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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1. Introduction

Nomenclature ASD

Atrial septal defect

SVASD

Sinus venosus atrial septal defect

SVC CAD

Superior vena cava Computer aided design

1.1. 3D printing and procedural planning Training for medical procedures has largely relied on real-life experience, where students are exposed to the different types of procedures they may be called to do in the future. In cardiac surgery and interventional cardiology, this experience is learnt on patients in the operating room or catheterization laboratory, on cases that appear on an opportunity basis rather than a standard curriculum. Over the course of their training, medical trainees will gradually gain more responsibilities and finally, will be able to perform procedures without their mentor. Later, they may then be called upon to mentor younger residents, to teach the next cohort of clinicians. This embodies the “See one, do one, teach one” philosophy based on the Halstedian method (Cameron 1997). For common procedures, this methodology is useful as residents can get plenty of practice and learning experiences. However, it can pose a problem in some specialty cases. A resident, or indeed, even a trained clinician, may never have been exposed to a given pathology, abnormality and/or procedure. This precludes many medical residencies to have a curriculum-based program as some complex and rare cases may not appear during the training of such a physician. There is therefore a need to supplement classic teaching methods with tools capable of recreating patient-specific geometries and pathologies, allowing to migrate from an opportunity-based medical training to a curriculum-based medical training. Procedural planning can be a useful form of training for complex procedures and anatomies. Endovascular procedures in particular benefit from careful planning. In these procedures, the clinician does not have direct access to the surgical field that open surgery provides. Procedural planning helps to determine the feasibility of an endovascular procedure, as well as which techniques are most suitable to the patient’s anatomy (Kicska and Litt 2009). 3D printing technology can be effectively used for the purposes of procedural planning and training due to the wide variety of geometries it can recreate. Complex patient-specific geometries have been recreated with high accuracy (Mobbs et al. 2017; Schmauss et al. 2014). Models can be used for anatomy visualization of the structures of interest, to determine how to access the organ, and how to fix a device (Son et al. 2015). Compared to the 2D medical images that they are based on, 3D models have the advantage that they show a global view of the anatomy compared to single slice views. 1.2. Sinus venosus atrial septal defects (SVASD) Case Study Atrial septal defects (ASD) are a cardiac pathology involving the septal wall separating the right and left atria. This congenital heart defect causes blood flow from the pulmonary and systemic circulation to mix (Kuijpers et al. 2015). This type of defect affects 56 out of 100 000 births. However, since the size of the defect can vary, some smaller defects do not cause any symptoms and go undiagnosed (Geva, Martins, and Wald 2014). There are different categories of ASD, and sinus venosus atrial septal defects (SVASD) involve communication between the right pulmonary veins and the superior aspect of the atrial septum at the junction of the atrium with superior vena cava. Unlike other ASD, SVASD involves a significant mixing of blood causing meaningful hemodynamic impact on the right cardiac chambers and therefore need to be repaired in all cases where is diagnosed. ASD repair can be performed surgically or percutaneously. Surgical repair can be done by suturing the defect closed, or by placing a patch to cover the defect (Webb and Gatzoulis 2006). Percutaneous repair typically involves a closure device placed at the defect position using a catheter. Once deployed, sections on either side of the defect expand and close it. However, the percutaneous approach is only limited to ASD at the level of the Fossa ovalis, so called Fossa ovalis defects.