Automated function imaging: a new operator-independent strain method for assessing left ventricular function.

BACKGROUND: Speckle tracking is a new technique based on pure 2D grayscale ultrasound acquisition allowing calculation of segmental strains. To facilitate clinical application, speckle tracking has been integrated into the most recent echocardiographic systems for quick, automated evaluation of left ventricular function (Automated Function Imaging, AFI). OBJECTIVE: To evaluate the feasibility, calculation time, accuracy and reproducibility of global longitudinal strain (GLS) from AFI in determining LV function in comparison to reference echocardiographic and angiographic methods-whatever the operator's experience. METHODS: Echocardiography was performed in 65 patients scheduled for cardiac catheterization using a Vivid 7 system. They were divided into 3 groups according to EF (>55%, 35< or =EF< or =55%,<35%). Image quality, global LV function parameters (ejection fraction, aortic flow, dp/dt) and segmental contraction were analyzed by one experienced operator and one beginner. GLS was obtained from apical 2, 3 and 4 chamber views. GLS was compared to both echocardiographic and angiographic EF, as well as to other echocardiographic parameters. RESULTS: GLS was obtained successfully in 97% of patients. Mean calculation time including correction of endocardial detection was less than 60 seconds. GLS was significantly different between the 3 groups, respectively -18.1+/-2.5%, -11.5+/-2.1% and -6.0+/-1.2% (p<0.01). Strong correlations were observed between GLS and LV function (r from 0.68 to 0.87) with a high level of reproducibility. No difference was observed between experienced and inexperienced operators. CONCLUSION: AFI is clinically applicable and an effective means of assessing LV function due to its short acquisition time, feasibility and accuracy, whatever the experience of the operator.

[Exercise test in athletes]. / Epreuves d'effort chez les sportifs.

The particularities of exercise tests in athletes concern mainly the exertion protocols adapted to their increased physical capacities and the interpretation of ECG tracing which can sometimes be very special at rest and also misleading during exercise. In the great majority of cases, the test used is both cardiac and pulmonary, in order to assess the aerobic capacities, the maximal aerobic power, and the determination of ventilation thresholds (programming and follow-up of training...). More infrequently, the test is used to detect cardiovascular diseases, especially during a longitudinal follow-up of high-level athletes, or to exclude it in case of cardiovascular symptoms, atypical resting ECG or even in case of suspicion of disease (arrhythmia, cardiac chamber hypertrophy or dilation at echocardiography). In more aged sportsmen (athletes masters), exercise tests performed are usually required for screening coronary heart disease. In this case the test protocols should be more adapted for screening than for the assessment of sportive capacities.

Radiation-induced peroxidation of small unilamellar vesicles of phosphatidylcholine generated by sonication.

The present study was aimed at determining the peroxidation of model membranes constituted of liposomes of 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (PLPC) submitted to hydroxyl free radicals (generated by gamma-radiolysis) attack. Liposomes of PLPC were prepared using the sonication technique, and dynamic light-scattering (DLS) measurements allowed characterization of the liposomal dispersions. Irradiation damages in sonication-generated liposomes were assessed by monitoring several oxidation products, such as conjugated dienes (by means of UV--visible spectrophotometry) and hydroperoxides (using reverse phase high-performance liquid chromatography (HPLC) associated with chemiluminescence detection). It has been shown that three different families of hydroperoxides are formed: the first one (at low radiation doses) results from HO. attack on the linoleyl chain of PLPC, giving phosphatidylcholine hydroperoxides possessing a conjugated dienic structure; the two others (at high radiation doses) are obtained by the secondary HO. attack on the primary hydroperoxide family. The quantification of these products associated with the comparison of their radiation-dose-dependent formation has provided valuable information concerning the mechanisms of their formation. Analysis by HPLC -- mass spectrometry has confirmed the presence of hydroperoxides and underlined various other products, like chain-shortened fragments and oxygenated derivatives of polyunsaturated sn-2 fatty acyl chain residues. Structural assignment proposals of some oxidation products have been proposed.