An intracardiac electrogram model to bridge virtual hearts and implantable cardiac devices

Virtual heart models have been proposed to enhance the safety of implantable cardiac devices through closed loop validation. To communicate with a virtual heart, devices have been driven by cardiac signals at specific sites. As a result, only the action potentials of these sites are sensed. However, the real device implanted in the heart will sense a complex combination of near and far-field extracellular potential signals. Therefore many device functions, such as blanking periods and refractory periods, are designed to handle these unexpected signals. To represent these signals, we develop an intracardiac electrogram (IEGM) model as an interface between the virtual heart and the device. The model can capture not only the local excitation but also far-field signals and pacing afterpotentials. Moreover, the sensing controller can specify unipolar or bipolar electrogram (EGM) sensing configurations and introduce various oversensing and undersensing modes. The simulation results show that the model is able to reproduce clinically observed sensing problems, which significantly extends the capabilities of the virtual heart model in the context of device validation

The responses of people to virtual humans in an immersive virtual environment

This paper presents an experiment investigating the impact of behavior and responsiveness on social responses to virtual humans in an immersive virtual environment (IVE). A number of responses are investigated, including presence, copresence, and two physiological responses—heart rate and electrodermal activity (EDA). Our findings suggest that increasing agents’ responsiveness even on a simple level can have a significant impact on certain aspects of people’s social responses to humanoid agents. Despite being aware that the agents were computer-generated, participants with higher levels of social anxiety were significantly more likely to avoid “disturbing” them. This suggests that on some level people can respond to virtual humans as social actors even in the absence of complex interaction. Responses appear to be shaped both by the agents’ behaviors and by people’s expectations of the technology. Participants experienced a significantly higher sense of personal contact when the agents were visually responsive to them, as opposed to static or simply moving. However, this effect diminished with experienced computer users. Our preliminary analysis of objective heart-rate data reveals an identical pattern of responses

Writing with Pictures: Immersive Technology and 21st Century Professional Development

In The Language of New Media, Lev Manovich asks, “What kind of space is virtual space?” (254). This seemingly simple question will pose a number of challenges for writing centers as they develop services that transcend physical space. As writing center administrators integrate new media and technology into their operations, they must continue to invent and articulate theory that informs the development of virtual spaces. In Heuretics, Gregory Ulmer poses a related question: “What will research be like in an electronic apparatus?” (32). Ulmer explains that the notion of spatiality has changed since the development and widespread adoption of the computer (Heuretics 36). Indeed, it has, and the cultural and political landscape of the university has changed as well, as educational technology and virtual spaces are often at the heart of many academic institutions.University Writing Cente

Efficacy of augmented reality-based virtual hiking in cardiorespiratory endurance: a pilot study

Exergames can be used to overcome a sedentary lifestyle. Virtual Reality (VR) has made exergames successful, and they can be used to increase heart rate, but some limitations are found, such as the adaptation of the heart rate in exergames to the player's fitness profile. VR technology has been used to simulate virtual cycling and walking experiences. We designed and developed an exergame' Virtual Levadas' in a cave-based VR environment to simulate the Levadas hiking tracks. They are the main attraction for tourists in Madeira Island, Portugal. This study's main objective was to assess player exertion, usability, participation, and realism of the simulation of the Levadas tracks. We performed this study with 13 participants who played Virtual Levadas for 6 minutes and found a significant increase in player's average physical activity and heart rate. Overall, our results demonstrate that Virtual Levada's exergame provides a higher exertion level, immersion, and realism of the virtual environment than the literature.info:eu-repo/semantics/publishedVersio

Exercise/recreation facility for a lunar or Mars analog

The University of Idaho, NASA/USRA project for the 1990-91 school year is an exercise/recreation station for an Earth-based simulator of a lunar or martian habitat. Specifically, a stationary bicycle that will help people keep fit and prevent muscular atrophy while stationed in space was designed. To help with motivation and provide an element of recreation during the workout, the bicycle is to be enhanced by a virtual reality system. The system simulates various riding situations, including the choice of a mountain bike or a road bike. The bike employs a magnetic brake that provides continuously changing tension to simulate actual riding conditions. This braking system is interfaced directly with the virtual reality system. Also, integrated into the virtual reality display will be a monitoring system that regulates heart rate, work rate, and other functions during the course of the session

Treatment with a new peroxisome proliferator-activated receptor gamma agonist, pyridinecarboxylic acid derivative, increases angiogenesis and reduces inflammatory mediators in the heart of Trypanosoma cruzi-infected mice

Trypanosoma cruzi infection induces an intense inflammatory response in diverse host tissues. The immune response and the microvascular abnormalities associated with infection are crucial aspects in the generation of heart damage in Chagas disease. Upon parasite uptake, macrophages, which are involved in the clearance of infection, increase inflammatory mediators, leading to parasite killing. The exacerbation of the inflammatory response may lead to tissue damage. Peroxisome proliferator-activated receptor gamma (PPAR\u3b3) is a ligand-dependent nuclear transcription factor that exerts important anti-inflammatory effects and is involved in improving endothelial functions and proangiogenic capacities. In this study, we evaluated the intermolecular interaction between PPAR\u3b3 and a new synthetic PPAR\u3b3 ligand, HP24, using virtual docking. Also, we showed that early treatment with HP24, decreases the expression of NOS2, a pro-inflammatory mediator, and stimulates proangiogenic mediators (vascular endothelial growth factor A, CD31, and Arginase I) both in macrophages and in the heart of T. cruzi-infected mice. Moreover, HP24 reduces the inflammatory response, cardiac fibrosis and the levels of inflammatory cytokines (TNF-\u3b1, interleukin 6) released by macrophages of T. cruzi-infected mice. We consider that PPAR\u3b3 agonists might be useful as coadjuvants of the antiparasitic treatment of Chagas disease, to delay, reverse, or preclude the onset of heart damage

A personalized real-time virtual model of whole heart electrophysiology

Computer models capable of representing the intrinsic personal electrophysiology (EP) of the heart in silico are termed virtual heart technologies. When anatomy and EP are tailored to individual patients within the model, such technologies are promising clinical and industrial tools. Regardless of their vast potential, few virtual technologies simulating the entire organ-scale EP of all four-chambers of the heart have been reported and widespread clinical use is limited due to high computational costs and difficulty in validation. We thus report on the development of a novel virtual technology representing the electrophysiology of all four-chambers of the heart aiming to overcome these limitations. In our previous work, a model of ventricular EP embedded in a torso was constructed from clinical magnetic resonance image (MRI) data and personalized according to the measured 12 lead electrocardiogram (ECG) of a single subject under normal sinus rhythm. This model is then expanded upon to include whole heart EP and a detailed representation of the His-Purkinje system (HPS). To test the capacities of the personalized virtual heart technology to replicate standard clinical morphological ECG features under such conditions, bundle branch blocks within both the right and the left ventricles under two different conduction velocity settings are modeled alongside sinus rhythm. To ensure clinical viability, model generation was completely automated and simulations were performed using an efficient real-time cardiac EP simulator. Close correspondence between the measured and simulated 12 lead ECG was observed under normal sinus conditions and all simulated bundle branch blocks manifested relevant clinical morphological features

Seeing pain and pleasure on self and others: behavioural and psychophysiological reactivity in immersive virtual reality

Studies have explored behavioral and neural responses to the observation of pain in others. However, much less is known about how taking a physical perspective influences reactivity to the observation of others' pain and pleasure. To explore this issue we devised a novel paradigm in which 24 healthy participants immersed in a virtual reality scenario observed a virtual: needle penetrating (pain), caress (pleasure), or ball touching (neutral) the hand of an avatar seen from a first (1PP)- or a third (3PP)-person perspective. Subjective ratings and physiological responses [skin conductance responses (SCR) and heart rate (HR)] were collected in each trial. All participants reported strong feelings of ownership of the virtual hand only in 1PP. Subjective measures also showed that pain and pleasure were experienced as more salient than neutral. SCR analysis demonstrated higher reactivity in 1PP than in 3PP. Importantly, vicarious pain induced stronger responses with respect to the other conditions in both perspectives. HR analysis revealed equally lower activity during pain and pleasure with respect to neutral. SCR may reflect egocentric perspective, and HR may merely index general arousal. The results suggest that behavioral and physiological indexes of reactivity to seeing others' pain and pleasure were qualitatively similar in 1PP and 3PP. Our paradigm indicates that virtual reality can be used to study vicarious sensation of pain and pleasure without actually delivering any stimulus to participants' real body and to explore behavioral and physiological reactivity when they observe pain and pleasure from ego- and allocentric perspectives

Efficacy of Using Virtual Reality to Reduce Perceived Exertion During Therapy When Compared to Traditional OT Intervention

This project looked at the differences in perceived and actual exertion in virtual reality therapy interventions and upper extremity ergometer. The goal of this project was to quantify the efficacy of virtual reality interventions as an alternative to more traditional upper extremity interventions. This project wanted to address the lack of research focused on perceived exertion in virtual reality interventions. The student objectives focused on conducting research, familiarizing oneself with the use of virtual reality in the in-patient setting, and dissemination of the results. This study found that there was no significant difference in perceived exertion scores, changes in heart rate, or changes in systolic blood pressure between virtual reality interventions and upper extremity ergometer interventions. However, virtual reality interventions were associated with a slight decrease in perceived exertion and a slight increase in heart rate and systolic blood pressure changes when compared to the upper extremity ergometer. This project shows that virtual reality interventions may be a viable alternative to more traditional upper extremity interventions as it does not show any adverse effects in perceived exertion