Impact of Three-Dimensional Printing on the Study and Treatment of Congenital Heart Disease

Comparing assisting technologies for proficiency in cardiac morphology: 3D printing and mixed reality versus CT slice images for morphological understanding of congenital heart defects by medical students

Learning cardiac morphology largely involves spatial abilities and studies indicate benefits from innovative 3D visualization technologies that speed up and increase the learning output. Studies comparing these teaching tools and their educational output are rare and few studies include complex congenital heart defects. This study compared the effects of 3D prints, mixed reality (MR) viewing of 3D meshes and standard cardiac CT slice images on medical students' understanding of complex congenital heart defect morphology, measuring both objective level of understanding and subjective educational experience. The objective of this study was to compare morphological understanding and user experiences of 3D printed models, MR 3D visualization and axial 2D CT slices, in medical students examining morphological details in complex congenital heart defects. Medical students in the median 4th year of study (range 2nd to 6th) examined three of five different complex congenital heart defects by three different modalities: 3D printed model, MR viewed 3D mesh, and cardiac CT slices, answering a questionnaire on morphology and user experience. Time to complete task, diagnostic accuracy, and user experience data were collected and compared on group level. Task times were similar for all modalities. The percentage of correct answers was higher with MR visualization, which was also the preferred modality overall. Medical students both prefer and better understand the morphology of complex congenital heart disease with 3D models viewed using MR, without spending more time than with 3D prints or 2D CT images.

Stereolithographic (SLA) 3D Printing for Preprocedural Planning in Endovascular Aortic Repair of a Thoracic Aneurysm

BACKGROUND

When treating aortic aneurysm patients with complex anatomical features, preprocedural planning aided by 3D-printed models offers valuable insights for endovascular intervention. This study highlights the use of stereolithographic (SLA) 3D printing to fabricate a phantom of a challenging aortic arch aneurysm with a complex neck anatomy.

CLINICAL CASE

A 75-year-old female presented with a 58 mm descending thoracic aortic aneurysm (TAA) extending to the distal arch, involving the left subclavian artery (LSA) and the left common carotid artery (LCCA). The computed tomography (CT) scans underwent scrutiny by radiology and vascular teams. Nevertheless, the precise spatial relationships of the ostial origins proved to be challenging to ascertain. To address this, a patient-specific phantom of the aortic arch was fabricated utilizing an SLA printer and a biomedical resin. The thoracic endovascular aortic repair (TEVAR) procedure was simulated using fluoroscopy on the phantom to enhance procedural preparedness. Subsequently, the patient underwent a right carotid-left carotid bypass and a right carotid-left subclavian bypass. After a 24-hour interval, the patient underwent the TEVAR procedure, during which a 37 mm × 150 mm stent graft (CTAG, WL Gore and Associates, Flagstaff, AZ, USA) and a 40 mm × 200 mm stent graft (CTAG, WL Gore and Associates, Flagstaff, AZ, USA) were deployed, effectively covering the LSA and LCCA. Notably, the aneurysm exhibited complete sealing, with no indications of endoleaks or graft infoldings. At the 12-month follow-up, the patient remains in good health, with no evidence of endoleaks or any other surgery-related complication.

CONCLUSION

This report showcases the successful use of a 3D-printed endovascular phantom in guiding the decision-making process during the preparation for a TEVAR procedure. The simulation played a pivotal role in selecting the appropriate stent graft, ensuring an intervention protocol optimized based on the patient-specific anatomy.

Quality assurance of 3D-printed patient specific anatomical models: a systematic review

BACKGROUND

The responsible use of 3D-printing in medicine includes a context-based quality assurance. Considerable literature has been published in this field, yet the quality of assessment varies widely. The limited discriminatory power of some assessment methods challenges the comparison of results. The total error for patient specific anatomical models comprises relevant partial errors of the production process: segmentation error (SegE), digital editing error (DEE), printing error (PrE). The present review provides an overview to improve the general understanding of the process specific errors, quantitative analysis, and standardized terminology.

METHODS

This review focuses on literature on quality assurance of patient-specific anatomical models in terms of geometric accuracy published before December 4th, 2022 (n = 139). In an attempt to organize the literature, the publications are assigned to comparable categories and the absolute values of the maximum mean deviation (AMMD) per publication are determined therein.

RESULTS

The three major examined types of original structures are teeth or jaw (n = 52), skull bones without jaw (n = 17) and heart with coronary arteries (n = 16). VPP (vat photopolymerization) is the most frequently employed basic 3D-printing technology (n = 112 experiments). The median values of AMMD (AMMD: The metric AMMD is defined as the largest linear deviation, based on an average value from at least two individual measurements.) are 0.8 mm for the SegE, 0.26 mm for the PrE and 0.825 mm for the total error. No average values are found for the DEE.

CONCLUSION

The total error is not significantly higher than the partial errors which may compensate each other. Consequently SegE, DEE and PrE should be analyzed individually to describe the result quality as their sum according to rules of error propagation. Current methods for quality assurance of the segmentation are often either realistic and accurate or resource efficient. Future research should focus on implementing models for cost effective evaluations with high accuracy and realism. Our system of categorization may be enhancing the understanding of the overall process and a valuable contribution to the structural design and reporting of future experiments. It can be used to educate specialists for risk assessment and process validation within the additive manufacturing industry.

Graph matching and deep neural networks based whole heart and great vessel segmentation in congenital heart disease

Congenital heart disease (CHD) is one of the leading causes of mortality among birth defects, and due to significant variations in the whole heart and great vessel, automatic CHD segmentation using CT images has been always under-researched. Even though some segmentation algorithms have been developed in the literature, none perform very well under the complex structure of CHD. To deal with the challenges, we take advantage of deep learning in processing regular structures and graph algorithms in dealing with large variations and propose a framework combining both the whole heart and great vessel segmentation in complex CHD. We benefit from deep learning in segmenting the four chambers and myocardium based on the blood pool, and then we extract the connection information and apply graph matching to determine the categories of all the vessels. Experimental results on 68 3D CT images covering 14 types of CHD illustrate our framework can increase the Dice score by 12% on average compared with the state-of-the-art whole heart and great vessel segmentation method in normal anatomy. We further introduce two cardiovascular imaging specialists to evaluate our results in the standard of the Van Praagh classification system, and achieves well performance in clinical evaluation. All these results may pave the way for the clinical use of our method in the incoming future.

CMR and Percutaneous Treatment of Pulmonary Regurgitation: Outreach the Search for the Best Candidate

Performance of cardiovascular magnetic resonance (CMR) in the planning phase of percutaneous pulmonary valve implantation (PPVI) is needed for the accurate delineation of the right ventricular outflow tract (RVOT), coronary anatomy and the quantification of right ventricular (RV) volume overload in patients with significant pulmonary regurgitation (PR). This helps to find the correct timings for the intervention and prevention of PPVI-related complications such as coronary artery compression, device embolization and stent fractures. A defined CMR study protocol should be set for all PPVI candidates to reduce acquisition times and acquire essential sequences that are determinants for PPVI success. For correct RVOT sizing, contrast-free whole-heart sequences, preferably at end-systole, should be adopted in the pediatric population thanks to their high reproducibility and concordance with invasive angiographic data. When CMR is not feasible or contraindicated, cardiac computed tomography (CCT) may be performed for high-resolution cardiac imaging and eventually the acquisition of complementary functional data. The aim of this review is to underline the role of CMR and advanced multimodality imaging in the context of pre-procedural planning of PPVI concerning its current and potential future applications.

Uncertainty Quantification in the In Vivo Image-Based Estimation of Local Elastic Properties of Vascular Walls

Introduction: Patient-specific computational models are a powerful tool for planning cardiovascular interventions. However, the in vivo patient-specific mechanical properties of vessels represent a major source of uncertainty. In this study, we investigated the effect of uncertainty in the elastic module (E) on a Fluid–Structure Interaction (FSI) model of a patient-specific aorta. Methods: The image-based χ-method was used to compute the initial E value of the vascular wall. The uncertainty quantification was carried out using the generalized Polynomial Chaos (gPC) expansion technique. The stochastic analysis was based on four deterministic simulations considering four quadrature points. A deviation of about ±20% on the estimation of the E value was assumed. Results: The influence of the uncertain E parameter was evaluated along the cardiac cycle on area and flow variations extracted from five cross-sections of the aortic FSI model. Results of stochastic analysis showed the impact of E in the ascending aorta while an insignificant effect was observed in the descending tract. Conclusions: This study demonstrated the importance of the image-based methodology for inferring E, highlighting the feasibility of retrieving useful additional data and enhancing the reliability of in silico models in clinical practice.

Assessment of post-infarct ventricular septal defects through 3D printing and statistical shape analysis

BACKGROUND

Post-infarct ventricular septal defect (PIVSD) is a serious complication of myocardial infarction. We evaluated 3D-printing models in PIVSD clinical assessment and the feasibility of statistical shape modeling for morphological analysis of the defects.

METHODS

Models (n = 15) reconstructed from computed tomography data were evaluated by clinicians (n = 8). Statistical shape modeling was performed on 3D meshes to calculate the mean morphological configuration of the defects.

RESULTS

Clinicians' evaluation highlighted the models' utility in displaying defects for interventional/surgical planning, education/training and device development. However, models lack dynamic representation. Morphological analysis was feasible and revealed oval-shaped (n = 12) and complex channel-like (n = 3) defects.

CONCLUSION

3D-PIVSD models can complement imaging data for teaching and procedural planning. Statistical shape modeling is feasible in this scenario.

Considerations for Biventricular Conversion of Fontan Circulation

Despite significant improvements in the management of Fontan circulation in patients with single ventricle physiology, long-term outcomes continue to be suboptimal. Conversion to biventricular circulation is increasingly gaining popularity, particularly in the subset of patients who are not ideal Fontan candidates. Meticulous image-guided planning, extensive preoperative discussions, and a team-based approach are required for successful execution of complex biventricular conversion. A segmental approach to the anatomy of the heart defect allows methodical planning of the technique of biventricular conversion. Ventricular size and function continue to be the Achilles heel of successful biventricular repair. Long-term studies comparing outcomes in patients converted to biventricular circulation to those in patients with Fontan physiology are required to appropriately tailor management approaches to an individual patient.

3D‐Druck‐ und Silikonmodelle der Primäreffloreszenzen für die dermatologische Lehre im Fernstudium

Hintergrund und Ziele: Die Corona-Pandemie betrifft eine Fülle von verschiedenen Lebensaspekten - Herausforderungen in der medizinischen Behandlung sind hier unzweifelhaft von höchster Wichtigkeit. Allerdings muss auch, um die Ausbildung von Studierenden zu gewährleisten, fortlaufende medizinische Lehre stattfinden. Während eines Semesters mit Lockdown-Phasen und eingeschränktem Patientenkontakt für die Studierenden schickten wir jedem Studierenden ein Silikonmodell zu und baten um die Evaluation dieses Lernwerkzeugs. Methoden: Mittels zweier vollständig und irreversibel anonymisierter Online-Fragebögen befragten wir Studierende des Dermatologie-Semesters (n  =  222) an der Medizinischen Fakultät der Ludwig-Maximilians-Universität in München im Wintersemester 2020/2021 - anschließend an Online-Lehre - zu ihrem Verständnis und der Eigeneinschätzung zu Primäreffloreszenzen vor und nach Erhalt der Silikonübungsmodelle. Diese wurden durch Schichtung verschiedener Silikontypen in negative 3D-Polylactid-Formen hergestellt, um bestimmte Festigkeiten und Farben darzustellen. Ergebnisse: Insgesamt wurden Fragebögen von 211 (95,0 %) und 213 (95,9 %) der 222 Studierenden analysiert, jeweils vor und nach dem Erhalt der Silikonmodelle. Die Studierenden gaben eine statistisch signifikante Zunahme ihrer Fähigkeiten an (P < 0,001). Ein Großteil der Studierenden evaluierte die Silikonmodelle positiv und berichtete von einem besseren Verständnis und Lernen der Primäreffloreszenzen. Schlussfolgerungen: Diese Lehrstudie zeigt die Vorzüge der haptischen Erfahrung in der dermatologischen Lehre auf - nicht nur in Zeiten von COVID-19, sondern auch danach.

The usefulness of 3D printed heart models for medical student education in congenital heart disease

BACKGROUND

Three-dimensional (3D) printing technology enables the translation of 2-dimensional (2D) medical imaging into a physical replica of a patient's individual anatomy and may enhance the understanding of congenital heart defects (CHD). We aimed to evaluate the usefulness of a spectrum of 3D-printed models in teaching CHD to medical students.

RESULTS

We performed a prospective, randomized educational procedure to teach fifth year medical students four CHDs (atrial septal defect (ASD, n = 74), ventricular septal defect (VSD, n = 50), coarctation of aorta (CoA, n = 118) and tetralogy of Fallot (ToF, n = 105)). Students were randomized into printing groups or control groups. All students received the same 20 min lecture with projected digital 2D images. The printing groups also manipulated 3D printed models during the lecture. Both groups answered an objective survey (Multiple-choice questionnaire) twice, pre- and post-test, and completed a post-lecture subjective survey. Three hundred forty-seven students were included and both teaching groups for each CHD were comparable in age, sex and pre-test score. Overall, objective knowledge improved after the lecture and was higher in the printing group compared to the control group (16.3 ± 2.6 vs 14.8 ± 2.8 out of 20, p < 0.0001). Similar results were observed for each CHD (p = 0.0001 ASD group; p = 0.002 VSD group; p = 0.0005 CoA group; p = 0.003 ToF group). Students' opinion of their understanding of CHDs was higher in the printing group compared to the control group (respectively 4.2 ± 0.5 vs 3.8 ± 0.4 out of 5, p < 0.0001).

CONCLUSION

The use of 3D printed models in CHD lectures improve both objective knowledge and learner satisfaction for medical students. The practice should be mainstreamed.

3D Printing-A Cutting Edge Technology for Treating Post-Infarction Patients

The increasing complexity of cardiovascular interventions requires advanced peri-procedural imaging and tailored treatment. Three-dimensional printing technology represents one of the most significant advances in the field of cardiac imaging, interventional cardiology or cardiovascular surgery. Patient-specific models may provide substantial information on intervention planning in complex cardiovascular diseases, and volumetric medical imaging from CT or MRI can be translated into patient-specific 3D models using advanced post-processing applications. 3D printing and additive manufacturing have a great variety of clinical applications targeting anatomy, implants and devices, assisting optimal interventional treatment and post-interventional evaluation. Although the 3D printing technology still lacks scientific evidence, its benefits have been shown in structural heart diseases as well as for treatment of complex arrhythmias and corrective surgery interventions. Recent development has enabled transformation of conventional 3D printing into complex 3D functional living tissues contributing to regenerative medicine through engineered bionic materials such hydrogels, cell suspensions or matrix components. This review aims to present the most recent clinical applications of 3D printing in cardiovascular medicine, highlighting also the potential for future development of this revolutionary technology in the medical field.

3D Printing in Modern Cardiology

BACKGROUND

3D printing represents an emerging technology in the field of cardiovascular medicine. 3D printing can help to perform a better analysis of complex anatomies to optimize intervention planning.

METHODS

A systematic review was performed to illustrate the 3D printing technology and to describe the workflow to obtain 3D printed models from patient-specific images. Examples from our laboratory of the benefit of 3D printing in planning interventions were also reported.

RESULTS

3D printing technique is reliable when applied to high-quality 3D image data (CTA, CMR, 3D echography), but it still needs the involvement of expert operators for image segmentation and mesh refinement. 3D printed models could be useful in interventional planning, although prospective studies with comprehensive and clinically meaningful endpoints are required to demonstrate the clinical utility.

CONCLUSION

3D printing can be used to improve anatomy understanding and surgical planning.

Clinical Value of Virtual Reality versus 3D Printing in Congenital Heart Disease

Both three-dimensional (3D) printing and virtual reality (VR) are reported as being superior to the current visualization techniques in conveying more comprehensive visualization of congenital heart disease (CHD). However, little is known in terms of their clinical value in diagnostic assessment, medical education, and preoperative planning of CHD. This cross-sectional study aims to address these by involving 35 medical practitioners to subjectively evaluate VR visualization of four selected CHD cases in comparison with the corresponding 3D printed heart models (3DPHM). Six questionnaires were excluded due to incomplete sections, hence a total of 29 records were included for the analysis. The results showed both VR and 3D printed heart models were comparable in terms of the degree of realism. VR was perceived as more useful in medical education and preoperative planning compared to 3D printed heart models, although there was no significant difference in the ratings (p = 0.54 and 0.35, respectively). Twenty-one participants (72%) indicated both the VR and 3DPHM provided additional benefits compared to the conventional medical imaging visualizations. This study concludes the similar clinical value of both VR and 3DPHM in CHD, although further research is needed to involve more cardiac specialists for their views on the usefulness of these tools.

Application of 3D printing technology combined with PBL teaching model in teaching clinical nursing in congenital heart surgery: A case-control study

We aimed to explore the application of three-dimensional (3D) printing technology with problem-based learning (PBL) teaching model in clinical nursing education of congenital heart surgery, and to further improve the teaching quality of clinical nursing in congenital heart surgery. In this study, a total of 132 trainees of clinical nursing in congenital heart surgery from a grade-A tertiary hospital in 2019 were selected and randomly divided into 3D printing group or traditional group. The 3D printing group was taught with 3D printed heart models combined with PBL teaching technique, while the traditional group used conventional teaching aids combined with PBL technique for teaching. After the teaching process, the 2 groups of nursing students were assessed and surveyed separately to evaluate the results. Compared to the traditional group, the theoretical scores, clinical nursing thinking ability, self-evaluation for comprehensive ability, and teaching satisfaction from the questionnaires filled by the 3D printing group were all higher than the traditional group. The difference was found to be statistically significant (P < .05). Our study has shown the 3D printing technology combined with the PBL teaching technique in the clinical nursing teaching of congenital heart surgery achieved good results.

Stereoscopic virtual reality does not improve knowledge acquisition of congenital heart disease

Advances in virtual reality have made it possible for clinicians and trainees to interact with 3D renderings of hearts with congenital heart disease in 3D stereoscopic vision. No study to date has assessed whether this technology improved instruction compared to standard 2D interfaces. The purpose of this study was to assess whether stereoscopic virtual reality improves congenital heart disease anatomy education. Subjects in a prospective, blinded, randomized trial completed a pre-test assessing factual and visuospatial knowledge of common atrioventricular canal and were randomized to an intervention or control group based on their score. The intervention group used a 3D virtual reality (VR) headset to visualize a lecture with 3D heart models while the control group used a desktop (DT) computer interface with the same models. Subjects took a post-test and provided subjective feedback. 51 subjects were enrolled, 24 in the VR group & 27 in the DT group. The median score difference for VR subjects was 12 (IQR 9-13.3), compared to 10 (IQR 7.5-12) in the DT group. No difference in score improvement was found (p = 0.11). VR subjects' impression of the ease of use of their interface was higher than DT subjects (median 8 vs 7, respectively, p = 0.01). VR subjects' impression of their understanding of the subject matter was higher than desktop subjects (median 7 vs 5, respectively, p = 0.01). There was no statistically significant difference in the knowledge acquisition observed between the stereoscopic virtual reality group and the monoscopic desktop-based group. Participants in virtual reality reported a better learning experience and self-assessment suggesting virtual reality may increase learner engagement in understanding congenital heart disease.

Mixed reality holograms for heart surgery planning: first user experience in congenital heart disease

AIMS

Proof of concept and feasibility study for preoperative diagnostic use of mixed reality (MR) holograms of individual 3D heart models from standard cardiac computed tomography angiograms (CTA) images. Optimal repair for complex congenital heart disease poses high demands on 3D anatomical imagination. Three-dimensional printed heart models are increasingly used for improved morphological understanding during surgical and interventional planning. Holograms are a dynamic and interactive alternative, probably with wider applications.

METHODS AND RESULTS

A 3D heart model was segmented from CTA images in a patient with double outlet right ventricle and transposition of the great arteries (DORV-TGA). The hologram was visualized in the wearable MR platform HoloLens® for 36 paediatric heart team members who filled out a diagnostic and quality rating questionnaire. Morphological and diagnostic output from the hologram was assessed and the 3D experience was evaluated. Locally developed app tools such as hologram rotation, scaling, and cutting were rated. Anatomy identification and diagnostic output was high as well as rating of 3D experience. Younger and female users rated the app tools higher.

CONCLUSION

This preliminary study demonstrates that MR holograms as surgical planning tool for congenital heart disease may have a high diagnostic value and contribute to understanding complex morphology. The first users experience of the hologram presentation was found to be very positive, with a preference among the female and the younger users. There is potential for improvement of the hologram manipulation tools.

Utility of three-dimensional printed heart models for education on complex congenital heart diseases

OBJECTIVE

The objective of this study was to evaluate the feasibility and effects of education on complex congenital heart diseases using patient-specific three-dimensional printed heart models.

METHODS

Three-dimensional printed heart models were created using computed tomography data obtained from 11 patients with complex congenital heart disease. Fourteen kinds of heart models, encompassing nine kinds of complex congenital heart disease were printed. Using these models, a series of educational hands-on seminars, led by an experienced paediatric cardiac surgeon and a paediatric cardiologist, were conducted for medical personnel who were involved in the care of congenital heart disease patients. Contents of the seminars included anatomy, three-dimensional structure, pathophysiology, and surgery for each diagnosis. Likert-type (10-point scale) questionnaires were used before and after each seminar to evaluate the effects of education.

RESULTS

Between November 2019 and June 2020, a total of 16 sessions of hands-on seminar were conducted. The total number of questionnaire responses was 75. Overall, participants reported subjective improvement in understanding anatomy (4.8 ± 2.1 versus 8.4 ± 1.1, p < 0.001), three-dimensional structure (4.6 ± 2.2 versus 8.9 ± 1.0, p < 0.001), pathophysiology (4.8 ± 2.2 versus 8.5 ± 1.0, p < 0.001), and surgery (4.9 ± 2.3 versus 8.8 ± 0.9, p < 0.001) of the congenital heart disease investigated.

CONCLUSIONS

The utilisation of three-dimensional printed heart models for education on complex congenital heart disease was feasible and improved medical personnel's understanding of complex congenital heart disease. This education tool may be an effective alternative to conventional education tools for complex congenital heart disease.

Advanced Medical Use of Three-Dimensional Imaging in Congenital Heart Disease: Augmented Reality, Mixed Reality, Virtual Reality, and Three-Dimensional Printing

Three-dimensional (3D) imaging and image reconstruction play a prominent role in the diagnosis, treatment planning, and post-therapeutic monitoring of patients with congenital heart disease. More interactive and realistic medical experiences take advantage of advanced visualization techniques like augmented, mixed, and virtual reality. Further, 3D printing is now used in medicine. All these technologies improve the understanding of the complex morphologies of congenital heart disease. In this review article, we describe the technical advantages and disadvantages of various advanced visualization techniques and their medical applications in the field of congenital heart disease. In addition, unresolved issues and future perspectives of these evolving techniques are described.

Three-Dimensional Printing, Virtual Reality and Mixed Reality for Pulmonary Atresia: Early Surgical Outcomes Evaluation

BACKGROUND

Single-stage unifocalisation for pulmonary atresia (PA) with ventricular septal defect (VSD) and major aortopulmonary collateral arteries (MAPCA) requires a high degree of three-dimensional (3D) anatomical imagination. A previous study has reported the application of a 3D-printed heart model with virtual reality (VR) or mixed reality (MR). However, few studies have evaluated the surgical outcomes of the 3D model with VR or MR in PA/VSD patients.

METHODS

Three-dimensional (3D) heart models of five selected PA/VSD patients were derived from traditional imageology of their hearts. Using VR glasses, the 3D models were also visualised in the operating room. Both the 3D-printed heart models and preoperative evaluation by VR were used in the five selected patients for surgical simulation and better anatomical understanding. Mixed reality holograms were used as perioperative assistive tools. Surgical outcomes were assessed, including in-hospital and early follow-up clinical data.

RESULTS

The use of these three new technologies had favourable feedback from the surgeons on intraoperative judgment. There were no in-hospital or early deaths. No reintervention was required until the last follow-up. Three (3) patients developed postoperative complications: one had right bundle branch block and ST-segment change, one had chest drainage >7 days (>40 mL/day) and one had pneumonia.

CONCLUSION

The preoperative application of a 3D-printed heart model with VR or MR helped in aligning the surgical field. These technologies improved the understanding of complicated cardiac anatomy and achieved acceptable surgical outcomes as guiding surgical planning.

Three-Dimensional CAD in Skull Reconstruction: A Narrative Review with Focus on Cranioplasty and Its Potential Relevance to Brain Sciences

In patients suffering from severe traumatic brain injury and massive stroke (hemorrhagic or ischemic), decompressive craniectomy (DC) is a surgical strategy used to reduce intracranial pressure, and to prevent brainstem compromise from subsequent brain edema. In surviving patients, cranioplasty surgery helps to protect brain tissue, and correct the external deformity. The aesthetic outcome of cranioplasty using an asymmetrical implant can negatively influence patients physically and mentally, especially young patients. Advancements in the development of biomaterials have now made three-dimensional (3-D) computer-assisted design/manufacturing (CAD/CAM)-fabricated implants an optimal choice for the repair of skull defects following DC. Here, we summarize the various materials for cranioplasty, including xenogeneic, autogenous, and alloplastic grafts. The processing procedures of the CAD/CAM technique are briefly outlined, and reflected our experiences to reconstruct skull CAD models using commercial software, published previously, to assess aesthetic outcomes of regular 3-D CAD models without contouring elevation or depression. The establishment of a 3-D CAD model ensures a possibility for better aesthetic outcomes of CAM-derived alloplastic implants. Finally, clinical consideration of the CAD algorithms for adjusting contours and their potential application in prospective healthcare are briefly outlined.

Three-Dimensional CAD in Skull Reconstruction: A Narrative Review with Focus on Cranioplasty and Its Potential Relevance to Brain Sciences

In patients suffering from severe traumatic brain injury and massive stroke (hemorrhagic or ischemic), decompressive craniectomy (DC) is a surgical strategy used to reduce intracranial pressure, and to prevent brainstem compromise from subsequent brain edema. In surviving patients, cranioplasty surgery helps to protect brain tissue, and correct the external deformity. The aesthetic outcome of cranioplasty using an asymmetrical implant can negatively influence patients physically and mentally, especially young patients. Advancements in the development of biomaterials have now made three-dimensional (3-D) computer-assisted design/manufacturing (CAD/CAM)-fabricated implants an optimal choice for the repair of skull defects following DC. Here, we summarize the various materials for cranioplasty, including xenogeneic, autogenous, and alloplastic grafts. The processing procedures of the CAD/CAM technique are briefly outlined, and reflected our experiences to reconstruct skull CAD models using commercial software, published previously, to assess aesthetic outcomes of regular 3-D CAD models without contouring elevation or depression. The establishment of a 3-D CAD model ensures a possibility for better aesthetic outcomes of CAM-derived alloplastic implants. Finally, clinical consideration of the CAD algorithms for adjusting contours and their potential application in prospective healthcare are briefly outlined.

Three-dimensional printing in congenital heart disease

Three-dimensional printing (3Dp) has a broad array of medical applications and has been applied extensively in congenital heart disease given the variety and complexity of lesions encountered. 3Dps are unique when compared to other imaging modalities in that they are theoretically equally interpretable by radiologists, cardiologists and surgeons. The literature regarding 3Dp in congenital heart disease is recent and burgeoning. This review, categorized by application, should provide the reader with a comprehensive, albeit not complete, overview of 3Dp in congenital heart disease during the last decade.

3D Printing Applications for Transcatheter Aortic Valve Replacement

PURPOSE OF REVIEW

A combination of evolving 3D printing technologies, new 3D printable materials, and multi-disciplinary collaborations have made 3D printing applications for transcatheter aortic valve replacement (TAVR) a promising tool to promote innovation, increase procedural success, and provide a compelling educational tool. This review synthesizes the knowledge via publications and our group's experience in this area that exemplify uses of 3D printing for TAVR.

RECENT FINDINGS

Patient-specific 3D-printed models have been used for TAVR pre-procedural device sizing, benchtop prediction of procedural complications, planning for valve-in-valve and bicuspid aortic valve procedures, and more. Recent publications also demonstrate how 3D printing can be used to test assumptions about why certain complications occur during THV implantation. Finally, new materials and combinations of existing materials are starting to bridge the large divide between current 3D material and cardiac tissue properties. Several studies have demonstrated the utility of 3D printing in understanding challenges of TAVR. Innovative approaches to benchtop testing and multi-material printing have brought us closer to being able to predict how a THV will interact with a specific patient's aortic anatomy. This work to date is likely to open the door for advancements in other areas of structural heart disease, such as interventions involving the mitral valve, tricuspid valve, and left atrial appendage.

Impact of 3D Printouts in Optimizing Surgical Results for Complex Congenital Heart Disease

Planning corrective and palliative surgery for patients who have complex congenital heart disease often relies on the assessment of cardiac anatomy using two-dimensional noninvasive cardiac imaging modalities (echocardiography, cardiac magnetic resonance imaging, and computed tomography scan). Advances in cardiac noninvasive imaging now include the use of three-dimensional (3D) reconstruction tools that produce 3D images and 3D printouts. There is scant evidence available in the literature as to what effect the availability of 3D printouts of complex congenital heart defects has on surgical outcomes. Surgical outcomes of study subjects with a 3D cardiac printout available and their paired control subject without a 3D cardiac printout available were compared. We found a trend toward shorter surgical times in the study group who had the benefit of 3D models, but no statistical significance was found for bypass time, cross-clamp time, total time, length of stay, or respiratory support. These preliminary results support the proposal that 3D modeling be made readily available to congenital cardiac surgery teams, for use in patients with the most complex congenital heart disease.

Utility of 3D Printed Cardiac Models for Medical Student Education in Congenital Heart Disease: Across a Spectrum of Disease Severity

The most common modes of medical education for congenital heart disease (CHD) rely heavily on 2-dimensional imaging. Three-dimensional (3D) printing technology allows for the creation of physical cardiac models that can be used for teaching trainees. 3D printed cardiac models were created for the following lesions: pulmonic stenosis, atrial septal defect, tetralogy of Fallot, d-transposition of the great arteries, coarctation of the aorta, and hypoplastic left heart syndrome. Medical students participated in a workshop consisting of different teaching stations. At the 3D printed station, students completed a pre- and post-intervention survey assessing their knowledge of each cardiac lesion on a Likert scale. Students were asked to rank the educational benefit of each modality. Linear regression was utilized to assess the correlation of the mean increase in knowledge with increasing complexity of CHD based on the Aristotle Basic Complexity Level. 45 medical students attended the CHD workshop. Students' knowledge significantly improved for every lesion (p < 0.001). A strong positive correlation was found between mean increase in knowledge and increasing complexity of CHD (R² = 0.73, p < 0.05). The 3D printed models, pathology specimens and spoken explanation were found to be the most helpful modalities. Students "strongly agreed" the 3D printed models made them more confident in explaining congenital cardiac anatomy to others (mean = 4.23, ± 0.69), and that they recommend the use of 3D models for future educational sessions (mean = 4.40, ± 0.69). 3D printed cardiac models should be included in medical student education particularly for lesions that require a complex understanding of spatial relationships.

Utility of a super-flexible three-dimensional printed heart model in congenital heart surgery

OBJECTIVES

The objective of this study was to assess the utility of 3D printed heart models of congenital heart disease for preoperative surgical simulation.

METHODS

Twenty patient-specific 3D models were created between March 2015 and August 2017. All operations were performed by a young consultant surgeon who had no prior experience with complex biventricular repair. All 15 patients with balanced ventricles had outflow tract malformations (double-outlet right ventricle in 7 patients, congenitally corrected transposition of great arteries in 5, transposition of great arteries in 1, interrupted aortic arch Type B in 1, tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries in 1). One patient had hypoplastic left heart complex, and the remaining 4 patients had a functional single ventricle. The median age at operation was 1.4 (range 0.1-5.9) years. Based on a multislice computed tomography data set, the 3D models were made of polyurethane resins using stereolithography as the printing technology and vacuum casting as the manufacturing method.

RESULTS

All but 4 patients with a functional single ventricle underwent complete biventricular repair. The median cardiopulmonary bypass time and aortic cross-clamp time were 345 (110-570) min and 114 (35-293) min, respectively. During the median follow-up period of 1.3 (0.1-2.5) years, no mortality was observed. None of the patients experienced surgical heart block or systemic ventricular outflow tract obstruction.

CONCLUSIONS

Three-dimensional printed heart models showed potential utility, especially in understanding the relationship between intraventricular communications and great vessels, as well as in simulation for creating intracardiac pathways.

3D printing approaches for cardiac tissue engineering and role of immune modulation in tissue regeneration

Conventional tissue engineering, cell therapy, and current medical approaches were shown to be successful in reducing mortality rate and complications caused by cardiovascular diseases (CVDs). But still they have many limitations to fully manage CVDs due to complex composition of native myocardium and microvascularization. Fabrication of fully functional construct to replace infarcted area or regeneration of progenitor cells is important to address CVDs burden. Three-dimensional (3D) printed scaffolds and 3D bioprinting technique have potential to develop fully functional heart construct that can integrate with native tissues rapidly. In this review, we presented an overview of 3D printed approaches for cardiac tissue engineering, and advances in 3D bioprinting of cardiac construct and models. We also discussed role of immune modulation to promote tissue regeneration.

Cardiac patient-specific three-dimensional models as surgical planning tools

BACKGROUND

Three-dimensional printing is an additive manufacturing method that builds objects from digitally generated computational models. Core technologies behind three-dimensional printing are evolving rapidly with major advances in materials, resolution, and speed that enable greater realism and higher accuracy. These improvements have led to novel applications of these processes in the medical field.

METHODS

The process of going from a medical image data set (computed tomography, magnetic resonance imaging, ultrasound) to a physical three-dimensional print includes several steps that are described. Medical images originate from Digital Imaging and Communications in Medicine files or data sets, the current standard for storing and transmitting medical images. Via Digital Imaging and Communications in Medicine manipulation software packages, a segmentation process, and manual intervention by an expert user, three-dimensional digital and printed models can be constructed in great detail.

RESULTS

Cardiovascular medicine is one of the fastest growing applications for medical three-dimensional printing. The technology is more frequently being used for patient and clinician education, preprocedural planning, and medical device design and prototyping. We report on three case studies, describing how our three-dimensional printing has contributed to the care of cardiac patients at the University of Minnesota.

CONCLUSION

Medical applications of computational three-dimensional modeling and printing are already extensive and growing rapidly and are routinely used for visualizing complex anatomies from patient imaging files to plan surgeries and create surgical simulators. Studies are needed to determine whether three-dimensional printed models are cost effective and can consistently improve clinical outcomes before they become part of routine clinical practice.

3D Printing and Heart Failure: The Present and the Future

Advanced imaging modalities provide essential anatomic and spatial information in patients with complex heart disease. Two-dimensional imaging can be limited in the extent to which true 3-dimensional (3D) relationships are represented. The application of 3D printing technology has increased the creation of physical models that overcomes the limitations of a 2D screen. Many groups have reported the use of 3D printing for preprocedural planning in patients with different causes of heart failure. This paper reviews the innovative applications of this technique to provide patient-specific models to improve patient care.

Exploration of time sequential, patient specific 3D heart unlocks clinical understanding

Objectives

The purpose was to create a time sequential three-dimensional virtual reality model, also referred to as a four-dimensional model, to explore its possible benefit and clinical applications. We hypothesized that this novel solution allows for the visuospatial benefits of the 3D model and the dynamic benefits of other existing imaging modalities.

Background

We have seen how 3D models hold great value in medical decision making by eliminating the variable visuospatial skills of practitioners. They have proved especially invaluable concerning the correction of congenital heart defects and have altered the course of many surgeries. There are, however, limitations to three-dimensional models. The static models only show what the heart looks like in one snapshot of its cycle and do not allow for an understanding of the physiological and dynamic processes.

Methods

This solution segments a 3D heart derived from a 2D image stack, times the 18 phases of a cardiac cycle and creates a 4D model that can be manipulated in space and time through the use of virtual reality.

Results

We believe the 4D heart provides a unique understanding of in situ cardiac anatomy not possible with other imaging techniques. Our expanding case series of clinician experiences and their immediate recognition of the potency of this technique is highly encouraging and reveals the future of functional and dynamic 4D representations of anatomy.

Conclusions

The 4D heart improved our understanding around complex 3D relationships over time. We propose time and effort dedicated to 4D cardiac imaging analysis of dynamic cardiac pathologies such as hypertrophic obstructive cardiomyopathy or a pre-op Rastelli repair with a narrow outflow tract could offer tremendous insight into the medical decision-making process.

Electronic supplementary material

The online version of this article (10.1186/s41205-018-0034-7) contains supplementary material, which is available to authorized users.

Current and future applications of 3D printing in congenital cardiology and cardiac surgery

Three-dimensional (3D) printing technology in congenital cardiology and cardiac surgery has experienced a rapid development over the last decade. In presence of complex cardiac and extra-cardiac anatomies, the creation of a physical, patient-specific model is attractive to most clinicians. However, at the present time, there is still a lack of strong scientific evidence of the benefit of 3D models in clinical practice and only qualitative evaluation of the models has been used to investigate their clinical use. 3D models can be printed in rigid or flexible materials, and the original size can be augmented depending on the application the models are needed for. The most common applications of 3D models at present include procedural planning of complex surgical or interventional cases, in vitro simulation for research purposes, training and communication with patients and families. The aim of this pictorial review is to describe the basic principles of this technology and present its current and future applications.

Pre-procedural fit-testing of TAVR valves using parametric modeling and 3D printing

BACKGROUND

Successful transcatheter aortic valve replacement (TAVR) requires an understanding of how a prosthetic valve will interact with a patient's anatomy in advance of surgical deployment. To improve this understanding, we developed a benchtop workflow that allows for testing of physical interactions between prosthetic valves and patient-specific aortic root anatomy, including calcified leaflets, prior to actual prosthetic valve placement.

METHODS

This was a retrospective study of 30 patients who underwent TAVR at a single high volume center. By design, the dataset contained 15 patients with a successful annular seal (defined by an absence of paravalvular leaks) and 15 patients with a sub-optimal seal (presence of paravalvular leaks) on post-procedure transthoracic echocardiogram (TTE). Patients received either a balloon-expandable (Edwards Sapien or Sapien XT, n = 15), or a self-expanding (Medtronic CoreValve or Core Evolut, n = 14, St. Jude Portico, n = 1) valve. Pre-procedural computed tomography (CT) angiograms, parametric geometry modeling, and multi-material 3D printing were utilized to create flexible aortic root physical models, including displaceable calcified valve leaflets. A 3D printed adjustable sizing device was then positioned in the aortic root models and sequentially opened to larger valve sizes, progressively flattening the calcified leaflets against the aortic wall. Optimal valve size and fit were determined by visual inspection and quantitative pressure mapping of interactions between the sizer and models.

RESULTS

Benchtop-predicted "best fit" valve size showed a statistically significant correlation with gold standard CT measurements of the average annulus diameter (n = 30, p < 0.0001 Wilcoxon matched-pairs signed rank test). Adequateness of seal (presence or absence of paravalvular leak) was correctly predicted in 11/15 (73.3%) patients who received a balloon-expandable valve, and in 9/15 (60%) patients who received a self-expanding valve. Pressure testing provided a physical map of areas with an inadequate seal; these corresponded to areas of paravalvular leak documented by post-procedural transthoracic echocardiography.

CONCLUSION

We present and demonstrate the potential of a workflow for determining optimal prosthetic valve size that accounts for aortic annular dimensions as well as the active displacement of calcified valve leaflets during prosthetic valve deployment. The workflow's open source framework offers a platform for providing predictive insights into the design and testing of future prosthetic valves.

Utility of three-dimensional models in resident education on simple and complex intracardiac congenital heart defects

OBJECTIVE

Applications of three-dimensional (3D) printed models in medicine include preprocedure planning, patient education, and clinical training. Reproducing complex anatomy as a 3D printed model can be useful for understanding congenital heart defects (CHD). We hypothesized that using 3D printed models during didactic sessions with resident physicians will improve trainees' understanding of CHD.

DESIGN AND INTERVENTION

We performed a prospective, randomized educational intervention for teaching pediatric and pediatric/emergency medicine residents about simple (ventricular septal defect [VSD]) and moderately complex (tetralogy of Fallot [ToF]) CHD. Residents were divided into two groups: intervention and control. Each group completed a subjective survey about their comfort with the anatomy, evaluation, and treatment of VSD and ToF and took an objective test on VSD and ToF. They separately received the same 20 min lecture, including projected two-dimensional digital images of VSD and ToF; the intervention group was given 3D printed models created using the same imaging data. After the lecture, the groups repeated the survey and test questions.

RESULTS

Twenty-six residents participated in the VSD session, 34 in the ToF. There were no differences in demographics between control and intervention groups. All residents had higher subjective comfort with VSD and ToF after the lectures. There was no difference in baseline test scores for VSD or ToF groups. The control group scored higher on the VSD postlecture test. The intervention group scored higher on the ToF postlecture test.

CONCLUSION

Incorporation of 3D printed models into lectures about CHD imparts a greater acute level of understanding, both subjective and objective, for pediatric and combined pediatric/emergency medicine residents. There does not seem to be an added benefit for understanding ventricular septal defects, but there is for tetralogy of Fallot, likely due to increased complexity of the lesion and difficulty visualizing spatial relationships in CHD with multiple components.

Novel, 3D Display of Heart Models in the Postoperative Care Setting Improves CICU Caregiver Confidence

BACKGROUND

Postoperative care delivered in the pediatric cardiac intensive care unit (CICU) relies on providers' understanding of patients' congenital heart defects (CHDs) and procedure performed. Novel, bedside use of virtual, three-dimensional (3D) heart models creates access to patients' CHD to improve understanding. This study evaluates the impact of patient-specific virtual 3D heart models on CICU provider attitudes and care delivery.

METHODS

Virtual 3D heart models were created from standard preoperative cardiac imaging of ten patients with CHD undergoing repair and displayed on a bedside tablet in the CICU. Providers completed a Likert questionnaire evaluating the models' value in understanding anatomy and improving care delivery. Responses were compared using two-tailed t test and Mann-Whitney U test and were also compared to previously collected CICU provider responses regarding use of printed 3D heart models.

RESULTS

Fifty-three clinicians (19 physicians, 34 nurses/trainees) participated; 49 (92%) of 53 and 44 (83%) of 53 reported at least moderate to high satisfaction with the virtual 3D heart's ability to enhance understanding of anatomy and surgical repair, respectively. Seventy-one percent of participants felt strongly that virtual 3D models improved their ability to manage postoperative problems. The majority of both groups (63% physicians, 53% nurses) felt that virtual 3D heart models improved CICU handoffs. Virtual 3D heart models were as effective as printed models in improving understanding and care delivery, with a noted provider preference for printed 3D heart models.

CONCLUSIONS

Virtual 3D heart models depicting patient-specific CHDs are perceived to improve understanding and postoperative care delivery in the CICU.

Management of post-myocardial infarction ventricular septal defects: A critical assessment

BACKGROUND

Post-myocardial infarction (MI) ventricular septal defects (PIVSD) are an uncommon but life-threatening complication of acute MI. Although surgical closure has been the standard of care, mortality, and recurrence of VSD remain high even after emergent surgery. Transcatheter VSD closure (TCC) devices have become an alternative or adjunct to surgical closure.

METHODS

Online database search was performed for studies that included adults with PIVSD who underwent medical treatment (MT) alone, surgical closure (SC) (early or late), and TCC (early, late, or for post-surgical residual VSD).

RESULTS

Twenty-six studies were included with a total of 737 patients who underwent either MT (N = 100), SC (early (n = 167), late (n = 100)), and TCC (early (n = 176), late (n = 115), or post-surgical residual VSD (n = 79)). The 30-day mortality among MT group was 92 ± 6.3%, among SC was 61 ± 22.5% (early 56 ± 23%, late 41 ± 30%), and for all TCC patients was 33 ± 24% (early 54 ± 32.7%, late 16 ± 26%), and TCC for post-surgical residual VSD 11 ± 34.9%. The mortality among overall SC, overall TCC and early TCC groups was significantly lower as compared with the MT (P < 0.001 for all comparisons). The overall mortality among all TCC, and late TCC groups was significantly lower when compared with the late SC (P < 0.0001, P < 0.0001, respectively).

CONCLUSION

Closure of PIVSD decreases mortality as compared with MT alone and should be attempted as early as possible after diagnosis. Selection of TCC versus SC should be based on factors including complexity of the defect, availability of closure devices, expertise of the operator, and clinical condition of patient.

The Various Applications of 3D Printing in Cardiovascular Diseases

PURPOSE OF REVIEW

To highlight the various applications of 3D printing in cardiovascular disease and discuss its limitations and future direction.

RECENT FINDINGS

Use of handheld 3D printed models of cardiovascular structures has emerged as a facile modality in procedural and surgical planning as well as education and communication. Three-dimensional (3D) printing is a novel imaging modality which involves creating patient-specific models of cardiovascular structures. As percutaneous and surgical therapies evolve, spatial recognition of complex cardiovascular anatomic relationships by cardiologists and cardiovascular surgeons is imperative. Handheld 3D printed models of cardiovascular structures provide a facile and intuitive road map for procedural and surgical planning, complementing conventional imaging modalities. Moreover, 3D printed models are efficacious educational and communication tools. This review highlights the various applications of 3D printing in cardiovascular diseases and discusses its limitations and future directions.

Innovation in 3D Echocardiographic Imaging

PURPOSE OF REVIEW

The purpose of this review is to detail three-dimensional echocardiographic (3DE) innovations in pre-surgical planning of congenital heart disease, guidance of catheter interventions such as fusion imaging, and functional assessment of patients with congenital heart disease.

RECENT FINDINGS

Innovations in 3DE have helped us delineate the details of atrioventricular valve function and understand the mechanism of atrioventricular valve failure in patients with atrioventricular septal defect and single ventricle post repair. Advancement in holographic display of 3D datasets allows for better manipulation of 3D images in three dimensions and better understanding of anatomic relationships. 3DE with fusion imaging reduces radiation in catheter interventions and provides presentations of 3DE images in the similar fashion as the fluoroscopic images to improve communication between cardiologists. Lastly, 3DE allows for quantitative ventricular volumetric and functional assessment. Recent innovations in 3DE allow for pre-surgical planning for congenital heart disease, reduce radiation using fusion imaging in catheter interventions, and enable accurate assessment of ventricular volume and function without geometric assumptions.

Innovations in Preoperative Planning: Insights into Another Dimension Using 3D Printing for Cardiac Disease

Two-dimensional visualization of complex congenital heart disease has limitations in that there is variation in the interpretation by different individuals. Three-dimensional printing technology has been in use for decades but is currently becoming more commonly used in the medical field. Congenital heart disease serves as an ideal pathology to employ this technology because of the variation of anatomy between patients. In this review, the authors aim to discuss basics of applicability of three-dimensional printing, the process involved in creating a model, as well as challenges with establishing utility and quality.

Virtual medicine: Utilization of the advanced cardiac imaging patient avatar for procedural planning and facilitation

Advances in imaging technology have led to a paradigm shift from planning of cardiovascular procedures and surgeries requiring the actual patient in a "brick and mortar" hospital to utilization of the digitalized patient in the virtual hospital. Cardiovascular computed tomographic angiography (CCTA) and cardiovascular magnetic resonance (CMR) digitalized 3-D patient representation of individual patient anatomy and physiology serves as an avatar allowing for virtual delineation of the most optimal approaches to cardiovascular procedures and surgeries prior to actual hospitalization. Pre-hospitalization reconstruction and analysis of anatomy and pathophysiology previously only accessible during the actual procedure could potentially limit the intrinsic risks related to time in the operating room, cardiac procedural laboratory and overall hospital environment. Although applications are specific to areas of cardiovascular specialty focus, there are unifying themes related to the utilization of technologies. The virtual patient avatar computer can also be used for procedural planning, computational modeling of anatomy, simulation of predicted therapeutic result, printing of 3-D models, and augmentation of real time procedural performance. Examples of the above techniques are at various stages of development for application to the spectrum of cardiovascular disease processes, including percutaneous, surgical and hybrid minimally invasive interventions. A multidisciplinary approach within medicine and engineering is necessary for creation of robust algorithms for maximal utilization of the virtual patient avatar in the digital medical center. Utilization of the virtual advanced cardiac imaging patient avatar will play an important role in the virtual health care system. Although there has been a rapid proliferation of early data, advanced imaging applications require further assessment and validation of accuracy, reproducibility, standardization, safety, efficacy, quality, cost effectiveness, and overall value to medical care.