Development of an algorithm to plan and simulate a new interventional procedure

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-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.

Self-expandable valve-in-valve treatment for failing sutureless aortic bioprosthesis

Aortic valve replacement still represents the gold standard treatment for severe symptomatic aortic stenosis. Sutureless bioprostheses have been so far developed to enhance the minimally invasive approach, resulting in a reduction of cross-clamp time. Even if the first implantation was carried out more than 10 years ago, some cases of valve degeneration treated with balloon-expandable valve-in-valve procedures have been previously described in the literature. Here, we present a case of early sutureless valve degeneration resulting in severe aortic regurgitation. After careful evaluation of the patient's comorbidities, a successful valve-in-valve was finally performed using a self-expandable transcatheter prosthesis. A wide discussion of the Heart Team decision-making process and of the technical aspects has been addressed.

Cardiovascular Three-Dimensional Printing in Non-Congenital Percutaneous Interventions

Three-dimensional (3D) printing technology is emerging as a potential new tool for the planning of medical interventions. In the last few years, increasing data have accumulated on its ability to guide interventional cardiology procedures, going beyond initial reports in congenital heart disease settings. In fact, there is compelling evidence on the advantages of a 3D-printed guided strategy for left atrial appendage closure, suggesting a high success rate with optimal device selection and lower radiation load. Furthermore, there is emerging experience in aortic root printing, which may improve the success rate and safety of transcatheter aortic valve replacement and may be of particular interest for targeting low-risk populations. Additionally, there are stimulating reports in mitral valve intervention, setting the tone for this new field in cardiovascular percutaneous intervention. In this clinically oriented paper, we will review current 3D printing use in interventional cardiology and we will address future directions, with a focus on procedural planning and medical simulation.

3D printing for heart valve disease: a systematic review

BACKGROUND

Current developments showed a fast-increasing implementation and use of three-dimensional (3D) printing in medical applications. Our aim was to review the literature regarding the application of 3D printing to cardiac valve disease.

METHODS

A PubMed search for publications in English with the terms "3D printing" AND "cardiac valve", performed in January 2018, resulted in 64 items. After the analysis of the abstract and text, 27 remained related to the topic. From the references of these 27 papers, 7 papers were added resulting in a total of 34 papers. Of these, 5 were review papers, thus reducing the papers taken into consideration to 29.

RESULTS

The 29 papers showed that about a decade ago, the interest in 3D printing for this application area was emerging, but only in the past 2 to 3 years it really gained interest. Computed tomography is the most common imaging modality taken into consideration (62%), followed by ultrasound (28%), computer-generated models (computer-aided design) (7%), and magnetic resonance imaging (3%). Acrylonitrile butadiene styrene (4/14, 29%) and TangoPlus FullCure 930 (5/14, 36%) are the most used printing materials. Stereolithography (40%) and fused deposition modeling (30%) are the preferred printing techniques, while PolyJet (25%) and laser sintering (4%) are used in a minority of cases. The reported time ranges from 30 min to 3 days. The most reported application area is preoperative planning (63%), followed by training (19%), device testing (11%), and retrospective procedure evaluation (7%).

CONCLUSIONS

In most cases, CT datasets are used and models are printed for preoperative planning.

Valve-in-valve outcome: design impact of a pre-existing bioprosthesis on the hydrodynamics of an Edwards Sapien XT valve

Objectives

Bioprosthetic aortic heart valves are increasingly implanted in younger patients. Therefore, a strategy for potential valve failure should be developed before implanting the 'first valve'. The goal of this in vitro study was to provide insight into the effects of the design of a bioprosthesis on a valve-in-valve implanted Sapien XT valve.

Methods

The hydrodynamic performance of a 23-mm Sapien XT valve implanted in Vascutek Aspire, Edwards Perimount, Medtronic Mosaic and St. Jude Medical Trifecta heart valves was investigated in a left heart simulator. In addition to the hydrodynamic results, the leaflet dynamics were analysed in high-speed video recordings of the tests.

Results

All valve-in-valve combinations in this study fulfilled the minimum acceptance criteria defined by relevant approval standards (e.g. ISO 5840) but displayed significant differences in their performances. Small inner diameters of the bioprostheses were associated with increased mean pressure gradients, decreased effective orifice areas and geometric opening areas as well as with pin-wheeling and uneven leaflet motion. In addition, implantation in bioprostheses with internally mounted leaflets was associated with lower paravalvular leakage.

Conclusions

The results of this study suggest that a surgical bioprosthesis with a large inner diameter and internally mounted leaflets improves the heamodynamics and potentially the durability of a valve-in-valve combination. These results should give the attending physicians critical information to consider when deciding on a bioprosthesis for younger patients.

Applications of 3D printing in cardiovascular diseases

3D-printed models fabricated from CT, MRI, or echocardiography data provide the advantage of haptic feedback, direct manipulation, and enhanced understanding of cardiovascular anatomy and underlying pathologies. Reported applications of cardiovascular 3D printing span from diagnostic assistance and optimization of management algorithms in complex cardiovascular diseases, to planning and simulating surgical and interventional procedures. The technology has been used in practically the entire range of structural, valvular, and congenital heart diseases, and the added-value of 3D printing is established. Patient-specific implants and custom-made devices can be designed, produced, and tested, thus opening new horizons in personalized patient care and cardiovascular research. Physicians and trainees can better elucidate anatomical abnormalities with the use of 3D-printed models, and communication with patients is markedly improved. Cardiovascular 3D bioprinting and molecular 3D printing, although currently not translated into clinical practice, hold revolutionary potential. 3D printing is expected to have a broad influence in cardiovascular care, and will prove pivotal for the future generation of cardiovascular imagers and care providers. In this Review, we summarize the cardiovascular 3D printing workflow, from image acquisition to the generation of a hand-held model, and discuss the cardiovascular applications and the current status and future perspectives of cardiovascular 3D printing.