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1.
J Neuroeng Rehabil ; 17(1): 63, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32404174

RESUMO

BACKGROUND: Human-likeliness of robot movements is a key component to enable a safe and effective human-robot interaction, since it contributes to increase acceptance and motion predictability of robots that have to closely interact with people, e.g. for assistance and rehabilitation purposes. Several parameters have been used to quantify how much a robot behaves like a human, which encompass aspects related to both the robot appearance and motion. The latter point is fundamental to allow the operator to interpret robotic actions, and plan a meaningful reactions. While different approaches have been presented in literature, which aim at devising bio-aware control guidelines, a direct implementation of human actions for robot planning is not straightforward, still representing an open issue in robotics. METHODS: We propose to embed a synergistic representation of human movements for robot motion generation. To do this, we recorded human upper-limb motions during daily living activities. We used functional Principal Component Analysis (fPCA) to extract principal motion patterns. We then formulated the planning problem by optimizing the weights of a reduced set of these components. For free-motions, our planning method results into a closed form solution which uses only one principal component. In case of obstacles, a numerical routine is proposed, incrementally enrolling principal components until the problem is solved with a suitable precision. RESULTS: Results of fPCA show that more than 80% of the observed variance can be explained by only three functional components. The application of our method to different meaningful movements, with and without obstacles, show that our approach is able to generate complex motions with a very reduced number of functional components. We show that the first synergy alone accounts for the 96% of cost reduction and that three components are able to achieve a satisfactory motion reconstruction in all the considered cases. CONCLUSIONS: In this work we moved from the analysis of human movements via fPCA characterization to the design of a novel human-like motion generation algorithm able to generate, efficiently and with a reduced set of basis elements, several complex movements in free space, both in free motion and in case of obstacle avoidance tasks.

2.
BMC Genomics ; 21(1): 307, 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-32299354

RESUMO

BACKGROUND: Hypothyroidism is a common complex endocrinopathy that typically has an autoimmune etiology, and it affects both humans and dogs. Genetic and environmental factors are both known to play important roles in the disease development. In this study, we sought to identify the genetic risk factors potentially involved in the susceptibility to the disease in the high-risk Giant Schnauzer dog breed. RESULTS: By employing genome-wide association followed by fine-mapping (top variant p-value = 5.7 × 10- 6), integrated with whole-genome resequencing and copy number variation analysis, we detected a ~ 8.9 kbp deletion strongly associated (p-value = 0.0001) with protection against development of hypothyroidism. The deletion is located between two predicted Interferon alpha (IFNA) genes and it may eliminate functional elements potentially involved in the transcriptional regulation of these genes. Remarkably, type I IFNs have been extensively associated to human autoimmune hypothyroidism and general autoimmunity. Nonetheless, the extreme genomic complexity of the associated region on CFA11 warrants further long-read sequencing and annotation efforts in order to ascribe functions to the identified deletion and to characterize the canine IFNA gene cluster in more detail. CONCLUSIONS: Our results expand the current knowledge on genetic determinants of canine hypothyroidism by revealing a significant link with the human counterpart disease, potentially translating into better diagnostic tools across species, and may contribute to improved canine breeding strategies.

3.
Cell Rep ; 30(11): 3755-3765.e7, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32187547

RESUMO

Rational immunogen design aims to focus antibody responses to vulnerable sites on primary antigens. Given the size of these antigens, there is, however, potential for eliciting unwanted, off-target responses. Here, we use our electron microscopy polyclonal epitope mapping approach to describe the antibody specificities elicited by immunization of non-human primates with soluble HIV envelope trimers and subsequent repeated viral challenge. An increased diversity of epitopes recognized and the approach angle by which these antibodies bind constitute a hallmark of the humoral response in most protected animals. We also show that fusion peptide-specific antibodies are likely responsible for some neutralization breadth. Moreover, cryoelectron microscopy (cryo-EM) analysis of a fully protected animal reveals a high degree of clonality within a subset of putatively neutralizing antibodies, enabling a detailed molecular description of the antibody paratope. Our results provide important insights into the immune response against a vaccine candidate that entered into clinical trials in 2019.

4.
IEEE Trans Haptics ; 13(1): 233-238, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32012026

RESUMO

In the previous work, we reported that tactile information (tactile slip) during finger sliding and reaching actions over a textured surface contributes to the control of the hand movement. More specifically, we observed a significant bias in the motion trajectories, which was explained by the tactile estimate accounted by the tactile flow model-i.e. a perceived motion direction always perpendicular to the ridge orientation, and its integration with the muscular-skeletal proprioceptive cues. However, to which extent this observed behavior also depends on the reaction force exerted by the surface ridges on the finger pad during the dynamic interaction still represents a largely unexplored research question. If not properly addressed, this point could rise the alternative explanation that the systematic bias is determined by the insufficient compensation of the reaction force by participants. In this article, we investigate the role of the lateral component of the reaction force on the surface plane (lateral force) in texture-related motion bias. We asked participants to slide their finger straight on a lubricated ridged plate towards a target goal displayed in a virtual reality environment. They exerted two different levels of normal force, which produced two different levels of lateral force during the finger interaction with the ridges. The effect of ridge orientation was found to be larger for the high compared to the low force level. However, also in the latter case, we still observed the same biased trajectories reported in our previous work, despite the negligible value of the lateral force. This supports our hypothesis that the motor bias arises from the integration of the tactile motion estimate, biased by the texture, and the other proprioceptive cues.

5.
IEEE Trans Haptics ; 13(1): 239-245, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32012027

RESUMO

Blindness represents one of the major disabling societal causes, impacting the life of visually impaired people and their families. For what concerns the access to written information, one of the main tools used by blind people is the traditional Braille code. This is the reason why in the recent years, there has been a technological effort to develop refreshable Braille devices. These consist of multiple physical dots that dynamically change their configuration to reproduce different sequences of the letters in Braille code. Although promising, these approaches have many drawbacks, which are mainly related to costs, design complexity, portability, and power consumption. Of note, while many solutions have been proposed for multi-cell devices, the investigation of the potentialities of single-cell refreshable systems has received little attention so far. This investigation could offer effective and viable manners to overcome the aforementioned drawbacks, likely fostering a widespread adoption of such assistive technologies with end-users. In this article, we present the design and characterization of a new cost-effective single-cell Electromagnetic Refreshable Braille Display, the Readable system. We also report on tests performed with blindfolded and blind expert Braille code readers. Results demonstrate the effectiveness of our device in correctly reproducing alphanumeric content, opening promising perspectives in every-day life applications.

6.
Artigo em Inglês | MEDLINE | ID: mdl-32095912

RESUMO

Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure that provides an effective alternative to open-heart surgical valve replacement for treating advanced calcific aortic valve disease patients. However, complications, such as valve durability, device migration, paravalvular leakage (PVL), and thrombogenicity may lead to increased overall post-TAVR morbidity and mortality. A series of numerical studies involving a self-expandable TAVR valve were performed to evaluate these complications. Structural studies were performed with finite element (FE) analysis, followed by computational fluid dynamics (CFD) simulations, and fluid-structure interaction (FSI) analysis. The FE analysis was utilized to study the effect of TAVR valve implantation depth on valve anchorage in the Living Heart Human Model, which is capable of simulating beating heart during repeated cardiac cycles. The TAVR deployment cases where no valve migration was observed were then used to calculate the post-deployment thrombogenic potential via CFD simulations. FSI analysis followed to further assess the post-deployment TAVR hemodynamic performance for different implantation depths. The deployed valves PVL, geometric and effective orifice areas, and the leaflets structural and flow stress magnitudes were compared to determine the device optimal landing zone. The combined structural and hemodynamic analysis indicated that with the TAVR valve deployed at an aft ventricle position an optimal performance was achieved in the specific anatomy studied. Given the TAVR's rapid expansion to younger lower-risk patients, the comprehensive numerical methodology proposed here can potentially be used as a predictive tool for both procedural planning and valve design optimization to minimize the reported complications.

7.
Biomech Model Mechanobiol ; 19(2): 779, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31965351

RESUMO

This is to inform that the original article was published without the "Conflict of Interest" statement.

8.
ASAIO J ; 66(2): 190-198, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-30845067

RESUMO

Transcatheter aortic valve replacement (TAVR) has emerged as an effective therapy for the unmet clinical need of inoperable patients with severe aortic stenosis (AS). Current clinically used tissue TAVR valves suffer from limited durability that hampers TAVR's rapid expansion to younger, lower risk patients. Polymeric TAVR valves optimized for hemodynamic performance, hemocompatibility, extended durability, and resistance to calcific degeneration offer a viable solution to this challenge. We present extensive in vitro durability and stability testing of a novel polymeric TAVR valve (PolyNova valve) using 1) accelerated wear testing (AWT, ISO 5840); 2) calcification susceptibility (in the AWT)-compared with clinically used tissue valves; and 3) extended crimping stability (valves crimped to 16 Fr for 8 days). Hydrodynamic testing was performed every 50M cycles. The valves were also evaluated visually for structural integrity and by scanning electron microscopy for evaluation of surface damage in the micro-scale. Calcium and phosphorus deposition was evaluated using micro-computed tomography (µCT) and inductive coupled plasma spectroscopy. The valves passed 400M cycles in the AWT without failure. The effective orifice area kept stable at 1.8 cm with a desired gradual decrease in transvalvular pressure gradient and regurgitation (10.4 mm Hg and 6.9%, respectively). Calcium and phosphorus deposition was significantly lower in the polymeric valve: down by a factor of 85 and 16, respectively-as compared to a tissue valve. Following the extended crimping testing, no tears nor surface damage were evident. The results of this study demonstrate the potential of a polymeric TAVR valve to be a viable alternative to tissue-based TAVR valves.

9.
Med Biol Eng Comput ; 57(10): 2129-2143, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31372826

RESUMO

Calcific aortic valve disease (CAVD) is characterized by stiffened aortic valve leaflets. Bicuspid aortic valve (BAV) is the most common congenital heart disease. Transcatheter aortic valve replacement (TAVR) is a treatment approach for CAVD where a stent with mounted bioprosthetic valve is deployed on the stenotic valve. Performing TAVR in calcified BAV patients may be associated with post-procedural complications due to the BAV asymmetrical structure. This study aims to develop refined computational models simulating the deployments of Evolut R and PRO TAVR devices in a representative calcified BAV. The paravalvular leakage (PVL) was also calculated by computational fluid dynamics simulations. Computed tomography scan of severely stenotic BAV patient was acquired. The 3D calcium deposits were generated and embedded inside a parametric model of the BAV. Deployments of the Evolut R and PRO inside the calcified BAV were simulated in five bioprosthesis leaflet orientations. The hypothesis of asymmetric and elliptic stent deployment was confirmed. Positioning the bioprosthesis commissures aligned with the native commissures yielded the lowest PVL (15.7 vs. 29.5 mL/beat). The Evolut PRO reduced the PVL in half compared with the Evolut R (15.7 vs. 28.7 mL/beat). The proposed biomechanical computational model could optimize future TAVR treatment in BAV patients. Graphical abstract.


Assuntos
Estenose da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/cirurgia , Valva Aórtica/anormalidades , Doenças das Valvas Cardíacas/fisiopatologia , Doenças das Valvas Cardíacas/cirurgia , Substituição da Valva Aórtica Transcateter , Idoso , Valva Aórtica/fisiopatologia , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/diagnóstico por imagem , Fenômenos Biomecânicos , Simulação por Computador , Elasticidade , Feminino , Análise de Elementos Finitos , Humanos , Hidrodinâmica , Modelos Cardiovasculares , Pressão , Stents , Tomografia Computadorizada por Raios X
10.
J Robot Surg ; 13(4): 585-588, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31062181

RESUMO

Uterine fibromatosis is common in women, with an estimated prevalence of up to 15-50% after 35 years. About 80% of women affected by fibromatosis have symptoms and require medical or surgical treatment. Nowadays, the gold standard for the surgical treatment of uterine fibromatosis is the use of minimally invasive surgery. The surgical skills and improvements offered by robotic approach can be relevant in reproductive surgery, in particular in minimally invasive myomectomy. However, the lack of tactile feedback of robotic platform is an important technical drawback that can reduce the accuracy of surgical procedures. Here, we present the design and the preliminary test of the wearable fabric, yielding display wearable haptic interfaces able to generate a real-time tactile feedback in terms of stiffness for applications in gynecologic robotic surgery. We preliminarily tested the device in the simulation of a real scenario of conservative myomectomy with the final purpose of increasing the accuracy and precision during surgery. The future goal is the integration of a haptic device with the commercially available robotic surgical systems with the purpose of improving the precision and accuracy of the surgical operation, thus allowing a better understanding concerning the anatomical relationship of the target structures. This in turn could determine a change in the surgical strategy in some cases, letting some patients selected for a demolitive approach retaining their uterus. This could improve surgical outcomes in fertile women enrolled for minimally invasive surgery for uterine fibroids and may be a facilitation for young gynecological surgeons or during residency teaching plans and learning programs.


Assuntos
Procedimentos Cirúrgicos Robóticos/instrumentação , Miomectomia Uterina/métodos , Dispositivos Eletrônicos Vestíveis , Feminino , Fibroma/cirurgia , Humanos , Procedimentos Cirúrgicos Minimamente Invasivos/instrumentação , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Procedimentos Cirúrgicos Robóticos/métodos , Percepção do Tato , Miomectomia Uterina/instrumentação , Neoplasias Uterinas/cirurgia , Útero/cirurgia
11.
IEEE Trans Haptics ; 12(4): 508-520, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31071053

RESUMO

Restoring hand function in individuals with upper limb loss is a challenging task, made difficult by the complexity of human hands from both a functional and sensory point of view. Users of commercial prostheses, even sophisticated devices, must visually attend to the hand to know its state, since in most cases they are not provided with any direct sensory information. Among the different types of haptic feedback that can be delivered, particularly information on hand opening is likely to reduce the requirement of constant visual attention. In recent years, there has been a trend of using underactuated, compliant multi-fingered hands as upper limb prostheses, in part due to their simplicity and ease of use attributed to low degree-of-freedom (d.o.f.) actuation. The trend toward underactuation encourages the design of one d.o.f. haptic devices to provide intuitive sensory feedback from the prosthesis. However, mapping the closure of a multi-d.o.f. prosthetic hand to a simple and intuitive haptic cue is not a trivial task. In this paper, we explore the use of a one d.o.f. skin stretch haptic device, the rice haptic rocker, to provide intuitive proprioceptive feedback indicating overall hand closure of an underactuated prosthesis. The benefits and challenges of the system are assessed in multi-tasking and reduced vision scenarios for an object-size discrimination task, in an effort to simulate challenges in daily life, and are compared against the haptic resolution of the device using the just noticeable difference. Finally, an evaluation done with a prosthesis user, in the form of a truncated version of the Activities Measure for Upper Limb Amputees (AM-ULA), shows possible benefits of the addition of haptic feedback in tasks with reduced visual attention.

12.
IEEE Trans Haptics ; 12(4): 581-593, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31144646

RESUMO

Haptic devices have a high potential for delivering tailored training to novices. These devices can simulate forces associated with real-world tasks, or provide guidance forces that convey task completion and learning strategies. It has been shown, however, that providing both task forces and guidance forces simultaneously through the same haptic interface can lead to novices depending on guidance, being unable to demonstrate skill transfer, or learning the wrong task altogether. This paper presents a novel solution whereby task forces are relayed via a kinesthetic haptic interface, while guidance forces are spatially separated through a cutaneous skin stretch modality. We explore different methods of delivering cutaneous based guidance to subjects in a dynamic trajectory following task. We next compare cutaneous guidance to kinesthetic guidance, as is traditional to spatially separated assistance. We further investigate the role of placing cutaneous guidance ipsilateral versus contralateral to the task force device. The efficacies of each guidance condition are compared by examining subject error and movement smoothness. Results show that cutaneous guidance can be as effective as kinesthetic guidance, making it a practical and cost-effective alternative for spatially separated assistance.

13.
IEEE Trans Neural Syst Rehabil Eng ; 27(7): 1397-1406, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31135365

RESUMO

In this paper, we present a novel approach to dynamically describe human upper limb trajectories, addressing the question on whether and to which extent synergistic multi-joint behavior is observed and preserved over time evolution and across subjects. To this goal, we performed experiments to collect human upper limb joint angle trajectories and organized them in a dataset of daily living tasks. We then characterized the upper limb poses at each time frame through a technique that we named repeated-principal component analysis (R-PCA). We found that, although there is no strong evidence on the predominance of one principal component (PC) over the others, the subspace identified by the first three PCs takes into account most of the motion variability. We evaluated the stability of these results over time, showing that during the reaching phase, there is a strong consistency of these findings across participants. In other words, our results suggest that there is a time-invariant low-dimensional approximation of upper limb kinematics, which can be used to define a suitable reduced dimensionality control space for upper limb robotic devices in motion phases.


Assuntos
Extremidade Superior/fisiologia , Atividades Cotidianas , Adulto , Algoritmos , Fenômenos Biomecânicos , Eletromiografia , Feminino , Força da Mão/fisiologia , Voluntários Saudáveis , Humanos , Articulações/fisiologia , Masculino , Modelos Teóricos , Análise de Componente Principal , Reprodutibilidade dos Testes , Robótica , Adulto Jovem
14.
IEEE Trans Neural Syst Rehabil Eng ; 27(3): 411-418, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30762562

RESUMO

Recent functional magnetic resonance imaging (fMRI) studies have identified specific neural patterns related to three different categories of movements: intransitive (i.e., meaningful gestures that do not include the use of objects), transitive (i.e., actions involving an object), and tool-mediated (i.e., actions involving a tool to interact with an object). However, fMRI intrinsically limits the exploitation of these results in a real scenario, such as a brain-machine interface. In this paper, we propose a new approach to automatically predict intransitive, transitive, or tool-mediated movements of the upper limb using electroencephalography (EEG) spectra estimated during a motor planning phase. To this end, high-resolution EEG data gathered from 33 healthy subjects were used as input of a three-class k-nearest neighbors classifier. Different combinations of EEG-derived spatial and frequency information were investigated to find the most accurate feature vector. In addition, we studied gender differences further splitting the dataset into only-male data, and only-female data. A remarkable difference was found between accuracies achieved with male and female data, the latter yielding the best performance (78.55% of accuracy for the prediction of intransitive, transitive, and tool-mediated actions). These results potentially suggest that different gender-based models should be employed for the future BMI applications.


Assuntos
Encéfalo/fisiologia , Eletroencefalografia , Gestos , Adulto , Mapeamento Encefálico , Interfaces Cérebro-Computador , Eletromiografia , Feminino , Voluntários Saudáveis , Humanos , Imagem por Ressonância Magnética , Masculino , Movimento , Lobo Parietal/fisiologia , Córtex Pré-Frontal/fisiologia , Reprodutibilidade dos Testes , Caracteres Sexuais , Extremidade Superior , Adulto Jovem
16.
IEEE J Biomed Health Inform ; 23(6): 2417-2427, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-30668509

RESUMO

In this study, we investigated brain dynamics from electroencephalographic (EEG) signals during affective tactile stimulation conveyed by the dynamical contact with different fabrics. Thirty-three healthy subjects (16 females) were enrolled to interact with a haptic device able to mimic caress-like stimuli conveyed by strips of different fabrics moved back and forth at different velocities. Specifically, two velocity levels (i.e., 9.4 and 65 mm/sec) and two kinds of fabric (i.e., burlap and silk) were selected to deliver pleasant and unpleasant affective elicitations, according to subjects' self-assessment. EEG power spectra and functional connectivity were then calculated and analyzed. Experimental results, reported in terms of p-value topographic maps, demonstrated that caresses administered through unpleasant fabrics increased brain activity in the θ (4-8 Hz), α (8-14 Hz), and ß (14-30 Hz) bands, whereas the use of pleasant fabrics enhanced functional connections in specific areas (e.g., frontal, occipital, and temporal cortices) depending on the oscillations frequency and caressing velocity. Furthermore, we adopted K-NN algorithms to automatically recognize the pleasantness of the haptic stimulation at a single-subject level using EEG power spectra, achieving a recognition accuracy up to 74.24%. Finally, we showed how brain oscillation power in the α and ß bands over contralateral frontal- and central-cortex were the most informative features characterizing the pleasantness of a tactile stimulus on the forearm.


Assuntos
Encéfalo/fisiologia , Emoções/fisiologia , Têxteis , Tato/fisiologia , Adulto , Eletroencefalografia , Desenho de Equipamento , Feminino , Antebraço/fisiologia , Humanos , Masculino , Processamento de Sinais Assistido por Computador
17.
Immunity ; 50(1): 241-252.e6, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30552025

RESUMO

Passive administration of HIV neutralizing antibodies (nAbs) can protect macaques from hard-to-neutralize (tier 2) chimeric simian-human immunodeficiency virus (SHIV) challenge. However, conditions for nAb-mediated protection after vaccination have not been established. Here, we selected groups of 6 rhesus macaques with either high or low serum nAb titers from a total of 78 animals immunized with recombinant native-like (SOSIP) Env trimers. Repeat intrarectal challenge with homologous tier 2 SHIVBG505 led to rapid infection in unimmunized and low-titer animals. High-titer animals, however, demonstrated protection that was gradually lost as nAb titers waned over time. An autologous serum ID50 nAb titer of ∼1:500 afforded more than 90% protection from medium-dose SHIV infection. In contrast, antibody-dependent cellular cytotoxicity and T cell activity did not correlate with protection. Therefore, Env protein-based vaccination strategies can protect against hard-to-neutralize SHIV challenge in rhesus macaques by inducing tier 2 nAbs, provided appropriate neutralizing titers can be reached and maintained.


Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , HIV/fisiologia , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Vírus da Imunodeficiência Símia/fisiologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Humanos , Macaca mulatta , Vacinação
18.
Biomech Model Mechanobiol ; 18(2): 435-451, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30460623

RESUMO

Transcatheter aortic valve replacement (TAVR) has emerged as an effective alternative to conventional surgical valve replacement in high-risk patients afflicted by severe aortic stenosis. Despite newer-generation devices enhancements, post-procedural complications such as paravalvular leakage (PVL) and related thromboembolic events have been hindering TAVR expansion into lower-risk patients. Computational methods can be used to build and simulate patient-specific deployment of transcatheter aortic valves (TAVs) and help predict the occurrence and degree of PVL. In this study finite element analysis and computational fluid dynamics were used to investigate the influence of procedural parameters on post-deployment hemodynamics on three retrospective clinical cases affected by PVL. Specifically, TAV implantation depth and balloon inflation volume effects on stent anchorage, degree of paravalvular regurgitation and thrombogenic potential were analyzed for cases in which Edwards SAPIEN and Medtronic CoreValve were employed. CFD results were in good agreement with corresponding echocardiography data measured in patients in terms of the PVL jets locations and overall PVL degree. Furthermore, parametric analyses demonstrated that positioning and balloon over-expansion may have a direct impact on the post-deployment TAVR performance, achieving as high as 47% in PVL volume reduction. While the model predicted very well clinical data, further validation on a larger cohort of patients is needed to verify the level of the model's predictions in various patient-specific conditions. This study demonstrated that rigorous and realistic patient-specific numerical models could potentially serve as a valuable tool to assist physicians in pre-operative TAVR planning and TAV selection to ultimately reduce the risk of clinical complications.


Assuntos
Valva Aórtica/cirurgia , Simulação por Computador , Substituição da Valva Aórtica Transcateter , Velocidade do Fluxo Sanguíneo/fisiologia , Hemodinâmica/fisiologia , Humanos , Fluxo Sanguíneo Regional/fisiologia , Stents , Estresse Mecânico , Trombose/patologia
19.
Ann Biomed Eng ; 47(1): 113-125, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30194551

RESUMO

Transcatheter aortic valve replacement (TAVR) is a minimally-invasive approach for treating severe aortic stenosis. All clinically-used TAVR valves to date utilize chemically-fixed xenograft as the leaflet material. Inherent limitation of the tissue (e.g., calcific degeneration) motivates the search for alternative leaflet material. Here we introduce a novel polymeric TAVR valve that was designed to address the limitations of tissue-valves. In this study, we experimentally evaluated the hemodynamic performance of the valve and compared its performance to clinically-used valves: a gold standard surgical tissue valve, and a TAVR valve. Our comparative testing protocols included: (i) baseline hydrodynamics (ISO:5840-3), (ii) complementary patient-specific hydrodynamics in a dedicated system, and (iii) thrombogenicity. The patient-specific testing system facilitated comparing TAVR valves performance under more realistic conditions. Baseline hydrodynamics results at CO 4-7 L/min showed superior effective orifice area (EOA) for the polymer valve, most-notably as compared to the reference TAVR valve. Regurgitation fraction was higher in the polymeric valve, but within the ISO minimum requirements. Thrombogenicity trends followed the EOA results with the polymeric valve being the least thrombogenic, and clinical TAVR being the most. Hemodynamic-wise, the results strongly indicate that our polymeric TAVR valve can outperform tissue valves.


Assuntos
Estenose da Valva Aórtica , Valva Aórtica , Bioprótese , Próteses Valvulares Cardíacas , Hemodinâmica , Modelos Cardiovasculares , Substituição da Valva Aórtica Transcateter , Valva Aórtica/patologia , Valva Aórtica/fisiopatologia , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/patologia , Estenose da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/cirurgia , Humanos , Trombose/etiologia , Trombose/patologia , Trombose/fisiopatologia , Trombose/prevenção & controle
20.
IEEE Trans Biomed Eng ; 66(1): 138-149, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29993527

RESUMO

OBJECTIVE: Myoelectric hand prostheses have reached a considerable technological level and gained an increasing attention in assistive robotics. However, their abandonment rate remains high, with unintuitive control and lack of sensory feedback being major causes. Among the different types of sensory information, proprioception, e.g., information on hand aperture, is crucial to successfully perform everyday actions. Despite the many attempts in literature to restore and convey this type of feedback, much remains to be done to close the action-perception loop in prosthetic devices. METHODS: With this as motivation, in this paper we introduce HapPro, a wearable, noninvasive haptic device that can convey proprioceptive information for a prosthetic hand. The device was used with an under-actuated, simple to control anthropomorphic robotic hand, providing information about hand aperture by mapping it to the position of a wheel that can run on the user's forearm. Tests with 43 able bodied subjects and one amputee subject were conducted in order to quantify the effectiveness of HapPro as a feedback device. RESULTS: HapPro provided a good level of accuracy for item discrimination. Participants also reported the device to be intuitive and effective in conveying proprioceptive cues. Similar results were obtained in the proof-of-concept experiment with an amputee subject. CONCLUSIONS: Results show that HapPro is able to convey information on the opening of a prosthetic hand in a noninvasive way. SIGNIFICANCE: Using this device for proprioceptive feedback could improve usability of myoelectric prostheses, potentially reducing abandonment and increasing quality of life for their users.


Assuntos
Membros Artificiais , Retroalimentação Sensorial/fisiologia , Propriocepção/fisiologia , Robótica/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Adulto , Eletromiografia/instrumentação , Feminino , Antebraço/fisiologia , Mãos/fisiologia , Humanos , Masculino , Desenho de Prótese , Dispositivos Eletrônicos Vestíveis , Adulto Jovem
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