The Role of Three-Dimensional Printing in Contemporary Vascular and Endovascular Surgery: A Systematic Review

Three-Dimensional Printing Application in a Challenging Case of Type II Endoleak

PURPOSE

To highlight the importance of 3-dimensional (3D) arterial printing in a case of type II endoleak (EL) embolization.

CASE REPORT

An 81-year-old patient, previously treated with endovascular aortic repair (EVAR), developed a type II EL requiring treatment. The EL's main origin was the median sacral artery (MSA). Initial attempts in embolization via a transsealing and transarterial approach were unsuccessful owing to extremely tortuous arterial communications between the left hypogastric artery and the MSA. The construction of a clear resin 3D model of the aorta and iliolumbar arteries improved anatomy understanding and moreover allowed a preoperative simulation. The subsequent transarterial attempt in embolization was resolutive, significantly reducing total procedural time and radiation dose.

CONCLUSION

Printing of clear resin 3D arterial models facilitates type II EL transarterial embolization, improving anatomy understanding and allowing simple fluoroscopy-free simulations.

CLINICAL IMPACT

The aim of our work is to highlight the additional value of three-dimensional (3D) printing during preoperative planning of challenging endovascular cases. To our best knowledge, this is the first report about 3D printing use in a case of type II endoleak (EL). We believe that realizing life-size aortic models in selected cases where a complex type II EL embolization procedure is indicated, could lead to a better understanding of arterial anatomy, thus allowing to increase procedural success and reduce operative and most importantly fluoroscopy time.

3D impression to facilitate in situ surgical renal segmental artery aneurysm repair: A novel open approach option for an unusual vascular condition

OBJECTIVES

Renal Artery Aneurysms (RAA) affect approximately 0.01%-0.97% of the population. Early diagnosis, thorough 3D-preoperative planning, and timely surgical treatment may offer effective and safe management.

METHODS

We report the open reparation of a segmental renal artery saccular aneurysm close to the bifurcation with detailed preoperative planning based on 3D printing, and with successful postoperative results.

RESULTS

We report the case of a 36-year-old man with a 3.5 × 5 cm segmental renal artery saccular aneurysm close to the bifurcation, for which endovascular management was ruled out and open management was chosen with detailed preoperative planning based on 3D printing and with successful postoperative results.

CONCLUSIONS

When an open approach is chosen in the RAA treatment, a detailed study of the anatomical configuration of the RAAs is mandatory, and life-size 3D printing is a valuable tool that could contribute to the operative technique, reduce surgical times associated with renal ischemia and provide minute details that would make a clear anatomical difference during in situ repair.

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.

Fabrication of Soft Transparent Patient-Specific Vascular Models with Stereolithographic 3D printing and Thiol-Based Photopolymerizable Coatings

An ideal vascular phantom should be anatomically accurate, have mechanical properties as close as possible to the tissue, and be sufficiently transparent for ease of visualization. However, materials that enable the convergence of these characteristics have remained elusive. The fabrication of patient-specific vascular phantoms with high anatomical fidelity, optical transparency, and mechanical properties close to those of vascular tissue is reported. These final properties are achieved by 3D printing patient-specific vascular models with commercial elastomeric acrylic-based resins before coating them with thiol-based photopolymerizable resins. Ternary thiol-ene-acrylate chemistry is found optimal. A PETMP/allyl glycerol ether (AGE)/polyethylene glycol diacrylate (PEGDA) coating with a 30/70% AGE/PEGDA ratio applied on a flexible resin yielded elastic modulus, UTS, and elongation of 3.41 MPa, 1.76 MPa, and 63.2%, respectively, in range with the human aortic wall. The PETMP/AGE/PEGDA coating doubled the optical transmission from 40% to 80%, approaching 88% of the benchmark silicone-based elastomer. Higher transparency correlates with a decrease in surface roughness from 2000 to 90 nm after coating. Coated 3D-printed anatomical replicas are showcased for pre-procedural planning and medical training with good radio-opacity and echogenicity. Thiol-click chemistry coatings, as a surface treatment for elastomeric stereolithographic 3D-printed objects, address inherent limitations of photopolymer-based additive manufacturing.

3D printing in the endovascular treatment of visceral artery aneurysms

Visceral artery aneurysms (VAAs) are vascular pathologies that are difficult to treat. The variable geometry of the vessels and the location of aneurysms render difficult their evaluation in radiological imaging studies. Less invasive endovascular procedures are increasingly used in common practice. Our aim was to test the feasibility of using 3D printing technology in the preparation of preoperative spatial models of visceral artery aneurysms and their impact on interventional treatment. In our observational study, we examined a group of patients with true aneurysms of the visceral arteries who were followed and who underwent endovascular procedures with the use of 3D prints for better imaging of vascular lesions. We analyzed the fused filament fabrication method of 3D printing and printable materials in the preparation of spatial vascular models. We confirmed that more accurate visualization and analysis of vascular anatomy could assist operators in attempting minimally invasive treatment with good results. Extending imaging studies using 3D printing models that allow for the assessment of the position, morphology and geometry of the aneurysm sac, particularly of vessel branches, could encourage surgeons to perform endovascular procedures.

Quality assurance in 3D-printing: A dimensional accuracy study of patient-specific 3D-printed vascular anatomical models

3D printing enables the rapid manufacture of patient-specific anatomical models that substantially improve patient consultation and offer unprecedented opportunities for surgical planning and training. However, the multistep preparation process may inadvertently lead to inaccurate anatomical representations which may impact clinical decision making detrimentally. Here, we investigated the dimensional accuracy of patient-specific vascular anatomical models manufactured via digital anatomical segmentation and Fused-Deposition Modelling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), and PolyJet 3D printing, respectively. All printing modalities reliably produced hand-held patient-specific models of high quality. Quantitative assessment revealed an overall dimensional error of 0.20 ± 3.23%, 0.53 ± 3.16%, -0.11 ± 2.81% and -0.72 ± 2.72% for FDM, SLA, PolyJet and SLS printed models, respectively, compared to unmodified Computed Tomography Angiograms (CTAs) data. Comparison of digital 3D models to CTA data revealed an average relative dimensional error of -0.83 ± 2.13% resulting from digital anatomical segmentation and processing. Therefore, dimensional error resulting from the print modality alone were 0.76 ± 2.88%, + 0.90 ± 2.26%, + 1.62 ± 2.20% and +0.88 ± 1.97%, for FDM, SLA, PolyJet and SLS printed models, respectively. Impact on absolute measurements of feature size were minimal and assessment of relative error showed a propensity for models to be marginally underestimated. This study revealed a high level of dimensional accuracy of 3D-printed patient-specific vascular anatomical models, suggesting they meet the requirements to be used as medical devices for clinical applications.

Three-dimensional printing in integrated multi-modality imaging approach for management of prosthetic valves infective endocarditis

After heart failure, infectious endocarditis is the second leading cause of death in patients with prosthetic valves. Aortic pseudoaneurysms are a serious complication of infective endocarditis in mechanical or bioprosthetic aortic prostheses. Diagnostic and management challenges are posed by aortic pseudoaneurysms. In these cases, a multi-modality imaging approach with a heart team is recommended. We described two cases of aortic pseudoaneurysms that developed as a result of infective endocarditis. The first case involved a TAVI patient who developed infective endocarditis as a result of diabetic foot complications. Because traditional echocardiography and computed tomography failed to show the anatomy of the lesion, we used 3D printing to show the anatomy, extension of the pseudoaneurysm, and proximity to the right coronary artery. The second case involved a patient who underwent Bentall's surgery with an aortic root and mechanical aortic valve and later developed infective endocarditis complicated by pseudoaneurysms. In this case, 3D printing was used for preoperative surgical planning.

Case report: Application of three-dimensional technologies for surgical treatment of portosystemic shunt with segmental caudal vena cava aplasia in two dogs

This case report describes the application of three-dimensional (3D) technologies for the surgical treatment of portosystemic shunt (PSS) with segmental caudal vena cava (CVC) aplasia. Two client-owned dogs were diagnosed with PSS along with segmental CVC aplasia using computed tomography. Through 3D volume and surface rendering, the vascular anatomic anomaly of each patient was identified in detail. A patient-specific 3D vascular model was used for preoperative planning. According to the plan established based on the 3D rendered image and printed model, shunt occlusion was performed using cellophane banding in the first case. An ameroid constrictor was used in the second case. Both patients showed good recovery without any clinical symptoms or complications. The use of 3D technologies in small animals has many advantages, and its use in vascular surgery, as in these cases, is also a therapeutic option worth considering.

A patient-specific multi-modality abdominal aortic aneurysm imaging phantom

Purpose

Multimodality imaging of the vascular system is a rapidly growing area of innovation and research, which is increasing with awareness of the dangers of ionizing radiation. Phantom models that are applicable across multiple imaging modalities facilitate testing and comparisons in pre-clinical studies of new devices. Additionally, phantom models are of benefit to surgical trainees for gaining experience with new techniques. We propose a temperature-stable, high-fidelity method for creating complex abdominal aortic aneurysm phantoms that are compatible with both radiation-based, and ultrasound-based imaging modalities, using low cost materials.

Methods

Volumetric CT data of an abdominal aortic aneurysm were acquired. Regions of interest were segmented to form a model compatible with 3D printing. The novel phantom fabrication method comprised a hybrid approach of using 3D printing of water-soluble materials to create wall-less, patient-derived vascular structures embedded within tailored tissue-mimicking materials to create realistic surrounding tissues. A non-soluble 3-D printed spine was included to provide a radiological landmark.

Results

The phantom was found to provide realistic appearances with intravascular ultrasound, computed tomography and transcutaneous ultrasound. Furthermore, the utility of this phantom as a training model was demonstrated during a simulated endovascular aneurysm repair procedure with image fusion.

Conclusion

With the hybrid fabrication method demonstrated here, complex multimodality imaging patient-derived vascular phantoms can be successfully fabricated. These have potential roles in the benchtop development of emerging imaging technologies, refinement of novel minimally invasive surgical techniques and as clinical training tools.

Endovascular embolization techniques in acute thoracic and abdominal bleedings can be technically reproduced and trained in a standardized simulation setting using SLA 3D printing: a 1-year single-center study

Background

Endovascular embolization techniques are nowadays well established in the management of acute arterial bleedings. However, the education and training of the next generation of interventionalists are still based on the traditional apprenticeship model, where the trainee learns and practices directly at the patient, which potentially affects the patient’s safety. The objective of this study was to design and develop a standardized endovascular simulation concept for the training of acute bleeding embolizations, based on real-life cases.

Results

An adaptable and cost-effective endovascular simulator was developed using an in-house 3D print laboratory. All thoracic and abdominal acute bleeding embolizations over more than a year with appropriate pre-interventional computed tomography scans were included to manufacture 3D printed vascular models. A peristaltic pump was used to generate pulsatile flow curves. Forty embolization cases were engaged in this study, and 27 cases were fully reproduced in the simulation setting (69.23%). The simulation success was significantly lower in pulmonary embolizations (p = 0.031) and significantly higher in soft tissue (p = 0.032) and coil embolizations (p = 0.045). The overall simulation success was 7.8 out of 10 available points.

Conclusions

Using stereolithography 3D printing in a standardized simulation concept, endovascular embolization techniques for treating acute internal hemorrhages in the chest and abdomen can be simulated and trained based on the patient-specific anatomy in a majority of the cases and at a broad spectrum of different causes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-022-01206-7.

Effects of Sterilization Methods on Different 3D Printable Materials for Templates of Physician-Modified Aortic Stent Grafts Used in Vascular Surgery-A Preliminary Study

Three-dimensionally-printed aortic templates are increasingly being used to aid in the modification of stent grafts in the treatment of urgent, complex aortic disorders, often of an emergency nature. The direct contact between the aortic template and the stent graft implies the necessity of complete sterility. Currently, the efficacy of sterilizing aortic templates and the effect of sterilization on the geometry of tubular aortic models are unknown. A complex case of aortic arch dissection was selected to prepare a 3D-printed aortic arch template, which was then manufactured in six popular printing materials: polylactic acid (PLA), nylon, polypropylene (PP), polyethylene terephthalate glycol (PETG), and a rigid and flexible photopolymer resin using fused deposition modeling (FDM) and stereolithography (SLA). The 3D models were contaminated with Geobacillus stearothermophilus broth and Bacillus atrophaeus. The sterilization was performed using three different methods: heat (105 °C and 121 °C), hydrogen peroxide plasma, and ethylene oxide gas. Before and after sterilization, the aortic templates were scanned using computed tomography to detect any changes in their morphology by comparing the dimensions. All sterilization methods were effective in the elimination of microorganisms. Steam sterilization in an autoclave at 121 °C caused significant deformation of the aortic templates made of PLA, PETG, and PP. The other materials had stable geometries, and changes during mesh comparisons were found to be submillimeter. Similarly, plasma, gas, and heat at 105 °C did not change the shapes of aortic templates observed macroscopically and using mesh analysis. All mean geometry differences were smaller than 0.5 mm. All sterilization protocols tested in our study were equally effective in destroying microorganisms; however, differences occurred in the ability to induce 3D object deformation. Sterilization at high temperatures deformed aortic templates composed of PLA, PETG, and PP. This method was suitable for nylon, flexible, and rigid resin-based models. Importantly, plasma and gas sterilization were appropriate for all tested printing materials, including PLA, PETG, PP, nylon, flexible and rigid resins. Moreover, sterilization of all the printed models using our novel protocol for steam autoclaving at 105 °C was also 100% effective, which could represent a significant advantage for health centers, which can therefore use one of the most popular and cheap methods of medical equipment disinfection for the sterilization of 3D models as well.

A three-dimensional biomodel of type A aortic dissection for endovascular interventions

Thoracic endovascular aortic repair is widely used for type B aortic dissection. However, there is no favorable stent-graft for type A aortic dissection. A significant limitation for device development is the lack of an experimental model for type A aortic dissection. We developed a novel three-dimensional biomodel of type A aortic dissection for endovascular interventions. Based on Digital Imaging and Communication in Medicine data from the computed tomography image of a patient with a type A aortic dissection, a three-dimensional biomodel with a true lumen, a false lumen, and an entry tear located at the ascending aorta was created using laser stereolithography and subsequent vacuum casting. The biomodel was connected to a pulsatile mock circuit. We conducted four tests: an endurance test for clinical hemodynamics, wire insertion into the biomodel, rapid pacing, and simulation of stent-graft placement. The biomodel successfully simulated clinical hemodynamics; the target blood pressure and cardiac output were achieved. The guidewire crossed both true and false lumens via the entry tear. The pressure and flow dropped upon rapid pacing and recovered after it was stopped. This simulation biomodel detected decreased false luminal flow by stent-graft placement and detected residual leak. The three-dimensional biomodel of type A aortic dissection with a pulsatile mock circuit achieved target clinical hemodynamics, demonstrated feasibility for future use during the simulated endovascular procedure, and evaluated changes in the hemodynamics.

Method, Material, and Machine: A Review for the Surgeon Using Three-Dimensional Printing for Accelerated Device Production

BACKGROUND

Physicians are at the forefront of identifying innovative targets to address current medical needs. 3D printing technology has emerged as a state-of-the-art method of prototyping medical devices or producing patient-specific models that is more cost-efficient, with faster turnaround time, in comparison to traditional prototype manufacturing. However, initiating 3D printing projects can be daunting due to the engineering learning curve, including the number of methodologies, variables, and techniques for printing from which to choose. To help address these challenges, we sought to create a guide for physicians interested in venturing into 3D printing.

STUDY DESIGN

All commercially available, plug-and-play, material and stereolithography printers costing less than $15,000 were identified via web search. Companies were contacted to obtain quotes and information sheets for all printer models. The qualifying printers' manufacturer specification sheets were reviewed, and pertinent variables were extracted.

RESULTS

We reviewed 309 commercially available printers and materials and identified 118 printers appropriate for clinicians desiring plug-and-play models for accelerated device production. We synthesized this information into a decision-making tool to choose the appropriate parameters based on project goals.

CONCLUSIONS

There is a growing clinical need for medical devices to reduce costs of care and increase access to personalized treatments; however, the learning curve may be daunting for surgeons. In this review paper, we introduce the "3Ms of 3D printing" for medical professionals and provide tools and data sheets for selection of commercially available, affordable, plug-and-play 3D printers appropriate for surgeons interested in innovation.

Quality Control in 3D Printing: Accuracy Analysis of 3D-Printed Models of Patient-Specific Anatomy

As comparative data on the precision of 3D-printed anatomical models are sparse, the aim of this study was to evaluate the accuracy of 3D-printed models of vascular anatomy generated by two commonly used printing technologies. Thirty-five 3D models of large (aortic, wall thickness of 2 mm, n = 30) and small (coronary, wall thickness of 1.25 mm, n = 5) vessels printed with fused deposition modeling (FDM) (rigid, n = 20) and PolyJet (flexible, n = 15) technology were subjected to high-resolution CT scans. From the resulting DICOM (Digital Imaging and Communications in Medicine) dataset, an STL file was generated and wall thickness as well as surface congruency were compared with the original STL file using dedicated 3D engineering software. The mean wall thickness for the large-scale aortic models was 2.11 µm (+5%), and 1.26 µm (+0.8%) for the coronary models, resulting in an overall mean wall thickness of +5% for all 35 3D models when compared to the original STL file. The mean surface deviation was found to be +120 µm for all models, with +100 µm for the aortic and +180 µm for the coronary 3D models, respectively. Both printing technologies were found to conform with the currently set standards of accuracy (<1 mm), demonstrating that accurate 3D models of large and small vessel anatomy can be generated by both FDM and PolyJet printing technology using rigid and flexible polymers.

Clinical Applications of Patient-Specific 3D Printed Models in Cardiovascular Disease: Current Status and Future Directions

Three-dimensional (3D) printing has been increasingly used in medicine with applications in many different fields ranging from orthopaedics and tumours to cardiovascular disease. Realistic 3D models can be printed with different materials to replicate anatomical structures and pathologies with high accuracy. 3D printed models generated from medical imaging data acquired with computed tomography, magnetic resonance imaging or ultrasound augment the understanding of complex anatomy and pathology, assist preoperative planning and simulate surgical or interventional procedures to achieve precision medicine for improvement of treatment outcomes, train young or junior doctors to gain their confidence in patient management and provide medical education to medical students or healthcare professionals as an effective training tool. This article provides an overview of patient-specific 3D printed models with a focus on the applications in cardiovascular disease including: 3D printed models in congenital heart disease, coronary artery disease, pulmonary embolism, aortic aneurysm and aortic dissection, and aortic valvular disease. Clinical value of the patient-specific 3D printed models in these areas is presented based on the current literature, while limitations and future research in 3D printing including bioprinting of cardiovascular disease are highlighted.

The role of 3D printed models in the teaching of human anatomy: a systematic review and meta-analysis

BACKGROUND

Three-dimensional (3D) printing is an emerging technology widely used in medical education. However, its role in the teaching of human anatomy needs further evaluation.

METHODS

PubMed, Embase, EBSCO, SpringerLink, and Nature databases were searched systematically for studies published from January 2011 to April 2020 in the English language. GRADEprofiler software was used to evaluate the quality of literature. In this study, a meta-analysis of continuous and binary data was conducted. Both descriptive and statistical analyses were used.

RESULTS

Comparing the post-training tests in neuroanatomy, cardiac anatomy, and abdominal anatomy, the standardized mean difference (SMD) of the 3D group and the conventional group were 1.27, 0.37, and 2.01, respectively (p < 0.05). For 3D vs. cadaver and 3D vs. 2D, the SMD were 0.69 and 1.05, respectively (p < 0.05). For answering time, the SMD of the 3D group vs. conventional group was - 0.61 (P < 0.05). For 3D print usefulness, RR = 2.29(P < 0.05). Five of the six studies showed that satisfaction of the 3D group was higher than that of the conventional group. Two studies showed that accuracy of answering questions in the 3D group was higher than that in the conventional group.

CONCLUSIONS

Compared with students in the conventional group, those in the 3D printing group had advantages in accuracy and answering time. In the test of anatomical knowledge, the test results of students in the 3D group were not inferior (higher or equal) to those in the conventional group. The post-training test results of the 3D group were higher than those in the cadaver or 2D group. More students in the 3D printing group were satisfied with their learning compared with the conventional group. The results could be influenced by the quality of the randomized controlled trials. In a framework of ethical rigor, the application of the 3D printing model in human anatomy teaching is expected to grow further.

Simulation and Training of Needle Puncture Procedure with a Patient-Specific 3D Printed Gluteal Artery Model

The puncture of the gluteal artery (GA) is a rare and difficult procedure. Less experienced clinicians do not always have the opportunity to practice and prepare for it, which creates a need for novel training tools. We aimed to investigate the feasibility of developing a 3D-printed, patient-specific phantom of the GA and its surrounding tissues to determine the extent to which the model can be used as an aid in needle puncture planning, simulation, and training. Computed tomography angiography scans of a patient with an endoleak to an internal iliac artery aneurysm with no intravascular antegrade access were processed. The arterial system, including the superior GA with its division branches, and pelvic area bones were 3D printed. The 3D model was embedded in the buttocks-shaped, patient-specific mold and cast. The manufactured, life-sized phantom was used to simulate the GA puncture procedure and was validated by 13 endovascular specialists. The printed GA was visible in the fluoroscopy, allowing for a needle puncture procedure simulation. The contrast medium was administered, simulating a digital subtraction angiography. Participating doctors suggested that the model could make a significant impact on preprocedural planning and resident training programs. Although the results are promising, we recommend that further studies be used to adjust the design and assess its clinical value.

Use of Three-dimensional Printing in the Development of Optimal Cardiac CT Scanning Protocols

Three-dimensional (3D) printing is increasingly used in medical applications with most of the studies focusing on its applications in medical education and training, pre-surgical planning and simulation, and doctor-patient communication. An emerging area of utilising 3D printed models lies in the development of cardiac computed tomography (CT) protocols for visualisation and detection of cardiovascular disease. Specifically, 3D printed heart and cardiovascular models have shown potential value in the evaluation of coronary plaques and coronary stents, aortic diseases and detection of pulmonary embolism. This review article provides an overview of the clinical value of 3D printed models in these areas with regard to the development of optimal CT scanning protocols for both diagnostic evaluation of cardiovascular disease and reduction of radiation dose. The expected outcomes are to encourage further research towards this direction.

[The Future of Vascular Medicine - Role of 3D Printing]

Digitalisation is one of the key challenges in current surgery and will impact the future of surgical care as well as upcoming generations of surgeons. 3D printing is a technology that has recently been transferred from industrial prototyping into cardiovascular medicine. The digital model of the anatomical structure which needs to be engineered represents the inherent link of 3D printing to digital medicine. 3D printing technology is able to provide the surgeon with patient-specific models of anatomy and disease for surgical planning and patient informed consent as well as training templates for students and residents, surgical templates and even ready-to-use surgical implants. In our service, we have established a full-inhouse workflow for 3D printing and we currently use this technology for the generation of patient-specific models, training templates and for patient education, as will be presented in this article. Future advances in software solutions, printing polymers and easy-to-handle printers will further propagate and expand the applicability of this technology in cardiovascular medicine.

Trends in use of 3D printing in vascular surgery: a survey

INTRODUCTION

The purpose of the following research was to provide a systematic survey on the use of additive manufacturing in vascular surgery. The survey focuses on applications of 3D printing in endovascular surgery like endovascular aneurysm repair (EVAR), a quite unexplored application domain. 3D printing is an additive production process of three-dimensional objects starting from a three-dimensional digital model. This kind of manufacturing process is getting great attention in the medical field and new applications have emerged in recent years especially thanks to the combination of additive printing with 3D imaging techniques. The purpose of the study is to reflect on additive manufacturing and its potential as an inclusive manufacturing practice which can provide benefits at economic and societal level.

EVIDENCE ACQUISITION

The article first introduces the use of 3D printing in surgery by summarizing the results of previous reviews which reveal three main usages of 3D printing: anatomic models, surgical tools, implants and prostheses. These studies point out that vascular surgery is still an unexplored field of application of 3D printing. Starting from this result, a new survey was carried out in databases Pubmed, Elsevier, Research Gate and ACM Digital Library for terms related to 3D printing in vascular surgery using the following keywords: 3D printing, vascular surgery, EVAR, aneurysm. The search screened articles published up to 2019 for relevance and practical application of the technology in vascular surgery, in particular the topic is related to the treatment of complex abdominal aortic aneurysm.

EVIDENCE SYNTHESIS

Initially 437 records published up to 2019 were found, but then were narrowed down to 29 full-text articles. The findings reveal that in addition to the applications found in the previous studies, new experiments are ongoing related to the use of 3D printing in the "Off label" practice to manually fenestrate the stent to improve the accuracy of the EVAR.

CONCLUSIONS

Different applications of the use of 3D printing and digital imaging in vascular surgery have been experimented with a different maturity level. Whilst the technology has increased its potential in the latest years, the number of studies documented in the literature is still quite narrow. Further research is necessary to fully test the potential of 3D printing, also in combination with other technologies (e.g. 3D imaging and CNC cutting). Early experimentations show that these technologies have the potential to radically change the vascular surgery practice in the near future, in particular in treatment like EVAR, to improve the planning and therefore the success of the surgery.

Holographically-Guided Endovascular Aneurysm Repair

Purpose: To demonstrate the feasibility of augmented reality visualization in planning and navigating endovascular aortic repair. Technique: A 77-year-old patient with abdominal aortic aneurysm was treated with endovascular repair. An augmented reality head-mounted display was used during the procedure. The aneurysm and bones were projected as 3-dimensional holograms. The operator controlled the device with gestures and voice commands (movement, rotation, cutting through, and zooming). Moreover, the hologram was placed in front of the angiography monitor and manually registered with fluoroscopy. Conclusion: Augmented reality with holographic rendering is feasible and helpful during endovascular aortic repair. Its routine use could possibly lead to shorter operating time, reduced contrast volume, and lower radiation dose; however, larger studies are required to obtain statistically significant results on the outcomes.

Applications of 3D printing in small animal magnetic resonance imaging

Three-dimensional (3D) printing has significantly impacted the quality, efficiency, and reproducibility of preclinical magnetic resonance imaging. It has vastly expanded the ability to produce MR-compatible parts that readily permit customization of animal handling, achieve consistent positioning of anatomy and RF coils promptly, and accelerate throughput. It permits the rapid and cost-effective creation of parts customized to a specific imaging study, animal species, animal weight, or even one unique animal, not routinely used in preclinical research. We illustrate the power of this technology by describing five preclinical studies and specific solutions enabled by different 3D printing processes and materials. We describe fixtures, assemblies, and devices that were created to ensure the safety of anesthetized lemurs during an MR examination of their brain or to facilitate localized, contrast-enhanced measurements of white blood cell concentration in a mouse model of pancreatitis. We illustrate expansive use of 3D printing to build a customized birdcage coil and components of a ventilator to enable imaging of pulmonary gas exchange in rats using hyperpolarizedXe 129 . Finally, we present applications of 3D printing to create high-quality, dual RF coils to accelerate brain connectivity mapping in mouse brain specimens and to increase the throughput of brain tumor examinations in a mouse model of pituitary adenoma.

State of the Art of Small-Diameter Vessel-Polyurethane Substitutes

Cardiovascular diseases are a severe threat to human health. Implantation of small-diameter vascular substitutes is a promising therapy in clinical operations. Polyurethane (PU) is considered one of the most suitable materials for this substitution due to its good mechanical properties, controlled biostability, and proper biocompatibility. According to biodegradability and biostability, in this review, PU small-diameter vascular substitutes are divided into two groups: biodegradable scaffolds and biostable prostheses, which are applied to the body for short- and long-term, respectively. Following this category, the degradation principles and mechanisms of different kinds of PUs are first discussed; then the chemical and physical methods for adjusting the properties and the research advances are summarized. On the basis of these discussions, the problems remaining at present are addressed, and the contour of future research and development of PU-based small-diameter vascular substitutes toward clinical applications is outlined.