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1
Nishta, B. V. "Artificial heart." Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/35027.
Testo completoAbstract (sommario):
An artificial heart is a device that replaces the heart. Artificial hearts are typically used to bridge the time to heart transplantation, or to permanently replace the heart in case heart transplantation is impossible. Although other similar inventions preceded it are going back to the late 1940s, the first artificial heart to be successfully implanted in a human was the Jarvik-7, designed by Robert Jarvik and implemented in 1982.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35027
2
Westaby, Stephen. "Towards a realistic artificial heart." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248952.
Testo completo
3
MICCIOLO, MATTEO. "ASSISTENZE MECCANICHE AL CIRCOLO: PADUA HEART PROJECT A TOTAL ARTIFICIAL HEART." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3423929.
Testo completoAbstract (sommario):
Background
While the prevalence of heart failure (HF) in Europe and the USA has increased constantly in the last decades up to 12 million patients, we are still missing available, effective therapeutic options for advanced HF refractory to medical management, accounting for 5% of the total HF patient population. In fact, cardiac transplantation remains the primary option for a select group of end-stage HF patients but it is strongly limited due to the shortage of donor organs. The research in the field of mechanical devices to support or substitute the pumping function of failing heart is therefore strongly pursued. Since the end of the 90’s, thanks to the improved performance and safety of left ventricular assist devices (LVADs), their clinical use has increased both as a bridge to cardiac transplantation (BTT) and as a lifelong therapy. In case of end-stage biventricular failure or candidates with restrictive or infiltrative cardiomyopathies with ventricular cavities too small to accommodate apical inflow cannulae, LVADs are not a viable option: bi-ventricular assist devices (BiVAD) or total artificial hearts (TAH) are needed. To date, in INTERMACS records, only less than 5% of implanted mechanical circulatory support devices are BiVAD or TAH; however these figures do not reflect the real need for total replacement of heart function due to the limitations of available TAH (SynCardia).
State of the Art
The only clinically available TAH to date is the pneumatically driven SynCardia, that was FDA approved for BTT in 2004. It requires no surgical pocket, can provide up to 10 L/min flow with physiological control through both pulsatile pumping chambers. However, the TAH requires adequate mediastinal space to accommodate the dual-chambered pump. Its last generation portable pneumatic controller allows patients to be discharged from the hospital, although patients’ quality of life is limited by noise and weight of the drive unit (6 kg) that they need to carry. Device malfunction, along with bleeding, stroke, and infection, remain concerns with this technology.
New TAHs research and development
Several new TAH projects were started and stopped at different stage of development such as Abiomed Abiocor, Cliveland Clinic Foundation Magscrew, Aachen AME ReinHeart, only to quote few recent ones. Either technical issues prevented projects to get regulatory approval for clinical use or lack of research funding did not allow project completion. At the time being, Carmat TAH (Carmat SA) is undergoing pre-clinical tests. It is an implantable, electro-hydraulically driven, pulsatile flow device with four bioprosthetic valves. The stroke volume (30–65 ml) and the beat rate (35–150 b/min) of the prosthesis adapt automatically in response to changes in preload and the resulting pulsatile blood flow ranges from 2 to 9 l/min. Its blood-pumping surfaces consist of processed bioprosthetic pericardial tissue, potentially allowing for the reduction of anti-coagulation. Despite such innovative aspect, the implantable pump is huge and needs sternum-to-vertebral column minimum distance of 13 cm to be implanted.
Conclusion: Padua Heart Project
In order to provide an innovative solution in the field of MCS, Padua Heart Project (PHP) pursues the design of a small size, electromechanically driven TAH, that can deliver pulsatile blood flow to meet physiological need. While all of the above mentioned TAH projects are based on rotary motors with a conversion gear, thus consisting of many wear-prone parts, limiting their durability, PHP is based on a linear motor having only one moving component. Due to its original design and control mode, the size of the linear motor can be only slightly larger than the blood sacs. Furthermore, its inner lining can be coated by processed pericardial tissue. As a proof of concept, a first linear drive prototype was developed and set up. The movable part of the linear motor consists of a flat magnet including two valvular prostheses. Its linear movement back and forward within the driving coil, allows compression and relaxation of a flexible blood sac and its filling and emptying through the valves. The prototype has been tested in a simple mock loop to deliver flow varying between 4.5 and 7.5 L/min with 120 mmHg of afterload. Further tests are under way to optimize blood sac shape and control mode at different sets of preload and afterload conditions.<br>Studio dello stato dell’arte del cuore artificiale totale (TAH) nella pratica clinica: la ricerca bibliografica è stata orientata all’analisi delle più recenti esperienze cliniche con TAH per individuarne limiti e punti di forza. L’obiettivo di tale ricerca documentale era quello di dedurre le specifiche per un nuovo TAH, in grado di soddisfare le esigenze terapeutiche ancora parzialmente o totalmente irrisolte dai sistemi attualmente disponibili:
• CARATTERISTICHE DI PESO E INGOMBRO IDEALI: diametro <90 mm, lunghezza < 100 mm; peso < 800 gr (peso del cuore naturale 300- 400 gr), per poter essere impiantato anche in pazienti di piccola BSA
• ATTUATORE impiantabile, elettromeccanico, efficiente, silenzioso, in grado di produrre un flusso medio di circa 6 L/min contro una pressione media di circa 100 mmHg, con capacità di sostenere sovraccarichi e picchi di flusso, con bassa dissipazione di calore verso il sangue e i tessuti
• DISEGNO DELLE CAMERE VENTRICOLARI E DELLE VALVOLE rispetto al flusso ematico tale da minimizzare l’emolisi e le zone di stagnazione del flusso e il conseguente pericolo di formazione di trombi
• MATERIALI USATI BIO ED EMOCOMPATIBILI: plastica, metallo, materiale biologico (PERICARDIO DECELLULARIZZATO), con caratteristiche di non tossicità, non carcinogenicità, stabilità chimica e resistenza meccanica, sterilizzabilità
• INTERFACCIA DEL TAH con il circolo (atri, arterie) rispettosa dell’anatomia e con agevoli meccanismi di aggancio
• DURATA DISPOSITIVO : circa 5 anni (per un sistema pulsatile, ciò corrisponde ad un numero di cicli variabile tra 225 e 350 Milioni, a seconda che lo Stroke Volume vari tra 70 e 45 ml), per poter offrire un supporto di lungo termine
Studio di nuovi modelli di TAH ancora in corso di sviluppo e ricerca brevettuale su TAH innovativi: attraverso tale ricerca sono stati individuati gli spunti più interessanti tra le tecnologie in divenire ed è stato definito come orientare il progetto del TAH di Padova. In particolare, si è optato per un sistema con pompe volumetriche, a camere flessibili valvolate, azionate da motori elettrici lineari (quindi, con meno trasduzioni) di piccole dimensioni. L’attuazione prevede un movimento push-pull del piano delle valvole, che realizza contemporaneamente il riempimento e l’eiezione dalle camere ventricolari. Questo consente, a parità di ingombro, l’aumento della portata o, viceversa, a parità di portata una considerevole riduzione di volume della pompa. Sono stati disegnate diverse possibili configurazioni della pompa push-pull e infine viene scelta soluzione con movimento dei piani valvolari, interposti tra sacco ventricolare e “atri”, disposti a “U”,con frequenza minima 60 b/min, SV 80 ml (40ml +40ml). Primi test su banco: il sistema push-pull con uno stroke volume complessivo di 80 ml ottenuto attraverso 2 eiezioni successive di 40 ml ciascuna, con frequenza di salita/discesa del motore lineare di 60b/min (1Hz) riesce a pompare 4,8 L/min contro un afterload di 120 mmHg Aumentando la frequenza a 92b/min, il sistema riesce a erogare una portata di 7.2 L/min contro lo stesso postcarico Emerge l’originalità progettuale del disegno in cui le valvole si comportano sia da organi di intercettazione sia da elementi di spinta della massa fluida. Prove su banco di confronto Drive Units di dispositive in uso clinico (Cardiowest Companion vs Freedom): sono state eseguite prove su banco di unità di controllo differenti impiegate sullo stesso modello di TAH (Cardiowest) allo scopo di individuare le variabili di controllo salienti su cui basare il sistema di attuazione del nuovo TAH. Lo spunto è stato fornito da un reale “clinical dilemma”: il paziente 1Z, a cui era stato impiantato il CardioWest nel 2007, ha iniziato a manifestare problemi di dispnea con edema polmonare, nonostante un flusso di 5 L/min, appena è passato dal sistema di attuazione Companion al più recente Freedom. Non aveva tali sintomi coi precedenti drive units Excor e Companion; nessun altro organo presentava segnali di scompenso. Le prove su banco hanno dimostrato che la più recente drive unit (Freedom), essendo molto rigida, poiché non permette la regolazione delle pressioni di attuazione dei due ventricoli, e non avendo alcun feedback sulle pressioni di riempimento del paziente, può determinare squilibri tra circolo destro e sinistro. Appare quindi molto importante nel progetto di nuovo TAH includere la possibilità di modulazione della portata in funzione delle pressioni di riempimento. Progetto di fitting virtuale del TAH: lo studio si propone di convertire TAC del torace in un modello 3D semplice rapido e affidabile della cavità toracica. I risultati attesi consistono nella definizione ottimale degli ingombri e delle forme della protesi impiantabile del TAH che si sta progettando, incluse le interfacce con atri e grandi vasi del ricevente. Inoltre, lo strumento sarebbe disponibile per la determinazione ottimale pre-operatoria del fitting anatomico in un dato paziente di un dato sistema di supporto circolatorio impiantabile. La ricerca è stata avviata in collaborazione con l’Unità di Ricerca “3DOM” della Fondazione Bruno Kessler di Trento.
4
Ranawake, Manoja, and n/a. "Development of the artificial heart for serial production." University of Canberra. Industrial Design, 1995. http://erl.canberra.edu.au./public/adt-AUC20061113.151545.
Testo completoAbstract (sommario):
Heart disease is the principal cause of death in most
industrialised countries. In the U.S.A. for example, 2.3 million individuals
suffer from chronic heart failure, with an annual increase in numbers of 17%.
It is estimated that 17,000 to 35,000 of them per year will die from this
disease if they are not given either a heart transplant or an artificial heart.
Unfortunately, the numbers of heart donors cannot meet the demand for
transplantation, and, at present, the artificial heart is a prohibitively
expensive alternative.
The total artificial heart (TAH) intended for the total replacement of the
natural heart is still some years away from realisation. However, the
ventricular assist device (VAD) which is used temporarily to maintain an ailing
heart is available now, although only in restricted numbers due to difficulties
in processing the biocompatible materials used during manufacture.
Consequently, such devices are expensive, costing anywhere from
AUS$30,000 for the pump head to AUS$200,000 for a complete system.
In this study, the Australian designed $quot;Spiral Vortex$quot; VAD was used to
investigate fabrication techniques for use in the eventual cost-effective
manufacture of a pump head costing approximately AUS$4,000. A second
VAD originally designed at the Kolff Laboratory, University of Utah, U.S.A.
was also used for comparative evaluation. The hard-shell Spiral Vortex VAD
is intended to be used outside the body, while the soft-shell Kolff VAD has the
advantage of being implantable for long-term use. They were cast from
epoxy resin and vacuum formed from polyurethane, respectively. Several
units of each were fabricated, including 60 of the Kolff VAD, for use in vitro
and in vivo experiments. From these experiments it was found that both the
Spiral Vortex and Kolff VADs could be fabricated to quality controllable
standards. The Kolff VAD was used exclusively in chronic animal
experiments, and was able to sustain sheep and goats for periods of up to
five weeks. Furthermore, it became evident that techniques used in
fabrication of the Kolff VAD could be adopted for use in the mass production
of the Spiral Vortex VAD.
The two other areas investigated in this study were the prosthetic heart
valves and drive systems used for an artificial heart. A high percentage of
the cost of an artificial heart is accounted for by the inflow/outflow valves.
The trileaflet valve used in the Kolff VAD, which mimics the natural heart
valve, was fabricated using inexpensive vacuum-forming techniques. Quality
control was found to be adequate, with good flow characteristics which could
be maintained for several weeks in animal experiments. Both the Spiral
Vortex and Kolff VADs are pulsation pumps which require a pneumatic driver
unit. This driver is the single most expensive component in a VAD system,
costing upwards of AUS$150,000. The theoretical efficiency of a compact
hydromechanical drive unit was investigated using a test rig to simulate an
original design based primarily on proprietary components. Results obtained
so far indicate that the proposed driver can operate only under limited
conditions as a result of its severe reduction in size.
By adopting mass production techniques wherever possible in the fabrication
of the VAD (pump head) and valves, and by reducing the cost and size of the
driver unit, it may therefore be possible to produce a cost effective ventricular
assist device system.
5
Menon, Vinay. "Fuzzy logic controller for an artificial heart." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq32405.pdf.
Testo completo
6
Hui, Andrew J. "Hydrogel-based artificial heart valve stent material." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0018/MQ58005.pdf.
Testo completo
7
Alsalamah, Mashail. "Heart diseases diagnosis using artificial neural networks." Thesis, Coventry University, 2017. http://curve.coventry.ac.uk/open/items/a9564d2b-df62-4573-8888-cabdbbdcd4e0/1.
Testo completoAbstract (sommario):
Information technology has virtually altered every aspect of human life in the present era. The application of informatics in the health sector is rapidly gaining prominence and the benefits of this innovative paradigm are being realized across the globe. This evolution produced large number of patients’ data that can be employed by computer technologies and machine learning techniques, and turned into useful information and knowledge. This data can be used to develop expert systems to help in diagnosing some life-threating diseases such as heart diseases, with less cost, processing time and improved diagnosis accuracy. Even though, modern medicine is generating huge amount of data every day, little has been done to use this available data to solve challenges faced in the successful diagnosis of heart diseases. Highlighting the need for more research into the usage of robust data mining techniques to help health care professionals in the diagnosis of heart diseases and other debilitating disease conditions. Based on the foregoing, this thesis aims to develop a health informatics system for the classification of heart diseases using data mining techniques focusing on Radial Basis functions and emerging Neural Networks approach. The presented research involves three development stages; firstly, the development of a preliminary classification system for Coronary Artery Disease (CAD) using Radial Basis Function (RBF) neural networks. The research then deploys the deep learning approach to detect three different types of heart diseases i.e. Sleep Apnea, Arrhythmias and CAD by designing two novel classification systems; the first adopt a novel deep neural network method (with Rectified Linear unit activation) design as the second approach in this thesis and the other implements a novel multilayer kernel machine to mimic the behaviour of deep learning as the third approach. Additionally, this thesis uses a dataset obtained from patients, and employs normalization and feature extraction means to explore it in a unique way that facilitates its usage for training and validating different classification methods. This unique dataset is useful to researchers and practitioners working in heart disease treatment and diagnosis. The findings from the study reveal that the proposed models have high classification performance that is comparable, or perhaps exceed in some cases, the existing automated and manual methods of heart disease diagnosis. Besides, the proposed deep-learning models provide better performance when applied on large data sets (e.g., in the case of Sleep Apnea), with reasonable performance with smaller data sets. The proposed system for clinical diagnoses of heart diseases, contributes to the accurate detection of such disease, and could serve as an important tool in the area of clinic support system. The outcome of this study in form of implementation tool can be used by cardiologists to help them make more consistent diagnosis of heart diseases.
8
Barsanti, Stephen. "Observations on the mechanical behaviour of polyurethane heart valves." Thesis, University of the West of Scotland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265928.
Testo completo
9
Nugent, Allen Harold Biomedical Engineering UNSW. "Fluid dynamical investigation of a ventricular assist device." Awarded by:University of New South Wales. Biomedical Engineering, 2005. http://handle.unsw.edu.au/1959.4/35035.
Testo completoAbstract (sommario):
The Spiral Vortex (SV) ventricular assist device (VAD) was investigated by 2-component laser Doppler anemometry (LDA) while pumping a refractive index-matched blood analogue fluid. The VAD was operated under physiological conditions corresponding to 75% assist (4 litres/minute) or weaning from assist (2 litres/minute). Data were sampled on a 5-mm grid throughout most of the interior of the blood chamber, using two orthogonal LDA configurations from which 3D velocity data were synthesised. Data were subjected to statistical analysis of quasistatic time intervals and approximation by Fourier series. The velocity vector fields were explored statically (via 2D plots) and dynamically (using 3D animations of the reduced data). Reynolds stresses were computed and visualised in 2D. Fluid pathlines were simulated and plotted in 3D. The flow was found to be dominated by an irrotational vortex that accelerated and precessed in phase with the pumping diaphragm. Two unexpected flow structures, a rising, swirling near-wall layer in diastole and a reflection of the outflow vortex upon valve closure, enhanced washing of the walls. The thickness of the boundary layer was estimated to be 2 mm. Fluid velocities were generally lower than those reported in steady-flow studies on the SV VAD, although turbulence was comparable. Under the weaning mode, the coherence of the main vortex was degraded and flow recirculation was observed distal to the inflow port; this operating mode must be regarded as an indication for anticoagulation. In both pumping modes, turbulence was elevated in association with asymmetric buckling of the pneumatically driven diaphragm. Suboptimal orientation of the tilting-disc inlet valve gave rise to augmented turbulence production and skewing of the main vortex; similar results were obtained for an axisymmetric polymer (Jellyfish) valve, despite its advantageous haemodynamics. Flow stagnation was apparent where the inflow stream impinged on the wall, opposite the inflow port. The overall design of the SV VAD appears to almost ideal, in the context of current technology. However, elimination of recirculation/stagnation zones, especially in the weaning mode, remains a priority for the ultimate optimisation of haemocompatibility. Pulsatile VADs will probably never be entirely free of flow recirculation or stagnation, and published claims to the contrary probably reflect study limitations.
10
Sedighian, Pouye. "Pediatric heart sound segmentation." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1526952.
Testo completoAbstract (sommario):
<p> Recent advances in technology have facilitated the prospect of automatic cardiac auscultation by using digital stethoscopes. This in turn creates the need for development of algorithms capable of automatic segmentation of the heart sound. Pediatric heart sound segmentation is a challenging task due to various factors including the significant influence of respiration on the heart sound. This project studies the application of homomorphic filtering and Hidden Markov Model for the purpose of pediatric heart sound segmentation. The efficacy of the proposed method is evaluated on a publicly available dataset and its performance is compared with those of three other existing methods. The results show that our proposed method achieves accuracy of 92.4% ±1.1% and 93.5% ±1.1% in identification of first and second heart sound components, and is superior to four other existing methods in term of accuracy or time complexity.</p>
11
Collin, Sophie. "Preoperative planning and simulation for artificial heart implantation surgery." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S025/document.
Testo completoAbstract (sommario):
L'utilisation d'Assistance Circulatoire Mécanique (ACM) augmente dans le cas d'insuffisance cardiaque terminale ne répondant pas aux traitements médicaux. Dans ce contexte nous avons: 1) présenté une vue d'ensemble des problématiques cliniques, 2) élaboré une nouvelle approche de planification assistée par ordinateur pour l'implantation d'ACM, 3) implémenté un modèle CFD pour comprendre l'hémodynamique ventriculaire induite par la canule apicale. Afin de diminuer les complications, des critères quantitatifs optimisant la décharge ventriculaire pourraient être déterminés par CFD. La planification fournirait des informations permettant de choisir le dispositif et adapter la stratégie clinique<br>Mechanical Circulatory Support (MCS) therapy is increasingly considered for patients with advanced heart failure unresponsive to optimal medical treatments. In this context, we: 1) presented an overview of clinical issues raised by MCS implantation, 2) designed a novel computer-assisted approach for planning the implantation, 3) implemented a CFD model to understand the ventricle hemodynamics induced by the inflow cannula pose. With the aim of decreasing complications and morbidity, quantitative criteria for optimizing ventricle unloading could be determined through CFD, and the planning approach may provide valuable information for choosing the device and adapting the clinical strategy
12
Isayeva, N. "The artificial heart is the step in the future." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/62811.
Testo completoAbstract (sommario):
Nowadays the problem of heart diseases is actual and current. Speaking about our country the situation is even worse than all over the world. Since 1991 the amount of cardiovascular system pathologies has been increasing every year. It`s a pity, but there are many young people among patients of the cardiac centres and hospitals.
13
Watson, Stuart Kent. "Carbon deposition for artificial heart valves using liquid reagent CVD." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16908.
Testo completo
14
Yeh, Han Hung. "Computational analysis of fluid structure interaction in artificial heart valves." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44921.
Testo completoAbstract (sommario):
The development of heart valve stenosis and sclerosis can lead to the development of fatal complications such as congestive heart failure. Therefore, severe valve stenosis requires a surgical operation with artificial heart valve replacement. Given that the geometrical differences between artificial valves would significantly influence hemodynamic performance around the implanted valve, additional knowledge for the interactions between blood flow and the artificial valve is necessary. Therefore, in order to proceed, this study proposes an advanced computational fluid dynamics (CFD) simulation using a fluid-structure interaction (FSI) technique to investigate artificial valve leaflet motion under different physiological conditions.
Among various FSI technique, it is proposed to simulate the motion of the artificial heart valve with a fully-coupled algorithm and arbitrary Lagrangian-Eulerian formulation (ALE) using a monolithic solver. Models are constructed using a realistic aortic root for both the bileaflet and bioprosthetic valves with additional modifications and considerations for the flexible arterial wall. Normal physiological blood pressure and conditions are used to simulate healthy scenarios, which are compared with experiments. Validation is conducted by analysing particle image velocimetry (PIV) experimental data from ViVitro Lab. Hemodynamic performance analyses are conducted and found that both velocity and maximum von Mises stress are higher if calculated using a rigid wall model. The leaflet dynamics, on the other hand, is relatively the same for rigid or flexible wall model. Clinically relevant scenarios are also simulated for both mechanical and bioprosthetic valves. The clinical focus for the mechanical valve is on the malfunction of the valve due to leaflet restrictions. In addition, the clinical focus for the bioprosthetic valve is on the systolic deficiency due to different tissue properties.
15
Davies, P. "Artificial cardiac pacing stimulation thresholds in the in vitro rabbit heart." Thesis, Coventry University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383671.
Testo completo
16
Forsythe, R. N. "A partitioned approach to fluid-structure interaction for artificial heart valves." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438630.
Testo completo
17
Dal, Sasso Eleonora. "Towards an increased biocompatibility in total heart replacements: a new hybrid membrane for artificial blood pumps and the whole bioengineered heart." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426692.
Testo completoAbstract (sommario):
The only definitive treatment currently used for end-stage heart failure (HF) is cardiac transplantation. However, the procedure is limited by organ shortage and the side-effects of life-long immunosuppression. The need for new therapeutic strategies paved the way for the development of mechanical circulatory supports (e.g., total artificial hearts, TAHs) and the whole bioengineered heart. Although the two approaches may appear to be in conflict, TAHs are intended for short- to middle-term applications and can be developed and clinically applied relatively faster; the bioengineered heart approaches a definitive solution but, although current results are promising, a full organ equivalent has not yet been achieved.
The creation of a novel TAH internal lining and the generation of a decellularized matrix for total heart bioengineering were the aim of this doctoral thesis, in order to improve the common goal of biocompatibility in formulating whole heart replacements.
The TAH approach was investigated by coupling a TriCol-decellularized bovine pericardial scaffold (DBP) with a medical-grade polycarbonate urethane. This combination gave rise to a hybrid membrane (HM) capable of overcoming materials’ reciprocal limitations. The DBP was assessed by histology, two-photon microscopy (TPM)-combined immunofluorescence and TPM-mediated morphometric quantifications. Following HM assembly, surface analyses showed that the polymer penetrated the DBP scaffold. In vitro cytocompatibility was performed according to ISO 10993-5 with human umbilical vein endothelial cells (HUVECs) and human bone marrow-derived mesenchymal stem cells (hBM-MSCs). All tests confirmed unaltered morphology, proliferation, viability, and absence of cytotoxicity. No activation of the complement system, part of ISO 10993-4, was reported for HM.
The poor endothelialization and occurrence of thromboembolism in TAH may be prevented by accelerating endothelial adhesion through immobilization of short synthetic peptides. TriCol DBP scaffolds were selectively and covalently linked by Arg-Glu-Asp-Val (REDV) and rhodamine-conjugated REDV (RhodREDV) at different concentrations. After functionalization, the amount of bound RhodREDV was quantified with a TPM. The bioactivity of REDV was evaluated by in vitro static seeding of HUVECs. Live/dead staining and MTS reduction quantification demonstrated improved early adhesion, viability and proliferation of HUVECs on 10-5 M REDV-functionalized DBP at 24 hours. The LDH assay reported negligible levels of cytotoxicity. Histological evaluations revealed a near-continuous type of cell lining.
The first step towards whole heart bioengineering was performed by developing a preservative decellularization protocol for cardiac organs. Rat hearts were decellularized by a combination of myorelaxant, protease inhibitors, sodium dodecyl sulfate (SDS) and Triton X-100. All solutions were administered by retrograde coronary perfusion. The effectiveness of the protocol was evaluated by histology, TPM-combined immunofluorescence, DNA quantification, and proteomic analysis. Cytocompatibility was assessed according to ISO 10993-5 by static seeding of hBM-MSCs on isolated ventricles. The results confirmed unaltered morphology, maintained proliferation and the absence of cytotoxicity. Histology showed continuous monolayer of hBM-MSCs at 24 hours, whereas cell penetration was visible at days 7 and 14.
Concluding, this doctoral thesis describes the progresses towards the biocompatibility of heart replacements. A first generation of HM, based on DBP and polyurethane, was created and demonstrated its suitability for TAH internal lining. The covalent and selective functionalization of 10-5 M REDV peptide on DBP proved its efficacy in accelerating endothelial adhesion and promoting cell proliferation. A more preservative and cytocompatible protocol for whole heart decellularization was developed and achieved complete cell removal well-maintaining cardiac matrix.<br>Il trapianto di cuore è l’unico trattamento dell’insufficienza cardiaca terminale, ma la sua applicazione è limitata dalla carenza di organi e dagli effetti collaterali delle terapie immunosoppressive. La necessità di nuove strategie terapeutiche ha portato allo sviluppo delle assistenze meccaniche ed al cuore bioingegnerizzato. Sebbene possano sembrare in contrasto, i cuori artificiali totali (TAH) sono impiantati a breve/medio termine e possono essere sviluppati ed introdotti nella clinica più rapidamente, mentre il cuore bioingegnerizzato si avvicina ad una soluzione definitiva, ma nonostante i risultati promettenti non è ancora stato prodotto un organo equivalente completo.
La creazione di un nuovo rivestimento interno per i TAH e la generazione di una matrice decellularizzata per la bioingegnerizzazione del cuore sono stati l’obiettivo di questa tesi di dottorato al fine di migliorare la biocompatibilità dei sostituti cardiaci.
Il rivestimento per i TAH è stato realizzato accoppiando pericardio bovino decellularizzato TriCol (DBP) ad un poliuretano, producendo una membrana ibrida (HM). Il DBP è stato valutato con istologie, immunofluorescenza combinata con microscopia a due fotoni (TPM) e quantificazione morfometrica. Le analisi superficiali della HM hanno mostrato la penetrazione del polimero. La citocompatibilità in vitro (ISO 10993-5) è stata valutata con cellule endoteliali di vena ombelicale umana (HUVEC) e mesenchimali staminali derivate da midollo osseo umano (hBM-MSC). I test hanno confermato inalterate morfologia, proliferazione, vitalità ed assenza di citotossicità. Nessuna attivazione del sistema del complemento (ISO 10993-4) è stata segnalata per HM.
La scarsa endotelizzazione ed il verificarsi di tromboembolia nei TAH possono essere prevenuti accelerando l’adesione endoteliale con brevi peptidi sintetici. Gli scaffold TriCol DBP sono stati selettivamente e covalentemente legati ad Arg-Glu-Asp-Val (REDV) e REDV coniugato con rodamina (RhodREDV). Dopo la funzionalizzazione, la quantità di RhodREDV legato è stata quantificata con il TPM. La bioattività di REDV è stata valutata mediante semina statica di HUVEC in vitro. Il live/dead staining e la quantificazione della riduzione di MTS hanno dimostrato adesione precoce e migliore vitalità e proliferazione delle cellule nei DBP funzionalizzati con 10-5 M di REDV a 24 ore. Il saggio LDH ha riportato livelli trascurabili di citotossicità. Le valutazioni istologiche hanno rivelato un rivestimento cellulare quasi continuo.
Il primo passo verso la bioingegnerizzazione del cuore è stato eseguito sviluppando un protocollo di decellularizzazione più conservativo. I cuori di ratto sono stati decellularizzati con miorilassante, inibitori delle proteasi, sodio dodecil solfato e Triton X-100. Le soluzioni sono state somministrate mediante perfusione coronarica retrograda. L’efficienza del protocollo è stata valutata con istologie, immunofluorescenza combinata con TPM, quantificazione del DNA e analisi proteomica. La citocompatibilità è stata eseguita mediante semina statica di hBM-MSC in ventricoli isolati (ISO 10993-5). I risultati hanno confermato morfologia inalterata, mantenimento della proliferazione e assenza di citotossicità. Le hBM-MSC hanno formato un monolayer continuo a 24 ore, mentre a 7 e 14 giorni era visibile la penetrazione.
Concludendo, questa tesi di dottorato descrive i progressi verso la biocompatibilità dei sostituti cardiaci. La prima generazione di HM, basata su DBP e poliuretano, ha dimostrato la sua idoneità per il rivestimento interno dei TAH. La funzionalizzazione covalente e selettiva di DBP con 10-5 M di REDV ha provato la sua efficacia nell’accelerare l’adesione e proliferazione endoteliale. Un protocollo più conservativo e citocompatibile per la decellularizzazione del cuore totale è stato sviluppato e ha determinato la completa rimozione delle cellule endogene, preservando la matrice cardiaca.
18
Braunschweig, Frieder. "Implantable devices in heart failure : studies on biventricular pacing and continuous hemodynamic monitoring /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-345-7/.
Testo completo
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Iborra, Egea Oriol. "Novel approaches towards precision medicine in acute and chronic heart failure." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669734.
Testo completoAbstract (sommario):
L’infart de miocardi (IM) és causat per una aturada sobtada del flux de sang que provoca isquèmia local al cor i desencadena un remodelat patològic, que es pot desenvolupar en insuficiència cardíaca (IC). Tot i que pot presentar-se com un esdeveniment estàtic, aquest és un procés complex i dinàmic.
En aquesta tesi, es va valorar la IC considerant tot l'espectre de la malaltia. A més, estudis recents donen suport a la idea que processos biològics específics probablement estiguin influïts pel context biològic (p. ex: un teixit específic o una determinada malaltia). Aquesta aproximació constantment genera grans quantitats de dades, de manera que el recull, l’anàlisi i la interpretació d’aquesta informació constitueixen una tasca aclaparadora.
En conseqüència, vam utilitzar tècniques d’intel·ligència artificial per combinar dades moleculars amb respostes clíniques observades en pacients, generant així un model matemàtic capaç de discernir els MoAs ocults en milers d’interaccions moleculars, altrament inaccessibles.
Primer, vam voler analitzar els dos fàrmacs que estan revolucionant la gestió de la IC: Sacubitril/Valsartan, que ha demostrat una reducció del nombre de morts i ingressos en un 22% en assajos clínics recents, i Empagliflozina (un inhibidor de SGLT2 indicat per a pacients amb diabetis mellitus tipus 2) que va sorprendre amb una disminució del 32% en el desenvolupament de nous casos de IC a l’assaig EMPAREG.
El nostre primer estudi va revelar que Sacubitril/Valsartan actua de manera sinèrgica bloquejant tant la mort cel·lular com el remodelat patològic de la matriu extracel·lular dels cardiomiòcits. El que és més important, vam descobrir un nucli de 8 proteïnes que es posicionen com a actors clau en aquest procés.
En segon lloc, el MoA d’Empagliflozina suggeria una millora de la mort cardiomiocítica mitjançant la restauració de l’activitat de dos gens suprimits durant la IC, XIAP i BIRC5. Aquests resultats es van confirmar en un model de rata in vivo i van demostrar ser independents de la presència de diabetis, indicant que Empagliflozina podria establir-se com a nou tractament en el maneig de la IC.
Tot i que ambdós fàrmacs presenten indicacions i mecanismes moleculars molt diferents, els seus beneficis en la reducció de la progressió de la IC eren notablement similars, evidenciant un paper clau del remodelat ventricular.
Així doncs, a continuació vam voler explorar aquest remodelat per delinear una imatge estructurada i clara del procés complet post-IM. Aquí, vam identificar aquelles proteïnes alterades més relacionades amb la remodelació cardíaca tant en IM com en IC, i les vam utilitzar per buscar processos amb un enriquiment sostingut al llarg de la progressió de l’infart. Un cop establerts quins processos es veuen afectats en diferents etapes i la seva evolució durant l’IM, finalment vam identificar les proteïnes clau que impulsen aquestes cascades de senyalització.
La IC crònica és la principal causa de mortalitat interhospitalària a tot el món, i es constitueix com a autèntica pandèmia. Tot i això, molts d’aquests pacients o bé desenvolupen IC derivat d’un esdeveniment agut o experimenten un deteriorament dràstic de la condició durant les hospitalitzacions recurrents. De fet, l’IC aguda és la principal causa de mortalitat intrahospitalària en països més desenvolupats, i el xoc cardiogènic (CS) representa la seva forma més agressiva. No obstant això, la IC aguda rep poca atenció en comparació amb la forma crònica de la malaltia
Mitjançant tècniques de proteòmica i transcriptòmica avançades, primer vam investigar nous biomarcadors per ajudar a la gestió del CS. Avaluant els microRNAs i les proteïnes expressades diferencialment en pacients afectats, hem descrit l’estat actual de la investigació sobre biomarcadors en CS, així com desenvolupat un nou test molecular, el CS4P, per predir de forma fiable els resultats pronòstics d’aquests pacients.<br>Myocardial infarction (MI) is caused by a sudden stop of blood flow that can lead to local ischemia in the heart and cause a pathologic remodeling, which ultimately give rise to heart failure (HF). Although it might present as a static event, this is a complex and dynamic process.
In this thesis, we aimed to assess HF considering the whole spectrum of the disease. From the acute phase, in which a patient suddenly falls victim to a drastic illness, to investigate the molecular transition towards its chronification and elucidate the mechanisms of action (MoA) of the most novel pharmaceutical therapies in chronic HF. Moreover, growing evidence supports the idea that specific biological processes are likely influenced by their biological context—for example, a specific tissue or a certain disease. This approach constantly generates vast amounts of data, such that putting together, analyzing, and interpreting this information constitutes an overwhelming task.
Consequently, we harnessed artificial intelligence techniques to combine molecular data with clinical responses observed in patients, thus generating a mathematical model capable of both reproducing existing knowledge and discern MoAs hidden under thousands of molecular interactions, otherwise inaccessible.
First, we analyzed the two drugs that are revolutionizing HF management: Entresto® (Sacubitril/Valsartan), which showed a reduction in the number of deaths and admissions by 22% in recent clinical trials, and Empagliflozin (a SGLT2 inhibitor indicated for type2 diabetes mellitus patients) that showed an unexpected 32% slash in development of new HF cases in the EMPAREG trial.
Our first study revealed that Sacubitril/Valsartan acts synergistically by blocking both cell death and the pathological makeover of the extracellular matrix of cardiac cells. Most importantly, we discovered a core of 8 proteins that emerge as key players in this process.
Secondly, the MoA of Empagliflozin was deciphered using deep learning analyses, which achieved 94.7% accuracy and showed an amelioration of cardiomyocyte cell death by restoring the activity of two genes suppressed during HF, XIAP and BIRC5. These results were confirmed in an in vivo rat model, and proved independent of the presence of diabetes, suggesting that Empagliflozin may emerge as a new standalone treatment in HF.
Although both drugs have very distinct indications and intrinsic MoAs, their benefits in slowing HF progression were remarkably similar, evidencing a key role for ventricular remodeling.
Thus, next we aimed to explore cardiac remodeling to delineate a structured and clear picture of the complete post-MI remodeling process towards HF. Here, we identified those altered proteins most related to cardiac remodeling in both MI and HF, and used them to look for processes with sustained enrichment throughout MI progression. Once we established which processes are affected at different stages and their evolution during MI, we finally sought to identify the key proteins driving these signaling cascades.
Chronic HF is the leading cause of inter-hospital mortality worldwide, which constitutes an authentic pandemic. However, many of these patients either develop HF derived from an acute event or experience a drastic worsening of the condition during the recurrent hospitalizations. Indeed, acute HF is the leading cause of intra-hospital mortality in more-developed countries, in which cardiogenic shock (CS) represents its most aggressive form. Yet, acute HF receives little attention compared to the chronic form of the disease
By using transcriptomic and advanced proteomics techniques, we first investigated new potential biomarkers to aid CS management, which remains the leading intra-hospital cardiovascular cause of death worldwide. Assessing microRNA and proteins differentially expressed in afflicted patients, we describe the current status of biomarker research in CS, as well as a new molecular score, the CS4P, to reliably predict the prognostic outcomes of these patients.
20
Conlon, Martin J. "Design and evaluation of a neural network-based controller for an artificial heart." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0015/MQ57723.pdf.
Testo completo
21
Curtis, Corinna Briony Anne. "Flow-related clot deposition around artificial heart valves and its analysis by ultrasound." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/13535.
Testo completoAbstract (sommario):
The principle objectives of this study were to investigate deposition around test objects of a more complex geometry than bodies of revolution, using ultrasound, whilst over coming some of the problems previously encountered with ultrasonic imaging. Development of a new deaeration system reduced the number of bubbles (which attenuate ultrasound) in the milk flow to a satisfactory level, subsequently improving the quality of the ultrasound images. Further changes included the selection of a new rennet due to the unavailability of the original rennet used in the milk studies. Several rennets were investigated basing the final selection upon the similarity in behaviour, of the new and the original rennets, in response to agitation. A new test chamber was designed which allowed ultrasonic observation of the progressive development of clot structures and rate of deposition around various test objects, namely monoleaflet mechanical heart valves and monoleaflet valve models, during steady flow. Deposition resulting from pulsatile flow was too thin to be detected by ultrasound. It was seen from ultrasonic and visual observation that deposition thickness in regions of highest shear was thinner than in lower shear regions. Several mechanisms of deposition structure development were observed ultrasonically during steady flow, including a previously unreported mechanism.
22
Hind, Andrew Kenneth. "An investigation into the flow fields around bluff bodies and artificial heart valves." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/15029.
Testo completoAbstract (sommario):
A milk analogue for clotting blood was developed by Lewis. This was then used by Christy, and subsequently Marosek, to investigate the clot deposited in the region of a series of bluff bodies and heart valves in both steady and pulsatile flows. Bodies of revolution, such as a teardrop, were used to simplify the flow structures present in the flow, making the relation of flow features to the deposition of clot more amenable to analysis. Christy concluded that stasis was a necessary but not sufficient condition for thrombus deposition. A quantitative flow visualisation technique known as particle image velocimetry (PIV) has been developed and applied to the flows investigated by Christy but with water as the test fluid. Steady flow PIV investigations around a Björk-Shiley valve showed significant three dimensional structure which varied markedly over time. In pulsatile flows, both at and below physiologically relevant flowrates, significant variation was observed between recordings made at the same point in successive pulse cycles. This may indicate that the assumptions underlying the sampling methods used in LDA investigations to estimate the Reynolds stresses downstream of heart valve prostheses in pulsatile flows are flawed. In pulsatile flows of a period of 1 Hz and a mean volumetric flowrate of 6.7x10<SUP>-5</SUP> m<SUP>3</SUP>/s, the maximum bulk viscous shear stresses determined using PIV were of the order of 0.05 N/m<SUP>2</SUP> with maximum values of 0.5 N/m<SUP>2</SUP> near the wall, well below the value expected to cause lysis of red blood cells even for extended exposure. In the same physiologically relevant flow conditions, the maximum viscous shear stress at the trailing tip of the valve designed by Dr Norman Macleod was again of the order of 0.5 N/m<SUP>2</SUP>. This level of wall shear is at the lower end of the range over which behavioural and shape changes are induced in endothelial cells and the adhesion of platelets to endothelial cells may be promoted. Particle image velocimetry is a powerful augmentation to the range of techniques available for assessing the performance of heart valve prostheses <I>in vitro. </I>
23
Conlon, Martin J. (Martin John) Carleton University Dissertation Engineering Mechanical and Aerospace. "Design and evaluation of a neural network-based controller for an artificial heart." Ottawa, 2000.
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24
Muslmani, Bassam Mohamed 1965. "The use of high resolution phonocardiography in the assessment of artificial heart valves." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278220.
Testo completoAbstract (sommario):
A non-invasive research tool to assess mechanical prosthetic heart valves using high resolution phonocardiography and signal processing was developed. The theory and motivation responsible for this system along with the actual hardware design and software coding will be presented. Studies employing this experimental system on patients with mechanical heart valves followed by the Sections of Cardiothoracic Surgery and Pediatric Cardiology at University Medical Center have revealed that the leaflets of normally functioning bileaflet mechanical heart valves do not close synchronously. The degree of asynchronous closure of the valve leaflets ranged from 3 msec to 4 msec to 5.5 msec. In addition, the data collected revealed that the closing sounds created by the prosthetic valves had significant frequencies above 10 kHz.
25
Greatrex, Nicholas Anthony. "Design of physiological control and magnetic levitation systems for a total artificial heart." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/65642/1/Nicholas_Greatrex_Thesis.pdf.
Testo completoAbstract (sommario):
Total Artificial Hearts are mechanical pumps which can be used to replace the failing natural heart. This novel study developed a means of controlling a new design of pump to reproduce physiological flow bringing closer the realisation of a practical artificial heart.
Using a mathematical model of the device, an optimisation algorithm was used to determine the best configuration for the magnetic levitation system of the pump. The prototype device was constructed and tested in a mock circulation loop. A physiological controller was designed to replicate the Frank-Starling like balancing behaviour of the natural heart. The device and controller provided sufficient support for a human patient while also demonstrating good response to various physiological conditions and events. This novel work brings the design of a practical artificial heart closer to realisation.
26
Jones, Mark I. "Haemocompatibility and charactersation of candidate coatings for heart valve prosthesis." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301695.
Testo completoAbstract (sommario):
Prosthetic cardiac valve surgery is a well-established technique, but the search continues for engineering materials with sup..e rior mechanical characteristics in order to extend the service life of the implant. The introduction of pyrolytic carbon was seen as a breakthrough in the development of wear resistant, non-thrombogenic materials for such applications. However, thrombo-embolic phenomena and the need for anticoagulation treatment following valve insertion remain the main problems associated with artificial materials in this application. The work carried out in this research has studied the haemocompatibility of a commercially available, wear resistant TiffiN/TiCfDLC multilayer structure, and a second TiN coating deposited by RF reactive sputtering of a titanium target in a ArIN2 environment, as candidate materials for a heart valve prosthesis. The structure of the RF deposited tiN coating was assessed as a function of deposition conditions, and was seen to develop a particular preferred crystallographic orientation. The nature of this texture was influenced by the condition of the underlying substrate. The effect of substrate condition on the biocompatibility of the tiN coating was studied by assessment of fibroblast attachment and spreading, and by haemolytic analysis of released haemoglobin. The results showed that the initial attachment and orientation of fibroblast cells was influenced by the substrate condition, but no influence on the degree of spreading and haemolytic nature was observed. Characterisation of the TiN coating and the components of the multilayer structure was carried out by Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), stylus profilometry and contact angle measurement. Haemocompatibility was studied by the interaction of the surfaces with plasma proteins, blood platelets and red blood ceUs. Cytotoxicity was studied using the MTT test. The degree of platelet activation on the surfaces correlated with their surface energy. The greatest degree of platelet spreading was observed on the more hydrophilic coatings. The lack of platelet activation seen on the DLC coating is attributed to its smooth surface and hydrophobic nature, resulting in higher levels of adsorption of anticoagulation proteins. The RF sputtered TiN coating caused significant levels of haemolysis and fibroblast cell death. None of the components of the multilayer structure caused such effects, although thrombus formation was observed to a degree on the Ti, TiN and TiC components of this structure. The toxic nature of the RF deposited TiN coating was not attributed to surface chemistry or roughness, but rather to a combination of the hydrophilic nature and the defect state of the surface.
27
Henker, Richard. "PNEUMATIC ARTIFICIAL HEART DRIVER PARAMETER EFFECTS ON THE RATE OF PRESSURE CHANGE ((+) DP/DT MAX)." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276466.
Testo completoAbstract (sommario):
The aim of the research was to investigate the effects of three parameters of the artificial heart on the (+) dP/dt max. The study was conducted using a mock circulation which was connected to an artificial heart. The data were collected using the COMDU software developed for the computer which monitors the artificial heart. Stepwise regression analysis was utilized to test the three hypotheses. Two of the null hypotheses for the study could not be rejected, as the independent variable did not significantly affect (+) dP/dt max. Although the third hypothesis was accepted, the results were not clinically significant. Limitations in the study were multicollinearity among the independent variables, small sample size, and the inability of the mock circulation to represent human responses.
28
Swarbrick, Martin Damian. "Acoustic diagnosis of heart defects using time-domain signal processing and artificial neural networks." Thesis, University of Hull, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273661.
Testo completo
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Vonesh, Michael John 1964. "A non-invasive method of estimating pulmonary artery pressure in the total artificial heart." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276785.
Testo completoAbstract (sommario):
A non-invasive, in vitro method of estimating mean pulmonary artery pressure (PAP) was developed. This information was obtained by establishing a relationship between the pneumatic right drive pressure (RDP) and PAP waveforms. The RDP-PAP relationship was formalized into a series of multiple-linear regression equations for TAH cardiac cycles of known fill volume (FV). Correlation of computed estimates of PAP to actual measurements showed that these equations were greater than 92% accurate within 1.84 mmHg. In addition, while the RDP-PAP relationships were wholly dependent on FV, it was shown that they are independent of the manner in which FV was obtained. This method proved useful over the clinical operating range of the pneumatic heart driver, as well as over the normal physiological range of PAP in the human. Effectiveness of this method in vivo needs to be demonstrated.
30
Janney, Joseph T. "The design, development and in vitro testing of an electric motor driven artificial heart." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/104538.
Testo completo
31
Canada, Justin M. "A Comparison of Maximal Exercise Responses among Patients with a Total Artificial Heart, a Left Ventricular Assist Device, or Advanced Heart Failure." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/340.
Testo completoAbstract (sommario):
The purpose of this study was to evaluate graded exercise responses to treadmill exercise in patients with a total artificial heat (SynCardia, Tucson, AZ). Additionally, this study sought to compare the exercise response in total artificial heart (TAH) patients to both advanced heart failure (HF) patients on medical management only and HeartMate II (Thoratec Corp., Pleasanton, CA) left‐ventricular assist device (HMII) patients. For patients with biventricular heart failure the TAH is a viable option to bridge patients until transplant becomes available. Its demonstrated improvement in mortality and increasing usage necessitates a shift in focus to quality of life in the TAH patient including functional ability. The evaluation of cardiorespiratory responses to graded exercise provides an objective measure of functional ability. There is very limited information in the literature on the exercise response of the mechanical circulatory support (MCS) device patient, particularly the TAH patient. A review was performed on MCS patients who underwent symptom‐limited cardiopulmonary exercise testing (CPET) following device implant of either TAH or HMII. ANOVA was performed to compare differences between the two device groups and HF patients listed for heart transplant. Fourteen TAH patients underwent CPET (9 male, 5 female) with peak oxygen consumption (VȩO2) of 0.926 + .168 L∙min, 36 + 8% % predicted, 11.0 + 2.3 ml.kg.min or 3.1 + 0.7 METs. Ventilatory anaerobic threshold (VAT) was 0.706 + .181 L∙min. Peak (VȩO2, % pred. (VȩO2 and VAT were significantly lower in the TAH compared with HMII and advanced HF (p = 0.0012, p = 0.0106, p = 0.0009, respectively). Peak RER was significantly higher (p = <.0001) and OUES was significantly lower (p = 0.0004) in the TAH. Exercise capacity is significantly reduced in the TAH patient below that observed in HMII LVAD and advanced HF patients. This provides a baseline for expected functional status and has implications on the ADL tolerance of these individuals. The next step is to develop strategies to ameliorate this continued exercise intolerance. The documents herein contain a review of literature including a background in heart failure and the use of the exercise response in the heart failure patient. An overview is also presented on the use of MCS describing physiology, device function, and exercise physiology of the MCS device patient. A manuscript has also been included detailing a cross‐sectional review of the effects of graded exercise in the TAH patient and comparing it to the HMII and advanced HF patient.
32
Lima, Jose Marco Nogueira. "Efeito hemodinamico da sincronização eletrica biventricular prolongada no pos-operatorio de revascularização do miocardio." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310236.
Testo completoAbstract (sommario):
Orientador: Kleber Gomes Franchini<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas<br>Made available in DSpace on 2018-08-06T19:09:29Z (GMT). No. of bitstreams: 1
Lima_JoseMarcoNogueira_D.pdf: 1108641 bytes, checksum: 52decb99b4c7eb40cf6e3df4bdda5d47 (MD5)
Previous issue date: 2006<br>Resumo: O presente estudo tem como objetivo avaliar a influência da estimulação biventricular prolongada no pós-operatório de revascularização miocárdica em pacientes portadores de disfunção ventricular esquerda, FE = 40%, associada à duração do QRS menor ou igual a 130ms. Foram selecionados 21 pacientes dos quais 16 foram randomizados em dois grupos denominados: Grupo de estimulação biventricular (Grupo EBV) e Grupo Controle. Os dois grupos foram submetidos à monitorização contínua por um período de 12 horas com os seguintes parâmetros coletados: parâmetros hemodinâmicos sistêmicos (pressão arterial média, índice de resistência vascular sistêmica e temperatura), parâmetros hemodinâmicos cardíacos (débito cardíaco, índice cardíaco, índice do volume sistólico do ventrículo esquerdo e freqüência cardíaca) e parâmetros hemodinâmicos pulmonares (pressão em cunha de capilar pulmonar, pressão venosa central e índice de resistência vascular pulmonar). Para análise dos resultados foram empregados o teste t de Student, teste de Wilcoxon, teste exato de Fisher, teste de Wilks e MANOVA. A sincronização obtida através da estimulação biventricular sob captação atrial (sinusal) aumentou o índice cardíaco em conseqüência do aumento do volume sistólico. Observou-se também uma redução significativa da resistência vascular sistêmica em comparação com os pacientes não estimulados. Esses efeitos permaneceram nas 6 horas que se seguiram após a parada da estimulação no Grupo EBV. Não houve diferença estatisticamente significativa na pressão arterial média entre os grupos. O grupo estimulado apresentou uma menor pressão em cunha de capilar pulmonar do que o grupo controle durante o período da estimulação. Podemos concluir que a estimulação biventricular produziu nesses pacientes uma melhora do desempenho sistólico do ventrículo esquerdo por restaurar a coordenação da contratilidade cardíaca em conseqüência da sincronização independente da variável freqüência cardíaca e duração do QRS<br>Abstract: The present study aims to evaluate the influence of lengthened biventricular stimulation on the post-surgical period of myocardical revascularization in patients that carry left ventricular dysfunction, FE = 40%, associated to QRS endurance equal to or less than 130 ms. From a selection of 21 patients, 16 of which were randomized in 2 groups named: Biventricular Stimulation Group (EBV Group) and Control Group. Both groups have been submitted to a 12-hour continuous monitoring period, with the following parameters being collected: systemic hemodynamic parameters (mean arterial pressure, systemic vascular resistance index and temperature), cardiac hemodynamic parameters (cardiac output, cardiac index, left ventricle stroke volume index and heart rate) and pulmonary hemodynamic parameters (pulmonary artery wedge pressure, central venous pressure and pulmonary vascular resistance index). For the analysis of the results we have applied the Student's t test, Wilcoxon rank-sum test, Fisher's exact test, Wilks' test and MANOVA. The synchronization obtained through biventricular stimulation under atrial sense increased the cardiac index, as a consequence of the increased systolic volume. A significant reduction of systemic vascular resistance has also been observed, in comparison to that of the non-stimulated patients. These effects have endured for the 6-hour period that succeeded the interruption of the stimulation in the EBV Group. There was no statistically significant difference in the average blood pressure between the groups. The stimulated group presented a lower pulmonary artery wedge pressure than that of the control group over the stimulation period. We can concluded the biventricular stimulation has produce an improvement on the systolic performance as the left ventricular do the restoration of the ventricular contractibility as a consequence of a synchronization that the not depend the frequency and the QRS lasting<br>Doutorado<br>Medicina Experimental<br>Doutor em Fisiopatologia Medica
33
Claiborne, Thomas Edward III. "Development and evaluation of a catheter deliverable artificial aortic heart valve prosthesis and delivery system." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/2371.
Testo completoAbstract (sommario):
Currently, malfunctioning heart valves are replaced via highly invasive and costly open-heart procedures. A new alternative approach is a catheter deliverable or percutaneous heart valve. Current PHV prototypes utilize fixed animal tissue as valves. This research investigated the feasibility of an artificial PHV and the development of a delivery system. A left hea11 simulator and a tensile tester were used to characterize the hydrodynamics and mechanics of a novel artificial PHV. Test results showed equal or better in vitro hydrodynamic performance when compared to a St. Jude mechanical valve and an Edwards-Sapien PHV, with a mean pressure drop of <15 mmHg and a mean regurgitation of <5%. The PHV's exceeded requirements for fixation and radial force. The 24 F delivery system successfully delivered and deployed a PHV. The work described herein proves the feasibility of an artificial PHV and delivery system and justifies further investigation into its design and function.
34
Davis, Carol Elizabeth 1964. "Non-invasive detection of full-filling in the symbion artificial heart and ventricular assist devices." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278427.
Testo completoAbstract (sommario):
The anatomy and physiology of the human heart, the historical development of heart transplantation and mechanical assistance, and total artificial heart and ventricular assist device systems are discussed. The focus of the investigation is on the detection of waveform indicators corresponding to full-filling of the artificial heart and ventricular assist device chambers. The developed software monitors the drive pressure waveform produced by the circulatory assist system until a full-fill indicator is detected. The event is verified by the detection of a corresponding indication during the same period within the flow waveform of the circulatory assist system. The appropriate alarm (for the right or left chamber) is updated each time a full-fill event is verified. When the user specified alarm limit is reached, an entry describing the alarm event is entered into the patient data file and a +5 volt analog signal is made available for external alarm activation.
35
Plewa, Luke Joseph. "Sudden Cardiac Arrest Prediction through Heart Rate Variability Analysis." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1449.
Testo completoAbstract (sommario):
The increase in popularity for wearable technologies (see: Apple Watch and Microsoft Band) has opened the door for an Internet of Things solution to healthcare. One of the most prevalent healthcare problems today is the poor survival rate of out-of hospital sudden cardiac arrests (9.5% on 360,000 cases in the USA in 2013). It has been proven that heart rate derived features can give an early indicator of sudden cardiac arrest, and that providing an early warning has the potential to save many lives. Many of these new wearable devices are capable of providing this warning through their heart rate sensors. This thesis paper introduces a prospective dataset of physical activity heart rates collected via Microsoft Band. This dataset is indicative of the heart rates that would be observed in the proposed Internet of Things solution. This dataset is combined with public heart rate datasets to provide a dataset larger than many of the ones used in related works and more indicative of out-of-hospital heart rates. This paper introduces the use of LogitBoost as a classifier for sudden cardiac arrest prediction. Using this technique, a five minute warning of sudden cardiac arrest is provided with 96.36% accuracy and F-score of 0.9375. These results are better than existing solutions that only include in-hospital data.
36
Botha, J. S. F. "Autonomous auscultation of the human heart." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4239.
Testo completoAbstract (sommario):
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: The research presented in this thesis serves to provide a tool to autonomously
screen for cardiovascular disease in the rural areas of Africa. Vital information
thus obtained from patients can be communicated to advanced medical centres by
Telemedicine. Cardiovascular disease is then detected in its initial stages, which is
essential to its effective treatment. The system developed in this study uses recorded
heart sounds and electrocardiogram signals to distinguish between normal
and abnormal heart conditions. This system improves on standard diagnostic tools
in that it does not require cumbersome and expensive imaging equipment or a
highly trained operator.
Heart sound- and electrocardiogram signals from 62 volunteers were recorded
with the prototype Precordialcardiogram device as part of a clinical study to aid in
the development of the autonomous auscultation software and to screen patients
for cardiovascular disease. These volunteers consisted of 28 patients of Tygerberg
Hospital with cardiovascular disease and, for control purposes, 34 persons with
normal heart conditions.
The autonomous auscultation system developed during this study, interprets
data obtained with the Precordialcardiogram device to autonomously acquire a
normal or abnormal diagnosis. The system employs wavelet soft thresholding to
denoise the recorded signals, followed by the segmentation of heart sound by
identifying peaks in the electrocardiogram. Novel frequency spectral information
was extracted as features from the heart sounds, by means of ensemble empirical
mode decomposition and auto regressive modelling. These features proved to be
particularly significant and played a major role in the screening capability of the
system. New time domain based features were identified, established on the specific
characteristics of the various cardiovascular diseases encountered during the
study. These features were extracted via the energy ratios between different parts
of ventricular systole and diastole of each recorded cardiac cycle.
The respective features were classified to characterise typical heart diseases as
well as healthy hearts with an ensemble artificial neural network. Herein the decisions
of all the members were combined to obtain a final diagnosis. The performance
of the autonomous auscultation system used in concert with the Precordialcardiogram
device prototype, as determined through the leave-one-out crossvalidation
method, had a sensitivity rating of 82% and a specificity rating of 88%.
These results demonstrate the potential benefit of the Precordialcardiogram device
and the developed autonomous auscultation software in a Telemedicine environment.<br>AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die navorsing van 'n outonome toetsing en sifting stelsel
vir kardiovaskulêre siektes in landelike dele van Afrika, vanwaar mediese inligting
per telefoon versend kan word. Die apparaat maak vroeë opsporing van kardiovaskulêre
siektes moontlik, wat essensieel is vir effektiewe behandeling daarvan
en ook die koste-effek van hierdie siektes verminder. In die huidige ontwikkelde
stelsel word normale sowel as abnormale hart-toestande getipeer met opnames
van hartklanke sowel as elektrokardiogram-seine. Voordele wat hierdie
stelsel bo standaard diagnostiese metodes het, sluit die hanteerbare formaat van
die hele apparaat sowel as die nie-noodsaaklikheid van duur beeldskeppende apparaat,
of hoogs opgeleide personeel.
Hartklank- en elektrokardiogramseine van 62 vrywilligers is met die prototipe
"Precordialcardiogram" apparaat opgeneem om by te dra tot die ontwikkeling van
die rekenaar sagteware vir die outonome auscultatsie stelsel en om die pasiëntsiftingsvermoë
daarvan te toets. Die vrywilligers het 28 pasiënte van Tygerberg
hospitaal met abnormale harttoestande ingesluit, sowel as ‘n kontrolegroep van 34
persone met normale harttoestande. Die outonome auskultasie-stelsel wat tot stand
gekom het deur hierdie ondersoek maak gebruik van “wavelet” sagte drempeling
om geraas uit die opgeneemde seine te verwyder. Daarna word die hartklanke gesegmenteer
deur die pieke van die elektrokardiogram te identifiseer.
Deur middel van "ensemble empirical mode decomposition" en outoregressiewe
modellering, is nuwe inligting aangaande die frekwensie spektra van
hartklanke, aanwysend van spesifieke harttoestande, verkry. Die beduidendheid
van hierdie eienskappe is bewys en het 'n belangrike rol in die siftingsvermoë van
die stelsel gespeel. Hierbenewens is nuwe tyd-gebaseerde eienskappe van die
onderskeie kardiovaskulêre siektes wat tydens die ondersoek bestudeer is, geïdentifiseer.
Hierdie eienskappe is geëien deur die energie-verhoudings tussen verskillende
dele van die ventrikulêre sistolie en diastolie van elke opgeneemde hartsiklus
te ontleed.
'n "Ensemble artificial neural network" is gebruik om die geïdentifiseerde eienskappe
van hartsiektes sowel as normale harttoestande, te klassifiseer. Hierin is
besluite van al die lede van die netwerk gekombineer, ten einde ‘n finale diagnose
te maak. Die klassifiseerder se geldigheid is kruis-bevestig deur middel van
die laat-een-uit kruisbevestigings-metode.
Deur middel van die kruis-bevestigingsmetode is die bedryfsvermoëns van die
outonome auskultasie-stelsel, toegerus met die "Precordialcardiogram" apparaat,
repektiewelik op 82% vir sensitiwiteit en 88% vir spesifisiteit vasgestel. Hierdie resultate demonstreer die benuttingspotensiaal van die apparaat in 'n Telemedisyne
omgewing.
37
Lawlor, Mary Ann C. "Predictors of Health Service Use in Persons with Heart Failure." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1619702345236178.
Testo completo
38
Moore, Ryan A. M. D. "Virtual Implantation of Mechanical Circulatory Support Devices." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479476350842492.
Testo completo
39
Crosby, Jessica Renee. "Expanding the Performance Envelope of the Total Artificial Heart: Physiological Characterization, Development of a Heart Failure Model, And Evaluation Tool for Mechanical Circulatory Support Devices." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/344221.
Testo completoAbstract (sommario):
Heart failure (HF) affects an estimated 5.8 million Americans, accounting for near 250,000 deaths each year. With shortages in available donor hearts, mechanical circulatory support (MCS) has emerged as a life-saving treatment for advanced stage HF. With growth in MCS use, a clinical and developmental need has emerged for a standard characterization and evaluation platform that may be utilized for inter-device comparison and system training. The goal of this research was to harness SynCardia's total artificial heart (TAH) to meet this need. We first sought to characterize the TAH in modern physiological terms - i.e. hemodynamics and pressure-volume loops. We then developed a model of HF using the TAH and mock circulatory system operating in a reduced output mode. We demonstrated that MCS devices could be incorporated and evaluated within the HF model. Finally, we characterized the operational envelope of SynCardia's Freedom (portable), Driver operating against varying loading conditions. Our results describe the hemodynamic envelope of the TAH. Uniquely, the TAH was found not to operate with time-varying elastance, to be insensitive to variations in afterload up to at least 135 mmHg mean aortic pressure, and exhibit Starling-like behavior. After transitioning the setup to mimic heart failure conditions, left atrial pressure and left ventricular pressure were noted to be elevated, aortic flow was reduced, sensitivity to afterload was increased, and Starling-like behavior was blunted, consistent with human heart failure. The system was then configured to allow ready addition of ventricular assist devices, which upon placement in the flow circuit resulted in restoration of hemodynamics to normal. Lastly, we demonstrated that the Freedom Driver is capable of overcoming systolic pressures of 200 mmHg as an upper driving limit. Understanding the physiology and hemodynamics of MCS devices is vital for proper use, future device development, and operator training. Characterization of the TAH affords insight into the functional parameters that govern artificial heart behavior providing perspective on differences compared to the human heart. The use of the system as a heart failure model has the potential to serve as a valuable research and teaching tool to foster safe MCS device use.
40
Yoo, Doo-Sung. "Organ-machine Hybrids (Artificial Animals)." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1281418915.
Testo completo
41
Assunção, Luís Pedro Santos de. "Heart rate estimation using video in psychology experiments." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18459.
Testo completoAbstract (sommario):
Mestrado em Engenharia de Computadores e Telemática<br>Heart rate is a relevant physiological marker used in several areas, namely psychology, as a measure of the anxiety and stress among other states. Typically, the heart rate is calculated from ECG that implies using dedicated equipment with electrodes placed on the human subject which can be considered invasive in many situations i.e. not comfortable or humanly suitable.
With the advances in computer vision several works proposed methods to estimate the heart rate from video capturing skin patches of the subjects (e.g. for head, overall face, …). However, although promising results there no conclusive proofs on the accuracy and applicability in more realistic conditions (e.g. outside of the laboratory) namely due to the very controlled scenarios or limited sampling time.
In this dissertation we proposed to evaluate the usefulness of heart rate estimation based on video and built upon the state of the art to address more realistic and challenging conditions i.e. less controlled scenarios and evaluate it under larger monitoring sessions (>1 minute). We performed two experiments based on video stimulus where the objective was to measure the HR changes induced by the video. In both scenarios, ECG was used to extract the HR that was used as ground truth. The first scenario was acquired with videos to elicit disgust (25 minutes), the second using smaller videos (<1 minute) using a neutral and “happiness” inducing videos.
Our results show that the heart rate estimation is very sensitive to noise and not clear relation on the complete studies was observed in any of the scenarios. However, when studying the relation between the HR estimated from video and from ECG it was clear that both were highly correlated in limited time intervals suggesting that video estimated HR may be worthy to explore.
In the process we developed PsyVidLab that besides incorporating the video estimated HR allows synchronous acquisition of video, ECG and some basic image processing modules namely emotion estimation from facial expression.<br>Devido aos avanços em visão de computador, vários trabalhos propuseram métodos para estimar o ritmo cardíaco utilizando partes da pele do sujeito (testa, face completa, ...).
Contudo, embora se tenha obtido resultados promissores não há provas conclusivas acerca da precisão e aplicabilidade em condições mais realistas (fora do laboratório), devido aos senários muito controlados ou tempo de amostragem limitado. Nesta dissertação, propusemo-nos avaliar a utilidade da estimação de ritmo cardíaco por vídeo e contruído no estado da arte para atender a cenários mais realistas e exigentes, isto é, cenários menos controlados e avaliar os resultados em sessões de monitorização mais longos (>1 minuto). Nós efetuamos duas experiencias baseadas vídeo de estímulo onde o objetivo era de medir as alterações de ritmo cardíaco produzidas pelo vídeo. Em ambos os senários, ECG foi utilizado para extrair ritmo cardíaco que foi usado como comparação. O primeiro cenário foi adquirido com vídeos cujo estímulo foi “Nojo” (25 minutos), o segundo cenário usou vídeos mais pequenos (<10minutos) usando um estimulo neutro e de “felicidade”. Os resultados mostram que a estimação do ritmo cardíaco é bastante sensível ao ruido e não é clara a relação no estudo completo. Contudo, quando estudamos a relação entre o ritmo cardíaco estimado por vídeo e por ECG tornou-se claro que ambos eram altamente correlacionados em intervalos de tempo limitados, sugerindo que o ritmo cardíaco estimado por vídeo deve ser explorado. Durante o processo desenvolvemos o PsyVidLab que, para alem de incorporar a estimação de ritmo cardíaco por vídeo, permite a aquisição síncrona de vídeo, ECG, e alguns módulos de processamento de vídeo básicos especificamente estimação de emoção de expressões faciais.
42
Veiga, Viviane Cordeiro 1976. "Avaliação ecocardiografica da terapia de ressincronização cardiaca : dois anos de seguimento." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311904.
Testo completoAbstract (sommario):
Orientador: Salomon Soriano Ordinola Rojas<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas<br>Made available in DSpace on 2018-08-12T15:05:14Z (GMT). No. of bitstreams: 1
Veiga_VivianeCordeiro_M.pdf: 4383215 bytes, checksum: 4ac235c87c9173ad91395fd7c6466208 (MD5)
Previous issue date: 2008<br>Resumo: Introdução A terapia de ressincronização cardíaca é uma opção efetiva nos pacientes com insuficiência cardíaca avançada. No entanto, 20 a 30% dos pacientes não apresentam benefícios à esta terapêutica. Critérios clínicos, eletrocardiográficos e ecocardiográficos têm sido estudados na tentativa de selecionar os pacientes que serão beneficiados com a ressincronização cardíaca, sendo o ecocardiograma um método utilizado tanto na seleção, quanto na avaliação e otimização desta terapêutica. Objetivo: O objetivo deste trabalho é analisar a utilização do ecocardiograma na avaliação da terapia de ressincronização cardíaca em pacientes portadores de insuficiência cardíaca refratária, no seguimento a curto prazo (dez dias) e após dois anos de evolução. Casuística e Método: Foram avaliados 20 pacientes com indicação de implante de marcapasso biventricular para terapia de ressincronização cardíaca no período de dois anos, sendo 16 (80%) do sexo masculino, com idade variando de 27 a 80 anos (59,70 ± 12,59 anos). A etiologia da cardiomiopatia era isquêmica em 10 pacientes (50%), chagásica em seis (30%) e idiopática em 4 (20%). Quinze pacientes encontravam-se em classe funcional III (New York Heart Association) e cinco em classe funcional IV no momento do implante do marcapasso. Foi aplicado o Questionário de Qualidade de Vida de Minnesota e realizado o teste de caminhada de seis minutos para avaliação das condições clínicas dos pacientes. Realizado ecodopplercardiograma bidimensional para avaliação da função ventricular, diâmetros cavitários, índice de performance miocárdica, estudo da dissincronia interventricular (avaliação do atraso eletromecânico entre os ventrículos esquerdo e direito) e intraventricular (análise pelo modo unidimensional e Doppler tecidual), da função diastólica e do grau da regurgitação mitral. Dez dias após o implante do marcapasso biventricular, foi repetida toda a avaliação inicial e, novamente, após dois anos. Resultados: Em dois anos, cinco pacientes (25%) foram à óbito, sendo que destes, quatro apresentavam etiologia chagásica. A duração média do complexo QRS era de 154,5±18,48 x 129,0±22,91 x 134,0±24,14 ms, respectivamente nos períodos pré-operatório, dez dias e dois anos de pós-operatório. Não houve alteração estatisticamente significante da fração de ejeção entre os períodos pré-operatório e dez dias, mas houve alteração significante entre os períodos pré-operatório e dois anos e dez dias e dois anos. No seguimento de dez dias, houve piora da dissincronia intraventricular avaliada pelo Doppler tecidual, assim como a pontuação no escore de qualidade de vida foi maior, no grupo óbito. Conclusão: A ecocardiografia é uma tecnologia em evolução e dos parâmetros avaliados, somente a avaliação da dissincronia intraventricular pelo Doppler tecidual após o procedimento, foi capaz de predizer a eficácia da terapia de ressincronização cardíaca, em relação à mortalidade. Não houve correlação entre os parâmetros ecocardiográficos e a melhora clínica de alguns pacientes.<br>Abstract: Introduction In the cardiac resynchronization therapy is an effective option for patients with advanced heart failure. However, 20 to 30% of patients did not show benefits to this therapy. Clinical criteria, electrocardiography and the echocardiography have been studied in an attempt to select the patients who will benefit from the cardiac resynchronization, and the echocardiogram is a method used in both the selection, as in the evaluation and optimization of this therapy. Objective: The objective of this study is to evaluate the use of echocardiography in the evaluation of patients undergoing cardiac resynchronization therapy for a period of two years. Patients and Methods: We evaluated 20 patients with the implantation of biventricular pacemaker for cardiac resynchronization therapy for over two years, and 16 (80%) males, ranging in age from 27 to 80 years (59.70±12.59 years). The etiology of cardiomyopathy was ischemic in 10 patients (50%), Chagas disease in six (30%) and idiophatic in 4 (20%). Fifteen patients were in functional class III (New York Heart Association) and five in functional class IV at the time of implantation of the pacemaker. We applied the Quality of Life Questionnaire of Minnesota and conducted the test of a six-minute walk to evaluate the clinical conditions of patients. Directed two-dimensional Doppler echocardiography for evaluation of ventricular function, cavity diameters, myocardial performance index, study of interventricular dyssynchrony (eletromechanical delay left ventricle - the right ventricle) and intraventricular (by way dimensional analysis and tissue Doppler), the diastolic function and degree of mitral regurgitation. Ten days after implantation of biventricular pacemaker, was repeated throughout the initial assessment and again after two years. Results: In two years, five patients (25%) were to death, and that these, four had Chagas disease. The average duration of the QRS complex was 154.5±18.48 x 129.0±22.91 x 134.0±24.14 ms, respectively in preoperative, ten days and two years after surgery. There was no statistically significant change in the ejection fraction between preoperative and ten days but there was significant change between periods preoperative and 2 years and 10 days and 2 years. Following ten days, the evaluation of intraventricular dyssynchrony by tissue Doppler and quality of life scores were significantly higher in the group died. Conclusion: The echocardiography is an evolving technology and the parameters evaluated, only the assessment of intraventricular dyssynchrony by Doppler tissue after the procedure was able to predict the effectiveness of the cardiac resynchronization therapy, in relation to mortality. There was no correlation between echocardiographic parameters and clinical improvement in some patients.<br>Mestrado<br>Mestre em Cirurgia
43
Silva, Bruno Utiyama da. "Avaliação e aperfeiçoamento de uma bomba de sangue centrífuga implantável ápice ventricular para assistência cardíaca." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264976.
Testo completoAbstract (sommario):
Orientadores: Carlos Kenichi Suzuki, Aron José Pazin de Andrade<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica<br>Made available in DSpace on 2018-08-21T07:29:25Z (GMT). No. of bitstreams: 1
Silva_BrunoUtiyamada_M.pdf: 3089036 bytes, checksum: 01d1bb268591e2388a9bb34046fbd188 (MD5)
Previous issue date: 2012<br>Resumo: Neste trabalho, foi realizado um estudo experimental de uma Bomba de Sangue Ápice Ventricular (BSAV) para sua análise como um dispositivo de assistência ventricular. Este estudo faz parte do desenvolvimento desta bomba e serviu como fundamentação na evolução do projeto. A BSAV é uma bomba de sangue centrífuga de fluxo contínuo, para ser utilizada como dispositivo de assistência ventricular em pacientes com doenças cardíacas crônicas. Foi realizado um estudo de posicionamento anatômico, onde a bomba foi implantada em um coração de um porco e não foram encontrados indícios de possíveis danos aos tecidos e órgãos circunvizinhos. Em seguida, foi feito um ensaio experimental, onde foi comparado o desempenho de protótipos com características distintas, visando sua otimização em relação ao desempenho hidrodinâmico. Também foi realizado um estudo para avaliação do trauma as células do sangue causado pela ação da bomba, no qual os resultados mostraram um baixo dano as células. A seguir, foi feito estudo com um protótipo conectado em um simulador cardiovascular híbrido (matemático e físico), onde este protótipo às condições simuladas de um sistema cardiovascular com insuficiência cardíaca. Com a BSAV conectada ao sistema obteve-se, uma melhora no fluxo de sangue, frequência cardíaca e pressão aórtica. Os resultados indicam que a BSAV é adequada para aplicação como dispositivo de assistência ventricular esquerda e é uma alternativa promissora no tratamento de pacientes com doenças cardíacas crônicas<br>Abstract: In this work an experimental study was realized with the Apico-Ventricular Blood Pump (AVBP) used as a ventricular assist device. This study is part of the device's development and the results were used for project evaluation and improvement. AVBP is a continuous flow centrifugal blood pump for ventricular assistance in chronic cardiac patients. Initially, an anatomic study was performed, in this study an AVBP prototype was implanted in a corpse of a pig, the clinical staff appointed, none damage to the nearby tissues and organs due to the contact with the device. Following step consists in an experimental hydrodynamic performance test. For this test the prototypes used had distinct specific construction characteristics variations among themselves, for device optimization, the performance of these different prototypes were compared, and the prototypes which presented a better performance had their characteristic adopted in the project. A study to determine the traumatic effect of the pump on blood cells was conducted, the results showed low damage to the blood cells. A hybrid mock loop circulation system (mathematical and physic) where the pump, was connected to a system with heart disease, was used. When the AVBP was inserted in the system, cardiac output, heart rate and aortic pressure went to normal values. All results indicated the performance of the AVBP as ventricular assist device, an alternative for treatment of patients with cardiac chronic diseases<br>Mestrado<br>Materiais e Processos de Fabricação<br>Mestre em Engenharia Mecânica
44
Stenberg, Mattias. "Concept design and In Vitro evaluation of a novel dynamic displacement Ventricular Assist Device." Licentiate thesis, Stockholm : KTH Technology and Health, 2006. http://www.diva-portal.org/kth/theses/abstract.xsql?dbid=3991.
Testo completo
45
Willson, Grant Neville. "Nocturnal non-invasive ventilation for the treatment of Cheyne-Stokes respiration in chronic heart failure." Thesis, The University of Sydney, 2004. https://hdl.handle.net/2123/27912.
Testo completoAbstract (sommario):
This thesis has investigated the efficacy of non-invasive ventilation in subjects with
congestive heart failure (CHF) and Cheyne—Stokes respiration (CSR). The effect of this
therapy on sleep, breathing and haemodynamic variables has been examined. This thesis
also describes the morphology and magnitude of the blood pressure (BP) and heart rate
(HR) oscillations associated with CSR and elucidates contributing factors to the changes
observed.
Chapter 1 - literature review - outlines the presentation and treatment of CSR in patients
with CHF. Cheyne-Stokes respiration is described with particular emphasis on the
polysomnographic features and haemodynamic consequences of this breathing pattern.
The mechanisms postulated for the genesis of CSR are reviewed. The prevalence and
consequences of CSR are discussed, highlighting the clinical features and their effects
on prognosis. The proposed treatments are considered, with attention being paid to the
mechanisms of action, the effect on sleep, breathing, haemodynamics and the clinical
utility of each therapy. Special emphasis is placed on oxygen and continuous positive
airway pressure (CPAP) therapy. It is proposed that given the lack of universal
acceptance of any one treatment modality, the role of new therapies that emulate the
positive effects of current treatments, warrant further investigation. A review of noninvasive
ventilation including a survey of its historical use, methodological
considerations, physiological consequences and clinical applications has been
undertaken.
46
Bock, Eduardo Guy Perpétuo. "Projeto, construção e testes de um dispositivo de assistência ventricular = bomba de sangue centrífuga implantável." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263298.
Testo completoAbstract (sommario):
Orientadores: Antonio Celso Fonseca de Arruda, Aron José Pazin de Andrade<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica<br>Made available in DSpace on 2018-08-17T22:34:18Z (GMT). No. of bitstreams: 1
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Previous issue date: 2011<br>Resumo: Uma Bomba de Sangue Centrífuga Implantável (BSCI) foi projetada e construída para assistência ventricular de longa duração no tratamento de pacientes portadores de doenças cardiovasculares. A proposta do projeto foi desenvolver um Dispositivo de Assistência Ventricular (DAV) com custos reduzidos, originalidade de desenho e tecnologia nacional. A geometria do rotor da bomba, aliando um cone em espiral com aletas centrífugas, deu origem ao pedido de Patente de Invenção (PI 0706163-3). O desenvolvimento de seus sistemas propulsores se inclui no Projeto Temático FAPESP nº 2006/58773-1. A metodologia baseou-se em testes individuais dos mancais, atuador e rotor, seguidos de testes do conjunto da BSCI em bancada, com sangue humano e em animais. Foram realizadas simulações numéricas por computador que resultaram no dimensionamento da bomba e definição da sua geometria. Foi testado o atrito nos mancais e os resultados que apresentaram maior durabilidade foram do par alumina-polietileno. Testes em dinamômetro resultaram na caracterização do propulsor eletromagnético, um motor sem escovas trifásico de corrente contínua, e seu controlador eletrônico baseado na técnica de controle sem sensores. Foram realizados testes de hemólise de acordo com as Normas ASTM F1830 e ASTM F1841 para quantificar os danos causados ao sangue pela BSCI e seu índice de hemólise foi de 0,0054 mg/100L, considerado excelente. Testes prospectivos em animais para avaliação do implante resultaram na possibilidade de posicionamento da bomba no tórax ou abdome. Após os testes realizados, a BSCI projetada e construída foi considerada uma opção segura para o tratamento das doenças cardiovasculares. Como trabalhos futuros, serão realizados mais testes em animais para avaliação do funcionamento da BSCI antes dos testes em pacientes<br>Abstract: An Implantable Centrifugal Blood Pump was developed for long-term ventricular assistance in cardiac patients. In vitro tests were performed, as wear evaluation, performance tests and hemolysis tests in human blood. Preliminary tests were performed with a non-implantable pump in order to properly locate the inlet port. Numerical computational simulations were performed in order to predict its best geometry. Wear evaluations helped to select the best materials for double pivot bearing system proposed to achieve longer durability. Performance tests pointed the best impeller geometry. The Implantable Centrifugal Blood Pump was compared with other two blood pumps. One is a centrifugal blood pump for cardiopulmonary bypass and the other is a similar implantable device called Gyro - Nedo Pump. The proposed implantable centrifugal blood pump showed the best performance. But, its results showed a strong descendant curve in high flow. Other prototype was manufactured with a different inlet port angle to overcome this problem. According to ASTM, the normalized index of hemolysis (NIH) tests were performed "In Vitro" with human blood in closed circuit (mock loop) in normalized conditions, as flow of 5 L/min and total pressure ahead of 100 mm Hg. After six hours, NIH measured 0.0054 mg/100L that can be considered excellent since it is close to the minimum found in literature (between 0.004 g/ 100L e 0.02 g/ 100L). Prior to evaluate performance during "In Vivo" animal studies, anatomical studies were necessary to achieve best configuration and cannulation for Left Ventricular Assistance. Results were considered satisfactory and "In Vivo" tests will be performed looking forward to implant it in patients<br>Doutorado<br>Materiais e Processos de Fabricação<br>Doutor em Engenharia Mecânica
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Choksi, Tejas Dilipkumar. "Modification of a novel polymer with potential use in artificial heart valves : effects on hemocompatibility and mechanical properties." FIU Digital Commons, 2004. http://digitalcommons.fiu.edu/etd/2345.
Testo completoAbstract (sommario):
Platelet mediated thrombosis has been a major source of mortality and morbidity in cardiovascular device patients as the device surface upon contact with blood induces surface thrombosis. Two specific objectives of this thesis are: 1) Identify the effect of phospholipid modification on Quatromer and 2) Identify the most effective modification technique that will inhibit the surface induced thrombosis and enhance the long-term blood compatibility of Quatromer. Six different phospholipids were grafted in the Quatromer and the role of each of the modified substrates was evaluated in terms of mechanical properties and hemocompatibility. The surface analysis studies showed a significant decrease in contact angle while an increase in the surface energy and the O/C ratio with phospholipid modification, indicating a highly hydrophilic surface with increased carbonyl groups on the surface contributing to lower platelet adhesion and activation. The comparative platelet adhesion tests showed significant decrease in platelet adhesion with phospholipid modification. Hence, phospholipid modification proves to be promising in increasing the long-term blood compatibility of Quatromer.
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DeCook, Katrina Jolene. "System and Method for Comparison and Training of Mechanical Circulatory Support Devices: A Patient Independent Platform Using the Total Artificial Heart and Donovan Mock Circulation System." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/556703.
Testo completoAbstract (sommario):
Mechanical circulatory support (MCS) is a viable therapy for end stage heart failure. However, despite clinical success, the ability to compare MCS devices in vitro and perform training scenarios is extremely limited. Comparative studies are limited as different devices cannot be interchanged in a patient due to the surgical nature of implant. Further, training and failure scenarios cannot be performed on patients with devices as this would subject a patient to a failure mode. A need exists for a readily available mock system that can perform comparative testing and training scenarios with MCS devices. Previously, our group has fabricated a well characterized mock circulation system consisting of a SynCardia temporary Total Artificial Heart (TAH) and Donovan Mock Circulation tank (DMC tank). Further, utilizing this system with the TAH operating in reduced output mode, a heart failure model was developed. In the present study, three ventricular assist devices (VADs) were independently attached to the heart failure model to compare device performances over a range of preloads and afterloads. In addition, specific clinical scenarios were created with the system to analyze how VAD-displayed waveforms from the system correlate with clinical scenarios. Finally, each VAD was powered off while attached to the heart failure model to compare fluid flow through the VAD in a pump-failure scenario. We demonstrated that this system can successfully be utilized to compare MCS devices (i.e. ventricular assist devices) and for successful training of patients and clinicians.
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Natale, James. "A Strategy for Reducing Congestive Heart Failure Readmissions Through the Use of Interventions Targeted by Machine Learning." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1428233380.
Testo completo
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Souza, Fernando Sergio Oliva de. "Aspectos tecnicos da cateterização do seio coronariano baseado no componente atrial do eletrograma intracavitario durante o procedimento de implante de marcapasso biventricular." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311523.
Testo completoAbstract (sommario):
Orientador: Orlando Petrucci Junior<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas<br>Made available in DSpace on 2018-08-11T10:51:42Z (GMT). No. of bitstreams: 1
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Previous issue date: 2008<br>Resumo: A estimulação elétrica biventricular apresenta bons resultados no tratamento da insuficiência cardíaca congestiva refratária em portadores de cardiomiopatia dilatada com distúrbios de condução interventricular. OBJETIVO: Apresentar proposição utilizando técnica original simplificada para o implante de eletrodo de estimulação ventricular esquerda epicárdica, baseado na anatomia radiológica e no eletrograma intracavitário,enfatizando o componente atrial, demonstrando o resultado, complicações, ressaltando tempo total de utilização de fluoroscópio. CASUÍSTICA E MÉTODO: De Outubro de 2001 a Março de 2007 foram realizados 234 implantes de marca-passo biventricular em pacientes previamente selecionados, utilizando-se anatomia radiológica e observação de eletrograma intracavitário, dando-se prioridade ao componente atrial, demonstrando a taxa de sucesso, complicações e tempo total de utilização de radioscopia. RESULTADOS: O implante do sistema, utilizando-se a estimulação do ventrículo esquerdo via seio coronariano não foi possível em 19(8,1%) pacientes. Em 30(12,8%) pacientes foram observadas dificuldades na canulação do óstio coronário e em 52(22%) pacientes observaram-se dificuldades de progressão do eletrodo através do seio coronário. O tempo médio de utilização de radioscopia foi 18,69(±15,2) min. CONCLUSÃO: A utilização da técnica simplificada para cateterização do seio coronário sem utilização de bainha, baseada na anatomia radiológica e no eletrograma intracavitário, enfatizando o componente atrial, no tratamento de portadores de cardiomiopatia dilatada avançada, pela terapia de ressincronização cardíaca, demonstrou resultado satisfatório, índice de complicações pequeno, e baixa exposição do operador a radiação ionizante<br>Abstract: Biventricular pacing has present good results in treatment of congestive cardiac heart failure in patients with dilated miocardyopathy and interventricular conduction disturbance. PURPOSE: to present a proposal of using a original simplified technique for left epicardial ventricular lead stimulation, based on the radiological imaging of the anatomy and intracavitary electrogram, emphasizing the atrial component, showing the results, complications, highlighting the total fluoro time. METHODS: From October, 2001 up to March, 2007, 234 biventricular pacemaker implantations were performed in previously selected patients, using radiological anatomy and observation of the intracavitary electrogram, focusing on the atrial component, and showing the success rate, complications and total time of radioscopy utilization. RESULTS: The implantation of the system using left ventricular pacing via coronary sinus was not possible in 19(8,1%) patients. Difficulties on the cannulation of the coronary ostium were felt in 30(12,8%) patients and difficulties of lead advancement through the coronary sinus were felt in 52(22%) patients. The mean time of radioscopy utilization was 18.69(±15,2) min. CONCLUSION: the use of a simplified technique for coronary sinus cannulation without the aid of a sheath, based on the radiological imaging of the anatomy and intracavitary electrogram, emphasizing the atrial component, for the treatment of advanced dilated cardiomyopathy patients with cardiac resynchronization therapy, has shown satisfactory results, low incidence of complications, and low exposure of the operator to ionizing radiation<br>Doutorado<br>Cirurgia<br>Doutor em Cirurgia