339 research outputs found
Classification of Chimney EVAR-Related Endoleaks: Insights from the PERICLES Registry
Juxtarenal aortic aneurysms (JAAs) pose significant challenges for endovascular aneurysm repair (EVAR). A short or absent infrarenal neck typically excludes standard EVAR as a viable or reasonable treatment option. In this context, the use of chimney grafts (chEVAR) is gaining in popularity and applicability. These grafts are designed to course in the aortic lumen outside the main stent-graft to maintain normal perfusion to the involved target branches. As such, they may represent a promising and less resource-intensive option for management of JAAs. However, this technical strategy is not without challenges of its own, particularly the inevitable creation of \u201cgutters\u201d that result from the interaction of the chimney graft with the main aortic stent-graft. These gutters can become a conduit for type Ia endoleak formation, hence they represent the Achilles\u2019 heel of chEVAR. Current reports point to a relatively wide-ranging incidence (0%\u201313%) of type Ia endoleaks related to chEVAR. The PERICLES Registry collected the global transatlantic experience of 13 European and US vascular centers reporting 517 patients with complex aneurysms treated with EVAR and chimney parallel grafts. Overall, 6% of
PERICLES chEVAR patients had a type Ia endoleak at completion angiography, but the rate of persistent endoleaks was only 2.9% at a mean 17.1 months of follow-up. Close review of the postoperative computed tomography angiograms of these persistent endoleak patients revealed distinct types and patterns of chEVAR-related type Ia endoleaks and form the basis of a new classification proposed
herein. It is hoped that these observations will lead to development of new treatment algorithms for effective management of chimney-related endoleaks and, in some cases, to prevent them from occurring in the first place
Collected world experience about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies: The PERICLES registry
Objectives: We sought to analyze the collected worldwide experience with use of snorkel/chimney endovascular aneurysm repair (EVAR) for complex abdominal aneurysm treatment. Background: EVAR has largely replaced open surgery worldwide for anatomically suitable aortic aneurysms. Lack of availability of fenestrated and branched devices has encouraged an alternative strategy utilizing parallel or snorkel/chimney grafts (ch-EVAR). Methods: Clinical and radiographic information was retrospectively reviewed and analyzed on 517 patients treated by ch-EVAR from 2008 from 2014 by prearranged defined and documented protocols. Results: A total of 119 patients in US centers and 398 in European centers were treated during the study period. US centers preferentially used Zenith stent-grafts (54.2%) and European centers Endurant stent-grafts (62.2%) for the main body component. Overall 898 chimney grafts (49.2% balloon expandable, 39.6% self-expanding covered stents, and 11.2% balloon expandable bare metal stents) were placed in 692 renal arteries, 156 superior mesenteric arteries (SMA), and 50 celiac arteries. At a mean follow-up of 17.1 months (range: 1-70 months), primary patency was 94%, with secondary patency of 95.3%. Overall survival of patients in this high-risk cohort for open repair at latest follow-up was 79%. Conclusions: This global experience represents the largest series in the ch-EVAR literature and demonstrates comparable outcomes to those in published reports of branched/fenestrated devices, suggesting the appropriateness of broader applicability and the need for continued careful surveillance. These results support ch-EVAR as a valid off-the-shelf and immediately available alternative in the treatment of complex abdominal EVAR and provide impetus for the standardization of these techniques in the future
The Clustering of Extragalactic Extremely Red Objects
We have measured the angular and spatial clustering of 671 K5
Extremely Red Objects (EROs) from a 0.98 square degree sub-region of the NOAO
Deep Wide-Field Survey (NDWFS). Our study covers nearly 5 times the area and
has twice the sample size of any previous ERO clustering study. The wide field
of view and BwRIK passbands of the NDWFS allow us to place improved constraints
on the clustering of z=1 EROs. We find the angular clustering of EROs is
slightly weaker than in previous measurements, and w(1')=0.25+/-0.05 for
K<18.40 EROs. We find no significant correlation of ERO spatial clustering with
redshift, apparent color or absolute magnitude, although given the
uncertainties, such correlations remain plausible. We find the spatial
clustering of K5 EROs is well approximated by a power-law, with
r_0=9.7+/-1.1 Mpc/h in comoving coordinates. This is comparable to the
clustering of 4L* early-type galaxies at z<1, and is consistent with the
brightest EROs being the progenitors of the most massive ellipticals. There is
evidence of the angular clustering of EROs decreasing with increasing apparent
magnitude, when NDWFS measurements of ERO clustering are combined with those
from the literature. Unless the redshift distribution of K>20 EROs is very
broad, the spatial clustering of EROs decreases from r_0=9.7+/-1.1 Mpc/h for
K20 EROs.Comment: Accepted for publication in the ApJ. 29 pages with 10 figures. The
NOAO Deep Wide-Field Survey Bootes data release is available online at
http://www.noao.edu/noao/noaodeep
The GALEX UV luminosity function of the cluster of galaxies Abell 1367
We present the GALEX NUV (2310 A) and FUV (1530 A) galaxy luminosity
functions of the nearby cluster of galaxies A1367 in the magnitude range -20.3<
M_AB < -13.3. The luminosity functions are consistent with previous (~ 2 mag
shallower) estimates based on the FOCA and FAUST experiments, but display a
steeper faint-end slope than the GALEX luminosity function for local field
galaxies. Using spectro-photometric optical data we select out star-forming
systems from quiescent galaxies and study their separate contributions to the
cluster luminosity function. We find that the UV luminosity function of cluster
star-forming galaxies is consistent with the field. The difference between the
cluster and field LF is entirely due to the contribution at low luminosities
(M_AB >-16 mag) of non star-forming, early-type galaxies that are significantly
over dense in clusters.Comment: 4 pages, 4 figures, 1 table. Accepted for publication in
Astrophysical Journal Letter
Ultraviolet through Infrared Spectral Energy Distributions from 1000 SDSS Galaxies: Dust Attenuation
The meaningful comparison of models of galaxy evolution to observations is
critically dependent on the accurate treatment of dust attenuation. To
investigate dust absorption and emission in galaxies we have assembled a sample
of ~1000 galaxies with ultraviolet (UV) through infrared (IR) photometry from
GALEX, SDSS, and Spitzer and optical spectroscopy from SDSS. The ratio of IR to
UV emission (IRX) is used to constrain the dust attenuation in galaxies. We use
the 4000A break as a robust and useful, although coarse, indicator of star
formation history (SFH). We examine the relationship between IRX and the UV
spectral slope (a common attenuation indicator at high-redshift) and find
little dependence of the scatter on 4000A break strength. We construct average
UV through far-IR spectral energy distributions (SEDs) for different ranges of
IRX, 4000A break strength, and stellar mass (M_*) to show the variation of the
entire SED with these parameters. When binned simultaneously by IRX, 4000A
break strength, and M_* these SEDs allow us to determine a low resolution
average attenuation curve for different ranges of M_*. The attenuation curves
thus derived are consistent with a lambda^{-0.7} attenuation law, and we find
no significant variations with M_*. Finally, we show the relationship between
IRX and the global stellar mass surface density and gas-phase-metallicity.
Among star forming galaxies we find a strong correlation between IRX and
stellar mass surface density, even at constant metallicity, a result that is
closely linked to the well-known correlation between IRX and star-formation
rate.Comment: 12 pages, 8 figures, 2 tables, appearing in the Dec 2007 GALEX
special issue of ApJ Supp (29 papers
Ultraviolet Imaging of the z=0.23 Cluster Abell 2246
We present deep ultraviolet observations of a field containing the cluster
Abell 2246 (z=0.225) which provide far-ultraviolet (FUV) images of some of the
faintest galaxies yet observed in that bandpass. Abell 2246 lies within the
field of view of Ultraviolet Imaging Telescope (UIT) observations of the quasar
HS1700+64, which accumulated over 7100 seconds of UIT FUV exposure time during
the Astro-2 mission in March 1995. For objects found on both the FUV and
ground-based V-band images, we obtain FUV (l ~ 1520 A) photometry and V-band
photometry, as well as mid-UV (l ~ 2490 A) photometry from UIT Astro-1
observations and ground-based I-band photometry. We find five objects in the
images which are probably galaxies at the distance of Abell 2246, with FUV
magnitudes (m(FUV)) between 18.6 and 19.6, and V magnitudes between 18.4 and
19.6. We find that their absolute FUV fluxes and colors imply strongly that
they are luminous galaxies with significant current star formation, as well as
some relatively recent, but not current, (> 400 Myr ago) star formation. We
interpret the colors of these five objects by comparing them with local
objects, redshift-corrected template spectra and stellar population models,
finding that they are plausibly matched by 10-Gyr-old population models with
decaying star formation, with decay time constants in the range 3 Gyr < t < 5
Gyr, with an additional color component from a single burst of moderate ( ~
400-500 Myr) age. From derived FUV luminosities we compute current star
formation rates. We compare the UV properties of Abell 2246 with those of the
Coma cluster, finding that Abell 2246 has significantly more recent star
formation, consistent with the Butcher-Oemler phenomenon.Comment: Accepted for publication in the Astronomical Journal, June 1998. 17
Pages AAS latex, includes 4 bitmap .jpg format images and 4 other figures.
PDF, Embedded Gzipped PS version (1.9Mb) TeX source and figures available at
http://www.astro.virginia.edu/~bd4r/galaxies.htm
UV properties of early-type galaxies in the Virgo cluster
We study the UV properties of a volume limited sample of early-type galaxies
in the Virgo cluster combining new GALEX far- (1530 A) and near-ultraviolet
(2310 A) data with spectro-photometric data available at other wavelengths. The
sample includes 264 ellipticals, lenticulars and dwarfs spanning a large range
in luminosity (M(B)<-15). While the NUV to optical or near-IR color magnitude
relations (CMR) are similar to those observed at optical wavelengths, with a
monotonic reddening of the color index with increasing luminosity, the (FUV-V)
and (FUV-H) CMRs show a discontinuity between massive and dwarf objects. An
even more pronounced dichotomy is observed in the (FUV-NUV) CMR. For
ellipticals the (FUV-NUV) color becomes bluer with increasing luminosity and
with increasing reddening of the optical or near-IR color indices. For the
dwarfs the opposite trend is observed. These observational evidences are
consistent with the idea that the UV emission is dominated by hot, evolved
stars in giant systems, while in dwarf ellipticals residual star formation
activity is more common.Comment: 5 pages, 2 figures, 1 table. Accepted for publication in
Astrophysical Journal Letter
Endovascular Management of Juxtarenal and Pararenal Abdominal Aortic Aneurysms: Role of Chimney Technique
The use of chimney technique in endovascular repair of abdominal aortic aneurysms (ChEVAR) has had a secondary role. Although it was first
developed in an emergent/urgent setting, the publication of various important studies has helped overcome scepticism towards this technique
in elective procedures. This paper reviews current evidence about ChEVAR, focusing on clinical results, technical notes and comparisons with
other techniques. The new ChEVAR findings show favourable mid- and long-term clinical outcomes, even in elective patients. These results,
comparable to those related to fenestrated endografts, have been achieved through standardisation in planning and materials. An adequate
endograft oversizing associated to the right aortic neck length is fundamental to avoid ChEVAR-related complications, such as type 1a endoleaks.
These data indicate that ChEVAR, compared to other complex endovascular treatments, has comparable outcomes along with features that
could make it an essential option in every clinical settin
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