Manejo del neonato con coartación de aorta e hipoplasia de arco

ResumenIntroducciónLa coartación aórtica del neonato puede asociar en un porcentaje importante hipoplasia del arco aórtico, llegando en algunas series al 60%.Cuando existe hipoplasia del arco aórtico distal el tratamiento estándar consiste en la resección de la zona de coartación y anastomosis termino-terminal extendida.En casos de hipoplasia severa del arco aórtico distal y arco distal largo, podría no ser suficiente con la resección y anastomosis termino-terminal extendida, por lo que sería razonable realizar alguna técnica adicional para ampliar el arco aórtico distal, evitando así un abordaje anterior, el uso de parada circulatoria con o sin perfusión cerebral selectiva y el aumento de la morbimortalidad perioperatoria.MétodosPresentamos los resultados de 4 neonatos, a los que se les realizó una ampliación del arco aórtico distal, según técnica de Amato (anastomosis latero-lateral entre las arterias carótida y subclavia izquierdas), para posteriormente resecar la zona de coartación y anastomosar la aorta descendente al arco aórtico previamente ampliado.ResultadosEn todos los casos el ecocardiograma postoperatorio mostró arco reconstruido con flujo laminar. No se ha presentado ningún caso de recoartación durante un período de seguimiento medio de 12 meses.ConclusiónConsideramos que la técnica de elección en la coartación con hipoplasia de arco distal es la resección y anastomosis termino-terminal extendida.En casos seleccionados, con arco aórtico distal muy largo y severamente hipoplásico, la técnica de Amato es una alternativa atractiva, con el objeto de evitar un abordaje anterior y el uso de CEC. Además, puede realizarse en un primer tiempo, manteniendo perfusión sistémica ductus-dependiente.AbstractIntroductionNeonatal aortic coarctation can be combined with a significant percentage of aortic arch hypoplasia, reaching 60% in some series.When there is hypoplasia of the distal aortic arch, the standard treatment consists of resection of the coarctation zone and extended end-to-end anastomosis.In cases of severe distal aortic arch hypoplasia and a long distal arch, resection and extended end-to-end anastomosis would not be sufficient, making it reasonable to perform an additional technique to widen the distal aortic arch, thus avoiding an anterior approach and interrupting the blood circulation with or without selective cerebral infusion, with the resulting risk of an increase in perioperative morbidity and mortality.MethodsThe results are presented on 4 neonates on whom a widening of the distal aortic arch was performed using the Amato technique (side-to-side anastomosis between the left carotid and subclavian arteries), in order to subsequently resect the coarctation zone and perform an anastomosis of the descending aorta to the previously widened aortic arch.ResultsThe post-operative echocardiogram showed a reconstructed arch with laminar flow in all cases. There has been no recurrence of coarctation in any of the cases during a mean follow-up of 12 months.ConclusionWe believe that resection with extended end-to-end anastomosis is the technique of choice in coarctation with distal arch hypoplasia.The Amato technique is an attractive alternative in selected cases with a very long and severely hypoplastic distal arch, with the aim of avoiding an anterior approach and the use of extracorporeal circulation. This could also be performed initially, maintaining ductal-dependent systemic perfusion

Ingeniería de tejidos: aplicaciones en el diseño de implantes cardiovasculares

The development of biodegradable grafts for Cardiovascular Surgery by Tissue Engineering techniques is at present a promising research field in Biomedical research for repairing both congenital and acquired cardiovascular diseases in neonatal and adult patients. These grafts should be constituted by a suitable biodegradable material covered with cultured cells that allows a progressive and complete substitution of the damaged tissue. The design and preparation of functional biodegradable grafts requires a multidisciplinary approach and a coordinated research in Cardiovascular Surgery, Biomaterials, Biochemistry, Cell Biology and Bioengineering fields. The biomedical research groups of the Universidad Complutense (UCM), Rey Juan Carlos (URJC), Politécnica (UPM) and the Instituto Pediátrico del Corazón (IPC) – Cirugía Cardiaca Infantil of the Hospital Universitario «12 de Octubre» de Madrid, develop a multidisciplinar coordinated project for obtaining autologue, non trombogenic and biodegradable grafts, by Tissue Engineering techniques, that fulfill specific characteristics, from the point of view of scaffold’s adequacy, biochemical function and mechanical resistance to the usual surgical techniques with growth capacity in agreement with the patient development avoiding the successive operations that are necessary nowadays when artificial prosthesis are used. The biopolymer poli(å-caprolactona) (PCL), modified to improve the cell adhesion and proliferation, has been selected as scaffold for culturing different cells (endothelial, vascular smooth muscle, HUVEC and mesenchymal cells) carrying out in vitro biocompatibility, biofunctionality studies and mechanical assays to evaluate the grafts’ viability.El desarrollo de implantes biodegradables para Cirugía Cardiovascular mediante Ingeniería de tejidos es una de las áreas actualmente más prometedoras dentro de la investigación Biomédica para reparar patologías cardiovasculares congénitas o adquiridas en pacientes neonatos y adultos. Estos implantes deberan estar formados por un material biodegradable adecuado recubierto de celulas cultivadas que permitan una sustitucion progresiva y completa del tejido danado. El diseno y la obtencion de implantes biodegradables funcionales requiere una aproximacion multidisciplinar y una investigacion coordinada en las areas de Cirugia Cardiovascular, Biomateriales, Bioquimica, Biologia Celular y Bioingenieria. Los grupos de investigacion Biomedica de las Universidades Complutense (UCM), Rey Juan Carlos (URJC), Politecnica (UPM) y el Instituto Pediatrico del Corazon (IPC) - Cirugia Cardiaca Infantil del Hospital Universitario á12 de Octubre â de Madrid, desarrollan un proyecto coordinado y multidisciplinar para la obtencion de implantes biodegradables autologos y no trombogenicos, mediante tecnicas de Ingenieria de tejidos, que puedan cumplir todas las caracteristicas requeridas desde el punto de vista de adecuacion del soporte, funcionalidad bioquimica y resistencia mecanica a las tecnicas quirurgicas habituales y que presenten una capacidad de crecimiento acorde con el desarrollo del paciente, evitando las reoperaciones que se requieren en la actualidad al utilizar protesis artificiales. El biopolimero poli(ƒÃ-caprolactona) (PCL), modificado para mejorar la adhesion y proliferacion celular, se ha seleccionado como soporte para el cultivo de distintas poblaciones celulares (endotelio, musculo liso vascular, HUVEC y celulas mesenquimales) realizandose estudios de biocompatibilidad, biofuncionalidad in vitro y pruebas de resistencia mecanica para comprobar la viabilidad de los bioimplantes

Surgery for complications of trans-catheter closure of atrial septal defects: a multi-institutional study from the European Congenital Heart Surgeons Association

Objective: This study aims to analyse the collective experience of participating European Congenital Heart Surgeons Association centres in the surgical management of complications resulting from trans-catheter closure of atrial septal defects (ASDs). Methods: The records of all (n=56) patients, aged 3-70 years (median 18 years), who underwent surgery for complications of trans-catheter ASD closure in 19 participating institutions over a 10-year period (1997-2007) were retrospectively reviewed. Risk factors for surgical complications were sought. Surgical outcomes were compared with those reported for primary surgical ASD closure in the European Association of Cardio-thoracic Surgery Congenital Database. Results: A wide range of ASD sizes (5-34mm) and devices of various types and sizes (range 12-60mm) were involved, including 13 devices less than 20mm. Complications leading to surgery included embolisation (n=29), thrombosis/thrombo-embolism/cerebral ischaemia or stroke (n=12), significant residual shunt (n=12), aortic or atrial perforation or erosion (n=9), haemopericardium with tamponade (n=5), aortic or mitral valve injury (n=2) and endocarditis (n=1). Surgery (39 early emergent and 17 late operations) involved device removal, repair of damaged structures and ASD closure. Late operations were needed 12 days to 8 years (median 3 years) after device implantation. There were three hospital deaths (mortality 5.4%). During the same time period, mortality for all 4453 surgical ASD closures reported in the European Association of Cardio-Thoracic Surgery Congenital Database was 0.36% (p=0.001). Conclusions: Trans-catheter device closure of ASDs, even in cases when small devices are used, can lead to significant complications requiring surgical intervention. Once a complication leading to surgery occurs, mortality is significantly greater than that of primary surgical ASD closure. Major complications can occur late after device placement. Therefore, lifelong follow-up of patients in whom ASDs have been closed by devices is mandator

Understanding the complex geomorphology of a deep sea area affected by continental tectonic indentation: the case of the Gulf of Vera (Western Mediterranean)

We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The inden tation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plain

Expected Performances of the NOMAD/ExoMars instrument

NOMAD (Nadir and Occultation for MArs Discovery) is one of the four instruments on board the ExoMars Trace Gas Orbiter, scheduled for launch in March 2016. It consists of a suite of three high-resolution spectrometers – SO (Solar Occultation), LNO (Limb, Nadir and Occultation) and UVIS (Ultraviolet and Visible Spectrometer). Based upon the characteristics of the channels and the values of Signal-to-Noise Ratio obtained from radiometric models discussed in [Vandaele et al., Optics Express, 2015] and [Thomas et al., Optics Express, 2015], the expected performances of the instrument in terms of sensitivity to detection have been investigated. The analysis led to the determination of detection limits for 18 molecules, namely CO, H2O, HDO, C2H2, C2H4, C2H6, H2CO, CH4, SO2, H2S, HCl, HCN, HO2, NH3, N2O, NO2, OCS, O3. NOMAD should have the ability to measure methane concentrations <25 parts per trillion (ppt) in solar occultation mode, and 11 parts per billion in nadir mode. Occultation detections as low as 10 ppt could be made if spectra are averaged [Drummond et al., Planetary Space and Science, 2011]. Results have been obtained for all three channels in nadir and in solar occultation

Polarized blazar X-rays imply particle acceleration in shocks

Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization—the only range available until now—probe extended regions of the jet containing particles that left the acceleration site days to years earlier1,2,3, and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree ΠX of around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally

Martian dust storm impact on atmospheric H₂O and D/H observed by ExoMars Trace Gas Orbiter

Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere

Water Vapor Vertical Profiles on Mars in Dust Storms Observed by TGO/NOMAD

It has been suggested that dust storms efficiently transport water vapor from the near‐surface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to mid‐September 2018) and a regional storm (January 2019). Here we present water vapor vertical profiles in the periods of the two dust storms (Ls = 162–260° and Ls = 298–345°) from the solar occultation measurements by Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). We show a significant increase of water vapor abundance in the middle atmosphere (40–100 km) during the global dust storm. The water enhancement rapidly occurs following the onset of the storm (Ls~190°) and has a peak at the most active period (Ls~200°). Water vapor reaches very high altitudes (up to 100 km) with a volume mixing ratio of ~50 ppm. The water vapor abundance in the middle atmosphere shows high values consistently at 60°S‐60°N at the growth phase of the dust storm (Ls = 195°–220°), and peaks at latitudes greater than 60°S at the decay phase (Ls = 220°–260°). This is explained by the seasonal change of meridional circulation: from equinoctial Hadley circulation (two cells) to the solstitial one (a single pole‐to‐pole cell). We also find a conspicuous increase of water vapor density in the middle atmosphere at the period of the regional dust storm (Ls = 322–327°), in particular at latitudes greater than 60°S

X-ray Polarization Observations of BL Lacertae

Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae performed with the Imaging X-ray Polarimetry Explorer ({IXPE}), from which an upper limit to the polarization degree $\Pi_X<$12.6\% was found in the 2-8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.Comment: 17 pages, 5 figures, accepted for publication in ApJ