, precise sizing of key landmarks and virtual device positioning. Congenital heart defects are an area where 3D reconstruction and 3D printing can have a large impact. These pathologies are rare and can lead to complex anatomies. For clinicians who do not have direct experience with a similar case, these reconstructions offer an understanding of the anatomy without harm to the patient, thereby improving procedural outcomes. They serve as a learning tool as well as a planning tool for all those involved.