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Letteratura scientifica selezionata sul tema "Ventricles"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 1 agosto 2024

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Articoli di riviste sul tema "Ventricles"

Erdener, Timurkaynak, L. Rhoton Albert e Barry Margaret. "Microsurgical Anatomy and Operative Approaches to the Lateral Ventricles". Neurosurgery 19, n. 5 (1 novembre 1986): 685–723. http://dx.doi.org/10.1227/00006123-198611000-00001.

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Abstract The anatomy needed to plan microoperative approaches to the lateral ventricles was examined in 20 cadaveric cerebral hemispheres. The neural, arterial, and venous structures in the walls of the lateral ventricles and the relationship of the lateral ventricles to the third ventricle and basal cisterns were examined. The operative approaches to the lateral ventricle are reviewed.

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Shapoval, Lyudmila. "Atrioventricular junction symmetry in children with different anatomical variants of atrioventricular communication: echocardiographic parameters". Radiation Diagnostics, Radiation Therapy, n. 3 (2019): 15–23. http://dx.doi.org/10.37336/2707-0700-2019-3-1.

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Atrioventricular (AVC) communication is a group of congenital heart diseases with common atrioventricular connection. The symmetry of the connection and, as a result, anatomy and physiology of atrio-ventricular infl ow plays the key role in possibility of double-ventricle correction in this anomaly. Nowadays there is tendency to mix new concepts with described parameters that characterize AVC in one whole guidelines. The ultimate pathway has to be the one that minimizes morbidity and mortality outcomes. In the article author present the correlation between main cardiac echocardiography measurements, that characterize the symmetry of atrioventriculat connection (atrioventricular valves indexes, left ventricle inflow index, inflow angle between left and right ventricles) and their correlation with size of common atrio-ventricular valve and ventricle’s size. Key words: unbalanced atrioventricular communication, atrioventricular valve index, left ventricular flow index, inflow angle between right and left ventricles, ventricular cavity index.

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Kurtcuoglu, Vartan, Dimos Poulikakos e Yiannis Ventikos. "Computational Modeling of the Mechanical Behavior of the Cerebrospinal Fluid System". Journal of Biomechanical Engineering 127, n. 2 (6 novembre 2004): 264–69. http://dx.doi.org/10.1115/1.1865191.

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A computational fluid dynamics (CFD) model of the cerebrospinal fluid system was constructed based on a simplified geometry of the brain ventricles and their connecting pathways. The flow is driven by a prescribed sinusoidal motion of the third ventricle lateral walls, with all other boundaries being rigid. The pressure propagation between the third and lateral ventricles was examined and compared to data obtained from a similar geometry with a stenosed aqueduct. It could be shown that the pressure amplitude in the lateral ventricles increases in the presence of aqueduct stenosis. No difference in phase shift between the motion of the third ventricle walls and the pressure in the lateral ventricles because of the aqueduct stenosis could be observed. It is deduced that CFD can be used to analyze the pressure propagation and its phase shift relative to the ventricle wall motion. It is further deduced that only models that take into account the coupling between ventricles, which feature a representation of the original geometry that is as accurate as possible and which represent the ventricle boundary motion realistically, should be used to make quantitative statements on flow and pressure in the ventricular space.

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Pipitone, Salvatore. "Superoinferior ventricles with superior left ventricle". Journal of Cardiovascular Medicine 13, n. 9 (settembre 2012): 607–13. http://dx.doi.org/10.2459/jcm.0b013e3283515bf6.

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Dezena, Roberto Alexandre. "Endoscopic anatomy of the ventricles". Archives of Pediatric Neurosurgery 5 (27 dicembre 2023): e1322022. http://dx.doi.org/10.46900/apn.v5suppl1.132.

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The cerebral ventricles are structures known since antiquity. At the beginning of its description there was a belief that human thoughts and intellect were generated inside the ventricular cavity, and this idea persisted even after the Renaissance. In this period after the Dark Ages, the anatomical description of the ventricles evolved a lot, but it took a long time to conclude the true liquid nature of the ventricular content. The ventricles are divided into lateral, third and fourth ventricles, and each of these regions presents communications between themselves and very precise limits. For endoscopic procedures, a thorough knowledge of the anatomy of the lateral and third ventricles is extremely important. The cerebrospinal fluid circulates inside the ventricles according to a complex mechanism, and there are still controversies nowadays, especially regarding its resorption. Each lateral ventricle is a “C”-shaped cavity that surrounds the thalamus and is deeply located in the brain, following the contour of the choroid fissure. These structures represent, from an embryological point of view, the light of the telencephalic vesicles. Each lateral ventricle has five parts: frontal horn, body, atrium, occipital horn, and temporal horn. The frontal horn is the part of the lateral ventricle located anteriorly to the foramen of Monro. The lateral ventricle body extends from the posterior margin of the foramen of Monro to the point where the fornix and the corpus callosum converge, thus disappearing the septum pellucidum. The atrium of the lateral ventricle and its occipital extension form a triangle with an anterior base in the pulvinar and a posterior apex in the occipital lobe. The occipital horn is triangular, with a posterior vertex and a base in the atrium. The temporal horn is the inferior extension of the ventricle, being the continuation of the atrium, directing itself anteriorly and laterally. Each of these divisions has a medial, lateral, ceiling, and floor wall. In addition, the frontal, temporal, and atrial horns have anterior walls. These walls are formed by the thalamus, septum pellucidum, white matter, corpus callosum, caudate nucleus, and fornix. The third ventricle is a funnel-shaped, unilocular, narrow midline cavity. It communicates at the anterosuperior margin with each lateral ventricle through the foramen of Monro and, subsequently, with the fourth ventricle through the cerebral aqueduct. In adult individuals, the lateral distance of the third ventricle is 5.5 mm on average. In a study using MRI images, the hydrocephalic configuration of the third ventricle disappeared after the endoscopic third ventriculostomy (ETV), with a decrease in diameter, elevation, and horizontal direction of the floor and reduction of the infundibular angle . The floor of the third ventricle extends from the optic chiasm anteriorly to the opening of the cerebral aqueduct posteriorly. It descends ventral and is formed by at least 12 cellular clusters or nuclei within the hypothalamic region. Anatomically, three portions can be described on the floor of the third ventricle: (1) premammillary portion, which extends from the infundibulum to the premammillary sulcus, constituting a very thin layer of gray substance of the hypothalamus; (2) interpeduncular portion, which extends from the postmammillary recess to the posterior margin of the interpeduncular space, being formed of gray substance and firmer than the first; and (3) peduncular portion, which corresponds to the portion of the cerebral peduncles, being the most solid portion, being formed by the medial aspect of the peduncles covered by the peduncular ependyma. The knowledge of the endoscopic anatomy of the ventricles is of the key importance for endoscopic neuroendoscopy

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Bernal-Ramirez, Judith, Magda C. Díaz-Vesga, Matias Talamilla, Andrea Méndez, Clara Quiroga, Javier A. Garza-Cervantes, Anay Lázaro-Alfaro et al. "Exploring Functional Differences between the Right and Left Ventricles to Better Understand Right Ventricular Dysfunction". Oxidative Medicine and Cellular Longevity 2021 (28 agosto 2021): 1–21. http://dx.doi.org/10.1155/2021/9993060.

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The right and left ventricles have traditionally been studied as individual entities. Furthermore, modifications found in diseased left ventricles are assumed to influence on right ventricle alterations, but the connection is poorly understood. In this review, we describe the differences between ventricles under physiological and pathological conditions. Understanding the mechanisms that differentiate both ventricles would facilitate a more effective use of therapeutics and broaden our knowledge of right ventricle (RV) dysfunction. RV failure is the strongest predictor of mortality in pulmonary arterial hypertension, but at present, there are no definitive therapies directly targeting RV failure. We further explore the current state of drugs and molecules that improve RV failure in experimental therapeutics and clinical trials to treat pulmonary arterial hypertension and provide evidence of their potential benefits in heart failure.

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Ogiwara, Hideki, e Nobuhito Morota. "Flexible endoscopy for management of intraventricular brain tumors in patients with small ventricles". Journal of Neurosurgery: Pediatrics 14, n. 5 (novembre 2014): 490–94. http://dx.doi.org/10.3171/2014.7.peds13648.

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Object Endoscopic surgery is generally withheld in patients with small ventricles due to difficulties in ventricular cannulation and intraventricular manipulation. The effectiveness of flexible endoscopy for management of intraventricular brain tumors in patients with small ventricles was evaluated. Methods Forty-five patients who underwent endoscopic surgery with a flexible endoscope for intraventricular brain tumors were divided into small-ventricle and ventriculomegaly groups according to the frontal and occipital horn ratio (FOR). Retrospective review of these cases was performed and achievement of surgical goals and morbidity were assessed. Results Among the 45 patients, there were 14 with small ventricles and 31 with ventriculomegaly. In the smallventricle group, targeted tumors were located in the suprasellar region in 12 patients and in the pineal region in 2. In the ventriculomegaly group, tumors were located in the pineal region in 15 patients, in the suprasellar region in 9, in the lateral ventricle in 4, in the midbrain in 2, and in the fourth ventricle in 1. In the small-ventricle group, ventricular cannulation was successful and the surgical goals were accomplished in all patients. In ventriculomegaly group, sampling of the tumor was not diagnostic due to intraoperative hemorrhage in 1 patient. There were no significant differences in the rate of achieving the surgical goals or the morbidity between the 2 groups. Conclusions Endoscopic surgery using a flexible endoscope is useful for management of intraventricular brain tumors in patients with small ventricles. A flexible endoscope allows excellent maneuverability in introducing the device into the lateral ventricle and manipulating through small ventricles.

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Sethi, R., K. S. Dhalla, R. E. Beamish e N. S. Dhalla. "Differential changes in left and right ventricular adenylyl cyclase activities in congestive heart failure". American Journal of Physiology-Heart and Circulatory Physiology 272, n. 2 (1 febbraio 1997): H884—H893. http://dx.doi.org/10.1152/ajpheart.1997.272.2.h884.

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The status of beta-adrenergic receptors and adenylyl cyclase in crude membranes from both left and right ventricles was examined when the left coronary artery in rats was occluded for 4, 8, and 16 wk. The adenylyl cyclase activity in the presence of isoproterenol was decreased in the uninfarcted (viable) left ventricle and increased in the right ventricle subsequent to myocardial infarction. The density of beta1-adrenergic receptors, unlike beta2-receptors, was reduced in the left ventricle, whereas no change in the characteristics of beta1- and beta2-adrenergic receptors was seen in the right ventricle. The catalytic activity of adenylyl cyclase was depressed in the viable left ventricle but was unchanged in the right ventricle. In comparison to sham controls, the basal, as well as NaF-, forskolin-, and 5'-guanylyl imidodiphosphate [Gpp(NH)p]-stimulated adenylyl cyclase activities were decreased in the left ventricle and increased in the right ventricle of the experimental animals. Opposite alterations in the adenylyl cyclase activities in left and right ventricles from infarcted animals were also seen when two types of purified sarcolemmal preparations were employed. These changes in adenylyl cyclase activities in the left and right ventricles were dependent on the degree of heart failure. Furthermore, adenosine 3',5'-cyclic monophosphate contents were higher in the right ventricle and lower in the left ventricle from infarcted animals injected with saline, isoproterenol, or forskolin in comparison to the controls. The results suggest differential changes in the viable left and right ventricles with respect to adenylyl cyclase activities during the development of congestive heart failure due to myocardial infarction.

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Anderson, Robert H., Timothy J. Mohun e Antoon F. M. Moorman. "What is a ventricle?" Cardiology in the Young 21, S2 (13 dicembre 2011): 14–22. http://dx.doi.org/10.1017/s1047951111001387.

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AbstractOn the basis of both developmental and morphological evidence, we would suggest that a ventricle is best defined as any chamber within the ventricular mass possessing an apical trabecular component. Such ventricles can be of right or left morphology, and always coexist. The ventricles are normally formed when possessing all three of the inlet, apical trabecular, and outlet components, but incomplete when lacking one or both of the inlet and outlet components. Ventricles that are incomplete because of lack of the inlet component are always hypoplastic, with incomplete right ventricles being positioned antero-superiorly within the ventricular mass, and incomplete left ventricles located postero-inferiorly. Patients having such incomplete ventricles because of the lack of the inlet component have functionally univentricular hearts, although the functionally univentricular arrangement can also be produced in the setting of normally constituted but hypertrophied ventricles. Full analysis of ventricular morphology, therefore, requires attention not only to component make-up, but also size.

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Nakazawa, Ken, Yutaka Kusuya e Koki Shigenobu. "Developmental increase in the inotropic and cyclic AMP response to isoproterenol in embryonic and newly hatched chicks". Canadian Journal of Physiology and Pharmacology 67, n. 9 (1 settembre 1989): 1109–11. http://dx.doi.org/10.1139/y89-176.

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The cyclic adenosine 3′,5′-monophosphate (cyclic AMP) levels of ventricles isolated from 15- to 20-day-old chick embryos and 0- to 3-day-old hatched chicks were compared to clarify the mechanism underlying the change in sensitivity to isoproterenol during perinatal developmental stages when the functional sympathetic innervation has been completely achieved. Isoproterenol produced a positive inotropic effect on ventricles isolated from both embryonic and hatched chicks, but the ventricles from the hatched chicks were more sensitive. At both developmental stages sotalol was an equipotent antagonist of isoproterenol. 3-Isobutyl-1-methylxanthine (IBMX) produced an increment in the contractile force of the ventricles at both stages, but the ventricles from the hatched chicks responded to lower doses of IBMX. The reactivity to isoproterenol in increasing cyclic AMP level was significantly higher in the hatched ventricles than in the embryonic ventricles. The results suggest that the different sensitivities to isoproterenol between embryonic and newly hatched chick ventricles may be due to some changes in the process for cyclic AMP production.Key words: chick ventricle, development, β-adrenergic sensitivity, cyclic AMP.

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Più fonti

Tesi sul tema "Ventricles"

Lewis, Timothy J. "Modeling conduction in the ventricles". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60501.

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Two models of electrical conduction in the cardiac ventricles are considered. The first model considered is that of a strand of ventricular muscle which uses the one-dimensional cable equation with the Beeler-Reuter model to represent the transmembrane currents. The effect of periodic stimulation on the strand is numerically simulated, and it is found that as simulation frequency is increased, the rhythms of synchronization are successively encountered. It is shown that this sequence of rhythms can be accounted for by considering the response of the strand to premature stimulation. This involves deriving a one-dimensional finite-difference equation or "map" from the response to premature stimulation, and then iterating this map to predict the response to periodic stimulation.
The second model states that the highly ramified His-Purkinje system is reminiscent of a fractal branching structure, and that the ventricular myocardium is activated in a "fractal" (time-scale invariant) fashion, since it is activated via the His-Purkinje system. A 1/$f sp alpha$ power spectrum can sometimes be linked to fractal processes. The averaged power spectrum of single QRS complexes falls off as 1/$f sp alpha$ ($ alpha sim$ 4).

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Kwende, Martin M. N. "The biomechanics of skeletal muscle ventricles". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283451.

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Benson, Alan Philip. "Computational electromechanics of the mammalian ventricles". Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432313.

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Liu, Zhan-Qiu. "QUANTIFICATION OF MYOCARDIAL MECHANICS IN LEFT VENTRICLES UNDER INOTROPIC STIMULATION AND IN HEALTHY RIGHT VENTRICLES USING 3D DENSE CMR". UKnowledge, 2019. https://uknowledge.uky.edu/me_etds/130.

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Statistical data from clinical studies indicate that the death rate caused by heart disease has decreased due to an increased use of evidence-based medical therapies. This includes the use of magnetic resonance imaging (MRI), which is one of the most common non-invasive approaches in evidence-based health care research. In the current work, I present 3D Lagrangian strains and torsion in the left ventricle of healthy and isoproterenol-stimulated rats, which were investigated using Displacement ENcoding with Stimulated Echoes (DENSE) cardiac magnetic resonance (CMR) imaging. With the implementation of the 12-segment model, a detailed profile of regional cardiac mechanics was reconstructed for each subject. Statistical analysis revealed that isoproterenol induced a significant change in the strains and torsion in certain regions at the mid-ventricle level. In addition, I investigated right ventricular cardiac mechanics with the methodologies developed for the left ventricle. This included a comparison of different regions within the basal and mid-ventricular regions. Despite no regional variation found in the peak circumferential strain, the peak longitudinal strain exhibited regional variation at the anterior side of the RV due to the differences in biventricular torsion, mechanism of RV free wall contraction, and fiber architecture at RV insertions. Future applications of the experimental work presented here include the construction and validation of biventricular finite element models. Specifically, the strains predicted by the models will be statistically compared with experimental strains. In addition, the results of the present study provide an essential reference of RV baseline evaluated with DENSE MRI, a highly objective technique.

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Iudicello, Francesca. "Numerical simulation of the flow in model skeletal muscle ventricles". Thesis, City University London, 1995. http://openaccess.city.ac.uk/7738/.

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Until recently, the only realistic form of treatment available to patients in end stage heart failure was transplantation. In the last few years, the possibility of diverting skeletal muscle from its normal function to perform a cardiac assist role has emerged as a potential alternative to transplant surgery. The introduction of an Skeletal Muscle Ventricle (SMV) to the circulation is a potential long-term hazard, as the patient's blood comes into contact with the non-endothelialised surfaces of the wall of the new ventricle and the connecting conduits. This may trigger a cascade of events leading to deposition of thrombus, whose formation is dependent on the nature of the blood flow. The potential problem of haemostasis may arise in the apex of the artificial ventricle, where little mixing and large residence times may occur. There is therefore a strong need for carrying out flow analysis studies to address in detail the questions of haemostasis and thrombogenesis and in this context to evaluate possible candidate SMV configurations. Research on the dynamics of the flow inside model SMVs has been carried out on physical and numerical models with the objective of aialysing the effect of the size and shape of the ventricle and inlet/outlet orientation of the duct. Due to the physiological limit on the power available to pump the blood out of the ventricle, the efficiency of these potential assistance devices has to be maximized. It is also necessary to minimize the risks of haemolysis and thrombogenesis, which are both related, in different ways, to the level of shear stress on the wall and within the flow. A common feature of these flows is the formation of vortex rings. Vortices enhance mixing, and this is a useful process to encourage in an SMV, as it could assist in the mixing of the blood components and in the reduction of apical residence time. Being able to predict accurately the dynamics of the vortices is therefore important, as this will affect the prediction of residence times and shear stresses at the wall and within the flow. It is also very important to know whether numerical codes can predict vortex ring dynamics from both qualitative and quantitative points of view. In order to study the dynamics of the formation of these vortices, first, mathematical models were studied. The general purpose CFDS-FLOW3D code was used in all numerical simulations. Initial investigations of this research project concerned a progressive validation of the numerical solution predicted by the code when the domain where the flow is calculated had moving boundaries. Firstly, comparisons were made with the analytical solution for expanding/contracting pipes. An adapted compliant SMV model was then generated with a truncated apex using sinusoidally prescribed motion of the wall. With this model, two vortex rings could be predicted as in the experiments. The spherical-end model also gave good agreement with experimental flow patterns (ludicello et al., 1994). Frequency-dependent studies were carried out over the range of cardiac values using single- and multi-block versions of the code. A further validation exercise involved the use of sigmoidal filling curves in the in vitro models (Shortland et a!., 1994). Experimental data provided by such studies were used to drive the wall motion in the numerical simulations, and parametric studies of several simulation parameters were carried out. Flow field features and trajectories of the vortex paths were compared with the experiments for different filling curves, with reasonable agreement. However, because shear stress discontinuities occurred in the predictions a strict volume-defined analytical model was constructed for wall movement with smooth spatial and temporal behaviour reproducing experimental filling curves. Numerical predictions showed not only an improvement in the qualitative features of the flow compared with the experiments, but also a quantitative improvement in the prediction of the vortex core paths. Also the shear stress discontinuities were no longer evident. In order to be able to estimate residence times, instantaneous streamlines and particle tracks were produced. Analysis of shear stresses in the fluid and generation of particle pathlines for residence calculation in 3-D geometries will be carried out in the next feature for model candidates for the final SMV design. Some of the material published during the course of the project is included in APPENDIX 1. In this thesis, attention is paid to the SMV fluid dynamics. However, SMV behaviour is a coupled fluid-solid problem. Future work will be carried out in the muscle modelling. To this end, a careful review has been carried out, and is included in the thesis. Implications for future work are also discussed.

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Deserranno, Dimitri. "A Multi-Scale Finite Element Model of the Cardiac Ventricles". Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1148984314.

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Zainy, Mohammed. "Hydrodynamic modelling of cerebrospinal fluid motion within the human ventricular system". Thesis, Nottingham Trent University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272855.

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Boyers, Albert S. "SPECT myocardial perfusion scans : a left ventricular defect size estimation algorithm and a three dimensional computer simulation". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/14879.

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Stevenson, David. "Estimation of the time-varying elastance of the left and right ventricles". Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8794.

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The intensive care unit treats the most critically ill patients in the hospital, and as such the clinical staff in the intensive care unit have to deal with complex, time-sensitive and life-critical situations. Commonly, patients present with multiple organ dysfunctions, require breathing and cardiovascular support, which make diagnosis and treatment even more challenging. As a result, clinical staff are faced with processing large quantities of often confusing information, and have to rely on experience and trial and error. This occurs despite the wealth of cardiovascular metrics that are available to the clinician. Computer models of the cardiovascular system can help enormously in an intensive care setting, as they can take the monitored data, and aggregate it in such a way as to present a clear and understandable picture of the cardiovascular system. With additional help that such systems can provide, diagnosis can be more accurate and arrived at faster, alone with better optimised treatment that can start sooner, all of which results in decreased mortality, length of stay and cost. This thesis presents a model of the cardiovascular system, which mimics a specific patient’s cardiovascular state, based on only metrics that are commonly measured in an intensive care setting. This intentional limitation gives rise to additional complexities and challenges in identifying the model, but do not stand in the way of achieving a model that can represent and track all the important cardiovascular dynamics of a specific patient. One important complication that comes from limiting the data set is need for an estimation for the ventricular time-varying elastance waveform. This waveform is central to the dynamics of the cardiovascular model and is far too invasive to measure in an intensive care setting. This thesis thus goes on to present a method in which the value-normalised ventricular time-varying elastance is estimated from only metrics which are commonly available in an intensive care setting. Both the left and the right ventricular time-varying elastance are estimated with good accuracy, capturing both the shape and timing through the progress of pulmonary embolism and septic shock. For pulmonary embolism, with the algorithm built from septic shock data, a time-varying elastance waveform with median error of 1.26% and 2.52% results for the left and right ventricles respectively. For septic shock, with the algorithm built from pulmonary embolism data, a time-varying elastance waveform with median error of 2.54% and 2.90% results for the left and right ventricles respectively. These results give confidence that the method will generalise to a wider set of cardiovascular dysfunctions. Furthermore, once the ventricular time-varying elastance is known, or estimated to a adequate degree of accuracy, the time-varying elastance can be used in its own right to access valuable information about the state of the cardiovascular system. Due to the centrality and energetic nature of the time-varying elastance waveform, much of the state of the cardiovascular system can be found within the waveform itself. In this manner this thesis presents three important metrics which can help a clinician distinguish between, and track the progress of, the cardiovascular dysfunctions of pulmonary embolism and septic shock, from estimations based of the monitored pressure waveforms. With these three metrics, a clinician can increase or decrease their probabilistic measure of pulmonary embolism and septic shock.

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Cardone-Noott, Louie. "A computational investigation of the electrocardiogram with healthy and diseased human ventricles". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:6d1521dc-e490-40c3-97ac-86fa54bf570e.

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Cardiovascular diseases are the leading cause of death worldwide, and are estimated to kill over 17 million people each year, about 31% of all deaths. In the clinic, the first diagnostic procedure for a suspected cardiac abnormality is often acquisition of an electrocardiogram (ECG), which measures the electrical potential of the heart at the body surface. Understanding the mechanisms underlying generation of the ECG waveforms is crucial for optimal clinical benefit. Computer simulations possess several strengths as a tool to gain this understanding, particularly in terms of human-specificity, flexibility, repeatability, and ethics. The ventricles make up the majority of the cardiac volume and are therefore responsible for the majority of ECG waveforms. Ventricular disorders are the most life-threatening, because the ventricles are responsible for pumping blood to the body. Due to their size it has only recently become possible to perform biophysically detailed simulations of the ventricles and torso using supercomputers. In this thesis, multiscale, mathematical models of the ventricles and torso using the Chaste software library are simulated on high performance computing systems. A description is included of the performance enhancements made in Chaste to improve resource efficiency and accelerate job turnaround, particularly in data storage and the auxiliary tasks of post-processing and data conversion. A novel model of ventricular activation is presented and parametrized using multi-modal human data, and successfully used to simulate normal and pathological QRS complexes. Similarly, repolarization gradients are imposed based on the literature and result in a variety of T waves. Finally, the developed human whole-ventricular and torso models are utilized to gain new insights into possible ionic mechanisms underlying the clinical manifestations of the early repolarization syndrome. Overall, this thesis presents a novel framework for simulation of the human ECG using high performance computers, with possible applications in basic science and computational medicine.

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Più fonti

Libri sul tema "Ventricles"

Salih, Hayder R., Samer S. Hoz, Ali A. Dolachee, Mohammed A. Alrawi, Zaid Aljuboori, Mayur Sharma, Mustafa Ismail e Norberto Andaluz, a cura di. Cerebral Ventricles. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-42342-0.

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J, Apuzzo Michael L., a cura di. Surgery of the third ventricle. Baltimore: Williams & Wilkins, 1987.

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1928-, Levine Herbert J., e Gaasch William H, a cura di. The Ventricle: Basic and clinical aspects. Boston: Nijhoff, 1985.

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E, Pérez Julio, Lang Roberto M e Mor-Avi Victor, a cura di. Echocardiography and cardiovascular function: Tools for the next decade. Dordrecht [Netherlands]: Kluwer Academic Publishers, 1997.

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J, Apuzzo Michael L., a cura di. Surgery of the third ventricle. 2^a ed. Baltimore: Williams & Wilkins, 1998.

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A, Konstam Marvin, e Isner Jeffrey M, a cura di. The Right ventricle. Boston: Kluwer Academic Publishers, 1988.

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Madjid, Samii, a cura di. Surgery in and around the brain stem and the third ventricle: Anatomy, pathology, neurophysiology, diagnosis, treatment. Berlin: Springer-Verlag, 1986.

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1946-, Cohen Alan, a cura di. Surgical disorders of the fourth ventricle. Cambridge, Mass., USA: Blackwell Science, 1996.

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Lundbäck, Stig. Cardiac pumping and function of the ventricular septum. Oxford ; Boston: Published for Scandinavian Physiological Society by Blackwell Scientific Publications, 1986.

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1936-, Liebson Philip R., Devereux Richard B, Horan Michael J, American Heart Association e Conference on Echocardiography in the Measurement of Left Ventricular Wall Mass (1984 : Chicago)., a cura di. Hypertension research: Echocardiography in the measurement of left ventricular wall mass. [Dallas, Tex.]: American Heart Association, 1987.

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Capitoli di libri sul tema "Ventricles"

Merchant, Randall E. "Ventricles". In Encyclopedia of Clinical Neuropsychology, 3570. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-57111-9_374.

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Merchant, Randall E. "Ventricles". In Encyclopedia of Clinical Neuropsychology, 1. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56782-2_374-2.

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Seward, James B., A. Jamil Tajik, William D. Edwards e Donald J. Hagler. "Ventricles". In Two-Dimensional Echocardiographic Atlas, 317–68. New York, NY: Springer New York, 1987. http://dx.doi.org/10.1007/978-1-4612-4726-5_5.

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Vegas, Annette. "Ventricles". In Perioperative Two-Dimensional Transesophageal Echocardiography, 51–75. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-9952-8_3.

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Benzagmout, Mohammed, Amadou Hassane Ali e Meryem Himmiche. "Ventricles". In Tuberculosis of the Central Nervous System, 119–26. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-50712-5_10.

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Misra, Deepika, e Dayana Eslava. "Ventricles". In Practical Manual of Echocardiography in the Urgent Setting, 57–78. Oxford: John Wiley & Sons, 2013. http://dx.doi.org/10.1002/9781118613382.ch4.

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Offit, Paul A., Anne Snow, Thomas Fernandez, Laurie Cardona, Elena L. Grigorenko, Carolyn A. Doyle, Christopher J. McDougle et al. "Ventricles". In Encyclopedia of Autism Spectrum Disorders, 3225. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-1698-3_590.

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Bolling, Danielle. "Ventricles". In Encyclopedia of Autism Spectrum Disorders, 5011. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-319-91280-6_590.

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Merchant, Randall E. "Ventricles". In Encyclopedia of Clinical Neuropsychology, 2600. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-0-387-79948-3_374.

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Al Ramadan, Abdullah H., Sarah A. Basindwah, Sadeem A. Albulaihed, Abdulaziz Y. Alahmed, Abdulaziz S. Alayyaf, Wafa M. Almuallim e Mustafa Ismail. "Lateral Ventricle: Pathology: Tumors". In Cerebral Ventricles, 9–21. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-42342-0_2.

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Atti di convegni sul tema "Ventricles"

Hendra, William R., Joel A. Lefever, José J. García e Joshua H. Smith. "A Flow-Controlled Finite Element Model of Noncommunicating Hydrocephalus". In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14058.

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Cerebrospinal fluid (CSF) is produced at a constant rate in the choroid plexuses of the lateral and third ventricles, and it predominately drains through the Sylvius aqueduct to the fourth ventricle. If the Sylvius aqueduct becomes obstructed, such as caused by a growing tumor adjacent to it, CSF accumulates in the ventricles and the ventricles expand significantly, leading to a medical condition known as noncommunicating, hydrocephalus.

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Shriram, K. S., S. Suryanarayanan, V. Vaidya e R. Srinivasan. "Unbiased multiple-subject alignment of left ventricles". In 2008 5th IEEE International Symposium on Biomedical Imaging (ISBI 2008). IEEE, 2008. http://dx.doi.org/10.1109/isbi.2008.4541278.

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Ozturk, Cengizhan, e Elliot R. McVeigh. "Motion analysis of both ventricles using tagged MRI". In Medical Imaging 2000, a cura di Chin-Tu Chen e Anne V. Clough. SPIE, 2000. http://dx.doi.org/10.1117/12.383402.

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Gonzalo-Domínguez, Miguel, Cristina Hernández-Rodríguez, Pablo Ruisoto, Juan Antonio Juanes, José Martín Marín Balbin e Alberto Prats-Galino. "3d reconstructions of brain ventricles using anaglyph images". In TEEM'16: 4th International Conference on Technological Ecosystems for Enhancing Multiculturality. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/3012430.3012562.

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Sim, K. S., M. K. Ong, S. S. Chong, J. T. Ng, C. P. Tso, S. L. Choo e A. H. Rozalina. "Auto detection of brain ventricles using Hausdorff distance". In 2010 IEEE EMBS Conference on Biomedical Engineering and Sciences (IECBES). IEEE, 2010. http://dx.doi.org/10.1109/iecbes.2010.5742228.

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Niebel, Casandra, e Takahiro Ohara. "The Dispersive Characteristics of the Left Ventricle Filling Wave". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80728.

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Left Ventricular Diastolic Dysfunction (LVDD) is impairment in the filling of the left ventricle (LV) and is presumed to affect all heart failure patients including over 50% of patients with a preserved ejection fraction. Despite drastic changes in LV filling dynamics between healthy and diseased ventricles, LVDD remains difficult to diagnose due to inherent compensatory mechanisms such as increased atrial pressure, heart rate, and LV contractility. The propagation velocity (VP) of the filling wave entering the LV is a common parameter used to assess diastolic filling. Current methods of measuring VP are not physically based and neglect much of the fluid motion entering the LV. In this work, we investigate the physics of the filling wave. We posit that it is governed by a dispersive behavior and we explore its clinical significance.

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Lefever, Joel A., José Jaime García e Joshua H. Smith. "A Large Deformation Finite Element Model for Non-Communicating Hydrocephalus". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80179.

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In a healthy brain, a continuous flow of cerebrospinal fluid (CSF) is produced in the choroid plexus, located in the lateral ventricles. Most of the CSF drains via the Sylvius aqueduct into the subarachnoid space around the brain, but a small amount flows directly through the cerebrum into the subarachnoid space inside the skull. Non-communicating hydrocephalus occurs when an obstruction blocks the Sylvius aqueduct. Because the cerebrum has only limited capacity for CSF to flow through it, CSF accumulates in the ventricles, yielding a significant increase in ventricular volume and deformation of the cerebrum, which may lead to tissue damage.

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Zhingre Sanchez, Jorge D., Lars M. Mattison, Michael G. Bateman e Paul A. Iaizzo. "Computational Simulations of Ventricular Outflow Tract Obstructions Associated With Varied Replacement Valve Geometries". In 2018 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/dmd2018-6916.

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Transcatheter replacement therapies for the atrioventricular (AV) valves are considered as the next frontier for the treatment of valvular regurgitation. The AV valves, tricuspid and mitral, are the regulators of blood flow from the atria into the ventricles. During diastole, blood flows through the open tricuspid and mitral valves to fill the right and left ventricles, respectively. During systole, the ventricles contract, closing the AV valves, and forcing the blood to exit through their respective ventricular outflow tracts (VOTs) to the arterial circulations. Although the current gold standard for the treatment of valvular regurgitation is surgical replacement or repair, the field of transcatheter therapies is rapidly expanding as new treatment options for patients; especially for those individuals considered to be at greater risks for surgical complications. Market released bioprosthetic devices for replacing the aortic and pulmonary valves have shown great promise and success. However, the advancement of similar therapies for either the mitral and tricuspid valves remain in the early stages of development. This slower progress is attributed to the high complexities and variabilities of the AV valves, which present challenges for both device design and post-implantation functions.

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Zhang, Yaonan, Xiangfei Meng, Chuanshen Chen, Qian Song e Yu Xu. "Accurate segmentation for right ventricles based on Multi-Atlas". In 2013 IEEE International Conference on Medical Imaging Physics and Engineering (ICMIPE). IEEE, 2013. http://dx.doi.org/10.1109/icmipe.2013.6864527.

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Rodriguez, Blanca, Brock Tice, Robert Blake, David Gavaghan e Natalia Trayanova. "Vulnerability to electric shocks in the regionally-ischemic ventricles". In Conference Proceedings. Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2006. http://dx.doi.org/10.1109/iembs.2006.259919.

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Rapporti di organizzazioni sul tema "Ventricles"

Kluthe, Gregory. Relative Heart Ventricle Mass and Cardiac Performance in Amphibians. Portland State University Library, gennaio 2000. http://dx.doi.org/10.15760/etd.920.

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Rohmer, Damien, Arkadiusz Sitek e Grant T. Gullberg. Visualization of Fiber Structurein the Left and Right Ventricleof a Human Heart. Office of Scientific and Technical Information (OSTI), luglio 2006. http://dx.doi.org/10.2172/920253.

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