35 research outputs found
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Validation of Noninvasive Measurements of Cardiac Output in Mice Using Echocardiography
Although multiple echocardiographic methods exist to calculate cardiac output (CO), they have not been validated in mice using a reference method. Echocardiographic and flow probe measurements of CO were obtained in mice before and after albumin infusion and inferior vena cava occlusions. Echocardiography was also performed before and after endotoxin injection. Cardiac output was calculated using LV volumes obtained from a M Mode or a 2D view, LV stroke volume calculated using the pulmonary flow, or estimated using pulmonary VTI. Close correlations were demonstrated between flow probe-measured CO and all echocardiographic measurements of CO. All echocardiographic-derived CO overestimated the flow-probe measured CO. 2D images-derived CO was associated with the smallest overestimation of CO. Interobserver variability was lowest for pulmonary VTI derived CO. In mice, CO calculated from 2D parasternal long axis images is most accurate when compared to flow probe measurements, however, pulmonary VTI-derived CO is subject to less variability
Méthode d'évaluation de l'asynchronisme mécanique chez les insuffisants cardiaques systoliques par l'étude du rocking ventriculaire en IRM
L'asynchronisme mécanique produit un mouvement caractéristique de rocking du ventricule gauche (VG) autour de son petit axe mais dont la mesure objective reste difficile. Objectifs: 1) développer une nouvelle méthode de mesure de ce rocking à partir d'une IRM cardiaque 2) étudier ce paramètre chez des insuffisants cardiaques (le) et 3) évaluer l'impact du rocking sur l'évolution de l'IC. Méthodes: La mesure du rocking a été mise au point à partir d'images d'IRM taggées 4-cavités puis rétrospectivement étudiée sur une population d'IC. Les résultats ont été confrontés aux caractéristiques des patients ainsi qu'à l'évolution de leur cardiopathie. Résultats: Les IRMs de 54 patients ont été analysées rétrospectivement. Le rocking moyen du VG était de 2,6+-1,6 et positivement corrélé avec l'asynchronisme électrique et le sexe féminin (P<O,05) mais pas avec la fibrose myocardique ou la fonction ventriculaire droite. L'absence de rocking était associée à 3-6 mois à une meilleure augmentation de FEVG. Conclusions: Le rocking ventriculaire est mesurable en IRM cardiaque et pourrait impacter l'évolution d'une cardiopathie.PARIS13-BU Serge Lebovici (930082101) / SudocSudocFranceF
Impact cardio-vasculaire de l entraînement au marathon chez des sportifs amateurs
PARIS7-Xavier Bichat (751182101) / SudocSudocFranceF
Evaluation en échocardiographie d'effort de l'asynchronisme cardiaque dans les cardiomyopathies dilatées hypokinétiques
PARIS-BIUM (751062103) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF
Comment évaluer et traiter l'insuffisance cardiaque à fraction d'éjection préservée
L'insuffisance cardiaque à fraction d'éjection préservée est
une définition qui remplace l'insuffisance cardiaque diastolique. Elle
est aujourd'hui la forme la plus fréquente des formes d'insuffisance
cardiaque du fait du vieillissement de la population. Son pronostic semble
être proche de celui de l'insuffisance cardiaque à fonction
systolique altérée. Le diagnostic s'aide de l'écho doppler
cardiaque et du dosage du peptide natriurétique de type B. À ce jour,
aucun traitement n'a fait la preuve de son efficacité mais les essais
thérapeutiques ont été rares à ce jour. Les bloqueurs du
système rénine-angiotensine, qui apparaissaient prometteurs, n'ont
pas démontré leur efficacité. Cette revue reprend les aspects
épidémiologiques, diagnostiques, physiopathologiques et
thérapeutiques de cette affection
A Dual Tissue-Doppler Optical-Flow Method for Speckle Tracking Echocardiography at High Frame Rate
International audienc
Coupling myocardium and vortex dynamics in diverging-wave echocardiography
International audienc
High-Frame-Rate Echocardiography Using Coherent Compounding With Doppler-Based Motion-Compensation
International audience—High-frame-rate ultrasonography based on coherent compounding of unfocused beams can potentially transform the assessment of cardiac function. As it requires successive waves to be combined coherently, this approach is sensitive to high-velocity tissue motion. We investigated coherent compounding of tilted diverging waves, emitted from a 2.5 MHz clinical phased array transducer. To cope with high myocardial velocities, a triangle transmit sequence of diverging waves is proposed, combined with tissue Doppler imaging to perform motion compensation (MoCo). The compound sequence with integrated MoCo was adjusted from simulations and was tested in vitro and in vivo. Realistic myocardial velocities were analyzed in an in vitro spinning disk with anechoic cysts. While a 8 dB decrease (no motion versus high motion) was observed without MoCo, the contrast-to-noise ratio of the cysts was preserved with the MoCo approach. With this method, we could provide high-quality in vivo B-mode cardiac images with tissue Doppler at 250 frames per second. Although the septum and the anterior mitral leaflet were poorly apparent without MoCo, they became well perceptible and well contrasted with MoCo. The septal and lateral mitral annulus velocities determined by tissue Doppler were concordant with those measured by pulsed-wave Doppler with a clinical scanner. To conclude, high-contrast echo-Manuscrip
Staggered Multiple-PRF Ultrafast Color Doppler
International audienceColor Doppler imaging is an established pulsed ultrasound technique to visualize blood flow non-invasively. High-frame-rate (ultrafast) color Doppler, by emissions of plane or circular wavefronts, allows severalfold increase in frame rates. Conventional and ultrafast color Doppler are both limited by the range-velocity dilemma, which may result in velocity folding (aliasing) for large depths and/or large velocities. We investigated multiple pulse-repetition-frequency (PRF) emissions arranged in a series of staggered intervals to remove aliasing in ultrafast color Doppler. Staggered PRF is an emission process where time delays between successive pulse transmissions change in an alternating way. We tested staggered dual-and triple-PRF ultrafast color Doppler, 1) in vitro in a spinning disc and a free jet flow, and 2) in vivo in a human left ventricle. The in vitro results showed that the Nyquist velocity could be extended to up to 6 times the conventional limit. We found coefficients of determination between the de-aliased and ground-truth velocities. Consistent de-aliased Doppler images were also obtained in the human left heart. Our results demonstrate that staggered multiple -PRF ultrafast color Doppler is efficient for high-velocity high-frame-rate blood flow imaging. This is particularly relevant for new developments in ultrasound imaging relying on accurate velocity measurements. Index Terms—De-aliasing, Nyquist velocity extension, staggered multiple-PRF, ultrafast color Doppler