3D printed mitral valve models: affordable simulation for robotic mitral valve repair

Three-dimensional printing of mitral valve models using echocardiographic data improves the knowledge of cardiology fellow physicians in training

Background

High fidelity three-dimensional Mitral valve models (3D MVM) printed from echocardiography are currently being used in preparation for surgical repair.

Aim

We hypothesize that printed 3DMVM could have relevance to cardiologists in training by improving their understanding of normal anatomy and pathology.

Methods

Sixteen fellow physicians in pediatric and adult cardiology training were recruited. 3D echocardiography (3DE) video clips of six mitral valves (one normal and five pathological) were displayed and the fellows were asked to name the prolapsing segments in each. Following that, three still images of 3D MVMs in different projections: enface, profile and tilted corresponding to the same MVs seen in the clip were presented on a screen. Participating physicians were presented with a comprehensive questionnaire aimed at assessing whether the 3D MVM has improved their understanding of valvular anatomy. Finally, a printed 3D MVM of each of the valves was handed out, and the same questionnaire was re-administered to identify any further improvement in the participants' perception of the anatomy.

Results

The correct diagnosis using the echocardiography video clip of the Mitral valve was attained by 45% of the study participants. Both pediatric and adult trainees, regardless of the year of training demonstrated improved understanding of the anatomy of MV after observing the corresponding model image. Significant improvement in their understanding was noted after participants had seen and physically examined the printed model.

Conclusion

Printed 3D MVM has a beneficial impact on the cardiology trainees' understanding of MV anatomy and pathology compared to 3DE images.

Simulation-based training in cardiac surgery: a systematic review

OBJECTIVES

The increase in the complexity of operations, the rising quest for improved outcomes and the scrutiny of surgical practice and its associated complications have led to a decreased educational value of in-patient surgical training within cardiac surgery. Simulation-based training has emerged as an adjunct to the apprenticeship model. In the following review, we aimed to evaluate the currently available evidence regarding simulation-based training in cardiac surgery.

METHODS

A systematic database search was conducted as per PRISMA guidelines, of original articles that explored the use of simulation-based training in adult cardiac surgery programs in EMBASE, MEDLINE, Cochrane database and Google Scholar, from inception to 2022. Data extraction covered the study characteristics, simulation modality, main methodology and main outcomes.

RESULTS

Our search yielded 341 articles, of which 28 studies were included in this review. Three main areas of focus were identified: (i) validity testing of the models; (ii) impact on surgeons' skills; and (iii) impact on clinical practice. Fouteen studies reported animal-based models and 14 reported on non-tissue-based models covering a wide spectrum of surgical operations. The results of the included studies suggest that validity assessment is scarce within the field, being carried out for only 4 of the models. Nonetheless, all studies reported improvement in trainees' confidence, clinical knowledge and surgical skills (including accuracy, speed, dexterity) of trainees both at senior and junior levels. The direct clinical impact included initiation of minimally invasive programmes and improved board exam pass rates, and creating positive behavioural changes to minimize further cardiovascular risk.

CONCLUSIONS

Surgical simulation has been shown to provide substantial benefits to trainees. Further evidence is needed to explore its direct impact on clinical practice.

Translating Imaging Into 3D Printed Cardiovascular Phantoms

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3D printed patient specific phantoms can visualize complex cardiovascular anatomy

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Common imaging modalities for 3D printing are CCT and CMR

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Material jetting/PolyJet and stereolithography are widely used printing techniques

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Standardized validation is warranted to compare different 3D printing technologies

Translation of imaging into 3-dimensional (3D) printed patient-specific phantoms (3DPSPs) can help visualize complex cardiovascular anatomy and enable tailoring of therapy. The aim of this paper is to review the entire process of phantom production, including imaging, materials, 3D printing technologies, and the validation of 3DPSPs. A systematic review of published research was conducted using Embase and MEDLINE, including studies that investigated 3DPSPs in cardiovascular medicine. Among 2,534 screened papers, 212 fulfilled inclusion criteria and described 3DPSPs as a valuable adjunct for planning and guiding interventions (n = 108 [51%]), simulation of physiological or pathological conditions (n = 19 [9%]), teaching of health care professionals (n = 23 [11%]), patient education (n = 3 [1.4%]), outcome prediction (n = 6 [2.8%]), or other purposes (n = 53 [25%]). The most common imaging modalities to enable 3D printing were cardiac computed tomography (n = 131 [61.8%]) and cardiac magnetic resonance (n = 26 [12.3%]). The printing process was conducted mostly by material jetting (n = 54 [25.5%]) or stereolithography (n = 43 [20.3%]). The 10 largest studies that evaluated the geometric accuracy of 3DPSPs described a mean bias <±1 mm; however, the validation process was very heterogeneous among the studies. Three-dimensional printed patient-specific phantoms are highly accurate, used for teaching, and applied to guide cardiovascular therapy. Systematic comparison of imaging and printing modalities following a standardized validation process is warranted to allow conclusions on the optimal production process of 3DPSPs in the field of cardiovascular medicine.

Establishing a point-of-care additive manufacturing workflow for clinical use

Additive manufacturing, or 3-Dimensional (3-D) Printing, is built with technology that utilizes layering techniques to build 3-D structures. Today, its use in medicine includes tissue and organ engineering, creation of prosthetics, the manufacturing of anatomical models for preoperative planning, education with high-fidelity simulations, and the production of surgical guides. Traditionally, these 3-D prints have been manufactured by commercial vendors. However, there are various limitations in the adaptability of these vendors to program-specific needs. Therefore, the implementation of a point-of-care in-house 3-D modeling and printing workflow that allows for customization of 3-D model production is desired. In this manuscript, we detail the process of additive manufacturing within the scope of medicine, focusing on the individual components to create a centralized in-house point-of-care manufacturing workflow. Finally, we highlight a myriad of clinical examples to demonstrate the impact that additive manufacturing brings to the field of medicine.

Three-dimensional virtual and printed models for planning adult cardiovascular surgery

BACKGROUND

The objective of this study was to explore the usefulness of virtual models and three-dimensional (3D) printing technologies for planning complex non-congenital cardiovascular surgery.

METHODS

Between July 2018 and December 2019, adult patients with different cardiovascular structural diseases were included in a clinical protocol to explore the usefulness of Standard Tessellation Language (STL)-based virtual models and 3D printing for prospectively planning surgery. A qualitative descriptive analysis from the surgeon's viewpoint was done based on the characteristics, advantages and usefulness of 3D models for guiding, planning and simulating the surgical procedures.

RESULTS

A total of 14 custom 3D-printed heart and great vessel replicas with their corresponding 3D virtual models were created for preoperative surgical planning. Six of 14 models helped to redefine the surgical approach, 3 were useful to verify device delivery, while the rest did not change the surgical decision. In all open surgery cases, cardiac and vascular anatomy accuracy of virtual and physical 3D replicas was validated by direct visualisation of the organs during surgery. Printing was achieved through an external provider associated with the Hospital, who printed the final prototype in 5-7 days. Printed production cost was between 100 and 500 USD per model.

CONCLUSIONS

In the current study, the selected 3D printed models presented different advantages (visual, tactile, and instrumental) over the traditional flat anatomical images when simulating and planning some complex types of surgery. Notwithstanding 3D printing advantages, STL-based virtual models were pre-printing useful tools when instrumentation on a physical replica was not required.

3D Printing for Cardiovascular Applications: From End-to-End Processes to Emerging Developments

3D printing as a means of fabrication has seen increasing applications in medicine in the last decade, becoming invaluable for cardiovascular applications. This rapidly developing technology has had a significant impact on cardiovascular research, its clinical translation and education. It has expanded our understanding of the cardiovascular system resulting in better devices, tools and consequently improved patient outcomes. This review discusses the latest developments and future directions of generating medical replicas ('phantoms') for use in the cardiovascular field, detailing the end-to-end process from medical imaging to capture structures of interest, to production and use of 3D printed models. We provide comparisons of available imaging modalities and overview of segmentation and post-processing techniques to process images for printing, detailed exploration of latest 3D printing methods and materials, and a comprehensive, up-to-date review of milestone applications and their impact within the cardiovascular domain across research, clinical use and education. We then provide an in-depth exploration of future technologies and innovations around these methods, capturing opportunities and emerging directions across increasingly realistic representations, bioprinting and tissue engineering, and complementary virtual and mixed reality solutions. The next generation of 3D printing techniques allow patient-specific models that are increasingly realistic, replicating properties, anatomy and function.

3D-printed anatomical models of the cystic duct and its variants, a low-cost solution for an in-house built simulator for laparoscopic surgery training

OBJECTIVES

To explore a method to create affordable anatomical models of the biliary tree that are adequate for training laparoscopic cholecystectomy with an in-house built simulator.

METHODS

We used a fused deposition modeling 3D printer to create molds of Acrylonitrile Butadiene Styrene (ABS) from Digital Imaging and Communication on Medicine (DICOM) images, and the molds were filled with silicone rubber. Thirteen surgeons with 4-5-year experience in the procedure evaluated the molds using a low-cost in-house built simulator utilizing a 5-point Likert-type scale.

RESULTS

Molds produced through this method had a consistent anatomical appearance and overall realism that evaluators agreed or definitely agreed (4.5/5). Evaluators agreed on recommending the mold for resident surgical training.

CONCLUSIONS

3D-printed molds created through this method can be applied to create affordable high-quality educational anatomical models of the biliary tree for training laparoscopic cholecystectomy.

3D Echocardiography Provides Highly Accurate 3D Printed Models in Congenital Heart Disease

Cardiac 3D printing is mainly performed from magnetic resonance imaging (MRI) and computed tomography (CT) 3D datasets, though anatomic detail of atrioventricular (AV) valves may be limited. 3D echo provides excellent visualization of AV valves. Thus, we tested the feasibility and accuracy of 3D printing from 3D echo in this pilot series of subjects with congenital heart disease (CHD), with a focus on valve anatomy. Five subjects with CHD were identified. 3D echo data were converted to 3D printable files and printed in collaboration with 3D Systems Healthcare (Golden, Colorado). A novel technique for valve modeling was utilized using commercially available software. Two readers (KM, SA) independently measured valve structures from 3D models and compared to source echo images. 3D printing was feasible for all cases. Table 1 shows measurements comparing 2D echo to 3D models. Bland Altman analysis showed close agreement and no significant bias between 2D and digital 3D models (mean difference 0.0, 95% CI 1.1 to - 1.1) or 2D vs printed 3D models, though with wider limits of agreement (mean difference - 0.3, 95% CI 1.9 to - 2.6). Accuracy of 3D models compared to 2D was within < 0.5 mm. This pilot study shows 3D echo datasets can be used to reliably print AV and semilunar valve structures in CHD. The 3D models are highly accurate compared to the source echo images. This is a novel and value-added technique that adds incremental information on cardiac anatomy over current methods.

Clinical situations for which 3D printing is considered an appropriate representation or extension of data contained in a medical imaging examination: adult cardiac conditions

BACKGROUND

Medical 3D printing as a component of care for adults with cardiovascular diseases has expanded dramatically. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides appropriateness criteria for adult cardiac 3D printing indications.

METHODS

A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with a number of adult cardiac indications, physiologic, and pathologic processes. Each study was vetted by the authors and graded according to published guidelines.

RESULTS

Evidence-based appropriateness guidelines are provided for the following areas in adult cardiac care; cardiac fundamentals, perioperative and intraoperative care, coronary disease and ischemic heart disease, complications of myocardial infarction, valve disease, cardiac arrhythmias, cardiac neoplasm, cardiac transplant and mechanical circulatory support, heart failure, preventative cardiology, cardiac and pericardial disease and cardiac trauma.

CONCLUSIONS

Adoption of common clinical standards regarding appropriate use, information and material management, and quality control are needed to ensure the greatest possible clinical benefit from 3D printing. This consensus guideline document, created by the members of the RSNA 3D printing Special Interest Group, will provide a reference for clinical standards of 3D printing for adult cardiac indications.

Three Dimensionally Printed Interactive Training Model for Kidney Transplantation

OBJECTIVE

The purpose of this study is to describe the development of a low-cost, reusable, interactive 3D-printed model to simulate vascular anastomoses in kidney transplantation.

DESIGN

We used a de-identified high-resolution abdominal and pelvic computed tomography scan and computer-aided design software to create a model to simulate vascular anastomoses in kidney transplantation. Surgical residents were asked to tie anastomoses and complete a survey regarding the effectiveness of the model.

SETTING

University of Michigan (Ann Arbor, Michigan)-academic, tertiary care center.

PARTICIPANTS

University of Michigan general, vascular, and cardiothoracic surgery residents participated in this study (n = 12).

RESULTS

After using the model, all 12 residents reported having a better understanding of how to set up and sew the renal artery and vein anastomoses. All 12 residents found the model to be an effective teaching tool.

CONCLUSIONS

Surgical trainees find this low-cost, reusable, interactive 3D-printed model to be an effective way to develop the technical skills necessary for vascular anastomoses in kidney transplantation.

Three-dimensional printing in adult cardiovascular medicine for surgical and transcatheter procedural planning, teaching and technological innovation

Three-dimensional (3D)-printing technologies in cardiovascular surgery have provided a new way to tailor surgical and percutaneous treatments. Digital information from standard cardiac imaging is integrated into physical 3D models for an accurate spatial visualization of anatomical details. We reviewed the available literature and analysed the different printing technologies, the required procedural steps for 3D prototyping, the used cardiac imaging, the available materials and the clinical implications. We have highlighted different materials used to replicate aortic and mitral valves, vessels and myocardial properties. 3D printing allows a heuristic approach to investigate complex cardiovascular diseases, and it is a unique patient-specific technology providing enhanced understanding and tactile representation of cardiovascular anatomies for the procedural planning and decision-making process. 3D printing may also be used for medical education and surgical/transcatheter training. Communication between doctors and patients can also benefit from 3D models by improving the patient understanding of pathologies. Furthermore, medical device development and testing can be performed with rapid 3D prototyping. Additionally, widespread application of 3D printing in the cardiovascular field combined with tissue engineering will pave the way to 3D-bioprinted tissues for regenerative medicinal applications and 3D-printed organs.

3D printing in adult cardiovascular surgery and interventions: a systematic review

3D printing in adult cardiac and vascular surgery has been evaluated over the last 10 years, and all of the available literature reports benefits from the use of 3D models. In the present study, we analyzed the current applications of 3D printing for adult cardiovascular disease treated with surgical or catheter-based interventions, including the clinical medical simulation of physiological or pathology conducted with 3D printing in this field. A search of PubMed and MEDLINE databases were supplemented by searching through bibliographies of key articles. Thereafter, data on demographic, clinical scenarios and application, imaging modality, purposes of using with 3D printing, outcomes and follow-up were extracted. A total of 43 articles were deemed eligible and included. 296 patients (mean age: 65.4±14.2 years; male, 58.2%) received 3D printing for cardiac and vascular surgery or conditions [percutaneous left atrial appendage occlusion (LAAO), TAVR, mitral valve disease, aortic valve replacement, coronary artery abnormality, HOCM, aortic aneurysm and aortic dissection, Kommerell's diverticulum, primary cardiac tumor and ventricular aneurysm]. Eight papers reported the utility of 3D printing in the medical simulator and training fields. Most studies were conducted starting in 2014. Twenty-six was case report. The major scenario used with 3D printing technology was LAAO (50.3%) and followed by TAVR (17.6%). CT and echocardiography were two main imaging techniques that were used to generate 3D-printed heart models. All studies showed that 3D-printed models were helpful for preoperative planning, orientation, and medical teaching. The important finding is that 3D printing provides a unique patient-specific method to assess complex anatomy and is helpful for intraoperative orientation, decision-making, creating functional models, and teaching adult cardiac and vascular surgery, including catheter-based heart surgery.

Step-Specific Simulation: The Utility of 3D Printing for the Fabrication of a Low-Cost, Learning Needs-Based Rhinoplasty Simulator

BACKGROUND

Rhinoplasty is a complex procedure that requires meticulous planning and precise execution. Plastic surgeons involved in teaching residents must balance a trainee's hands-on experience while ensuring appropriate execution of difficult maneuvers. Surgical simulation, a field of growing importance with the shift towards competency-based education, may aid in trainee skill development. Through the concept of deliberate practice, the authors looked to explore the utility and economics of 3-dimensional (3D) printing technology to develop a step-specific rhinoplasty simulator.

OBJECTIVES

The main objective of this study was to address rhinoplasty skills previously identified as "learning areas of weakness" and develop a low-cost, step-specific simulator to help rhinoplasty teaching.

METHODS

A patient's facial bones, upper and lower lateral cartilages, and septum were segmented from a computed tomography scan and rendered in 3D format. This was 3D printed utilizing Ultimaker Polylactic filament with a polyvinyl acetate dissolvable support for bone, a mixture of Rigur 450 and Tango plus polyjet material for cartilage, and Smooth-On Dragon Skin for skin.

RESULTS

A modular simulator was developed with 3 separate, interchangeable components with a perfect fit design. The simulator allowed for deliberate practice of the 5 rhinoplasty learning areas of weakness, with a maximal recurring cost of $75 CAD.

CONCLUSIONS

Through the employment of 3D printing, a low-cost, maneuver-specific rhinoplasty simulator reinforcing deliberate practice was developed. This concept of simulation-based deliberate practice may be of increasing interest when considering the implementation of competency-based curricular standards in plastic surgery education.

Recent Applications of Three Dimensional Printing in Cardiovascular Medicine

Three dimensional (3D) printing, which consists in the conversion of digital images into a 3D physical model, is a promising and versatile field that, over the last decade, has experienced a rapid development in medicine. Cardiovascular medicine, in particular, is one of the fastest growing area for medical 3D printing. In this review, we firstly describe the major steps and the most common technologies used in the 3D printing process, then we present current applications of 3D printing with relevance to the cardiovascular field. The technology is more frequently used for the creation of anatomical 3D models useful for teaching, training, and procedural planning of complex surgical cases, as well as for facilitating communication with patients and their families. However, the most attractive and novel application of 3D printing in the last years is bioprinting, which holds the great potential to solve the ever-increasing crisis of organ shortage. In this review, we then present some of the 3D bioprinting strategies used for fabricating fully functional cardiovascular tissues, including myocardium, heart tissue patches, and heart valves. The implications of 3D bioprinting in drug discovery, development, and delivery systems are also briefly discussed, in terms of in vitro cardiovascular drug toxicity. Finally, we describe some applications of 3D printing in the development and testing of cardiovascular medical devices, and the current regulatory frameworks that apply to manufacturing and commercialization of 3D printed products.

Simulation of a Right Anterior Thoracotomy Access for Aortic Valve Replacement Using a 3D Printed Model

OBJECTIVE

The right anterior lateral thoracotomy (RALT) approach for aortic valve replacement provides excellent outcomes in expert hands while avoiding sternal disruption. It, however, remains a technically demanding niche operation. Instrument trajectories via this access are influenced by patient anatomy, the intercostal space chosen, and surgical retraction maneuvers.

METHODS

To simulate the typical surgical maneuvers, on an anatomically accurate model, and to measure the instrument trajectories, we generated a 3-dimensional (3D) printed model of the heart and chest cavity. A simulated approach to the base of the right coronary sinus via the medial-second intercostal, the lateral-second intercostal, or third intercostal space was made. Keeping the instrument in place, 3D scans of the models and geometrical measurements of the instrument trajectories were performed.

RESULTS

The 3D scans of the 3D printed model showed a high fidelity when compared to the original computed tomographic scan image geometry (mean deviation of 1.26 ± 1.27mm). The instrument intrathoracic distance was 75 mm via the medial-second, 115 mm via the lateral-second, and 80 mm via the third intercostal space. The 3D angulation of the instrument to the incision was 33.77^o, 55.93^o, and 38.4^o respectively. The distance of the instrument to the lateral margin was 12, 26, and 5 mm respectively. The cranial margin of the incision was always a limiting margin for the instrument.

CONCLUSIONS

Three-dimensional printing and 3D scanning facilitated a realistic simulation of the instrument trajectory during RALT approach. The lateral-second intercostal approach showed the most favorable approach angle and distance from the lateral margin, although it also had the longest intrathoracic distance.