266 research outputs found
Failed MitraClip therapy: surgical revision in high-risk patients
Background: MitraClip implantation is a valid interventional option that offers acceptable short-term results. Surgery after failed MitraClip procedures remains challenging in high-risk patients. The data on these cases are limited by the small sample numbers.
Aim: The aim of our study is to show, that mitral valve surgery could be possible and more advantageous, even in high-risk patients.
Methods: Between 2010 and 2016, nine patients underwent mitral valve surgery after failed MitraClip therapy at our institution.
Results: The patientsâ ages ranged from 19 to 75âyears (mean: 61.2â±â19.6âyears). The median interval between the MitraClip intervention and surgical revision was 45âdays (range: 0 to 1087âdays). In eight of nine patients, the MitraClip intervention was initially successful and the mitral regurgitation was reduced. Only one patient had undergone cardiac surgery previously. Intra-operatively, leaflet perforation or rupture, MitraClip detachment, and chordal or papillary muscle rupture were potentially the causes of recurrent mitral regurgitation. There were three early deaths. One year after surgery, the six remaining patients were alive.
Conclusions: Mitral valve surgery can be successfully performed after failed MitraClip therapy in high-risk patients. The initial indication for MitraClip therapy should be considered carefully for possible surgical repair
Stellar Envelopes as Sources of Broad Line Region Emission: New Possibilities Allowed
In Active Galactic Nuclei (AGNs) the presence of a star cluster around the
central black hole can have several effects on the dynamics and the emission of
the global system. In this paper we analyze the interaction of stellar
atmospheres with a wind outflowing from the central region of the AGN nucleus.
Even a small mass loss from stars, as well as possible star collisions, can
give a non-negligible contribution in feeding matter into the AGN nuclear wind.
Moreover, stellar mass loss can produce envelopes surrounding stars that turn
out to be suitable for reproducing the observed emission from the Broad Line
Region (BLR). In this framework, the envelope can be confined by the bow shock
arising from the interaction between the expanding stellar atmosphere and the
AGN nuclear wind.Comment: 21 pages, Latex, accepted for publication in A&
Unusual magnetoelectric effect in paramagnetic rare-earth langasite
Violation of time reversal and spatial inversion symmetries has profound
consequences for elementary particles and cosmology. Spontaneous breaking of
these symmetries at phase transitions gives rise to unconventional physical
phenomena in condensed matter systems, such as ferroelectricity induced by
magnetic spirals, electromagnons, non-reciprocal propagation of light and spin
waves, and the linear magnetoelectric (ME) effect - the electric polarization
proportional to the applied magnetic field and the magnetization induced by the
electric field. Here, we report the experimental study of the holmium-doped
langasite, HoLaGaSiO, showing a puzzling combination
of linear and highly non-linear ME responses in the disordered paramagnetic
state: its electric polarization grows linearly with the magnetic field but
oscillates many times upon rotation of the magnetic field vector. We propose a
simple phenomenological Hamiltonian describing this unusual behavior and derive
it microscopically using the coupling of magnetic multipoles of the rare-earth
ions to the electric field.Comment: 8 pages, 3 figure
Photometric redshifts from reconstructed QSO templates
From SDSS commissioning photometric and spectroscopic data, we investigate
the utility of photometric redshift techniques to the task of estimating QSO
redshifts. We consider empirical methods (e.g. nearest-neighbor searches and
polynomial fitting), standard spectral template fitting and hybrid approaches
(i.e. training spectral templates from spectroscopic and photometric
observations of QSOs). We find that in all cases, due to the presence of strong
emission-lines within the QSO spectra, the nearest-neighbor and template
fitting methods are superior to the polynomial fitting approach. Applying a
novel reconstruction technique, we can, from the SDSS multicolor photometry,
reconstruct a statistical representation of the underlying SEDs of the SDSS
QSOs. Although, the reconstructed templates are based on only broadband
photometry the common emission lines present within the QSO spectra can be
recovered in the resulting spectral energy distributions. The technique should
be useful in searching for spectral differences among QSOs at a given redshift,
in searching for spectral evolution of QSOs, in comparing photometric redshifts
for objects beyond the SDSS spectroscopic sample with those in the well
calibrated photometric redshifts for objects brighter than 20th magnitude and
in searching for systematic and time variable effects in the SDSS broad band
photometric and spectral photometric calibrations.Comment: 21 pages, 9 figures, LaTeX AASTeX, submitted to A
Central extracorporeal life support with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure
BACKGROUND: The purpose of this prospective study was to evaluate the effects and functional outcome of central extracorporeal life support (ECLS) with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure. METHODS: Between August 2010 and August 2013, 12 consecutive patients (2 female) with a mean age of 31.6 ± 15.1 years received central ECLS with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure. Underlying disease was acute cardiac decompensation due to dilated cardiomyopathy (n = 3, 25%), coronary artery disease with acute myocardial infarction (AMI) (n = 3, 25%), and acute myocarditis (n = 6, 50%). We routinely implemented ECLS by cannulating the ascending aorta, right atrium and inserting a left ventricular decompression cannula vent via the right superior pulmonary vein. RESULTS: All patients were successfully bridged to either recovery (n = 3, 25%), long-term biventricular support (n = 6, 50%) or cardiac transplantation (n = 3, 25%). Seven patients (58.3%) were discharged after a mean hospital stay of 42 ± 11.9 days. The overall survival from ECLS implantation to the end of the study was 58.3%. The cumulative ICU stay was 23.1 ± 9.6 days. The length of support was 8.0 ± 4.3 days (range 3-17 days). CONCLUSIONS: We strongly recommend left ventricular decompression in refractory cardiogenic shock and lung failure to avoid pulmonary edema, left heart distension and facilitate myocardial recovery
Total Aortic Arch Replacement: Superior Ventriculo-Arterial Coupling with Decellularized Allografts Compared with Conventional Prostheses.
BACKGROUND: To date, no experimental or clinical study provides detailed analysis of vascular impedance changes after total aortic arch replacement. This study investigated ventriculoarterial coupling and vascular impedance after replacement of the aortic arch with conventional prostheses vs. decellularized allografts. METHODS: After preparing decellularized aortic arch allografts, their mechanical, histological and biochemical properties were evaluated and compared to native aortic arches and conventional prostheses in vitro. In open-chest dogs, total aortic arch replacement was performed with conventional prostheses and compared to decellularized allografts (n = 5/group). Aortic flow and pressure were recorded continuously, left ventricular pressure-volume relations were measured by using a pressure-conductance catheter. From the hemodynamic variables end-systolic elastance (Ees), arterial elastance (Ea) and ventriculoarterial coupling were calculated. Characteristic impedance (Z) was assessed by Fourier analysis. RESULTS: While Ees did not differ between the groups and over time (4.1+/-1.19 vs. 4.58+/-1.39 mmHg/mL and 3.21+/-0.97 vs. 3.96+/-1.16 mmHg/mL), Ea showed a higher increase in the prosthesis group (4.01+/-0.67 vs. 6.18+/-0.20 mmHg/mL, P<0.05) in comparison to decellularized allografts (5.03+/-0.35 vs. 5.99+/-1.09 mmHg/mL). This led to impaired ventriculoarterial coupling in the prosthesis group, while it remained unchanged in the allograft group (62.5+/-50.9 vs. 3.9+/-23.4%). Z showed a strong increasing tendency in the prosthesis group and it was markedly higher after replacement when compared to decellularized allografts (44.6+/-8.3dyn.sec.cm-5 vs. 32.4+/-2.0dyn.sec.cm-5, P<0.05). CONCLUSIONS: Total aortic arch replacement leads to contractility-afterload mismatch by means of increased impedance and invert ventriculoarterial coupling ratio after implantation of conventional prostheses. Implantation of decellularized allografts preserves vascular impedance thereby improving ventriculoarterial mechanoenergetics after aortic arch replacement
Bioartificial heart: a human-sized porcine model - the way ahead
BACKGROUND: A bioartificial heart is a theoretical alternative to transplantation or mechanical left ventricular support. Native hearts decellularized with preserved architecture and vasculature may provide an acellular tissue platform for organ regeneration. We sought to develop a tissue-engineered whole-heart neoscaffold in human-sized porcine hearts. METHODS: We decellularized porcine hearts (n = 10) by coronary perfusion with ionic detergents in a modified Langendorff circuit. We confirmed decellularization by histology, transmission electron microscopy and fluorescence microscopy, quantified residual DNA by spectrophotometry, and evaluated biomechanical stability with ex-vivo left-ventricular pressure/volume studies, all compared to controls. We then mounted the decellularized porcine hearts in a bioreactor and reseeded them with murine neonatal cardiac cells and human umbilical cord derived endothelial cells (HUVEC) under simulated physiological conditions. RESULTS: Decellularized hearts lacked intracellular components but retained specific collagen fibers, proteoglycan, elastin and mechanical integrity; quantitative DNA analysis demonstrated a significant reduction of DNA compared to controls (82.6+/-3.2 ng DNA/mg tissue vs. 473.2+/-13.4 ng DNA/mg tissue, p<0.05). Recellularized porcine whole-heart neoscaffolds demonstrated re-endothelialization of coronary vasculature and measurable intrinsic myocardial electrical activity at 10 days, with perfused organ culture maintained for up to 3 weeks. CONCLUSIONS: Human-sized decellularized porcine hearts provide a promising tissue-engineering platform that may lead to future clinical strategies in the treatment of heart failure
Superior Ventriculo-Arterial Coupling with Decellularized Allografts Compared with Conventional Prostheses
Background To date, no experimental or clinical study provides detailed
analysis of vascular impedance changes after total aortic arch replacement.
This study investigated ventriculoarterial coupling and vascular impedance
after replacement of the aortic arch with conventional prostheses vs.
decellularized allografts. Methods After preparing decellularized aortic arch
allografts, their mechanical, histological and biochemical properties were
evaluated and compared to native aortic arches and conventional prostheses in
vitro. In open-chest dogs, total aortic arch replacement was performed with
conventional prostheses and compared to decellularized allografts (n =
5/group). Aortic flow and pressure were recorded continuously, left
ventricular pressure-volume relations were measured by using a pressure-
conductance catheter. From the hemodynamic variables end-systolic elastance
(Ees), arterial elastance (Ea) and ventriculoarterial coupling were
calculated. Characteristic impedance (Z) was assessed by Fourier analysis.
Results While Ees did not differ between the groups and over time (4.1±1.19
vs. 4.58±1.39 mmHg/mL and 3.21±0.97 vs. 3.96±1.16 mmHg/mL), Ea showed a higher
increase in the prosthesis group (4.01±0.67 vs. 6.18±0.20 mmHg/mL, P<0.05) in
comparison to decellularized allografts (5.03±0.35 vs. 5.99±1.09 mmHg/mL).
This led to impaired ventriculoarterial coupling in the prosthesis group,
while it remained unchanged in the allograft group (62.5±50.9 vs. 3.9±23.4%).
Z showed a strong increasing tendency in the prosthesis group and it was
markedly higher after replacement when compared to decellularized allografts
(44.6±8.3dyn·sec·cmâ5 vs. 32.4±2.0dyn·sec·cmâ5, P<0.05). Conclusions Total
aortic arch replacement leads to contractility-afterload mismatch by means of
increased impedance and invert ventriculoarterial coupling ratio after
implantation of conventional prostheses. Implantation of decellularized
allografts preserves vascular impedance thereby improving ventriculoarterial
mechanoenergetics after aortic arch replacement
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