• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 44
  • 34
  • 12
  • 11
  • 7
  • 3
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 142
  • 55
  • 54
  • 48
  • 45
  • 36
  • 28
  • 27
  • 27
  • 24
  • 24
  • 21
  • 20
  • 20
  • 19
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Cardiovascular magnetic resonance deformation imaging by feature tracking for assessment of left and right ventricular structure and function

Augustine, Daniel January 2014 (has links)
Cardiac magnetic resonance (CMR) imaging is the gold standard imaging technique for assessment of ventricular dimensions and function. CMR also allows assessment of ventricular deformation but this requires additional imaging sequences and time consuming post processing which has limited its widespread use. A novel CMR analysis software package, ‘feature tracking’ (Tom Tec, Germany) can measure ventricular deformation directly from cine CMR images. This thesis seeks to further our understanding of the feasibility of feature tracking to assess myocardial deformation and volumetric measures. Chapter 3 validates normal ranges for deformation parameters and compares values against traditional tagging measures. The work identifies global circumferential strain measures as being the most reproducible. In chapters 4 and 5, feature tracking values for left and right ventricular strain are compared with echocardiography derived speckle tracking indices of deformation. For left ventricular (LV) parameters, circumferential and longitudinal strain are most consistent and for the right ventricular (RV) measures, assessment of free wall strain using feature tracking shows promise and with modifications in algorithms is likely to further improve in the future. Chapter 6 assesses the ability of feature tracking to measure diastolic function. The results show that radial diastolic velocities and longitudinal diastolic strain rates can predict diastolic dysfunction (as diagnosed by echocardiography) with acceptable levels of sensitivity and specificity, particularly when used in combination. 11 The use of feature tracking to provide automated measures of ventricular volumes, mass and ejection fraction is assessed in chapter 7. Feature tracking in this context shows acceptable correlation but poor absolute agreement with manual contouring and further adjustments to algorithms is necessary to improve its accuracy. This work offers insights into the use of feature tracking for the assessment of ventricular deformation parameters. It is a technique with advantages over CMR tagging methods and given the speed of post processing has the potential to become the CMR preferred assessment for strain quantification in the future.
62

Avaliação ecocardiográfica dos índices de função sistólica e diastólica de cães com cardiomiopatia dilatada idiopática submetidos ao tratamento com carvedilol / Echocardiographic evaluation of systolic and diastolic parameters of dogs with dilated cardiomyopathy treated with carvedilol

Elaine Cristina Soares 13 January 2006 (has links)
A cardiomiopatia dilatada idiopática (CMD) é a segunda cardiopatia mais prevalente na espécie canina, acometendo principalmente raças grandes e gigantes, bem como o Cocker Spaniel. É uma doença que possui alta letalidade, além de comprometer substancialmente a qualidade de vida do animal. O diagnóstico definitivo é realizado por meio da ecocardiografia, onde se observam dilatação das cavidades cardíacas, mais freqüentemente do ventrículo e átrio esquerdos, e diminuição da função sistólica. Estudos realizados em seres humanos com CMD mostram que, além da sistólica, a função diastólica está comprometida, e que a análise do fluxo transmitral, importante para a detecção de alterações de relaxamento e/ou distensibilidade tem importante valor prognóstico para a sobrevida e evolução dos sintomas. O tratamento da CMD tradicionalmente baseia-se na utilização de digitálicos, diuréticos, e vasodilatadores. Contudo, nos últimos anos, visto a importância da ativação do sistema nervoso simpático sobre a fisiopatologia desta doença, os β-bloqueadores têm sido empregados. Muitos trabalhos mostram que estes fármacos melhoram a função sistólica e/ou diastólica do ventrículo esquerdo, e com isso aumentam a sobrevida e diminuindo a progressão dos sintomas. Estudaram-se 45 cães com cardiomiopatia dilatada, que foram divididos em dois grupos (A e B). O grupo A (n=25) recebeu o tratamento convencional, ou seja, digitálicos, diuréticos e vasodilatadores, e o grupo B (n=20) recebeu estes mesmos medicamentos acrescidos do carvedilol, um β-bloqueador de terceira geração. Os animais foram submetidos aos exames clínico e ecocardiográfico antes e após três, 13, 26 e 52 semanas do início do tratamento ou até o óbito. Não foram observadas diferenças nos valores dos índices de função sistólica e diastólica entre os grupos. Verificou-se que o grupo tratado com carvedilol apresentou maior tempo médio de sobrevida, porém esta diferença não foi estatisticamente significante. Quanto aos sintomas (classe funcional), observou-se que o grupo tratado com carvedilol apresentou evolução mais favorável, com maior número de animais classificados como "sintomas leves" após três meses de tratamento. Assim, embora o carvedilol tenha se mostrado benéfico, principalmente com relação aos sintomas, não se pode correlacionar esta melhora à ação do fármaco sobre as funções sistólica e diastólica / Dilated Cardiomyopathy (DCM) is the second more common heart disease in dogs, wherein large and giant breeds, as well as Cockers Spaniels, are predisposed. Such disease has a high mortality rate besides reducing the quality of life of the affected animals. The definitive diagnosis is based upon echocardiography which is characterized by dilation of cardiac chambers, mainly the left ones, and by reduced systolic function. Human medicine studies have reported that the diastolic dysfunction also plays an important role; so, an abnormal transmitral flow pattern, which represents the ventricular diastolic filling, has a great prognostic value in terms of survival and symptoms status (heart failure functional class) The management of DCM traditionally consists of digitalis, diuretics and vasodilators, however, in the late years, some attention has being paid to the importance of the sympathetic nervous system on the pathophysiology of this disorder; being so, β-blockers have been included in the therapy. Many authors have reported that these drugs improve the left ventricle systolic and diastolic function, and so they increase the survival rate and reduce the symptoms progression. Forty-five dogs with idiopathic dilated cardiomyopathy, divided into two groups (A and B), were studied. The group A (n=25) consisted of dogs that were put on the traditional therapy (digitalis, diuretics and vasodilators) and the group B (n=20) included those who were treated with all these drugs plus carvedilol, a third generation β-blocker. The animals went through clinical and echocardiographic assesment before and 3, 13, 26 and 52 weeks after starting the treatment or until death. The variables of systolic and diastolic function were not statistically different between the two groups. The median survival time of the dogs treated with carvedilol was higher, but the difference was not statistically significant. Concerning to the symptoms (heart failure funcional class), dogs who were put on carvedilol had a better progression, as more of them were classified as "mild symptoms" after three months of therapy. In conclusion, despite the beneficial effects of carvedilol on the symptoms, these can not be correlate with the systolic and diastolic functions
63

Etude cellulaire et moléculaire de l'insuffisance cardiaque à fonction systolique préservée / Heart failure with preserved systolic function : Cellular and molecular pathophysiological pathways

Rouhana, Sarah 30 November 2018 (has links)
L'insuffisance cardiaque à fraction d’éjection préservée (IC/FEp) constitue un problème de santé croissant. Elle pourrait devenir la principale cause d'IC d'ici une décennie. C’est une pathologie associée à un taux élevé de morbidité et de mortalité. La prise en charge thérapeutique de l’IC/FEp reste limitée en raison de sa physiopathologie encore mal élucidée. Dans le présent travail, après avoir mis au point un modèle d’IC/FEp sur le rat adulte mâle et l’avoir caractérisé, nous avons évalué le phénotype fonctionnel et l’homéostasie calcique des cardiomyocytes. Les cœurs de ces animaux ont montré une fraction d’éjection supérieure à 50%, associée à une congestion pulmonaire, une hypertrophie concentrique avec une augmentation de la masse du ventricule gauche, une rigidité myocardique, une relaxation et un remplissage ventriculaire passif altérés et une dilatation auriculaire. Au niveau cellulaire, la contraction mesurée sur des cardiomyocytes isolés ainsi que le transitoire calcique sont augmentées. On note, de même, une surcharge en Ca2+ diastolique favorisée par une fuite à travers les canaux Ryanodine 2 et par un dysfonctionnement de l’échangeur Na+ /Ca2+ qui contribuent à générer des événements calciques spontanés. La phosphorylation du phospholamban, régulateur de l’activité de la SERCA2a, a également augmenté, laissant suggérer une compensation adaptative du cycle de Ca2+. Enfin, en présence de Ranolazine, inhibiteur du courant sodique soutenu, les évènements calciques spontanés ont été réprimés. En conclusion, le remodelage cardiaque dans l’IC/FEp semble être diffèrent de celui observé dans l’IC/FEr et ouvre la voie vers de nouveaux acteurs physiopathologiques et thérapeutiques. / Heart failure with preserved ejection fraction (HFpEF) is a growing health problem. It could become the leading cause of HF within a decade. It is a pathology associated with high morbidity and mortality. Therapeutic options are limited due to a lack of knowledge of the pathology and its evolution. In this work, we investigated the cellular phenotype and Ca2+ handling in hearts recapitulating HFpEF criteria. HFpEF was induced in a portion of male Wistar rats four weeks after abdominal aortic banding. These animals had nearly normal ejection fraction and presented elevated blood pressure, lung congestion, concentric hypertrophy, increased LV mass, wall stiffness, impaired active relaxation and passive filling of the left ventricle, enlarged left atrium, and cardiomyocyte hypertrophy. Left ventricular cell contraction was stronger and the Ca2+ transient larger. Ca2+ cycling was modified with a RyR2 mediated Ca2+ leak from the sarcoplasmic reticulum and impaired Ca2+ extrusion through the Na+ /Ca2+ (NCX), which promoted an increase in diastolic Ca2+ and spontaneous Ca2+ waves. PLN phosphorylation which promotes SERCA2a activity, was increased, suggesting an adaptive compensation of Ca2+ cycling. In the presence of Ranolazine, a sustained sodium current inhibitor, spontaneous Ca2+ events were suppressed. Cardiac remodeling in hearts with a HFpEF status differs from that known for HFrEF and opens the way to new pathophysiological and therapeutic actors.
64

Effekte eines körperlichen Trainingsprogrammes auf die diastolische Funktion und die Leistungsfähigkeit bei Patienten mit diastolischer Herzinsuffizienz / Effects of exercise training on diastolic function and exercise capacity in patients with heart failure with preserves ejection fraction

Fröhling, Stefan 04 December 2012 (has links)
No description available.
65

Das obstruktive Schlafapnoesyndrom als Risikofaktor für eine diastolische Ventrikelfunktionsstörung / Impact of obstructive sleep apnoe on diastolic function

Klemmstein, Daniela Natalie 04 December 2012 (has links)
No description available.
66

Die Herzfunktion während milder Hypothermie bei anästhesierten Schweinen: gesteigerte Inotropie auf Kosten einer diastolischen Dysfunktion / Cardiac function during mild hypothermia in pigs: increased inotropy at the expense of diastolic dysfunction.

Christoph, Johannes 23 April 2012 (has links)
No description available.
67

Kardiologinių rodiklių priklausomybės nuo žmogaus amžiaus ir apkrovos tyrimas / Research of dependence human cardiovascular parameters upon human purchasing power and age

Razgaitytė, Rimantė 29 June 2007 (has links)
Baigiamajame magistriniame darbe nagrinėjama kardiologinių rodiklių priklausomybė nuo žmogaus amžiaus ir fizinės apkrovos. Pateikta kardiologinių rodiklių kriterijų analizė. Išnagrinėti pagrindiniai kardiologiniai rodikliai trijose skirtingose amžiaus grupėse, pateikta jų lyginamoji analizė. Išnagrinėjus teorinius ir praktinius kardiologinių rodiklių vertinimo aspektus, pateikiamos baigiamojo darbo išvados. / In this final master thesis are research cardiovascular parameters dependence of human purchasing power and age. There are given test analysis of cardiovascular parameters. It was research the main cardiovascular parameters in three different groups of age and was given comparable analysis of parameters. All theoretical and practical results are given in conclusion.
68

Arterinio kraujospūdžio žąsto, riešo ir piršto srityse kitimai atliekant pratimus esant statiniam ir dinaminiam krūviui / The change of arterial blood pressure in the areas of arm, wrist, finger and the change of heart‘s systole frequency using static and dynamic strain

Rauluševičienė, Raimonda 21 June 2005 (has links)
SUMMARY Purpose of work: Ascertain and estimate the change of arterial blood pressure in the areas of arm, wrist, finger and the change of heart��s systole frequency using static and dynamic strain for all kinds of groups: different age and sex. Goals: 1. Ascertain the effect of static and dynamic strain for arterial blood pressure and for heart‘s systole frequency. 2. Examine the phenomenon of blood repartition and the arterial blood pressure registering investigative groups of different age and sex. 3. Estimate the effect of static exercise for the change of arterial blood pressure in different investigative groups. 4. Estimate the effect of dynamic exercise for the change of arterial blood pressure in different investigative groups. Contingent of investigative and the methods of investigation: The contingent of investigative is constituted by 67 sound investigative, without any clinical complaints: 38 are men and 29 – women. 15 men and 16 women, they performed the static exercise to fortify the muscles of back. 23 men and 13 women, they performed the dynamic exercise to fortify the muscles of shoulders. To estimate functional rate of heart we were using the measurers of arterial blood pressure OMRON. The measurers were registered 2 times: before the exercise and 60s after the exercise. Arterial blood pressure was measured in 3 places of left hand-in the areas of arm, wrist and finger registering systolic and diastolic blood pressure. The systole frequency of heart... [to full text]
69

Quantification of 4D Left Ventricular Blood Flow in Health and Disease

Eriksson, Jonatan January 2013 (has links)
The main function of the heart is to pump blood throughout the cardiovascular system by generating pressure differences created through volume changes. Although the main purpose of the heart and vessels is to lead the flowing blood throughout the body, clinical assessments of cardiac function are usually based on morphology, approximating the flow features by viewing the motion of the myocardium and vessels. Measurement of three-directional, three-dimensional and time-resolved velocity (4D Flow) data is feasible using magnetic resonance (MR). The focus of this thesis is the development and application of methods that facilitate the analysis of larger groups of data in order to increase our understanding of intracardiac flow patterns and take the 4D flow technique closer to the clinical setting. In the first studies underlying this thesis, a pathline based method for analysis of intra ventricular blood flow patterns has been implemented and applied. A pathline is integrated from the velocity data and shows the path an imaginary massless particle would take through the data volume. This method separates the end-diastolic volume (EDV) into four functional components, based on the position for each individual pathline at end-diastole (ED) and end-systole (ES). This approach enables tracking of the full EDV over one cardiac cycle and facilitates calculation of parameters such as e.g. volumes and kinetic energy (KE). Besides blood flow, pressure plays an important role in the cardiac dynamics. In order to study this parameter in the left ventricle, the relative pressure field was computed using the pressure Poisson equation. A comprehensive presentation of the pressure data was obtained dividing the LV blood pool into 17 pie-shaped segments based on a modification of the standard seventeen segment model. Further insight into intracardiac blood flow dynamics was obtained by studying the turbulent kinetic energy (TKE) in the LV. The methods were applied to data from a group of healthy subjects and patients with dilated cardiomyopathy (DCM). DCM is a pathological state where the cardiac function is impaired and the left ventricle or both ventricles are dilated. The validation study of the flow analysis method showed that a reliable user friendly tool for intra ventricular blood flow analysis was obtained. The application of this tool also showed that roughly one third of the blood that enters the LV, directly leaves the LV again in the same heart beat. The distribution of the four LV EDV components was altered in the DCM group as compared to the healthy group; the component that enters and leaves the LV during one cardiac cycle (Direct Flow) was significantly larger in the healthy subjects. Furthermore, when the kinetic energy was normalized by the volume for each component, at time of ED, the Direct Flow had the highest values in the healthy subjects. In the DCM group, however, the Retained Inflow and Delayed Ejection Flow had higher values. The relative pressure field showed to be highly heterogeneous, in the healthy heart. During diastole the predominate pressure differences in the LV occur along the long axis from base to apex. The distribution and variability of 3D pressure fields differ between early and late diastolic filling phases, but common to both phases is a relatively lower pressure in the outflow segment. In the normal LV, TKE values are low. The highest TKE values can be seen during early diastole and are regionally distributed near the basal LV regions. In contrast, in a heterogeneous group of DCM patients, total diastolic and late diastolic TKE values are higher than in normals, and increase with the LV volume. In conclusion, in this thesis, methods for analysis of multidirectional intra cardiac velocity data have been obtained. These methods allow assessment of data quality, intra cardiac blood flow patterns, relative pressure fields, and TKE. Using these methods, new insights have been obtained in intra cardiac blood flow dynamics in health and disease. The work underlying this thesis facilitates assessment of data from a larger population of healthy subjects and patients, thus bringing the 4D Flow MRI technique closer to the clinical setting.
70

Comportamento do fluxo venoso pulmonar durante o ciclo respiratório fetal

Chemello, Keli January 2007 (has links)
Introdução- Os movimentos respiratórios têm influência na circulação fetal. Sua presença indica um sistema nervoso intacto, não deprimido, refletindo o bem-estar do concepto. Acredita-se que, em apnéia, a pressão exercida pelos órgãos intratorácicos no coração fetal, em particular os pulmões não expandidos, limita a distensibilidade ventricular. O padrão de fluxo das veias pulmonares, um parâmetro para avaliação Doppler-ecocardiográfica da função diastólica fetal, é determinado pelos eventos que ocorrem do lado esquerdo do coração, sendo influenciado pelas mudanças dinâmicas na pressão do átrio esquerdo criadas pela contração e pelo relaxamento do átrio e do ventrículo esquerdos. A impedância ao fluxo da veia pulmonar para o átrio esquerdo é representada pelo índice de pulsatilidade. Objetivo- Testar a hipótese de que o índice de pulsatilidade do fluxo venoso pulmonar fetal é menor na presença dos movimentos respiratórios fetais do que em apnéia. Métodos- Examinados 22 fetos normais de mães sem doença sistêmica, em apnéia (controles) e na presença de movimentos respiratórios fetais (casos). Os fetos foram examinados pela ecocardiografia pré-natal com Doppler e mapeamento de fluxo em cores. O índice de pulsatilidade da veia pulmonar foi obtido colocando-se a amostra volume do Doppler pulsado sobre a veia pulmonar superior direita ou inferior esquerda, e aplicando-se a fórmula velocidade máxima (sistólica ou diastólica)-velocidade pré-sistólica/velocidade média. Resultados- Os fetos apresentaram idade gestacional média de 28,9 ± 2,9 semanas. Na avaliação realizada nos fetos em apnéia as médias das velocidades sistólica, diastólica e pré-sistólica foram, respectivamente, 0,35 ± 0,08 m/s, 0,26 ± 0,07 m/s, 0,09 ± 0,03 m/s. Na avaliação realizada na presença de movimentos respiratórios fetais as médias das velocidades sistólica, diastólica e pré-sistólica foram, respectivamente, 0,33 ± 0,1 m/s, 0,28 ± 0,08 m/s, 0,11 ± 0,04 m/s. O índice de pulsatilidade da veia pulmonar médio, nos fetos em apnéia, foi de 1,25 ± 0,23 (1,69 a 0,82), e na presença de movimentos respiratórios fetais foi de 0,97 ± 0,2 (1,53 a 0,61). Conclusão- Demonstramos significante diminuição da impedância ao fluxo venoso pulmonar, representada pelo índice de pulsatilidade vascular, durante os movimentos respiratórios fetais, refletindo modificações da dinâmica atrial esquerda e da melhora complacência ventricular esquerda. / Introdution- Respiratory movements influence fetal circulation. Their presence indicates an intact, non-depressed nervous system, reflecting a good fetal clinical status. In apnea, the pressure of intrathoracic organs on the fetal heart, mainly the non-expanded lungs, limits ventricular distensibility. Flow pattern in pulmonary veins, a Doppler echocardiographic parameter in the assessment of fetal diastolic function, is determined by events occurring in the left heart and is influenced by dynamic changes in left atrial pressures created by left atrium and ventricle contraction and relaxation. Impedance to pulmonary venous flow to the left atrium is represented by the pulsatility index. Objective- To test the hypothesis that fetal pulmonary venous flow pulsatility index is lower during fetal respiratory movements than in apnea. Methods- Twenty-two normal fetuses of mothers without systemic disease were examined in apnea (controls) and in the presence of fetal respiratory movements (cases). Fetuses were examined by prenatal Doppler echocardiography with color flow mapping. The pulsatility index of the pulmonary vein was obtained placing the pulsed Doppler sample volume over the right upper or left lower pulmonary vein , and applying the formula [maximum velocity (systolic or diastolic)–pre-systolic velocity]/mean velocity. Results- Mean gestational age was 28.9 ± 2.9 weeks. During fetal apnea, mean systolic, diastolic and pre-systolic velocities were, respectively, 0.35 ± 0.08 m/s, 0.26 ± 0.07 m/s and 0.09 ± 0.03 m/s. In the presence of fetal respiratory movements, mean systolic, diastolic and pre-systolic velocities were, respectively, 0.33 ± 0.1 m/s, 0.28 ± 0.08 m/s and 0.11 ± 0.04 m/s. Pulsatility index pulmonary vein in apnea was 1.25 ± 0.23 (1.69 to 0.82), and during fetal respiratory movements it was 0.97 ± 0.2 (1.53 to 0.61). Conclusion- We showed a significant reduction in impedance of pulmonary venous flow, represented by pulmonary vein pulsatility index, during fetal respiratory movements, reflecting modifications of the left atrial dynamics and enhancement of left ventricular compliance.

Page generated in 0.0479 seconds