Human Vascular Network Research Articles

Multifractal Geometry in Analysis and Processing of Digital Retinal Photographs for Early Diagnosis of Human Diabetic Macular Edema

Objective: The purpose of this paper is to determine a quantitative assessment of the human retinal vascular network architecture for patients with diabetic macular edema (DME). Multifractal geometry and lacunarity parameters are used in this study.Materials and methods: A set of 10 segmented and skeletonized human retinal images, corresponding to both normal (five images) and DME states of the retina (five images), from the DRIVE database was analyzed using the Image J software. Statistical analyses were performed using Microsoft Office Excel 2003 and GraphPad InStat software.Results: The human retinal vascular network architecture has a multifractal geometry. The average of generalized dimensions (Dq) for q = 0, 1, 2 of the normal images (segmented versions), is similar to the DME cases (segmented versions). The average of generalized dimensions (Dq) for q = 0, 1 of the normal images (skeletonized versions), is slightly greater than the DME cases (skeletonized versions). However, the average of D2 for the normal images (skeletonized versions) is similar to the DME images. The average of lacunarity parameter, Λ, for the normal images (segmented and skeletonized versions) is slightly lower than the corresponding values for DME images (segmented and skeletonized versions).Conclusion: The multifractal and lacunarity analysis provides a non-invasive predictive complementary tool for an early diagnosis of patients with DME.

Integration and Regression of Implanted Engineered Human Vascular Networks During Deep Wound Healing

The ability of vascularized constructs to integrate with tissues may depend on the kinetics and stability of vascular structure development. This study assessed the functionality and durability of engineered human vasculatures from endothelial progenitors when implanted in a mouse deep burn-wound model. Human vascular networks, derived from endothelial colony-forming cells in hyaluronic acid hydrogels, were transplanted into third-degree burns. On day 3 following transplantation, macrophages rapidly degraded the hydrogel during a period of inflammation; through the transitions from inflammation to proliferation (days 5-7), the host's vasculatures infiltrated the construct, connecting with the human vessels within the wound area. The growth of mouse vessels near the wound area supported further integration with the implanted human vasculatures. During this period, the majority of the vessels (∼60%) in the treated wound area were human. Although no increase in the density of human vessels was detected during the proliferative phase, they temporarily increased in size. This growth peaked at day 7, the middle of the proliferation stage, and then decreased by the end of the proliferation stage. As the wound reached the remodeling period during the second week after transplantation, the vasculatures including the transplanted human vessels generally regressed, and few microvessels, wrapped by mouse smooth muscle cells and with a vessel area less than 200 μm² (including the human ones), remained in the healed wound. Overall, this study offers useful insights for the development of vascularization strategies for wound healing and ischemic conditions, for tissue-engineered constructs, and for tissue regeneration.

Control of brain blood flow by capillaries: a simulation study in an anatomically accurate large human vascular network

In this paper, the variations in cerebral blood flow induced by global or localised capillary vasodilations are studied. The results demonstrate that pericyte-mediated regulation of blood flowat capillary level would be efficient for neuro-vascular coupling. By contrast to a regulation situated at the level of arterioles (Lorthois et al. 2011b), the changes in blood volume can be highly localised in space, with the potential to be as close as possible of areas of neuronal activation. However, the changes in blood flow are much more diffuse. This imposes limits on the ultimate spatial resolution of hemodynamically based brain functional imaging techniques.

Generation of Functional Human Vascular Network

BackgroundOne of the major obstacles in regenerating thick, complex tissues such as the liver is their need for vascularization, which is essential to maintain cell viability during tissue growth and to induce structural organization. Herein, we have described a method to engineer a functional human vascular network. MethodsEnhanced green fluorescence protein-labeled human umbilical vein endothelial cells (GFP-HUVECs) were cocultivated with kusabira orange-labeled human mesenchymal stem cells (KO-hMSCs) inside a collagen/fibronectin matrix. Premature vascular network formation was visualized by fluorescence microscopy imaging. Furthermore, constructs prevascularized in vitro were implanted into a transparency window in immunodeficient mice. ResultsFollowing several days of cultivation, GFP-HUVECs formed vessel-like structures that were stabilized by pericytes differentiated from KO-hMSCs. After implantation in vivo, the patency of human vascular structures was proved by rhodamine dextran infusion. These functional vascular structures remained for over 2 months. DiscussionVascularization is the key challenge to organ generation. We successfully generated human vascular networks inside a matrix. Integration of parenchymal cells using our engineering technique should facilitate future efforts to reconstitute vascularized human organ systems in vitro.

Functional Human Vascular Network Generated in Photocrosslinkable Gelatin Methacrylate Hydrogels

The generation of functional, 3D vascular networks is a fundamental prerequisite for the development of many future tissue engineering-based therapies. Current approaches in vascular network bioengineering are largely carried out using natural hydrogels as embedding scaffolds. However, most natural hydrogels present a poor mechanical stability and a suboptimal durability, which are critical limitations that hamper their widespread applicability. The search for improved hydrogels has become a priority in tissue engineering research. Here, the suitability of a photopolymerizable gelatin methacrylate (GelMA) hydrogel to support human progenitor cell-based formation of vascular networks is demonstrated. Using GelMA as the embedding scaffold, it is shown that 3D constructs containing human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSCs) generate extensive capillary-like networks in vitro. These vascular structures contain distinct lumens that are formed by the fusion of ECFC intracellular vacuoles in a process of vascular morphogenesis. The process of vascular network formation is dependent on the presence of MSCs, which differentiate into perivascular cells occupying abluminal positions within the network. Importantly, it is shown that implantation of cell-laden GelMA hydrogels into immunodeficient mice results in a rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, it is shown that the degree of methacrylation of the GelMA can be used to modulate the cellular behavior and the extent of vascular network formation both in vitro and in vivo. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.

Fibroblast growth factor-2 facilitates rapid anastomosis formation between bioengineered human vascular networks and living vasculature

Many common diseases involve the injury, loss, or death of organ tissues. For these patients, organ transplantation is often the only viable solution. Nonetheless, organ transplantation is seriously limited by the relative scarcity of living and non-living donors, a situation that is worsening with aging of the world population. Tissue Engineering (TE) is a research discipline in regenerative medicine that aims to generate tissues in the laboratory that can replace diseased and damaged tissues in patients. Crucially, engineered tissues must have a vascular network that guarantees adequate nutrient supply, gas exchange, and elimination of waste products. Therefore, the search for clinically relevant sources of vasculogenic cells and the subsequent development of methods to achieve rapid vascularization is of utmost importance. We and others have previously shown that human blood-derived endothelial colony-forming cells (ECFCs) have the required vasculogenic capacity to form functional vascular networks in vivo. These studies demonstrated that, in the presence of an appropriate source of perivascular cells, ECFCs can self-assemble into microvascular networks and connect to the host vasculature, a process that takes approximately 7days in vivo. The prospect is to incorporate these vascular networks into future engineered tissues. However, engineered tissues must have a functional vasculature immediately after implantation in order to preserve viability and function. Thus, it is critical to further develop strategies for rapid formation of perfused vascular network in vivo. Here, we describe a methodology to deliver ECFCs and bone marrow-derived mesenchymal stem cells (MSCs) subcutaneously into immunodeficient mice in the presence of fibroblast growth factor-2 (FGF-2). This approach significantly reduces the time needed to achieve functional anastomoses between bioengineered human blood vessels and the host vasculature. This methodology includes (1) isolation, characterization and culture of ECFCs, (2) isolation, characterization and culture of MSCs, and (3) implantation of ECFCs and MSCs, in the presence of FGF-2, into immunodeficient mice to generate perfused vascular networks.

Bioengineered human vascular networks transplanted into secondary mice reconnect with the host vasculature and re-establish perfusion

AbstractThe ability to form anastomoses with the host circulation is essential for vascular networks incorporated within cell-seeded bioengineered tissues. Here, we tested whether and how rapidly human endothelial colony forming cell (ECFC)/mesenchymal progenitor cell (MPC)–derived bioengineered vessels, originally perfused in one mouse, could become reperfused in a secondary mouse. Using in vivo labeling with a systemically injected mixture of human- and murine-specific lectins, we demonstrate that ECFC/MPC blood vessels reconnect and are perfused at day 3 after transplantation. Furthermore, we quantified the longitudinal change in perfusion volume in the same implants before and after transplantation using contrast-enhanced micro-ultrasonic imaging. Perfusion was restored at day 3 after transplantation and increased with time, suggesting an important new feature of ECFC/MPC blood vessels: the bioengineered vessels can reconnect with the vasculature when transplanted to a new site. This feature extends the potential applications of this postnatal progenitor cell-based technology for transplantable large tissue-engineered constructs.

Induction of erythropoiesis using human vascular networks genetically engineered for controlled erythropoietin release

AbstractFor decades, autologous ex vivo gene therapy has been postulated as a potential alternative to parenteral administration of recombinant proteins. However, achieving effective cellular engraftment of previously retrieved patient cells is challenging. Recently, our ability to engineer vasculature in vivo has allowed for the introduction of instructions into tissues by genetically modifying the vascular cells that build these blood vessels. In the present study, we genetically engineered human blood–derived endothelial colony-forming cells (ECFCs) to express erythropoietin (EPO) under the control of a tetracycline-regulated system, and generated subcutaneous vascular networks capable of systemic EPO release in immunodeficient mice. These ECFC-lined vascular networks formed functional anastomoses with the mouse vasculature, allowing direct delivery of recombinant human EPO into the bloodstream. After activation of EPO expression, erythropoiesis was induced in both normal and anemic mice, a process that was completely reversible. This approach could relieve patients from frequent EPO injections, reducing the medical costs associated with the management of anemia. We propose this ECFC-based gene-delivery strategy as a viable alternative technology when routine administration of recombinant proteins is needed.

Bioengineering Human Microvascular Networks in Immunodeficient Mice

The future of tissue engineering and cell-based therapies for tissue regeneration will likely rely on our ability to generate functional vascular networks in vivo. In this regard, the search for experimental models to build blood vessel networks in vivo is of utmost importance 1. The feasibility of bioengineering microvascular networks in vivo was first shown using human tissue-derived mature endothelial cells (ECs) 2-4; however, such autologous endothelial cells present problems for wide clinical use, because they are difficult to obtain in sufficient quantities and require harvesting from existing vasculature. These limitations have instigated the search for other sources of ECs. The identification of endothelial colony-forming cells (ECFCs) in blood presented an opportunity to non-invasively obtain ECs 5-7. We and other authors have shown that adult and cord blood-derived ECFCs have the capacity to form functional vascular networks in vivo 7-11. Importantly, these studies have also shown that to obtain stable and durable vascular networks, ECFCs require co-implantation with perivascular cells. The assay we describe here illustrates this concept: we show how human cord blood-derived ECFCs can be combined with bone marrow-derived mesenchymal stem cells (MSCs) as a single cell suspension in a collagen/fibronectin/fibrinogen gel to form a functional human vascular network within 7 days after implantation into an immunodeficient mouse. The presence of human ECFC-lined lumens containing host erythrocytes can be seen throughout the implants indicating not only the formation (de novo) of a vascular network, but also the development of functional anastomoses with the host circulatory system. This murine model of bioengineered human vascular network is ideally suited for studies on the cellular and molecular mechanisms of human vascular network formation and for the development of strategies to vascularize engineered tissues.

Bioengineering Human Microvascular Networks in Immunodeficient Mice

The future of tissue engineering and cell-based therapies for tissue regeneration will likely rely on our ability to generate functional vascular networks in vivo. In this regard, the search for experimental models to build blood vessel networks in vivo is of utmost importance 1. The feasibility of bioengineering microvascular networks in vivo was first shown using human tissue-derived mature endothelial cells (ECs) 2-4; however, such autologous endothelial cells present problems for wide clinical use, because they are difficult to obtain in sufficient quantities and require harvesting from existing vasculature. These limitations have instigated the search for other sources of ECs. The identification of endothelial colony-forming cells (ECFCs) in blood presented an opportunity to non-invasively obtain ECs 5-7. We and other authors have shown that adult and cord blood-derived ECFCs have the capacity to form functional vascular networks in vivo 7-11. Importantly, these studies have also shown that to obtain stable and durable vascular networks, ECFCs require co-implantation with perivascular cells. The assay we describe here illustrates this concept: we show how human cord blood-derived ECFCs can be combined with bone marrow-derived mesenchymal stem cells (MSCs) as a single cell suspension in a collagen/fibronectin/fibrinogen gel to form a functional human vascular network within 7 days after implantation into an immunodeficient mouse. The presence of human ECFC-lined lumens containing host erythrocytes can be seen throughout the implants indicating not only the formation (de novo) of a vascular network, but also the development of functional anastomoses with the host circulatory system. This murine model of bioengineered human vascular network is ideally suited for studies on the cellular and molecular mechanisms of human vascular network formation and for the development of strategies to vascularize engineered tissues.

Controllable and robust morphogenesis of functional vascular network assembly within synthetic environments

The generation of functional vascular networks by endothelial colony-forming cells (ECFCs) has the potential to improve treatment for vascular diseases and to facilitate successful organ transplantation. Although this process has been elucidated using natural matrix, little is known about angiogenesis in synthetic matrix, a xeno-free scaffold which can provide a more clinically relevant alternative for regenerative medicine. Here, we utilized chemically and mechanically tunable hyaluronic acid (HA) hydrogels as scaffolds to investigate angiogenesis by ECFCs. We are able to control vascular morphogenesis and form robust microvasculatures by adjusting matrix elasticity, RGD binding, and MMP-sensitive crosslinkers. First we established the RGD concentration required to induce efficient vacuoles and lumen formation. Integration of MMP-sensitive-peptide enabled ECFCs to sprout, branch, and form complex vascular networks. Increased expression of Hyal-1, -2, MMP-1,-2, and MT1-MMP were followed by the decrease in matrix stiffness. Once the constructs were matured in vitro, indicated by an increased expression of TIMP-2 and -3, the constructs were implanted in vivo. After two weeks, most of the microvessels found were positive for human CD31 and perfused with blood cells, indicating that the implanted human vascular networks were able to anastomose with the host vasculatures to form functional vessel. Grant Funding Source: American Heart Association (AHA)

Simulation study of brain blood flow regulation by intra-cortical arterioles in an anatomically accurate large human vascular network. Part II: Flow variations induced by global or localized modifications of arteriolar diameters

In a companion paper (Lorthois et al., Neuroimage, in press), we perform the first simulations of blood flow in an anatomically accurate large human intra-cortical vascular network (~10000 segments), using a 1D non-linear model taking into account the complex rheological properties of blood flow in microcirculation. This model predicts blood pressure, blood flow and hematocrit distributions, volumes of functional vascular territories, regional flow at voxel and network scales, etc. Using the same approach, we study flow reorganizations induced by global arteriolar vasodilations (an isometabolic global increase in cerebral blood flow). For small to moderate global vasodilations, the relationship between changes in volume and changes in flow is in close agreement with Grubb's law, providing a quantitative tool for studying the variations of its exponent with underlying vascular architecture. A significant correlation between blood flow and vascular structure at the voxel scale, practically unchanged with respect to baseline, is demonstrated. Furthermore, the effects of localized arteriolar vasodilations, representative of a local increase in metabolic demand, are analyzed. In particular, localized vasodilations induce flow changes, including vascular steal, in the neighboring arteriolar trunks at small distances (<300μm), while their influence in the neighboring veins is much larger (about 1mm), which provides an estimate of the vascular point spread function. More generally, for the first time, the hemodynamic component of various functional neuroimaging techniques has been isolated from metabolic and neuronal components, and a direct relationship with several known characteristics of the BOLD signal has been demonstrated.

Engineered human tumor xenografts with functional human vascular networks

Animal models of human tumor angiogenesis would have multiple applications. However, they are extremely difficult to standardize. In this work, we tried to generate human tumor xenografts containing a human vascular bed in immunodeficient mice by subcutaneous co-implantation of matrigel-embedded human endothelial cells (EC), human mesenchymal stem cells (MSC) as a source of mural cells and HT1080 human fibrosarcoma cells. Unfortunately, in this context human EC were rapidly substituted by their murine counterparts, and by day 16 post-implantation human CD34 positive cells were hardly detectable in intratumoral vessels. In an attempt to inhibit host EC colonization of human xenografts and promote human EC grafting, we investigated the effect of radiation prior to implantation on the vascularization and growth of tumor xenografts. Nude mice underwent either localized (implantation area) or sublethal whole-body exposure to radiation. Localized radiation inhibited both human and murine neovascularization, and even the tumor growth rate was remarkably decreased when compared to control unirradiated mice and sublethally whole-body irradiated mice. Interestingly, numerous human vessels were detectable in sublethally irradiated mice at day 30, with murine EC only overpassing human EC when spontaneous hematopoietic reconstitution has taken place. This observation strongly suggests the implication of bone marrow-derived murine endothelial precursors in tumor neovascularization. In summary, we have established a model of human tumor neovascularization that is amenable to both the study of molecular aspects in the angiogenic process and the evaluation of potential new antiangiogenic drugs.

Simulation study of brain blood flow regulation by intra-cortical arterioles in an anatomically accurate large human vascular network: Part I: Methodology and baseline flow

Hemodynamically based functional neuroimaging techniques, such as BOLD fMRI and PET, provide indirect measures of neuronal activity. The quantitative relationship between neuronal activity and the measured signals is not yet precisely known, with uncertainties remaining about the relative contribution by their metabolic and hemodynamic components. Empirical observations have demonstrated the importance of the latter component and suggested that micro-vascular anatomy has a potential influence. The recent development of a 3D computer-assisted method for micro-vascular cerebral network analysis has produced a large quantitative library on the microcirculation of the human cerebral cortex (Cassot et al., 2006), which can be used to investigate the hemodynamic component of brain activation through fluid dynamic modeling. For this purpose, we perform the first simulations of blood flow in an anatomically accurate large human intra-cortical vascular network (~10000 segments), using a 1D non-linear model taking account of the complex rheological properties of blood flow in microcirculation. This model predicts blood pressure, blood flow and hematocrit distributions, as well as volumes of functional vascular territories, and regional flow at voxel and network scales. First, the influence of the prescribed boundary conditions (BCs) on the baseline flow structure is investigated, highlighting relevant lower- and upper-bound BCs. Independent of these BCs, large heterogeneities of baseline flow from vessel to vessel and from voxel to voxel, are demonstrated. These heterogeneities are controlled by the architecture of the intra-cortical vascular network. In particular, a correlation between the blood flow and the proportion of vascular volume occupied by arterioles or venules, at voxel scale, is highlighted. Then, the extent of venous contamination downstream to the sites of neuronal activation is investigated, demonstrating a linear relationship between the catchment surface of the activated area and the diameter of the intra-cortical draining vein.

Collective methods of propulsion and steering for untethered microscale nanorobots navigating in the human vascular network

In the field of medical nanorobotics, nanometre-scale components and phenomena are exploited within the context of robotics to provide new medical diagnostic and interventional procedures, or at least to enhance the existing ones. The best route for such miniature robots to access various regions inside the human body is certainly the vascular network. Such a network is made of nearly 100 000 km of blood vessels varying in diameters from a few millimetres in the arteries down to ∼ 4 μm in the capillaries with respective important variations in blood flow velocities. When injected in the blood circulatory network using existing modern techniques such as catheterization, such robots must travel from larger-diameter vessels before reaching much tinier capillaries. As such, the use of a single type of microscale robots capable of travelling in various environments and conditions related to such different blood vessels while being trackable by an external system seems, at the present time, inconceivable. Therefore, as explained in this article, an approach based on the use of several types of microscale robots with complementary methods of propulsion and steering capable of operating in a collective manner is more likely to achieve better results. This is especially true for interventions such as direct tumour targeting where the tiniest blood vessels such as the ones found in the angiogenesis network must be travelled.

A Simulation Study of Brain Blood Flow Regulation by Intra-cortical Arterioles in an Anatomically Accurate Large Human Vascular Network

A Simulation Study of Brain Blood Flow Regulation by Intra-cortical Arterioles in an Anatomically Accurate Large Human Vascular Network

A Study of the Vascular Network of the Iris Using Flat Preparation

PurposeThis study was performed to examine the vascular network of the human iris using flat preparation.MethodsThe ciliary body-iris structures were separated from human eyeballs, and a portion of the irises were treated with trypsin to remove the pigment granules. These iris tissues were unfolded and placed onto glass slides using flat preparation, and the vascular network of each iris was examined by fluorescein microscopy. The ciliary body-iris structures separated from the remaining eyes were stained with hematoxylin-eosin without trypsin treatment and were examined by light microscopy.ResultsThe long posterior ciliary artery formed several branches before entering the iris root, and such branches formed the major arterial circle of the iris with diverse diameters in the vicinity of the iris root and the ciliary process. In the pupillary margin, the iris vasculature network formed a cone shape and then formed an arcade by connecting to adjacent vasculatures. In the vicinity of the collarette, the iris vasculature network formed the minor arterial circle of the iris with diverse diameters perpendicular to the arcade of the iris network located in the pupillary margin. In the pupillary margin, the capillaries were somewhat thick and connected to the irregular traveling iris vein.ConclusionsThe above findings explain the human iris vascular network and provide a theoretical basis for the sectoral filling of the iris vasculature seen in fluorescein iris angiography.

Insulin-like growth factor-binding protein-3 inhibition of prostate cancer growth involves suppression of angiogenesis

Insulin-like growth factor-binding protein-3 (IGFBP-3) is a multifunctional protein that induces apoptosis utilizing both insulin-like growth factor receptor (IGF)-dependent and -independent mechanisms. We investigated the effects of IGFBP-3 on tumor growth and angiogenesis utilizing a human CaP xenograft model in severe-combined immunodeficiency mice. A 16-day course of IGFBP-3 injections reduced tumor size and increased apoptosis and also led to a reduction in the number of vessels stained with CD31. In vitro, IGFBP-3 inhibited both vascular endothelial growth factor- and IGF-stimulated human umbilical vein endothelial cells vascular network formation in a matrigel assay. This action is primarily IGF independent as shown by studies utilizing the non-IGFBP-binding IGF-1 analog Long-R3. Additionally, we used a fibroblast growth factor-enriched matrigel-plug assay and chick allantoic membrane assays to show that IGFBP-3 has potent antiangiogenic actions in vivo. Finally, overexpression of IGFBP-3 or the non-IGF-binding GGG-IGFBP-3 mutant in Zebrafish embryos confirmed that both IGFBP-3 and the non-IGF-binding mutant inhibited vessel formation in vivo, indicating that the antiangiogenic effect of IGFBP-3 is an IGF-independent phenomenon. Together, these studies provide the first evidence that IGFBP-3 has direct, IGF-independent inhibitory effects on angiogenesis providing an additional mechanism by which it exerts its tumor suppressive effects and further supporting its development for clinical use in the therapy of patients with prostate cancer.

Dissections aiguës de l'aorte : physiopathologie et diagnostic

Acute dissection of the aorta is defined by the sudden irruption of a pressurized blood flow trough a tear into the internal part of the aortic wall, resulting into longitudinal separation of the wall along its weakest constituent, and leading to the formation of two circulating channels. It represents the worst catastrophe affecting the human vascular network. Its spontaneous mortality, when the ascending aorta is involved, reaches 50% at 48 hours, 60% after one week and 90% after one month, due to aortic rupture, intrapericardial tamponnade, malperfusion of vital end organs or massive aortic valve regurgitation. Its prevalence is estimated between 4 and 10 for 100 000, and the male-female ratio is about 80%. Acute aortic dissections occur generally on aortas weakened by either hereditary dystrophic conditions such as Marfan’s syndrome or familial annulo-aortic ectasia, or congenital diseases such as bicuspid aortic valve or coarctation, or acquired diseases mainly related to atheroma. Arterial hypertension, either chronic or more often in the form of sudden thrust, plays a major role in the occurrence of acute dissection. The dissecting process extends more or less along the vessel but generally reaches the bifurcation and the iliac arteries. In most patients, the vascular damages, constituted within a few seconds or minutes, may explain the clinical symptoms, the observed complications and may determine the therapeutic strategy. The clinical patterns observed are highly heterogeneous. The most consistent symptom (present in 90% of the patients) consists in an intense thoracic pain which may be associated in a variable manner with cardiogenic shock, transient or permanent neurological disorders, peripheral ischemia, abdominal pain, etc… Any diagnostic suspicion must be confirmed by chest X ray, and above all by trans-thoracic echocardiography, a simple technique which can be performed easily even in emergency rooms or in non specialized units. In case of probable diagnosis, the patient must be referred to a cardio surgical ICU in order to confirm the acute dissection and to analyse its consequences. Presently, trans-oesophageal echocardiography and computerized tomography (CT scan) are the gold standard in terms of rapidity, safety, sensibility and specificity whereas, because of its invasive nature, aortography has lost its pre-eminence and Magnetic Resonance Imaging, although quite contributory, is difficult to perform on an emergency basis in patients with, generally, haemodynamic instability.

VR simulated training for less invasive vascular intervention

This paper describes a computerized simulation system for less invasive vascular interventions using virtual-reality (VR)-based technology. A virtual human patient is constructed on top of the visible human data (VHD) incorporating in various vascular disease cases. Specially, the human vascular network is modeled for the use of catheterization simulation. Physical modeling technique is applied to model the interaction between the blood vessels and vascular catheterization devices. A haptic interface is integrated with the computer simulation system to provide tactile sensations to the user during the simulated catheterization procedures. The system can be used for training and pre-treatment planning of interventional vascular procedures.