986 resultados para ULTRASONOGRAFIA DOPPLER - UTLIZACION
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Resumo: Meios de contraste iodado podem promover efeitos hemodinmicos relacionados vasoconstrio intrarrenal prolongada e reduo da perfuso, predispondo hipxia e isquemia medular. Alteraes de resistncia vascular renal podem representar os primeiros sinais de mudana funcional desse rgo. A tcnica Doppler pulsado considerada acessvel, no invasiva e permite avaliar a dinmica vascular dos rins, por meio da aferio dos ndices de resistividade (IR) e pulsatilidade (IP). Contudo, na espcie canina, a aquisio de traados espectrais pode ser penosa devido s dificuldades de varredura e captao de sinal Doppler, sobretudo em relao ao rim direito, devido sua localizao dorsocranial na cavidade abdominal, o que prolonga substancialmente a realizao do exame. O objetivo deste estudo comprovar que a avaliao Doppler pulsado das artrias intrarrenais do rim esquerdo de ces representa a repercusso hemodinmica renal da administrao intravenosa de meios de contraste iodado no sendo necessria a realizao do exame nos dois rins. Foram avaliados ambos os rins de seis cadelas adultas em quatro momentos distintos: antes da infuso intravenosa do contraste radiolgico e aps 1,5 horas, 24 horas e 48 horas, por meio da anlise subjetiva da morfologia, ecogenicidade cortical e grau de perfuso renais e anlise objetiva do comprimento, volume e resistncia vascular intrarrenais (IR e IP). Os parmetros avaliados ao modo B e Doppler dos rins direito e esquerdo no apresentaram diferenas estatisticamente significativas entre si em cada momento avaliado. Assim, constatou-se que o exame ultrassonogrfico Doppler pulsado do rim esquerdo representou a repercusso hemodinmica renal da aplicao intravenosa de meios de contraste iodado, desde que morfometria, morfologia, ecogenicidade cortical e perfuso de ambos os rins fossem consideradas semelhantes na abordagem ultrassonogrfica inicial.
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In this Master Thesis we discuss issues related to the measurement of the effective scattering surface, based on the Doppler Effect. Modeling of the detected signal was made. Narrowband signal filtering using low-frequency amplifier was observed. Parameters of the proposed horn antennas were studied; radar cross section charts for three different objects were received.
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Forty-seven patients with unilateral obstructive calculi (12 males and 35 females) were submitted to 99mTc-diethylene triamine pentaacetic acid (DTPA) or 99mTc-dimercaptosuccinic acid (DMSA) scans for assessment of renal function. The scans revealed unilateral functional deficit in 68 and 66% of the patients, respectively. A calculus size of 1.1 to 2.0 cm was significantly associated with deficit detected by DTPA, but duration of obstruction and calculus localization were not. After relief of the obstruction, the mean percent renal function of the affected kidney was found to be significantly increased from 25 12% to 29 12% in DTPA and from 21 15% to 24 12% in DMSA. Initial Doppler ultrasonography performed in 35 patients detected an increased resistive index in 10 (29%). In the remaining patients with a normal resistive index, ureteral urinary jet was observed, indicating partial obstruction. The high frequency of renal function impairment detected by DTPA and of tubulointerstitial damage detected by DMSA as well as the slight amelioration of unilateral renal function after relief of obstruction suggest that scintigraphy assessment may help evaluate the unilateral percentage of renal function and monitor renal function recovery when it occurs. The presence of a urinary jet detected by Doppler ultrasonography further indicates the severity of obstruction and the recovery prognosis.
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Borderline hypertension (BH) has been associated with an exaggerated blood pressure (BP) response during laboratory stressors. However, the incidence of target organ damage in this condition and its relation to BP hyperreactivity is an unsettled issue. Thus, we assessed the Doppler echocardiographic profile of a group of BH men (N = 36) according to office BP measurements with exaggerated BP in the cycloergometric test. A group of normotensive men (NT, N = 36) with a normal BP response during the cycloergometric test was used as control. To assess vascular function and reactivity, all subjects were submitted to the cold pressor test. Before Doppler echocardiography, the BP profile of all subjects was evaluated by 24-h ambulatory BP monitoring. All subjects from the NT group presented normal monitored levels of BP. In contrast, 19 subjects from the original BH group presented normal monitored BP levels and 17 presented elevated monitored BP levels. In the NT group all Doppler echocardiographic indexes were normal. All subjects from the original BH group presented normal left ventricular mass and geometrical pattern. However, in the subjects with elevated monitored BP levels, fractional shortening was greater, isovolumetric relaxation time longer, and early to late flow velocity ratio was reduced in relation to subjects from the original BH group with normal monitored BP levels (P<0.05). These subjects also presented an exaggerated BP response during the cold pressor test. These results support the notion of an integrated pattern of cardiac and vascular adaptation during the development of hypertension.
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Although echocardiography has been used in rats, few studies have determined its efficacy for estimating myocardial infarct size. Our objective was to estimate the myocardial infarct size, and to evaluate anatomic and functional variables of the left ventricle. Myocardial infarction was produced in 43 female Wistar rats by ligature of the left coronary artery. Echocardiography was performed 5 weeks later to measure left ventricular diameter and transverse area (mean of 3 transverse planes), infarct size (percentage of the arc with infarct on 3 transverse planes), systolic function by the change in fractional area, and diastolic function by mitral inflow parameters. The histologic measurement of myocardial infarction size was similar to the echocardiographic method. Myocardial infarct size ranged from 4.8 to 66.6% when determined by histology and from 5 to 69.8% when determined by echocardiography, with good correlation (r = 0.88; P < 0.05; Pearson correlation coefficient). Left ventricular diameter and mean diastolic transverse area correlated with myocardial infarct size by histology (r = 0.57 and r = 0.78; P < 0.0005). The fractional area change ranged from 28.5 5.6 (large-size myocardial infarction) to 53.1 1.5% (control) and correlated with myocardial infarct size by echocardiography (r = -0.87; P < 0.00001) and histology (r = -0.78; P < 00001). The E/A wave ratio of mitral inflow velocity for animals with large-size myocardial infarction (5.6 2.7) was significantly higher than for all others (control: 1.9 0.1; small-size myocardial infarction: 1.9 0.4; moderate-size myocardial infarction: 2.8 2.3). There was good agreement between echocardiographic and histologic estimates of myocardial infarct size in rats.
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The severity of left ventricular (LV) dysfunction in rats with myocardial infarction (MI) varies widely. Because homogeneity in baseline parameters is essential for experimental investigations, a study was conducted to establish whether Doppler echocardiography (DE) could accurately identify animals with high LV end-diastolic pressure as a marker of LV dysfunction soon after MI. Direct measurements of LV end-diastolic pressure were made and DE was performed simultaneously 1 week after surgically induced MI (N = 16) or sham-operation (N = 17) in female Wistar rats (200 to 250 g). The ratio of peak early (E) to late (A) diastolic LV filling velocities and the ratio of E velocity to peak early (Em) diastolic myocardial velocity were the best predictors of high LV end-diastolic pressure (>12 mmHg) soon after MI. Cut-off values of 1.77 for the E/A ratio (P = 0.001) identified rats with elevated LV end-diastolic pressure with 90% sensitivity and 80% specificity. Cut-off values of 20.4 for the E/Em ratio (P = 0.0001) identified rats with elevated LV end-diastolic pressure with 81.8% sensitivity and 80% specificity. Moreover, E/A and E/Em ratios were the only echocardiographic parameters independently associated with LV end-diastolic pressure in multiple linear regression analysis. Therefore, DE identifies rats with high LV end-diastolic pressure soon after MI. These findings have implications for using serial DE in animal selection and in the assessment of their response to experimental therapies.
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This study examined factors contributing to the differences in left ventricular mass as measured by Doppler echocardiography in children. Fourteen boys (10.3 0.3 years of age) and 1 1 girls (10.5 0.4 years of age) participated in the study. Height and weight were measured, and relative body fat was determined from the measurement of skinfold thickness according to Slaughter et al. (1988). Lean Body Mass was then calculated by subtracting the fat mass from the total body mass. Sexual maturation was self-assessed using the stages of sexual maturation by Tanner (1962). Both pubic hair development and genital (penis or breast for boys and girls respectively) development were used to determine sexual maturation. Carotid Pulse pressure was assessed by applanation tomometry in the left carotid artery. Cardiac mass was measured by Doppler Echocardiography. Images of cardiac structures were taken using B-Mode and were then translated to M- Mode. The dimensions at the end diastole were obtained at the onset of the QRS complex of the electrocardiogram in a plane through a standard position. Measurements included: (a) the diameter of the left ventricle at the end diastole was measured from the septum edge to the endocardium mean border, (b) the posterior wall was measured as the distance from to anterior wall to the epicardium surface, and (c) the interventricular septum was quantified as the distance from the surface of the left ventricle border to the right ventricle septum surface. Systolic time measurements were taken at the peak of the T-wave of the electrocardiogram. Each measurement was taken three to five times before averaging. Average values were used to calculate cardiac mass using the following equation (Deveraux et al. 1986). Weekly physical activity metabolic equivalent was calculated using a standardize activity questionnaire (Godin and Shepard, 1985) and peakV02 was measured on a cycloergometer. There were no significant differences in cardiovascular mesurements between boys and girls. Left ventricular mass was correlated (p<0.05) with size, maturation, peakV02 and physical activity metabolic equivalent. In boys, lean body mass alone explained 36% of the variance in left ventricular mass while weight was the single strongest predictor of left ventricular mass (R =0.80) in girls. Lean body mass, genital developemnt and physical activity metabolic equivalent together explained 46% and 81% in boys and girls, respectively. However, the combination of lean body mass, genital development and peakV02 (ml kgLBM^ min"') explained up to 84% of the variance in left ventricular mass in girls, but added nothing in boys. It is concluded that left ventricular mass was not statistically different between pre-adolescent boys and girls suggesting that hormonal, and therefore, body size changes in adolescence have a main effect on cardiac development and its final outcome. Although body size parameters were the strongest correlates of left ventricular mass in this pre-adolescent group of children, to our knowledge, this is the first study to report that sexual maturation, as well as physical activity and fitness, are also strong associated with left ventricular mass in pre-adolescents, especially young females. Arterial variables, such as systolic blood pressure and carotid pulse pressure, are not strong determinants of left ventricular mass in this pre-adolescent group. In general, these data suggest that although there is no gender differences in the absolute values of left ventricular mass, as children grow, the factors that determine cardiac mass differ between the genders, even in the same pre-adolescent age.
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Objectif: valuer l'efficacit du dpistage de lhypertension gestationnelle par les caractristiques dmographiques maternelles, les biomarqueurs sriques et le Doppler de l'artre utrine au premier et au deuxime trimestre de grossesse. laborer des modles prdictifs de lhypertension gestationnelle fondes sur ces paramtres. Methods: Il s'agit d'une tude prospective de cohorte incluant 598 femmes nullipares. Le Doppler utrin a t tudi par chographie transabdominale entre 11 +0 13 +6 semaines (1er trimestre) et entre 17 +0 21 +6 semaines (2e trimestre). Tous les chantillons de srum pour la mesure de plusieurs biomarqueurs placentaires ont t recueillis au 1er trimestre. Les caractristiques dmographiques maternelles ont t enregistres en mme temps. Des courbes ROC et les valeurs prdictives ont t utiliss pour analyser la puissance prdictive des paramtres ci-dessus. Diffrentes combinaisons et leurs modles de rgression logistique ont t galement analyss. Rsultats: Parmi 598 femmes, on a observ 20 pr-clampsies (3,3%), 7 pr-clampsies prcoces (1,2%), 52 cas dhypertension gestationnelle (8,7%) , 10 cas dhypertension gestationnelle avant 37 semaines (1,7%). Lindex de pulsatilit des artres utrines au 2e trimestre est le meilleur prdicteur. En analyse de rgression logistique multivarie, la meilleure valeur prdictive au 1er et au 2e trimestre a t obtenue pour la prvision de la pr-clampsie prcoce. Le dpistage combin a montr des rsultats nettement meilleurs compars avec les paramtres maternels ou Doppler seuls. Conclusion: Comme seul marqueur, le Doppler utrin du deuxime trimestre a la meilleure prdictive pour l'hypertension, la naissance prmature et la restriction de croissance. La combinaison des caractristiques dmographiques maternelles, des biomarqueurs sriques maternels et du Doppler utrin amliore l'efficacit du dpistage, en particulier pour la pr-clampsie ncessitant un accouchement prmatur.
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La dbitmtrie au laser effet Doppler (LDF) constitue une mthode prometteuse et non-invasive pour l'tude du dbit sanguin local dans l'il. Cette technique est base sur un changement de frquence subi par la lumire lors du mouvement des globules rouges dans les vaisseaux. Une nouvelle sonde LDF a t teste pour sa sensibilit valuer la circulation rtinienne/chorodienne sous des conditions hypercapniques et en prsence de diverses substances vasoactives ou suivant la photocoagulation des artres rtiniennes chez le rat. Aprs dilatation pupillaire, la sonde LDF a t place en contact avec la corne de rats anesthsis et parallle l'axe optique. L'hypercapnie a t provoque par inhalation de CO2 (8% dans de l'air mdical), alors que les agents pharmacologiques ont t injects de faon intravitrenne. La contribution relative la circulation chorodienne a t value la suite de la photocoagulation des artres rtiniennes. Le dbit sanguin s'est trouv significativement augment la suite de l'hypercanie (19%), de l'adnosine (14%) ou du nitroprusside de sodium (16%) comparativement au niveau de base, alors que l'endothline-1 a provoqu une baisse du dbit sanguin (11%). La photocoagulation des artres rtiniennes a significativement diminu le dbit sanguin (33%). Des mesures en conditions pathologiques ont ensuite t obtenues aprs l'injection intravitrenne d'un agoniste slectif du rcepteur B1 (RB1). Ce rcepteur des kinines est surexprim dans la rtine des rats rendus diabtiques avec la streptozotocine (STZ) en rponse l'hyperglycmie et au stress oxydatif. Les rsultats ont montr que le RB1 est surexprim dans la rtine chez les rats diabtiques-STZ 4 jours et 6 semaines. ces moments, le dbit sanguin rtinien/chorodien a t significativement augment (15 et 18 %) aprs l'injection de l'agoniste, suggrant un effet vasodilatateur des RB1 dans l'il diabtique. Bien que la circulation chorodienne contribue probablement au signal LDF, les rsultats dmontrent que le LDF reprsente une technique efficace et non-invasive pour l'tude de la microcirculation rtinienne in-vivo en continu. Cette mthode peut donc tre utilise pour valuer de faon rpte les rponses du dbit sanguin pendant des modifications mtaboliques ou pharmacologiques dans des modles animaux de maladies oculaires.
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En dpit du nombre croissant dtudes cliniques sur le canal artriel (CA), des failles mthodologiques entretiennent plusieurs incertitudes concernant lefficacit et la scurit des traitements chez les bbs ns prmaturs. Lobjectif de cette recherche tait de comparer les concentrations de prostaglandine E2 (PGE2) et les mesures du flux msentrique par chographie Doppler chez les enfants ns prmaturment et ayant un canal artriel trait libuprofne par voie intraveineuse ou entrale, en utilisant la mthodologie randomise contrle et double insu. Dans notre tude pilote, 20 nouveau-ns prmaturs de moins de 34 semaines ayant un CA symptomatique confirm par chocardiographie, furent randomiss au traitement libuprofne par voie intraveineuse ou entrale. La voie dadministration fut maintenue linsu de lquipe traitante, des cardiologues et des investigateurs. Des dosages des prostaglandines plasmatiques ont t mesurs avant le dbut du traitement ainsi que 3, 24 et 48 h aprs le dbut du traitement. Les mesures du flux msentrique ont t effectues avant le traitement libuprofne ainsi que 1 h et 3 h aprs le traitement. Nous avons dmontr partir de nos observations que les niveaux plasmatiques de prostaglandines E2 diminuent chez les patients ayant rpondu au traitement libuprofne, indpendamment de la voie dadministration. Nous navons pas observ de changement dans lvolution des dosages de PGE2 chez les patients qui nont pas rpondu au traitement. Les paramtres mesurs par chographie Doppler au niveau de lartre msentrique suprieure ntaient pas affects par la voie dadministration du traitement libuprofne, intraveineuse ou entrale. La prsente tude suggre ainsi que le traitement du CA par ibuprofne intraveineux ou entral ninflue pas sur le flux sanguin mesur par chographie Doppler. La baisse de la prostaglandine E2 concide avec la fermeture du CA, et son dosage pourrait jouer un rle dans la gestion du traitement. Nous avons dmontr la faisabilit dune tude clinique randomise double insu dans le traitement du canal artriel; une mthodologie qui devrait dsormait tre employ dans la recherche clinique sur les traitements de la persistance du CA.
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Nous proposons une nouvelle mthode pour quantifier la vorticit intracardiaque (vortographie Doppler), base sur limagerie Doppler conventionnelle. Afin de caractriser les vortex, nous utilisons un indice dnomm Blood Vortex Signature (BVS) (Signature Tourbillonnaire Sanguine) obtenu par lapplication dun filtre par noyau bas sur la covariance. La validation de lindice BVS mesur par vortographie Doppler a t ralise partir de champs Doppler issus de simulations et dexpriences in vitro. Des rsultats prliminaires obtenus chez des sujets sains et des patients atteints de complications cardiaques sont galement prsents dans ce mmoire. Des corrlations significatives ont t observes entre la vorticit estime par vortographie Doppler et la mthode de rfrence (in silico: r2 = 0.98, in vitro: r2 = 0.86). Nos rsultats suggrent que la vortographie Doppler est une technique dchographie cardiaque prometteuse pour quantifier les vortex intracardiaques. Cet outil dvaluation pourrait tre aisment appliqu en routine clinique pour dtecter la prsence dune insuffisance ventriculaire et valuer la fonction diastolique par chocardiographie Doppler.
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Using Doppler-free two-photon absorption spectroscopy, we have measured hyperfine splitting constants as well as isotopic level shifts of the 6s^2 np ^2 P_l/2,3/2 states in (n=7-10) in ^203 TI and ^205 TI. Calculations for hyperfine constants and electron density at the nucleus have been performed by the Dirac-Fock method. The experimental results are compared with these calculations as well as with the predictions of the semiempirical theory.
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Introduccin: El sndrome ictrico es una aproximacin diagnostica que rene distintos signos y sntomas. Dependiendo de su etiologa tiene como alternativa teraputica la realizacin de una colangiopancreatografa retrgrada endoscpica (CPRE), procedimiento invasivo, que tiene riesgos de morbilidad y mortalidad por esta razn su realizacin debe ser exclusivamente teraputica y no diagnostica para lo que se requiere estudios diagnsticos previos certeros. Es importante estudiar si la ecografa hepatobiliar adecuada para detectar signos de patologa ictrica obstructiva, puesto que en nuestro entorno, el ultrasonido determina la posible realizacin de una prueba invasiva, como es la CPRE. El objetivo del estudio es determinar la correlacin existente entre los hallazgos de la va biliar encontrados en la ultrasonografa hepatobiliar y los de la CPRE realizadas en el Hospital Departamental Universitario de la Samaritana (HUS), Bogot durante el periodo comprendido entre el 01.03.05 y 01.11.07 Materiales y Mtodo: Estudio de concordancia de pruebas diagnsticas retrospectivo. Mediante un cuestionario cerrado se recolecto la informacin relacionada con las caractersticas del paciente, hallazgos del ultrasonido hepatobiliar y reporte de CPRE. Se calcularon los valores de sensibilidad, especificidad y valores predictivos de la ultrasonografa hepatobiliar previa al CPRE. Se utiliz la razn de verosimilitud (RV) como indicador del desempeo del test diagnstico. El programa para el anlisis de datos usado fue EPIDAT versin 3.1. (Programa de acceso gratuito de la Xunta de Galicia, Espaa y la Organizacin Panamericana de la Salud (OPS)). Resultados: Durante el perodo de estudio, 457 pacientes fueron llevados a CPRE, de los cuales, 271 cumplieron los criterios de inclusin, la ecografa hepatobiliar para el diagnostico de va biliar dilatada tiene una sensibilidad del 66.5% (IC 95%: 60.2 -72.5) y una especificidad del 65.6% (IC 95%: 46.8 81.4), con un cociente de probabilidad negativo del 49% , para el diagnostico de coledocolitiasis una sensibilidad del 25.6% (IC 95%: 18.4 33.9) con una especificidad del 87.7% (IC 95%: 81.0 92.7). En conclusin, el estudio confirma en nuestro medio que la ecografa hepatobiliar tiene una baja sensibilidad y especificidad para el diagnostico de sndrome biliar obstructivo y coledocolitiasis y existe una baja concordancia entre los hallazgos de la ecografa hepatobiliar y la CPRE.
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La placenta creta es la implantacin anmala de la placenta en la pared uterina. Se presenta en 0.9% de todos los embarazos; actualmente es una de las causas ms importantes de morbimortalidad materna. Ecografa 2D y Doppler placentario son mtodos diagnsticos de primera y segunda lnea. Objetivo: Evaluar la utilidad diagnstica de ecogrfica 2D y Doppler color Placentario para diagnstico de acretismo placentario en gestantes con factores de riesgo comparndolos con diagnstico clnico e histopatolgico; y determinar incidencia de acretismo placentario en poblacin asistente a Clnica Universitaria Colombia. Metodologa: Estudio de evaluacin de tecnologa diagnstica. Entre Agosto a Noviembre de 2010 se incluyeron 53 gestantes entre 24 y 40 semanas de gestacin con factores de riesgo para acretismo placentario. El desempeo diagnstico de las pruebas se determinar por sensibilidad, especificidad, valores predictivos positivo y negativo. Las caractersticas demogrficas de las pacientes y resultados neonatales se analizaron mediante proporcin, media y rango. Resultados: Se determin incidencia de acretismo placentario en 4,54% de las gestantes con presencia de factores de riesgo para esta patologa. Los datos hasta el momento no nos permiten calcular valores de desempeo diagnstico. Un caso termino en histerectoma por acretismo placentario. Conclusin: Con los datos preliminares registramos una incidencia de acretismo placentario de 1 en 22 pacientes. Revisin de literatura sustenta la necesidad de realizacin diagnostica prenatal que impacte en la morbimortalidad materna y fetal, haciendo necesario la evaluacin diagnostica valida de herramientas como el Eco 2D y Doppler color en poblacin a riesgo.
