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  • 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.
21

OSTEOPONTIN PROMOTES PATHOLOGICAL CHANGES IN THE MYOCARDIUM DURING HIV INFECTION.

Robinson, Jake Arthur January 2023 (has links)
With the introduction of antiretroviral therapy (ART), human immunodeficiency virus (HIV) has progressed to a chronic inflammatory disease with accelerated, subclinical end-organ damage, specifically cardiovascular disease (CVD). People with HIV (PWH) have higher incidence, risk, and mortality from CVD, such as atherosclerosis, diastolic dysfunction, and heart failure. Several recent clinical reports have shown that PWH have a predisposition to developing heart failure with preserved ejection fraction (HFpEF), presenting with pathological concentric hypertrophy, diffuse fibrosis, and diastolic dysfunction. As such, an investigation into immunological and molecular mechanisms promoting pathological changes in the heart is necessary. Recent clinical reports show that people living with HFpEF have elevated plasma osteopontin (Opn), and plasma Opn is a powerful predictor of HFpEF severity, HFpEF-related hospitalizations, and mortality. Second, several animal models of HFpEF phenotypes have suggested Opn is involved in driving or perpetuating diastolic dysfunction and cardiac fibrosis. Therefore, we investigated changes in Opn in a cohort of PWH and two translationally relevant models of HIV infection (non-human primates and humanized mice) to identify the pathological role of Opn in cardiac fibrosis and detail the adjunctive potential of Opn for PWH presenting with HFpEF. In Chapter 2, twenty asymptomatic, antiretroviral-treated women with HIV (WHIV) and fourteen women without HIV (HIV-women) matched on age and body mass index underwent cardiac magnetic resonance imaging (MRI) and immune phenotyping. First, we compared a number of immunological parameters to the extensive cardiac MRI parameters in WHIV. Secondly, we analyzed relationships between plasma Opn with cardiac structure and function and markers of immune activation among WHIV, HIV- women, and the whole cohort. Multivariable modeling among the whole group was performed using myocardial fibrosis and myocardial steatosis, respectively, as the dependent variable and HIV status, atherosclerotic cardiovascular disease (ASCVD) risk score, and plasma Opn as independent variables. Among WHIV, multi-variable modeling was performed using plasma Opn as the dependent variable and CD4+ T cell count, HIV viral load, and the respective immune parameter, relating to plasma OPN in bivariate analyses, as an independent variable. In Chapter 3, we investigated bulk transcriptomic changes in the left ventricle of the heart in a model of HIV infection. We utilize the highly translatable simian immunodeficiency virus (SIV)-infected rhesus macaque model to identify changes in the myocardium with and without ART. Animals were selected by viral load, with SIV-infected animals having a high titer of plasma viral load and the SIV-infected animals with ART having a reduction in viral load by several logs. We performed total RNA-Seq on left ventricle tissue from uninfected animals, SIV-infected animals, and SIV-infected animals receiving a clinically relevant ART regimen. SIV infection led to high plasma viral load, but little to no SIV RNA was detectable in the left ventricle, shown by minimal of SIV RNA+ cells in the heart and no SIV sequences identified from RNA-Seq. SIV infection produced a highly inflammatory reaction in the heart, predominated by interferon and pathogen response. Additionally, interferon gamma (IFNg) and lipopolysaccharide (LPS) were both identified as potential upstream drivers of transcriptomic changes in the heart from SIV infection. Reduction of viral load by ART reduced the interferon and cytokine response in the heart; however, SIV-infected animals receiving ART exhibited decreased expression of integral genes directly involved in fatty acid (FA) metabolism, carnitine shuttling, and beta-oxidation. In Chapter 4, we use both in vitro and in vivo modeling to identify molecular mechanisms involved in the development of cardiac fibrosis. We utilized mouse embryonic fibroblasts (MEFs) modeled cardiac fibroblasts and were stimulated with IFNg, LPS, and TGF-b for phenotypic changes in contraction and cytokine production. The interplay of Opn and cardiac fibrosis was investigated in SIV-infected macaques with/without ART and HIVinfected humanized mice with/without an Opn-inhibiting RNA aptamer. LPS-stimulated MEFs retained myofibroblast-like contractility from TGF-b stimulation, secreted inflammatory cytokines/chemokines, and produced Opn (Spp1 transcripts). SIV-infected animals had elevated plasma Opn at necropsy, accumulation of full-length Opn in the ventricle, and ventricular interstitial fibrosis. Multivariate regression identified growth differentiation factor (GDF)-15, inflammatory CD14+CD16+ monocytes, and CD163 expression on CD14+ CD16+ monocytes as independent predictors of plasma Opn during SIV infection. HIV-infected humanized mice showed increased interstitial fibrosis compared to uninfected/untreated animals, and systemic inhibition of Opn by RNA aptamer reduced left ventricle fibrosis in HIV-infected humanized mice. These studies combined a clinical cohort of WHIV, SIV-infected rhesus macaques, and HIV-infected humanized mice to determine the role of Opn in the pathophysiology of cardiac deficits from HIV infection. Our primary goals were to begin to unravel the role of Opn in the development of HFpEF phenotypes seen in PWH, detail Opn as a converging biomarker of cardiac stress and remodeling and immune dysfunction in HIV infection, and investigate the therapeutic potential of Opn to reduce cardiac fibrosis from HIV infection. While Opn has a broad spectrum of physiological and pathological functions, we aimed to frame Opn as an important protein of interest in future studies into HFpEF in PWH. / Biomedical Sciences
22

Feasibility of Echocardiographic Particle Image Velocimetry for evaluation of cardiac left ventricular filling function

Meyers, Brett Albert 18 September 2014 (has links)
Heart disease is one of the primary causes of morbidity and mortality for the adult population over the age of 65. Furthermore, ailments such as hypertension can affect as many as 50% of the adult population over the age of 45. If left untreated, these ailments eventually precipitate the onset of diastolic dysfunction and heart failure. Diastolic dysfunction is the alteration or impairment of performance in either the left or right ventricle of the heart. Although there has been a marked increase in study of this disease, there is still an apparent difficulty to diagnose patients. Flow visualization techniques have been commonly employed to study the development of these diseases as they relate to the filling process of the ventricles. One method, Echo Particle Image Velocimetry (Echo-PIV) is a relatively new method for cardiac flow chamber visualization, with the potential to provide physicians with a cost-effective and safe method for obtaining high temporal resolution recordings for extending knowledge on the filling processes in cardiac chamber flow. This work presents a new approach to extending the capabilities of Echo-PIV for more accurate measurement of cardiac flows for patients with poor quality recordings. Currently, much of the literature notes that temporal resolution and poor acoustic windows results in exclusion from study. These recordings are more representative of the contrast-enhancement studies used by physicians to better identify chamber walls. When applying standard PIV cross-correlation techniques, measurements tend to fail due to image noise and artifacts. By implementing a Moving Ensemble (MWE) with Product of Correlation (PoC) processing scheme, measurement accuracy, reliability, and robustness can be obtained for measurement in left ventricular filling assessment. / Master of Science
23

Dysfonction diastolique, rigidité artérielle aortique et hypertension : facteurs anthropométriques et métaboliques associés et prise en charge en population générale / Diastolic dysfunction, aortic stiffness and hypertension : anthropometric and metabolic risk factors and management in general population

Chau, Kénora 10 December 2018 (has links)
L’augmentation de l’obésité durant les dernières décennies expose la population à un risque accru de problèmes métaboliques et des maladies cardiovasculaires. Ce travail étudiait, d’une part, l’association de l’obésité avec la dysfonction diastolique et la rigidité artérielle aortique vingt ans plus tard chez des adultes initialement en bonne santé. Cette étude montrait que l’obésité générale mesurée par l’indice de masse corporelle et l’adiposité abdominale mesurée par le tour de taille étaient associées positivement à la dysfonction diastolique. Mais elles semblaient jouer un rôle protecteur sur la rigidité artérielle. Le ratio “tour de taille/indice de masse corporelle” semblait mieux isoler l’adiposité abdominale/viscérale de l’obésité générale, et était associé positivement à la rigidité artérielle. Il permettrait de montrer un rôle néfaste à long terme de l’adiposité abdominale/viscérale sur la rigidité artérielle même quand le poids est normal. La présence combinée de l’obésité abdominale (mesurée par le tour de taille) et d’un taux plus élevé de triglycérides était associée à un risque élevé de dysfonction diastolique. Dans la deuxième partie, nous nous sommes intéressés aux individus ayant déjà une hypertension artérielle. Ce travail montrait que, parmi les sujets ayant une hypertension, ceux ayant une hypertension non-diagnostiquée avaient un profil spécifique (plus souvent de sexe masculin, un tour de taille moins élevé, et moins souvent de maladies cardiovasculaires/diabète, antécédents familiaux d’hypertension et consultations de soins primaires moins fréquents). La présence concomitante d’un nombre élevé de ces critères renforçait fortement l’absence de primo-diagnostic. Nos résultats peuvent aider dans l’identification précoce des sujets à risque, la prévention et le management thérapeutique / Worldwide increasing obesity over the last decades expose the population to an increased risk of metabolic perturbations and cardiovascular diseases. This research investigated first the association of obesity with diastolic dysfunction and aortic stiffness observed 20 years later in initially healthy adults. General obesity measured with body mass index and abdominal adiposity measured with waist circumference were positively associated with diastolic dysfunction. But, these anthropometric parameters played a protective role in aortic stiffness. The ratio “waist circumference / body mass index” appeared to better isolate abdominal adiposity from general obesity and was then positively associated with aortic stiffness. It allowed to evidence a harmful role of abdominal adiposity in aortic stiffness, even in subjects with normal body weight. The presence of abdominal adiposity (measured with waist circumference) combined with an elevated level of triglycerides was associated with a higher risk of diastolic dysfunction. In the second part, our research focused on hypertensive individuals. It showed that among hypertensive subjects, those having undiagnosed-hypertension had specific features (being more often male, having less elevated waist circumference, and having fewer cardiovascular diseases/diabetes, familial hypertension history, and primary care uses). The concomitant presence of a higher number of these criteria appeared to strongly reinforce the absence of diagnosis. Our findings may help to early identify subjects at risk, and to establish prevention and therapeutic management
24

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.
25

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.
26

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.
27

Diastolic echocardiographic parameters in patients with atrial fibrillation

Iqbal, Hena January 2017 (has links)
Vid flertalet hjärtsjukdomar kan det förekomma störningar i den diastoliska funktionen, detta tillstånd benämns diastolisk dysfunktion. Detta innebär att fyllnadstrycken i vänsterkammare ökar på grund av nedsatt eftergivlighet i kammaren. Bedömning av diastolisk funktion, hos patienter som utvecklat förmaksflimmer, är en utmaning inom ekokardiografi. Detta beror på att förmaksflimmer innebär utebliven förmakskontraktion, oregelbunden längd av hjärtcykeln och förmaksdilatation, vilket försvårar bedömningen. Syftet med studien var att med ekokardiografi studera diastoliska parametrar hos patienter med förmaksflimmer för att studera om dessa kan användas vid bedömning av den diastoliska vänsterkammarfunktionen hos denna patientgrupp. I studien inkluderades 37 deltagare med förmaksflimmer som var remitterade för en ekokardiografisk undersökning med olika frågeställningar. Pulsad doppler teknik och vävnads doppler teknik användes för att registrera följande diastoliska parametrar: förmaksvolym, mitralisinflöde (E-vågshastigheten) och myokardiets diastoliska hastigheter (e´). Utöver dessa uppskattades även ejektionsfraktion, hjärtfrekvens, hypertrofi och trycket i lilla kretsloppet, som togs med vid bedömningen. Mann-Whitneys test visade att det förelåg ett starkt statistiskt samband mellan fyllnadstrycket (E/e´) och E-vågen, e ´samt förmaksvolym (p = <0,05). Signifikant resultat erhölls även för sambandet mellan PA-tryck och fyllnadstryck (p = 0,014) genom ett chitvå-test. Vidare gav multipel linjär regression utslag på E-vågen och e´. Analysen visade att det förelåg en hög förklaringsgrad för E-vågen (p = <0,001) och e´ (p = 0,008). Sammanfattningsvis visade resultaten att ekokardiografi kan användas för diagnostik av förmaksflimmerpatienter avseende fyllnadstryck där förmaksvolym, E-vågshastigheten och e´ anses vara bästa parametrarna. / In the majority of heart diseases disturbances in the diastolic function may occur, this condition is called diastolic dysfunction. This means that the left ventricular filling pressure increases due to reduced compliance in the chamber. The assessment of diastolic function in patients who have developed atrial fibrillation (AF), is a challenge in echocardiography. This is a result of AF which involves absence of atrial contraction, irregular length of the cardiac cycle and left atrium dilatation that complicates the assessment. The aim of this study was to observe the diastolic echocardiographic parameters in patients with AF to examine if these can be used in the assessment of diastolic left ventricular function in this population. The study included 37 participants with AF who were remitted for an echocardiographic examination due to various concerns. Pulsed Doppler technique and tissue Doppler technique was used to record the following diastolic parameters: atrial volume, mitral inflow velocity (E) and the myocardial diastolic velocity (e'). Ejection fraction, heart-rate, hypertrophy and pulmonary artery pressure were also estimated and included in the assessment. Mann-Whitneys test showed that there was a strong statistical correlation between the filling pressure (E/e') and E, e' and atrial volume (p = <0.05). Significant results were also obtained for the relation between pulmonary artery pressure and the filling pressure (p = 0.014) by a chi-square test. A multiple linear regression showed association between E and e'. The analysis showed that there was a significant value of coefficient of determination for E (p = <0.001) and e' (p = 0.008). In conclusion, the results showed that echocardiography can be used for diagnosis of AF patients regarding filling pressures, where atrial volume, E velocity and e' are considered to be the best parameters.
28

Sélection de gènes de référence pour la normalisation des expériences de PCR quantitative dans un modèle de dysfonction diastolique de lapin

Nachar, Walid 08 1900 (has links)
La dysfonction diastolique du ventricule gauche (DDVG) réfère à une rigidité ainsi qu’à des troubles de relaxation au niveau de ce ventricule pendant la phase de la diastole. Nos connaissances sur les mécanismes moléculaires sous-jacents de cette pathologie demeurent limités. Les analyses géniques sont indispensables afin de bien identifier les voies par lesquelles cette maladie progresse. Plusieurs techniques de quantification de l’expression génique sont disponibles, par contre la RT-qPCR demeure la méthode la plus populaire vu sa haute sensibilité et de ses coûts modérés. Puisque la normalisation occupe un aspect très important dans les expériences de RT-qPCR, nous avons décidé de sélectionner des gènes montrant une haute stabilité d’expression dans un modèle de DDVG de lapin. Nous avons alors exposé 18 lapins blancs soit à une diète normale (n=7) ou bien à une diète hypercholestérolémiante additionnée de vitamine D2 (n=11). La DDVG a été évaluée par des mesures échocardiographiques. L’expression de l’ARNm de dix gènes communément utilisés dans la littérature comme normalisateur (Gapdh, Hprt1, Ppia, Sdha, Rpl5, Actb, Eef1e1, Ywhaz, Pgk1, et G6pd) a été mesurée par RT-qPCR. L’évaluation de leur stabilité a été vérifiée par les algorithmes de geNorm et Normfinder. Sdha et Gapdh ont obtenu les meilleurs scores de stabilité (M<0.2) et ont été suggérés par le geNorm, comme meilleure combinaison. Par contre, l’utilisation de Normfinder mène à la sélection d’Hprt1 et Rpl5 comme meilleure combinaison de gènes de normalisation (0.042). En normalisant par ces deux combinaisons de gènes, l’expression de l’ARNm des peptides natriurétiques de type A et B (Anp et Bnp), de la protéine chimiotactique des monocytes-1 (Mcp-1) et de la sous unité Nox-2 de la NADPH oxydase ont montré des augmentations similaires chez le groupe hypercholestérolémique comparé au groupe contrôle (p<0.05). Cette augmentation d’expressions a été corrélée avec plusieurs paramètres échocardiographiques de DDVG. À notre connaissance, c’est la première étude par laquelle une sélection de gènes de référence a été réalisée dans un modèle de lapin développant une DDVG. / Left ventricular diastolic dysfunction (LVDD) is characterized by the diminution of ventricle’s performance, its incapacity to relax normally and an increase of blood filling pressure. LVDD is considered as a main cause of heart failure in approximately 50% of patients suffering from this disease. However, the molecular mechanisms underlying LVDD remain unclear. Real-time quantitative PCR (RT-qPCR) is widely used in gene-expression studies. In this study we attempt to establish normalization genes for gene expression analysis in a rabbit model of LVDD. Eighteen New-Zealand white rabbits were exposed to normal (n=7) or 0.5% hypercholesterolemic (n=11) diet supplied by vitamin D2; an LVDD animal model previously characterized in our Laboratory. LVDD was assessed by echocardiography. RT-qPCR was performed using cDNA from left ventricle samples and measuring the stability of 10 candidate genes as normalisers (Gapdh, Hprt1, Ppia, Sdha, Rpl5, Actb, Eef1e1, Ywhaz, Pgk1, and G6pd). We found that Sdha and Gapdh are the most stable genes using geNorm analysis with very high stability average M <0.2. By contrast, Hprt1 and Rpl5 were found to be the best combination for normalization with a stability value of 0.042 when using Normfinder. Comparison of both normalization strategies highlighted an increase of Anp, Bnp, Mcp-1 and Nox-2 mRNA expression in the hypercholesterolemic rabbits (p<0.05) compared to normal controls. This increase correlates with different DD parameters and validates the development of the disease in our model. To our knowledge, this is the first study highlighting stable reference genes for RT-qPCR normalization in a validated rabbit model of LVDD.
29

Caractérisation physiopathologique et pharmacologique d'un modèle porcin de dysfonction diastolique avec éjection préservée. / Functional alterations and pharmacological modulation of diastolic heart failure

Rienzo, Mario 26 November 2013 (has links)
On estime qu'approximativement 20 millions de personnes dans le monde souffrent d'insuffisance cardiaque et la prévalence de cette pathologie ne cesse d'augmenter avec le vieillissement croissant de la population. L'évaluation de la fonction ventriculaire gauche par la mesure de la fraction d'éjection permet en fait de distinguer deux populations distinctes de patients insuffisants cardiaques : l'une avec et l'autre sans altération de la fraction d'éjection, encore dénommées respectivement Heart Failure with Reduced Ejection Fraction (IC-FEr) et Heart Failure with Preserved Ejection Fraction (IC-FEp). On ne sait pas aujourd'hui si ces deux entités représentent deux pathologies distinctes ou, au contraire, deux entités intimement liées. L'IC-FEp est actuellement observée chez environ 40 à 50% des patients présentant une insuffisance cardiaque et son évolution est semblable à celle des patients IC-FEr.Le concept d'IC-FEp soulève toutefois des difficultés conceptuelles : d'une part car la notion d'une fraction d'éjection préservée implique la connaissance de sa valeur de base et d'autre part, les valeurs dites "normales" de la fraction d'éjection sont encore à établir. Par ailleurs, la vision mécanique du cœur comme une pompe hémodynamique ou musculaire conditionne la compréhension de la physiopathologie de la IF-FEp.Dans ce contexte, nous avons mis au point un modèle porcin de dysfonction diastolique avec éjection préservée secondaire à une hypertension artérielle induite par une perfusion continue d'angiotensine II pendant 28 jours. Dans ces conditions, nous avons démontré une altération de la fonction ventriculaire gauche alors même que l'éjection était préservée. Ceci était objectivé par 1) une augmentation paradoxale des durées relatives de contraction et de relaxation isovolumiques, 2) des réponses inappropriées des phases isovolumiques du cycle cardiaque à des augmentations de la fréquence et de l'inotropisme cardiaques et 3) une étroite relation entre ces deux phases isovolumiques (couplage contraction-relaxation). L'inadéquation entre les niveaux de fréquence cardiaque et des phases isovolumiques nous a amené à évaluer les effets de la modulation pharmacologique de la fréquence cardiaque sur le couplage contraction-relaxation. Ainsi la réduction sélective de la fréquence cardiaque par l'administration d'ivabradine, un inhibiteur des canaux If, a réduit significativement la durée de ces deux phases et favorisé le remplissage. Cependant, cette normalisation n'était qu'apparente puisque le ratio entre la contraction et la relaxation isovolumiques restait augmenté à J28, en défaveur de la contraction isovolumique.En conclusion, le développement d'une dysfonction diastolique avec une éjection préservée s'accompagne d'une dysfonction systolique qui entrave une réponse adéquate du myocarde à un stress dans un contexte d'hypertension chronique. / Approximately 20 millions individuals in the world experience heart failure symptoms; heart failure prevalence is continuously rising with population aging. Left ventricular function evaluation by the ejection fraction allows distinguishing two different patient sets: one with and one other without ejection fraction alteration, respectively named Heart Failure with Reduced Ejection Fraction (HF-rEF) and Heart Failure with Preserved Ejection Fraction (HF-pEF). It is unknown if these two clinical presentations represent two different pathologies or two manifestations of the same clinical entity. HF-pEF is found in about 40-50% of patients with heart failure and its evolution is similar to that of patients with HF-rEF.However, several conceptual difficulties deal with the HFpEF: on one hand, talking about preserved ejection fraction implies the knowledge of its basal value; on the other, the normality needs to be established. Moreover, considering the heart either as a hemodynamic pump or as a muscular pump may modify the understanding of HFpEF physiopathology.We therefore set up a swine model of diastolic dysfunction with preserved ejection induced by chronic hypertension, which was obtained by continuous perfusion of angiotensin II during 28 days. In these conditions, we clearly demonstrated a LV function impairment, while the ejection phase parameters remained preserved. The LV impairment is demonstrated by: 1) the paradox increase of the relative durations of isovolumic contraction and relaxation; 2) the blunted responses of the isovolumic phases of cardiac cycle to heart rate augmentation and cardiac inotropisme; 3) a straight relationship between these two isovolumic phases (contraction-relaxation relationship).The mismatch between the heart rate and the isovolumic phases behaviour led us to investigate the possible effects of the heart rate pharmacological modulation on the contraction-relaxation coupling. The selective reduction of the heart rate by ivabradine administration (a selective If channel inhibitor) was able to significantly reduce the isovolumic contraction and relaxation phases' durations, thus improving filling phase dynamics. Anyway, this “normalisation” was only apparent, because the contraction to relaxation ratio was increased at day 28, to the detriment of the isovolumic contraction.In conclusion, chronic hypertension induces a diastolic dysfunction with a preserved ejection fraction paralleled by a systolic dysfunction which is responsible of a blunted myocardial response to stress.
30

Comparação da função diastólica entre o pré e pós-operatório de pacientes portadores de estenose aórtica ou insuficiência aórtica, baseados em dados bioquímicos e ecocardiográficos / Comparing after and before aortic valve replacement diastolic function in patients with aortic stenosis(AS) or aortic regurgitation(AR)

Boer, Berta Paula Napchan 09 February 2010 (has links)
INTRODUÇÃO: Avaliação da função diastólica de pacientes portadores de estenose ou insuficiência aórtica submetidos à troca valvar. OBJETIVOS: Avaliação da função diastólica através da análise do NTpró-BNP como método não invasivo para caracterização da insuficiência cardíaca diastólica, comparando com os dados ecocardiográficos através do Doppler Pulsado em Fluxo Mitral, Doppler Pulsado em Veias Pulmonares e Doppler Tecidual em portadores de IAO e EAO. MÉTODOS: Foram avaliados 63 pacientes, 32 pacientes com IAO (25 pacientes do sexo masculino e 7 do sexo feminino), 31 pacientes com EAO (11 pacientes do sexo masculino e 20 pacientes do sexo feminino). As variáveis foram comparadas na média entre os pacientes portador de IAO e EAO no pré e pós-operatório. RESULTADOS: A idade dos pacientes variou de 21 a 81 com média de 55 anos. Observa-se diferença quanto à média de idades entre as diferentes patologias (t-Student p< 0,0001). Os pacientes com IAO apresentam uma média de idade igual a 45,7±14,3 com variação entre 21 e 79 anos e os pacientes com EAO apresentam uma média de idade igual a 61,5±14,7 com variação entre 21 e 81 anos. Na IAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): TRIV (p=0,0011), diferença entre Tempo de onda A mitral e onda A pulmonar (p=0,0097), Vol. Sistólico de AE (p=0,0019), Vol Sistólico de AE Indexado (0,0011), Vol. Diastólico de AE (p=0,0110), DDVE (p<0,0001), DSVE (p<0,0001), VSF (p<0,0001), VDF (p<0,0001), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa do VE (p<0,0001). Na EAO em relação à disfunção diastólica tivemos os seguintes dados com significância estatística do pré para o pós-operatório (6 meses): E/E (p=0,0379), TRIV (p=0,0072), diferença entre o tempo de onda A mitral e tempo de onda A pulmonar (p=0,0176), Vol sistólico de AE(p=0,0242), Vol. Sistólico de AE indexado (p=0,0237), FEdeAE (p=0,0339), DDVE (p=0,0002), DSVE (p=0,0085), VDF (p=0,0194), Massa Indexada de VE (p<0,0001) e Relação Volume/Massa de VE(p<0,0001). O NTpró-BNP se correlacionou positivamente com os diversos graus de disfunção diastólica tanto no pré como pós-operatório CONCLUSÃO: Foram verificados no estudo da função diastólica variação com significância estatística tanto na IAO como na EAO na comparação do pré e o pós-operatório. Da mesma forma notamos variação do NT-proBNP com correlação com as variáveis ecocardiográficas que caracterizam a disfunção diastólica. / INTRODUCTION: Assessment of diastolic function in patients with aortic stenosis or aortic regurgitation waiting for aortic valve replacement. OBJECTIVE: Assesment of diastolic function with Doppler methods:Doppler signals from transvalvar mitral inflow, tissue Doppler imaging (TDI) and Doppler in pulmonary veins(DPV) correlating with serum brain peptide natriuretic (NTproNP) before and 6 months after aortic valve replacement (AVR). METHODS: We have analyzed 63 patients, 32 with AR (25 males and 7 females), 31 AS (11 males and 20 females).The indices were compared with AS and AR before and after AVR. RESULTS: The ages of patients ranged from 21 to 81 mean age was 55 years old.We have seen difference between mean age of AS and AR (t-Student-p<0.0001). Patients with AR have had mean age 45.67 plus/minus 14.28, range 21 to 79 years old and patients with AS have had mean age 61.50 plus/minus 14.72, range 21 to 81 years old. The patients who had AR the indices showed differences: Isovolumetric Relaxation Time IRT(p=0.0011), Diference between the pulmonary A wave duration and mitral A duration (p=0.0097), Left Atrial Systolic Volume (p=0.0019), Left Atrial Systolic Volume Index(p=0.0011), Left Atrial Diastolic Volume (p=0.0110), Left Ventricular Diastolic Diameter (p<0.0001), Left Ventricular Systolic Diameter (p<0.0001), End Systolic Volume (p<0.0001), End Diastolic Volume (p<0.0001), Left Ventricular Mass Index (p<0.0001) and Left Ventricular Volume and Left Ventricular Mass Index ratio (p<0.0001). Analyzing patients with AS the indices who showed differences: (The ratio of mitral velocity to early diastolic velocity of the mitral annulus) E/E (p=0.0379)(Isovolumetric Relaxation Time)(p=0.0072) IRT, Diference between the pulmonary A wave duration and mitral A duration (p=0.0176), Left Atrial Sistolic Volume (p=0.0242), Left Atrial Systolic Volume Index (p=0.0237), Left Atrial Ejection Fraction (p=0.0339) Left Ventricular Diastolic Diameter (p=0.0002), Left Ventricular Systolic Diameter (p=0.0085), End Diastolic Volume (LVEDV) (p=0.0194), Left ventricular Mass Index(p<0.0001), Left Ventricular Volume and Mass Index Ratio (p<0.0001). CONCLUSIONS: As we studied diastolic function we have verified significant statistic variation in aortic regurgitation and aortic stenosis comparing before and after aortic valve replacement. Likewise we have seen there is correlation between NTproBNP and echocardiographic variables that show diastolic dysfunction.

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