Multimodality imaging of aortic coarctation: From the fetus to the adolescent.

Aortic coarctation is a local narrowing of the aortic lumen, which is located at the level of the isthmus in 95% of patients. Aortic coarctation accounts for 5 to 8% of all congenital heart diseases. It may have an acute presentation in the form of heart failure in the neonate or may be discovered incidentally in adult because of severe treatment-resistant hypertension. Ultrasound may reveal the presence of aortic coarctation during the antenatal period. In this situation, associated abnormalities should be investigated (including karyotype), because they influence prognosis and indicates whether or not the birth should occur in a center with pediatric cardiology expertise. Postnatally, ultrasound and chest radiography are the basic imaging work-up. Computed tomography is often the second line imaging investigation in infants and young children for whom magnetic resonance imaging fails to confirm the diagnosis. Magnetic resonance imaging with cardiac synchronization is the preferred imaging tool in the post-treatment period. Aortic coarctation may be treated surgically or by endovascular techniques. Potential complications should be searched for using ultrasound and magnetic resonance imaging.

Detection of pulmonary and coronary artery anomalies in tetralogy of Fallot using non-ECG-gated CT angiography.

OBJECTIVES: To evaluate the use of non-ECG-gated computed tomography (CT) angiography to describe pulmonary and coronary defects in patients with tetralogy of Fallot (TOF). PATIENTS AND METHODS: This retrospective study was carried out on TOF patients having undergone pre-operative non-ECG-gated CT angiography between February 2007 and September 2012. The following clinical parameters were recorded: mean age at CT angiography, sex, the existence of genetic disease and the need to sedate the patient prior to CT angiography. CT data were analyzed retrospectively to determine the site(s) of pulmonary stenosis (infundibular, valvular or arterial), the size of pulmonary arteries and the presence of anomalous coronary artery courses. CT findings were then compared to the anatomy observed during surgery. RESULTS: Thirty-five patients were included in the study. The mean age was 4.30±1.91months (boys/girls=17/18). Two patients had associated chromosome disorders (one 22q11 microdeletion and one CHARGE syndrome). Sixteen patients (45.71%) were sedated prior to CT. Pulmonary artery assessment revealed 24 patients (68.57%) with infundibular stenosis, 5 (17.5%) with infundibular and/or valvular stenosis, and 6 (21%) with anomalous pulmonary arteries. CT angiography also evidenced anomalous coronary arteries in 8 patients (22.85%). CONCLUSION: Due to its reduced scanning time and high spatial resolution, non-ECG-gated CT angiography is a non-invasive imaging modality that provides accurate information on pulmonary and coronary artery anatomy in patients with TOF.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI.

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI.

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

[Kawasaki disease in older children and young adults: 10 years of experience in Marseille, France]. / Maladie de Kawasaki chez le grand enfant et l'adulte jeune : expérience marseillaise sur 10 ans.

Kawasaki disease is a well-known disease in young children. However, it can also affect older children. The aim of this study was to determine the different characteristics of Kawasaki disease in older children and young adults. This is a descriptive, retrospective, and multicenter study including all cases of Kawasaki disease occurring in children over 8 years and adults hospitalized at children's or adult Hospitals, in Marseille, France, between 1999 and 2009. The clinical, biological, prognostic, and therapeutic data were reviewed for each case. Over a 10-year period, 98 patients were hospitalized for Kawasaki disease. Six cases were aged between 8 years and 1 month and 21 years and 7 months. All patients showed a classic form of the disease with associated organ damage in 5 patients. A cardiac problem was present in 5 cases with 2 patients needing intensive care. The median time to diagnosis and treatment was 11.2 days, with all patients initially diagnosed erroneously. Current treatment guidelines were applied in 2 patients. Kawasaki disease in children over 8 years and adults under 30 years has a worse prognosis than in young children even though clinical features are atypical. It is rarely seen by clinicians in this age group, causing a delay in diagnosis, the main factor of the poor prognosis. The diagnosis of Kawasaki disease must be raised when predisposing factors are present in this group.

The low frequency dynamics of supercooled LiBr, 6H2O.

We present results of a series of experiments performed on LiBr, 6H(2)0 from room temperature down to 172 K ≈ 1.2T(g). These ultrasound, Brillouin and depolarized light scattering, and transient grating experiments show that, above 215 K, this solution behaves like supercooled water: its zero frequency sound velocity C(0) continuously decreases with decreasing temperature, and the reorientational dynamics of the water molecules can be directly detected at some temperatures of this domain. Conversely, below 215 K, a new regime sets in, where the apparent C(0) is practically temperature independent and where a ß, Arrenhius like, relaxation process coexists with the usual, Vogel-Fulcher like, α relaxation process of the supercooled liquid. These results are similar to those recently obtained in LiCl, 6H(2)O. The onset of the new regime is possibly due to an increase of the interaction of the water molecules with a neighboring Li(+) ion when lowering the temperature. We also compare our results with published dielectric data on water solutions of glass forming polyalcohols. Some of them present a low temperature splitting of their relaxation time similar to what is found in LiBr, 6H(2)O.

The low frequency phonons dynamics in supercooled LiCl, 6 H2O.

We report the results of a series of ultrasound, Brillouin scattering, and optical heterodyne detected transient grating experiments performed on a LiCl, 6H(2)O solution from room temperature down to the vicinity of its liquid-glass transition, T(g) approximately 138 K. Down to T approximately 215 K, the supercooled liquid has a behavior similar to what is expected for supercooled water: its zero frequency sound velocity, C(0), continuously decreases while the corresponding infinite frequency velocity, C(infinity), sharply increases, reflecting the increasing importance of H bonding when temperature is lowered. Below 215 K, specific aspects of the solution, presumably related to the role of the Li(+) and Cl(-) ions, modify the thermal behavior of C(0), while a beta relaxation process also appears and couples to the sound propagation. The origin of those two effects is briefly discussed.

Velocity of a SAW propagating in a 2D phononic crystal.

We have studied the propagation of a surface acoustic waves (SAW), in a structure constituted by a 2D phononic film (a few micrometers thick and having lattice constants of a few hundreds of micrometers in the two directions of the propagation plane) deposited onto a homogeneous semi-infinite substrate. First, we have calculated the dispersion relations of the acoustic modes by using a plane waves expansion method. We found that the surface branch exhibits both the folding effect and a band gap for the propagation along some particular directions. This is a very interesting result which demonstrates that the effects related to the existence of the band gap (sound velocity dispersion, diffraction, refraction, ultrasound tunneling, etc.) can all appear, even if the thickness of the phononic film is much less than the penetration depth of the SAW. Then, we used an all-optical technique to monitor the spectral content of the SAW propagating along the GammaX direction in the reduced Brillouin zone. We show that a wave with frequency in the stop band, is destructively diffracted after it propagates through less than ten periods. Finally, we report on measurements of the Rayleigh wave phase velocity and we show that the transit time is independent of the distance traveled inside the phononic crystal, suggesting that tunneling trough the sample is involved.

Propagation of guided elastic waves in 2D phononic crystals.

The phononic band structure of two-dimensional phononic guides is numerically studied. A plane wave expansion method is used to calculate the dispersion relations of guided elastic waves in these periodic media, including 2D phononic plates and thin layered periodic arrangements. We show that, for any guided elastic wave, Lamb or generalised Lamb modes, stop bands appear in the dispersion curves, displaying a phononic band structure in both cases.

Surface acoustic waves in the GHz range generated by periodically patterned metallic stripes illuminated by an ultrashort laser pulse.

The photoelastic response of periodic arrays of stripes attached to the surface of a substrate and illuminated by an ultrashort laser pulse were investigated. The samples were gold arrays on silicon and aluminum arrays either on crystalline quartz or on silicon. The metallic stripes had submicrometer lateral dimensions and the spatial periods ranged from about 1 microm up to 5 microm. The substrate being transparent (quartz) or slightly absorbing (silicon) at the laser wavelength (lambda = 750 nm), a laterally modulated thermal stress is generated near the surface of the substrate when a light pulse illuminates the structure. The studies of vibrations involved by the subsequent relaxation processes show that surface acoustic waves at frequency as high as about 5 GHz are excited with the samples consisting of aluminum stripes. In the case of the aluminum samples with the largest lateral spatial periods (aluminum on quartz), the surface acoustic wave propagates outside the illuminated area. In the case of the gold samples, a normal mode of individual bars is observed instead. Experimental evidence shows that these behaviors are mainly governed both by the lateral spatial period of the structure and by the density of the metal.

Experimental studies of the liquid-glass transition in trimethylheptane

The molecular glass former trimethylheptane was studied by calorimetric, dielectric, ultrasonic, neutron scattering, Brillouin scattering, and depolarized light-scattering techniques. The molecular structure appears to be nearly spherical optically as indicated by the low depolarization ratio and dielectric susceptibility values. A preliminary mode-coupling theory (MCT) analysis of the light-scattering and neutron-scattering data indicates that T(C) greater, similar150 K, at least 25 K above T(G). The susceptibility minima were analyzed with the MCT interpolation equation, and disagreement between the light and neutron results was observed despite the apparent isotropy of the molecules.