Three-dimensional virtual surgery models for percutaneous coronary intervention (PCI) optimization strategies

Sutureless vascular anastomotic approaches and their potential impacts

Sutureless anastomotic devices present several advantages over traditional suture anastomosis, including expanded global access to microvascular surgery, shorter operation and ischemic times, and reduced costs. However, their adaptation for arterial use remains a challenge. This review aims to provide a comprehensive overview of sutureless anastomotic approaches that are either FDA-approved or under investigation. These approaches include extraluminal couplers, intraluminal devices, and methods assisted by lasers or vacuums, with a particular emphasis on tissue adhesives. We analyze these devices for artery compatibility, material composition, potential for intimal damage, risks of thrombosis and restenosis, and complications arising from their deployment and maintenance. Additionally, we discuss the challenges faced in the development and clinical application of sutureless anastomotic techniques. Ideally, a sutureless anastomotic device or technique should eliminate the need for vessel eversion, mitigate thrombosis through either biodegradation or the release of antithrombotic drugs, and be easily deployable for broad use. The transformative potential of sutureless anastomotic approaches in microvascular surgery highlights the necessity for ongoing innovation to expand their applications and maximize their benefits.

Effects of Drag-Reducing Polymers on Hemodynamics and Whole Blood-Endothelial Interactions in 3D-Printed Vascular Topologies

Most in vitro models use culture medium to apply fluid shear stress to endothelial cells, which does not capture the interaction between blood and endothelial cells. Here, we describe a new system to characterize whole blood flow through a 3D-printed, endothelialized vascular topology that induces flow separation at a bifurcation. Drag-reducing polymers, which have been previously studied as a potential therapy to reduce the pressure drop across the vascular bed, are evaluated for their effect on mitigating the disturbed flow. Polymer concentrations of 1000 ppm prevented recirculation and disturbed flow at the wall. Proteomic analysis of plasma collected from whole blood recirculated through the vascularized channel with and without drag-reducing polymers provides insight into the effects of flow regimes on levels of proteins indicative of the endothelial-blood interaction. The results indicate that blood flow alters proteins associated with coagulation, inflammation, and other processes. Overall, these proof-of-concept experiments demonstrate the importance of using whole blood flow to study the endothelial response to perfusion.

Functioning tailor-made 3D-printed vascular graft for hemodialysis

BACKGROUND

The two ends of arteriovenous graft (AVG) are anastomosed to the upper limb vessels by surgery for hemodialysis therapy. However, the size of upper limb vessels varies to a large extent among different individuals.

METHODS

According to the shape and size of neck vessels quantified from the preoperative computed tomography angiographic scan, the ethylene-vinyl acetate (EVA)-based AVG was produced in H-shape by the three-dimensional (3D) printer and then sterilized. This study investigated the function of this novel 3D-printed AVG in vitro and in vivo.

RESULTS

This 3D-printed AVG can be implanted in the rabbit's common carotid artery and common jugular vein with ease and functions in vivo. The surgical procedure was quick, and no suture was required. The blood loss was minimal, and no hematoma was noted at least 1 week after the surgery. The blood flow velocity within the implanted AVG was 14.9 ± 3.7 cm/s. Additionally, the in vitro characterization experiments demonstrated that this EVA-based biomaterial is biocompatible and possesses a superior recovery property than ePTFE after hemodialysis needle cannulation.

CONCLUSIONS

Through the 3D printing technology, the EVA-based AVG can be tailor-made to fit the specific vessel size. This kind of 3D-printed AVG is functioning in vivo, and our results realize personalized vascular implants. Further large-animal studies are warranted to examine the long-term patency.

Long-term outcomes following ostial left anterior descending artery intervention with or without crossover to left-main

BACKGROUND

Ostial left anterior descending (LAD) artery lesions are a critical area for coronary stenting, given that the location subtends a large area of the myocardium and can also be more technically challenging. It remains controversial whether crossover stenting of ostial LAD back into the left-main (LM) is advantageous over stenting the ostium alone.

METHODS

To evaluate the long-term clinical outcomes of stenting ostial LAD lesions, we retrospectively reviewed all ostial LAD lesions cases at QEII Health Science Centre between 2008 and 2018. Specifically, we compared the outcomes in those patients that had left main stent crossover vs. ostial stenting (OS) alone.

RESULTS

The total number of patients included in the study was 175, with 25 patients (14%) having a crossover to the LM and 150 (86%) having OS. There were more patients with previous CABG (24%) in the crossover group compared to the OS group (9.2%) (P = 0.042). The one-year MACE was not significantly different between CO vs. OS (13.3% (10.5-16.1) vs. 12% (5.5-18.5)). The five-year MACE was numerically higher, although statistically not significant, in CO vs. OS (19.3 (15.9-22.7) vs. 25.9 (16.6-35.2)).

CONCLUSION

This study shows that percutaneous intervention provides reasonable long-term outcomes and low rates of repeat revascularization for isolated ostial LAD lesions, with no noticeable difference in outcomes with crossover stenting into the LM vs. OS alone. A larger, prospective study may be required to determine the optimal strategy for treating ostial LAD lesions.

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.

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.

Three-dimensional printing for cardiovascular diseases: from anatomical modeling to dynamic functionality

Three-dimensional (3D) printing is widely used in medicine. Most research remains focused on forming rigid anatomical models, but moving from static models to dynamic functionality could greatly aid preoperative surgical planning. This work reviews literature on dynamic 3D heart models made of flexible materials for use with a mock circulatory system. Such models allow simulation of surgical procedures under mock physiological conditions, and are; therefore, potentially very useful to clinical practice. For example, anatomical models of mitral regurgitation could provide a better display of lesion area, while dynamic 3D models could further simulate in vitro hemodynamics. Dynamic 3D models could also be used in setting standards for certain parameters for function evaluation, such as flow reserve fraction in coronary heart disease. As a bridge between medical image and clinical aid, 3D printing is now gradually changing the traditional pattern of diagnosis and treatment.

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.

Development of elastic artificial vessels with a digital pulse flow system to investigate the risk of restenosis and vasospasm

The postoperative risk of stenosis is a complex issue, with risk factors including the status of human umbilical vein endothelial cells, the shear stress of dynamic blood flow, and blood physiology. Current research would benefit from in vitro models that can mimic the microenvironment of living vessels, to study the response of endothelial cells to stent placement. In this study, we constructed a digital pulse flow system based on a group of programmable solenoid valves, to mimic dynamic blood flows in the left coronary artery. Elastic artificial vessels, with internally cultured endothelial cells, were used to simulate vessel function and physiology. Based on this novel platform, we systematically explored cell proliferation and function in artificial vessels implanted with bare metal stents or drug-eluting stents, using unstented vessels as controls, under static and pulse flow conditions. The results indicate that the natural shear stresses of dynamic blood flow actually benefit endothelial cell attachment and proliferation. And drug-eluting stents showed stronger inhibition of cell proliferation than bare metal stents, but had a more negative effect on the synthesis of nitric oxide synthase (NOS), suggesting that drug elution might reduce the postoperative risk of restenosis, while increasing the risk of vasospasm. The results suggest that stent evaluation should include both the risk of restenosis and the effect on endothelial cells. Our simulation establishes a realistic in vitro model for pathological studies of restenosis and vasospasm, shows potential for evaluation of new stent designs, and could help develop individualised therapies for patients with atherosclerosis.

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.

Personalized Three-Dimensional Printed Models in Congenital Heart Disease

Patient-specific three-dimensional (3D) printed models have been increasingly used in cardiology and cardiac surgery, in particular, showing great value in the domain of congenital heart disease (CHD). CHD is characterized by complex cardiac anomalies with disease variations between individuals; thus, it is difficult to obtain comprehensive spatial conceptualization of the cardiac structures based on the current imaging visualizations. 3D printed models derived from patient's cardiac imaging data overcome this limitation by creating personalized 3D heart models, which not only improve spatial visualization, but also assist preoperative planning and simulation of cardiac procedures, serve as a useful tool in medical education and training, and improve doctor-patient communication. This review article provides an overall view of the clinical applications and usefulness of 3D printed models in CHD. Current limitations and future research directions of 3D printed heart models are highlighted.

From functional structure to packaging: full-printing fabrication of a microfluidic chip

This paper presents a concept of a full-printing methodology aiming at convenient and fast fabrication of microfluidic devices. For the first time, we achieved a microfluidic biochemical sensor with all functional structures fabricated by inkjet printing, including electrodes, immobilized enzymes, microfluidic components and packaging. With the cost-effective and rapid process, this method provides the possibility of quick model validation of a novel lab-on-chip system. In this study, a three-electrode electrochemical system was integrated successfully with glucose oxidase immobilization gel and sealed in an ice channel, forming a disposable microfluidic sensor for glucose detection. This fully-printed chip was characterized and showed good sensitivity and a linear section at a low-level concentration of glucose (0-10 mM). With the aid of automatic equipment, the fully-printed sensor can be massively produced with low cost.

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.

Liquid metal-based amalgamation-assisted lithography for fabrication of complex channels with diverse structures and configurations

Numerous lab-on-a-chip applications benefit from channels with complex structures and configurations in the areas of tissue engineering and clinical diagnostics. The current fabrication approaches require time-consuming, complicated processes and bulky, expensive facilities. In this work, we propose a novel method for the fabrication of complex channels with the assistance of amalgamation of liquid metal with copper tape. This new technique enables the rapid fabrication of liquid metal molds with various dimensions and diverse structures. Two proof-of-concept experiments were conducted to verify the utilization of this method. First, the channel replicated from the liquid metal mold is used to enhance the mixing performance of liquids flowing through the channel. Second, a channel with a semicircular cross-section is fabricated to achieve 3D focusing in a simple way. This proposed technique can be readily used for fabricating complex channels for a wide range of applications.

Recent Advances in Treatment of Coronary Artery Disease: Role of Science and Technology

Coronary artery disease (CAD) is one of the most common causes of death worldwide. In the last decade, significant advancements in CAD treatment have been made. The existing treatment is medical, surgical or a combination of both depending on the extent, severity and clinical presentation of CAD. The collaboration between different science disciplines such as biotechnology and tissue engineering has led to the development of novel therapeutic strategies such as stem cells, nanotechnology, robotic surgery and other advancements (3-D printing and drugs). These treatment modalities show promising effects in managing CAD and associated conditions. Research on stem cells focuses on studying the potential for cardiac regeneration, while nanotechnology research investigates nano-drug delivery and percutaneous coronary interventions including stent modifications and coatings. This article aims to provide an update on the literature (in vitro, translational, animal and clinical) related to these novel strategies and to elucidate the rationale behind their potential treatment of CAD. Through the extensive and continued efforts of researchers and clinicians worldwide, these novel strategies hold the promise to be effective alternatives to existing treatment modalities.

Fabrication of truly 3D microfluidic channel using 3D-printed soluble mold

The field of complex microfluidic channels is rapidly expanding toward channels with variable cross-sections (i.e., beyond simple rounded channels with a constant diameter), as well as channels whose trajectory can be outside of a single plane. This paper introduces the use of three-dimensional (3D) printed soluble wax as cast molds for rapid fabrication of truly arbitrary microfluidic polydimethylsiloxane (PDMS) channels that are not achieved through typical soft lithography. The molds are printed directly from computer-aided design files, followed by simple dissolution using a solvent after molding PDMS, making rapid prototyping of microfluidic devices possible in hours. As part of the fabrication method, the solubility of several build materials in solvents and their effect on PDMS were investigated to remove the 3D-printed molds from inside the replicated PDMS microfluidic channels without damage. Technology limits, including surface roughness and resolution by comparing the designed channels with fabricated cylindrical channels with various diameters, are also characterized. We reproduced a 3D image of an actual human cerebral artery as cerebral artery-shaped PDMS channels with a diameter of 240 μm to prove the developed fabrication technique. It was confirmed that the fabricated vascular channels were free from any leakage by observing the fluorescence fluid fill.

Predictive Physiological Modeling of Percutaneous Coronary Intervention - Is Virtual Treatment Planning the Future?

Computational modeling has been used routinely in the pre-clinical development of medical devices such as coronary artery stents. The ability to simulate and predict physiological and structural parameters such as flow disturbance, wall shear-stress, and mechanical strain patterns is beneficial to stent manufacturers. These methods are now emerging as useful clinical tools, used by physicians in the assessment and management of patients. Computational models, which can predict the physiological response to intervention, offer clinicians the ability to evaluate a number of different treatment strategies in silico prior to treating the patient in the cardiac catheter laboratory. For the first time clinicians can perform a patient-specific assessment prior to making treatment decisions. This could be advantageous in patients with complex disease patterns where the optimal treatment strategy is not clear. This article reviews the key advances and the potential barriers to clinical adoption and translation of these virtual treatment planning models.

Clinical Applications of 3D Printing: Primer for Radiologists

Three-dimensional (3D) printing refers to a number of manufacturing technologies that create physical models from digital information. Radiology is poised to advance the application of 3D printing in health care because our specialty has an established history of acquiring and managing the digital information needed to create such models. The 3D Printing Task Force of the Radiology Research Alliance presents a review of the clinical applications of this burgeoning technology, with a focus on the opportunities for radiology. Topics include uses for treatment planning, medical education, and procedural simulation, as well as patient education. Challenges for creating custom implantable devices including financial and regulatory processes for clinical application are reviewed. Precedent procedures that may translate to this new technology are discussed. The task force identifies research opportunities needed to document the value of 3D printing as it relates to patient care.

Non-planar PDMS microfluidic channels and actuators: a review

This review examines the state of the art for manufacturing non-planar miniature channels and actuators from PDMS, where non-planar structures are defined here as those beyond simple extrusions of 2D designs, either with rounded or variable cross sections or with an emergence of the channel trajectory out-of-plane. The motivation for 3D PDMS structures and advances in their fabrication are described, focusing on geometries that were previously unachievable through conventional microfabrication. The motivation for non-planar microfluidic channels and actuators is first discussed and the existing literature is grouped into general fabrication themes and described. The structures are organized by their method of fabrication and evaluated based on their relevant properties, including the capability of producing structures with complex geometry, automation of the fabrication process, and minimum feature size. Additional properties are included for work in the more recently emerging field of non-planar PDMS actuators, where the feature size, actuation stroke, and actuation method are the key parameters of interest. In particular, this review considers the impact from recent advances in additive manufacturing, which now allow creation of truly arbitrary 3D structures down to ∼100 μm size scales.

Impact of spatial characteristics in the left stenotic coronary artery on the hemodynamics and visualization of 3D replica models

Cardiovascular disease has been the major cause of death worldwide. Although the initiation and progression mechanism of the atherosclerosis are similar, the stenotic characteristics and the corresponding medical decisions are different between individuals. In the present study, we performed anatomic and hemodynamic analysis on 8 left coronary arterial trees with 10 identified stenoses. A novel boundary condition method had been implemented for fast computational fluid dynamics simulations and patient-specific three-dimensional printed models had been built for visualizations. Our results suggested that the multiple spatial characteristics (curvature of the culprit vessel multiplied by an angle of the culprit's vessel to the upstream parent branch) could be an index of hemodynamics significance (r = -0.673, P-value = 0.033). and reduction of the maximum velocity from stenosis to downstream was found correlated to the FFRCT (r = 0.480, p = 0.160). In addition, 3D printed models could provide accurate replicas of the patient-specific left coronary arterial trees compare to virtual 3D models (r = 0.987, P-value < 0.001). Therefore, the visualization of the 3D printed models could help understand the spatial distribution of the stenoses and the hand-held experience could potentially benefit the educating and preparing of medical strategies.

Do 3D Printing Models Improve Anatomical Teaching About Hepatic Segments to Medical Students? A Randomized Controlled Study

BACKGROUND

It is a difficult and frustrating task for young surgeons and medical students to understand the anatomy of hepatic segments. We tried to develop an optimal 3D printing model of hepatic segments as a teaching aid to improve the teaching of hepatic segments.

METHODS

A fresh human cadaveric liver without hepatic disease was CT scanned. After 3D reconstruction, three types of 3D computer models of hepatic structures were designed and 3D printed as models of hepatic segments without parenchyma (type 1) and with transparent parenchyma (type 2), and hepatic ducts with segmental partitions (type 3). These models were evaluated by six experts using a five-point Likert scale. Ninety two medical freshmen were randomized into four groups to learn hepatic segments with the aid of the three types of models and traditional anatomic atlas (TAA). Their results of two quizzes were compared to evaluate the teaching effects of the four methods.

RESULTS

Three types of models were successful produced which displayed the structures of hepatic segments. By experts' evaluation, type 3 model was better than type 1 and 2 models in anatomical condition, type 2 and 3 models were better than type 1 model in tactility, and type 3 model was better than type 1 model in overall satisfaction (P < 0.05). The first quiz revealed that type 1 model was better than type 2 model and TAA, while type 3 model was better than type 2 and TAA in teaching effects (P < 0.05). The second quiz found that type 1 model was better than TAA, while type 3 model was better than type 2 model and TAA regarding teaching effects (P < 0.05). Only TAA group had significant declines between two quizzes (P < 0.05).

CONCLUSIONS

The model with segmental partitions proves to be optimal, because it can best improve anatomical teaching about hepatic segments.

Freeform fabrication of tissue-simulating phantom for potential use of surgical planning in conjoined twins separation surgery

Preoperative assessment of tissue anatomy and accurate surgical planning is crucial in conjoined twin separation surgery. We developed a new method that combines three-dimensional (3D) printing, assembling, and casting to produce anatomic models of high fidelity for surgical planning. The related anatomic features of the conjoined twins were captured by computed tomography (CT), classified as five organ groups, and reconstructed as five computer models. Among these organ groups, the skeleton was produced by fused deposition modeling (FDM) using acrylonitrile-butadiene-styrene. For the other four organ groups, shell molds were prepared by FDM and cast with silica gel to simulate soft tissues, with contrast enhancement pigments added to simulate different CT and visual contrasts. The produced models were assembled, positioned firmly within a 3D printed shell mold simulating the skin boundary, and cast with transparent silica gel. The produced phantom was subject to further CT scan in comparison with that of the patient data for fidelity evaluation. Further data analysis showed that the produced model reassembled the geometric features of the original CT data with an overall mean deviation of less than 2 mm, indicating the clinical potential to use this method for surgical planning in conjoined twin separation surgery.

Fabrication of arbitrary 3D components in cardiac surgery: from macro-, micro- to nanoscale

Fabrication of tissue-/organ-like structures at arbitrary geometries by mimicking the properties of the complex material offers enormous interest to the research and clinical applicability in cardiovascular diseases. Patient-specific, durable, and realistic three-dimensional (3D) cardiac models for anatomic consideration have been developed for education, pro-surgery planning, and intra-surgery guidance. In cardiac tissue engineering (TE), 3D printing technology is the most convenient and efficient microfabrication method to create biomimetic cardiovascular tissue for the potential in vivo implantation. Although booming rapidly, this technology is still in its infancy. Herein, we provide an emphasis on the application of this technology in clinical practices, micro- and nanoscale fabrications by cardiac TE. Initially, we will give an overview on the fabrication methods that can be used to synthesize the arbitrary 3D components with controlled features and will subsequently highlight the current limitations and future perspective of 3D printing used for cardiovascular diseases.

A retrograde y-stenting of the trachea for treatment of mediastinal fistula in an unusual situation

INTRODUCTION

Stents have been used for quite some time for the treatment of benign and malignant airway stenosis. Silicon stents are preferred for benign situations, whereas metallic self-expanding stents are preferred for malignant comorbidities.

PATIENT AND METHODS

In general, stents can be placed in different approach directions, although in pulmonary medicine it is logical to apply only antegrade techniques - until now. A 63-year-old patient, 168 cm height and 53 kg weight on referral, suffered chronical diseases. The patient was diagnosed with a papillary thyroid carcinoma in 1989, which was treated by resection and radiotherapy. In the following years, she developed a stenosis of the esophagus. The decision to try endobronchial stenting was made upon the plan to close that fistula with a pedicled omentum majus replacement through the diaphragmal opening of the esophagus. This surgical plastic needed an abutment and a secured continuous airway replacement above the tracheostoma level. A Freitag stent (FS), 11 cm in length (110-25-40) and an inner diameter of 13 mm, was placed successfully retrograde into the trachea and completely bridged the big fistula. Unfortunately the patient passed away due to pulmonary infections after several weeks.

DISCUSSION

In this case report, a successful but unusual case of retrograde stent placement of a modified FS is presented.

Structural and congenital heart disease interventions: the role of three-dimensional printing

Advances in catheter-based interventions in structural and congenital heart disease have mandated an increased demand for three-dimensional (3D) visualisation of complex cardiac anatomy. Despite progress in 3D imaging modalities, the pre- and periprocedural visualisation of spatial anatomy is relegated to two-dimensional flat screen representations. 3D printing is an evolving technology based on the concept of additive manufacturing, where computerised digital surface renders are converted into physical models. Printed models replicate complex structures in tangible forms that cardiovascular physicians and surgeons can use for education, preprocedural planning and device testing. In this review we discuss the different steps of the 3D printing process, which include image acquisition, segmentation, printing methods and materials. We also examine the expanded applications of 3D printing in the catheter-based treatment of adult patients with structural and congenital heart disease while highlighting the current limitations of this technology in terms of segmentation, model accuracy and dynamic capabilities. Furthermore, we provide information on the resources needed to establish a hospital-based 3D printing laboratory.

Randomized Comparison of the Crush Versus the Culotte Stenting for Coronary Artery Bifurcation Lesions

Background:

The crush and the culotte stenting were both reported to be effective for complex bifurcation lesion treatment. However, their comparative performance remains elusive.

Methods:

A total of 300 patients with coronary bifurcation lesions were randomly assigned to crush (n = 150) and culotte (n = 150) treatment. The primary endpoint was the occurrence of major adverse cardiac events (MACEs) at 12 months including cardiac death, myocardial infarction, stent thrombosis, and target vessel revascularization. Index lesion restenosis at 12 months was a secondary endpoint. The surface integrals of time-averaged wall shear stress at bifurcation sites were also be quantified.

Results:

There were no significant differences in MACE rates between the two groups at 12-month follow-up: Crush 6.7%, culotte 5.3% (P = 0.48). The rates of index lesion restenosis were 12.7% versus 6.0% (P = 0.047) in the crush and the culotte groups, respectively. At 12-month follow-up, the surface integrals of time-averaged wall shear stress at bifurcation sites in the crush group were significantly lower than the culotte group ([5.01 ± 0.95] × 10⁻⁴ Newton and [6.08 ± 1.16] × 10⁻⁴ Newton, respectively; P = 0.003).

Conclusions:

Both the crush and the culotte bifurcation stenting techniques showed satisfying clinical and angiographic results at 12-month follow-up. Bifurcation lesions treated with the culotte technique tended to have lower restenosis rates and more favorable flow patterns.

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.

Optimal Revascularization Strategy on Medina 0,1,0 Left Main Bifurcation Lesions in Type 2 Diabetes

Aim. Diabetes mellitus (DM) is a major risk factor for cardiovascular disease. The implications of a diagnosis of DM are as severe as the diagnosis of coronary artery disease. For many patients with complex coronary artery disease, optimal revascularization strategy selection and optimal medical therapy are equally important. In this study, we compared the hemodynamic results of different stenting techniques for Medina 0,1,0 left main bifurcation lesions. Methods. We use idealized left main bifurcation models and computational fluid dynamics analysis to evaluate hemodynamic parameters which are known to affect the risk of restenosis and thrombosis at stented bifurcation. The surface integrals of time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) at bifurcation site were quantified. Results. Crossover stenting without final kissing balloon angioplasty provided the most favorable hemodynamic results (integrated values of TAWSS = 2.96 × 10^-4 N, OSI = 4.75 × 10^-6 m²) with bifurcation area subjected to OSI values >0.25, >0.35, and >0.45 calculated as 0.39 mm², 0.06 mm², and 0 mm², respectively. Conclusion. Crossover stenting only offers hemodynamic advantages over other stenting techniques for Medina 0,1,0 left main bifurcation lesions and large bifurcation angle is associated with unfavorable flow profiles.

3D printing based on cardiac CT assists anatomic visualization prior to transcatheter aortic valve replacement

BACKGROUND

3D printing is a promising technique that may have applications in medicine, and there is expanding interest in the use of patient-specific 3D models to guide surgical interventions.

OBJECTIVE

To determine the feasibility of using cardiac CT to print individual models of the aortic root complex for transcatheter aortic valve replacement (TAVR) planning as well as to determine the ability to predict paravalvular aortic regurgitation (PAR).

METHODS

This retrospective study included 16 patients (9 with PAR identified on blinded interpretation of post-procedure trans-thoracic echocardiography and 7 age, sex, and valve size-matched controls with no PAR). 3D printed models of the aortic root were created from pre-TAVR cardiac computed tomography data. These models were fitted with printed valves and predictions regarding post-implant PAR were made using a light transmission test.

RESULTS

Aortic root 3D models were highly accurate, with excellent agreement between annulus measurements made on 3D models and those made on corresponding 2D data (mean difference of -0.34 mm, 95% limits of agreement: ± 1.3 mm). The 3D printed valve models were within 0.1 mm of their designed dimensions. Examination of the fit of valves within patient-specific aortic root models correctly predicted PAR in 6 of 9 patients (6 true positive, 3 false negative) and absence of PAR in 5 of 7 patients (5 true negative, 2 false positive).

CONCLUSIONS

Pre-TAVR 3D-printing based on cardiac CT provides a unique patient-specific method to assess the physical interplay of the aortic root and implanted valves. With additional optimization, 3D models may complement traditional techniques used for predicting which patients are more likely to develop PAR.