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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.
1

The 'athletic heart' : insights from modern imaging tools in Caucasian and West African athletes

Segun, Utomi Victor January 2015 (has links)
A seminal study by Morganroth et al (1975) demonstrated a differential pattern of cardiac adaptation with prolonged exercise training; of eccentric pattern of left ventricular hypertrophy (LVH) in endurance trained athletes (ET) and concentric LVH in resistance trained athletes (RT). Specific inconsistencies related to the nature of any adaptation to RT; the value of new imaging technologies; the relative importance of scaling of cardiac data for differences in body size; the impact of training on the right ventricle (RV) and the fit of differential pattern of adaptation in athletes with Black ethnicity have driven the rationale for the studies included in this thesis. Study one employed meta-analysis techniques to critically evaluate the evidence base supporting or refuting that MH exists in elite male Caucasian ET & RT. Modern echocardiographic techniques were used to test whether a dichotomous LV and RV structural as well as global and regional functional adaptation was apparent in elite Caucasian ET & RT in studies 2 & 3. The final study (exploratory) was to characterize the athletic heart phenotype in a homogenous population of elite RT of West African origin (WRT) to provide new insight in relation to cardiac adaptation and ECG characteristics in non-Caucasian athlete groups. Allometric scaling approach was deployed to index LV and RV data for individual body variance in body size. The novel findings of this thesis; larger LV data in ET (LVMg: ET 232 (200 to 260), RT 220 (205 to 234), CT 166 (145 to 186)) but no concentric hypertrophy in RT within the meta-analysis, predominance of normal geometry in male athletes (65% of ET and 95% of RT) and the lack of concentric pattern of hypertrophy in RT in a cross-sectional study; no RV adaptation in RT athletes (RVD1mm: ET 45 ± 5 (39 to 57), RT 40 ± 5 (32 to 51) CT 39 ± 4 (31 to 45)); no LV or RV adaptation in WRT athletes; the importance of appropriate scaling of cardiac parameters; provide a useful re-evaluation of concepts and models in the athletic heart literature. The findings have important implications for cardiovascular screening of athletes.
2

Evaluation of systolic and diastolic left ventricular function during exercise in athletes

Bilal, Dejan January 2019 (has links)
Idrottshjärta är ett kardiovaskulärt tillstånd som uppträder under längre perioder av intensiv träning som orsakar strukturella, funktionella och elektriska förändringar hos hjärtat och är en fysiologisk anpassning som svar på ett ökat hemodynamiskt behov under fysisk ansträngning. De fysiologiska anpassningarna har dock blivit ett diagnostiskt dilemma att urskilja från de patologiska förändringarna såsom hypertrofisk kardiomyopati. Det finns därför ett behov av standardisering av kardiovaskulär screening hos idrottare för att upptäcka underliggande eller dolda kardiomyopatier som kan leda till allvarliga konsekvenser under fysisk ansträngning. Studiens ändamål var att undersöka den systoliska och diastoliska vänsterkammarfunktionen under ansträngning hos idrottare och öka förståelsen om vad som händer med de olika variablerna under arbete. Nio friska idrottare genomförde stressekokardiografi där cardiac index, ejektionsfraktion, fyllnadstryck, mitralisklaffplanets longitudinella rörelse (MAPSE), mitralisinflöde, vävnadsdoppler (e´ och s´) och veninflöde undersöktes före, under och efter ett ansträngningstest på ergometercykel. Variablerna under och efter cykeltestet jämfördes sedan med värdena i vila. Resultaten visade en signifikant ökning av cardiac index, MAPSE och vävnadsdoppler under ansträngning. Sammanfattningsvis visade studien att flera av variablerna förbättrades under ansträngning och en del av de visade sig vara relativt okänsliga för störningar och artefakter vilket kan vara användbart för framtida studie protokoll som avser utföra en hjärtstudie under arbete. / Athlete’s heart is a cardiovascular condition that occurs during extended periods of intense exercise that causes structural, functional and electrical changes of the heart and is a physiological adaptation in response to increased hemodynamic needs during physical exertion. However, the physiological adaptations have become a diagnostic dilemma to distinguish from the pathological changes such as hypertrophic cardiomyopathy. Therefore, there is a need for standardization of cardiovascular screening in athletes to detect underlying or hidden cardiomyopathies that can lead to severe consequences during physical exercise. The aim of the present study was to investigate the systolic and diastolic left ventricular function during exercise in athletes and to increase the understanding of what happens to the various variables during exertion. Nine healthy athletes conducted stress echocardiography where cardiac index, ejection fraction, filling pressure, mitral annular plane systolic excursion (MAPSE), mitral inflow, tissue Doppler imaging (e 'and s') and pulmonary venous inflow were examined before, during and after a cycle ergometer test. The variables during and after the cycle test were then compared to baseline. The results showed a significant increase in cardiac index, MAPSE, and tissue Doppler imaging during exertion. In conclusion, the study showed that several of the variables improved during exertion and some of them proved to be quite insensitive to disturbances and artifacts, which may be useful in future study protocols that consider carrying out a cardiac study during work.
3

Adaptação ventricular esquerda em cães de pastoreio

Martins, Raimy Costa 21 March 2017 (has links)
Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2017-06-12T13:51:00Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) RAIMY COSTA MARTINS.pdf: 1412873 bytes, checksum: 1a015a5d3ada01cbd7dea500b27c388a (MD5) / Approved for entry into archive by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2017-06-12T13:51:13Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) RAIMY COSTA MARTINS.pdf: 1412873 bytes, checksum: 1a015a5d3ada01cbd7dea500b27c388a (MD5) / Made available in DSpace on 2017-06-12T13:51:13Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) RAIMY COSTA MARTINS.pdf: 1412873 bytes, checksum: 1a015a5d3ada01cbd7dea500b27c388a (MD5) Previous issue date: 2017-03-21 / O “coração atleta” é o termo designado para caracterizar as adaptações cardíacas funcionais e anatômicas secundárias ao treinamento físico intenso e prolongado em humanos e animais. O ecocardiograma desempenha papel fundamental em distinguir as adaptações fisiológicas secundárias ao exercício, outrossim, as recentes técnicas introduzidas como Speckle Tracking (Ste) têm permitido obter informações relevantes a respeito da função cardíaca em humanos atletas. Desta forma, objetivou-se avaliar por meio do ecocardiograma, a estrutura e função sistólica do ventrículo esquerdo de cães praticantes de pastoreio há no mínimo quatro meses, cinco a seis vezes por semana, de quatro a oito horas por dia. Para tanto, 31 cães foram divididos em dois grupos: grupo pastoreio (GP, n=15) e grupo sedentário (GS, n=16), avaliados em um único momento, em repouso, e posteriormente submetidas a análise de variância, multivariada (ANOVA), dois por dois, em nível de significância à 95% (p<0,05) e tendência à 90% (p<0.1). Os cães do GP apresentaram maiores valores de diâmetro interno do ventrículo esquerdo ao final da sístole (GP: 2,72 ± 0,09; GS: 2,43 ± 0,09; P<0,034) indicando predomínio isotônico desta atividade. O volume sistólico apresentou-se maior no GP (GP: 28,51 ± 2,20; GS: 22,13 ± 2,17; P<0,049), enquanto o índice de performance miocárdica do ventrículo esquerdo (GP: 0,37 ± 0,03; GS: 0,46 ± 0,03; P<0,028) e o movimento sistólico septal (GP: 0,13 ± 0,01; GS: 0,15 ± 0,01; P<0,044) foram menores em relação ao GS, indicando melhor função cardíaca sisto-diastólica nos cães de pastoreio. Por meio da técnica Ste foi possível observar diminuição dos valores de strain e ou strain rate de alguns segmentos nos cães do GP, nos sentidos radial, circunferencial, longitudinal e transversal em relação ao GS, indicando menor necessidade de deformação miocárdica para a manutenção da função sistólica. Os resultados encontrados indicam que as variáveis ecocardiográficas convencionais (estruturais e funcionais), teciduais e provenientes da técnica STe, foram complementares e fundamentais para a compreensão das adaptações cardiovasculares em cães de pastoreio. / The "athlete's heart" is the term designed to characterize functional and anatomic cardiac adaptations secondary to intense and prolonged physical training in humans and animals. The echocardiogram plays a fundamental role in distinguishing the physiological adaptations secondary to exercise, also, the recent techniques introduced as Speckle Tracking Echocardiography have allowed us to obtain relevant information regarding cardiac function in human athletes. The aim of this study was to evaluate the structure and systolic function of the left ventricle of dogs practicing herding for at least four months, five to six times a week, from four to eight hours a day using echocardiography. For this, 31 dogs were divided into two groups: herding group (GP, n=15) and sedentary group (GS, n=16), evaluated in a single moment, at rest, and then submitted the multivariate analysis of variance (ANOVA), two by two, at the level of significance at 95% (p<0,05) and tendency to 90% (p<0.1). The GP dogs showed higher values of internal diameter of the ventricle at the end of systole (GP: 2,72 ± 0,09; GS: 2,43 ± 0,09; P<0,034), indicating isotonic predominance of this activity. At respect functional adaptations variables, systolic volume was higher in GP (GP: 28,51 ± 2,20; GS: 22,13 ± 2,17; P<0,049), differently from myocardial performance index of the left ventricle (GP: 0,37 ± 0,03; GS: 0,46 ± 0,03; P<0,028) and septal systolic moviment to GS (GP: 0,13 ± 0,01; GS: 0,15 ± 0,01; P<0,044). By means of the Ste technique, it was possible to observe a decrease in the strain and or strain rate values in GP dogs, in the radial, circumferential, longitudinal and transverse directions in relation to GS, indicating a lower need for myocardial deformation to maintain systolic function. The results indicate that the conventional echocardiographic variables (structural and functional) and tissue, obtained by the STe technique, were complementary and essential for the understanding of cardiovascular adaptations in herding dogs.
4

Adaptations cardiaques à l’exercice aigu, chronique et épuisant de longue durée : mise en évidence du rôle clé du mécanisme de torsion - détorsion dans le remplissage ventriculaire gauche / Cardiac adaptations to acute, chronic and streneous exercise : key role of twisting - untwisting mecanism in left ventricular filling

Doucende, Grégory 23 November 2010 (has links)
Lors de la systole, le ventricule gauche (VG) se déforme suite à la contraction des cardiomyocytes. De part l’orientation en spirale des fibres myocardiques, ces déformations incluent un mouvement de torsion, la base et l’apex du VG tournant dans des sens opposés. L’emmagasinement d’énergie élastique par ce mécanisme et surtout sa restitution très précoce en début de diastole jouent un rôle clé dans le remplissage ventriculaire gauche. Les objectifs de ce travail ont été d’étudier les adaptations mécaniques ventriculaires gauche en se focalisant sur le rôle de la torsion 1) lors d’un exercice d’intensité croissante chez le sujet sédentaire jeune, 2) suite à l’entrainement aérobie au repos et lors d’un exercice d’intensité croissante et, 3) concomitantes aux dysfonctions cardiaques observées après un exercice épuisant de longue durée. Pour cela, nous avons effectué des échocardiographies au repos et/ou lors d’épreuves d’effort d’intensité croissante en incluant l’utilisation d’un nouvel outil échocardiographique basé sur le "speckle tracking" (STE). Nos résultats soulignent le rôle clé de la torsion dans le couplage systole – diastole à l’effort. De plus, nos résultats montrent une modification des adaptations mécaniques ventriculaires gauche à l’effort en parallèle à l’amélioration de la fonction diastolique chez les sportifs entrainés en endurance aérobie. Enfin, la dysfonction ventriculaire gauche transitoire observée après un exercice épuisant de longue durée est caractérisée par une diminution et un décalage dans le temps de la torsion, limitant probablement la diminution précoce des pressions intraventriculaires gauche et donc le remplissage. L’ensemble de ces résultats mettent en évidence, d’une part, l’intérêt de l’évaluation par STE de la mécanique ventriculaire gauche au repos et à l’effort, et d’autre part le rôle clé du mécanisme de torsion – détorsion dans l’explication de fonctions diastoliques améliorées ou altérées / During systole, contraction of cardiomyocytes induces left ventricular (LV) strains. Moreover, the helical orientation of myofibers induces LV torsion consequently to LV basal and apical rotations. LV torsion stores energy in elastic component that is released very early in diastole and constitutes a key factor of LV filling. The aims of this thesis were to characterize LV mechanicals adaptations focussing on the role of LV torsion 1) during a progressive exercise test in healthy sedentary subjects, 2) induced by aerobic training at rest and during a progressive exercise test and, 3) concomitant with cardiac dysfunctions after prolonged and strenuous exercise. We used a novel echocardiographic tool, based on Speckle Tracking (STE), in order to evaluate LV function at rest and/or during a progressive exercise test. Our results underlined the key role of LV torsion in systolic – diastolic coupling during exercise. Moreover, our results showed an alteration of LV mechanical adaptation paralleling the enhancement of diastolic function during effort in aerobic trained subjects. At last, transient LV dysfunction after prolonged and strenuous exercise was associated with decreased and delayed LV torsion, probably limiting the early drop of LV intraventricular pressures and thus LV filling. All together, these results underlined the usefulness to evaluate LV mechanics at rest and during effort by STE, and point out the key role of twisting – untwisting mechanism in improved or depressed LV diastolic function

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