134 research outputs found
Short- and long-term experience in pulmonary vein segmental ostial ablation for paroxysmal atrial fibrillation*
Introduction: Segmental ostial pulmonary vein isolation (PVI) is considered a potentially curative therapeutic approach in the treatment of paroxysmal atrial fibrillation (PAF). There is only limited data available on the long-term effect of this procedure.
Methods: Patients (Pts) underwent a regular clinical follow up visit at 3, 6 and 24 months after PVI. Clinical success was classified as complete (i.e. no arrhythmia recurrences, no antiarrhythmic drug), partial (i.e. no/only few recurrences, on drug) or as a failure (no benefit). The clinical responder rate (CRR) was determined by combining complete and partial success.
Results: 117 patients (96 male, 21 female), aged 51±11 years (range 25 to 73) underwent a total of 166 procedures (1.4/patient) in 2-4 pulmonary veins (PV). 115 patients (98%) had AF, 2 patients presented with regular PV atrial tachycardia. ,109/115 patients. exhibited PAF as the primary arrhythmia (versus persistent AF). A total of 113 patients with PVI in the years 2001 to 2003 were evaluated for their CRR after 6 (3) months. A single intervention was carried out in 63 patients (55.8%), two interventions were performed in 45 patients (39.8%) and three interventions in 5 patients (4.4%). The clinical response demonstrated a complete success of 52% (59 patients), a partial success of 26% (29 patients) and a failure rate of 22% (25 patients), leading to a CRR of 78% (88 patients). Ostial PVI in all 4 PVs exhibited a tendency towards higher curative success rates (54% versus 44% in patients with 3 PVs ablated for the 6 month follow up). Long-term clinical outcome was evaluated in 39 patients with an ablation attempt at 3 PVs only (excluding the right inferior PV in our early experience) and a mean clinical follow up of 21±6 months. At this point in time the success rate was 41% (complete, 16 patients) and 21% (partial, 8 patients), respectively, adding up to a CRR of 62% (24 patients). In total, 20 patients (17.1%) had either a single or 2 (3 patients, 2.6%) complications independent of the number of procedures performed with PV stenosis as the leading cause (7.7%).
Conclusion: The CRR of patients with medical refractory PAF in our patient cohort is 78% at the 6 month follow up. PV stenosis is the main cause for procedure-related complications. Ablation of all 4 PV exhibits a tendency towards higher complete success rates despite equal CRR. Calculation of the clinical response after a mid- to long-term follow of 21±6 months in those patients with an ostial PVI in only 3 pulmonary veins (sparing the right inferior PV) shows a further reduction to 62%, exclusively caused by a drop in patients with a former partial success. To evaluate the long-term clinical benefit of segmental ostial PVI in comparison with other ablation techniques, more extended follow up periods are mandatory, including a larger study cohort and a detailed description of procedural parameters
Three-dimensional analysis of regional left ventricular endocardial curvature from cardiac magnetic resonance images
Dyssynchrony by speckle-tracking echocardiography and response to cardiac resynchronization therapy: results of the Speckle Tracking and Resynchronization (STAR) study
A blended TROPOMI+GOSAT satellite data product for atmospheric methane using machine learning to correct retrieval biases
Satellite observations of dry-column methane mixing
ratios (XCH4) from shortwave infrared (SWIR) solar backscatter
radiation provide a powerful resource to quantify methane emissions in
service of climate action. The TROPOspheric Monitoring Instrument (TROPOMI), launched in October 2017,
provides global daily coverage at a 5.5 × 7 km2 (nadir) pixel
resolution, but its methane retrievals can suffer from biases associated with
SWIR surface albedo, scattering from aerosols and cirrus clouds, and
across-track variability (striping). The Greenhouse gases Observing SATellite (GOSAT) instrument, launched in 2009,
has better spectral characteristics and its methane retrieval is much less
subject to biases, but its data density is 250 times sparser than TROPOMI.
Here, we present a blended TROPOMI+GOSAT methane product obtained by
training a machine learning (ML) model to predict the difference between
TROPOMI and GOSAT co-located measurements, using only predictor variables
included in the TROPOMI retrieval, and then applying the correction to the
complete TROPOMI record from April 2018 to present. We find that the largest corrections are associated with coarse aerosol particles, high SWIR surface
albedo, and across-track pixel index. Our blended product corrects a
systematic difference between TROPOMI and GOSAT over water, and it features
corrections exceeding 10 ppb over arid land, persistently cloudy regions,
and high northern latitudes. It reduces the TROPOMI spatially variable bias
over land (referenced to GOSAT data) from 14.3 to 10.4 ppb at a
0.25∘ × 0.3125∘ resolution. Validation
with Total Carbon Column Observing Network (TCCON) ground-based column measurements shows reductions in variable
bias compared with the original TROPOMI data from 4.7 to 4.4 ppb and in
single-retrieval precision from 14.5 to 11.9 ppb. TCCON data are all in
locations with a SWIR surface albedo below 0.4 (where TROPOMI biases tend to be
relatively low), but they confirm the dependence of TROPOMI biases on SWIR
surface albedo and coarse aerosol particles, as well as the reduction of
these biases in the blended product. Fine-scale inspection of the Arabian
Peninsula shows that a number of hotspots in the original TROPOMI data are
removed as artifacts in the blended product. The blended product also
corrects striping and aerosol/cloud biases in single-orbit TROPOMI data,
enabling better detection and quantification of ultra-emitters. Residual
coastal biases can be removed by applying additional filters. The ML method
presented here can be applied more generally to validate and correct data
from any new satellite instrument by reference to a more established
instrument.</p
Preliminary clinical study of left ventricular myocardial strain in patients with non-ischemic dilated cardiomyopathy by three-dimensional speckle tracking imaging
<p>Abstract</p> <p>Background</p> <p>Non-ischemic dilated cardiomyopathy (DCM) is the most common cardiomyopathy worldwide, with significant mortality. Correct evaluation of the patient's myocardial function has important clinical significance in the diagnosis, therapeutic effect assessment and prognosis in non-ischemic DCM patients. This study evaluated the feasibility of three-dimensional speckle tracking imaging (3D-STE) for assessment of the left ventricular myocardial strain in patients with non-ischemic dilated cardiomyopathy (DCM).</p> <p>Methods</p> <p>Apical full-volume images were acquired from 65 patients with non-ischemic DCM (DCM group) and 59 age-matched normal controls (NC group), respectively. The following parameters were measured by 3D-STE: the peak systolic radial strain (RS), circumferential strain (CS), longitudinal strain (LS) of each segment. Then all the parameters were compared between the two groups.</p> <p>Results</p> <p>The peak systolic strain in different planes had certain regularities in normal groups, radial strain (RS) was the largest in the mid region, the smallest in the apical region, while circumferential strain (CS) and longitudinal strain (LS) increased from the basal to the apical region. In contrast, the regularity could not be applied to the DCM group. RS, CS, LS were significantly decreased in DCM group as compared with NC group (<it>P </it>< 0.001 for all). The interobserver, intraobserver and test-retest reliability were acceptable.</p> <p>Conclusions</p> <p>3D-STE is a reliable tool for evaluation of left ventricular myocardial strain in patients with non-ischemic DCM, with huge advantage in clinical application.</p
Satellite quantification of methane emissions and oil–gas methane intensities from individual countries in the Middle East and North Africa: implications for climate action
We use 2019 TROPOMI satellite observations of atmospheric methane
in an analytical inversion to quantify methane emissions from the Middle
East and North Africa at up to ∼25 km × 25 km
resolution, using spatially allocated national United Nations Framework
Convention on Climate Change (UNFCCC) reports as prior
estimates for the fuel sector. Our resulting best estimate of anthropogenic
emissions for the region is 35 % higher than the prior bottom-up
inventories (+103 % for gas, +53 % for waste, +49 % for
livestock, −14 % for oil) with large variability across countries. Oil and
gas account for 38 % of total anthropogenic emissions in the region.
TROPOMI observations can effectively optimize and separate national
emissions by sector for most of the 23 countries in the region, with 6
countries accounting for most of total anthropogenic emissions including
Iran (5.3 (5.0–5.5) Tg a−1; best estimate and uncertainty range),
Turkmenistan (4.4 (2.8–5.1) Tg a−1), Saudi Arabia (4.3 (2.4–6.0) Tg a−1), Algeria (3.5 (2.4–4.4) Tg a−1), Egypt (3.4 (2.5–4.0) Tg a−1), and Turkey (3.0 (2.0–4.1) Tg a−1). Most oil–gas emissions
are from the production (upstream) subsector, but Iran, Turkmenistan, and
Saudi Arabia have large gas emissions from transmission and distribution
subsectors. We identify a high number of annual oil–gas emission hotspots in
Turkmenistan, Algeria, and Oman and offshore in the Persian Gulf. We show that
oil–gas methane emissions for individual countries are not related to
production, invalidating a basic premise in the construction of
activity-based bottom-up inventories. Instead, local infrastructure and
management practices appear to be key drivers of oil–gas emissions,
emphasizing the need for including top-down information from atmospheric
observations in the construction of oil–gas emission inventories. We
examined the methane intensity, defined as the upstream oil–gas emission per
unit of methane gas produced, as a measure of the potential for decreasing
emissions from the oil–gas sector and using as reference the 0.2 % target
set by the industry. We find that the methane intensity in most countries is
considerably higher than this target, reflecting leaky infrastructure
combined with deliberate venting or incomplete flaring of gas. However, we
also find that Kuwait, Saudi Arabia, and Qatar meet the industry target and
thus show that the target is achievable through the capture of associated gas,
modern infrastructure, and the concentration of operations. Decreasing methane
intensities across the Middle East and North Africa to 0.2 % would achieve
a 90 % decrease in oil–gas upstream emissions and a 26 % decrease in
total anthropogenic methane emissions in the region, making a significant
contribution toward the Global Methane Pledge.</p
Integrated Methane Inversion (IMI 1.0): a user-friendly, cloud-based facility for inferring high-resolution methane emissions from TROPOMI satellite observations
We present a user-friendly, cloud-based facility for quantifying methane emissions with 0.25∘ × 0.3125∘
(≈ 25 km × 25 km) resolution by inverse analysis of satellite observations from the TROPOspheric Monitoring
Instrument (TROPOMI). The facility is built on an Integrated Methane Inversion optimal estimation workflow (IMI 1.0) and supported for use on the
Amazon Web Services (AWS) cloud. It exploits the GEOS-Chem chemical transport model and TROPOMI data already resident on AWS, thus avoiding
cumbersome big-data download. Users select a region and period of interest, and the IMI returns an analytical solution for the Bayesian optimal
estimate of period-average emissions on the 0.25∘ × 0.3125∘ grid including error statistics, information content, and
visualization code for inspection of results. The inversion uses an advanced research-grade algorithm fully documented in the literature. An
out-of-the-box inversion with rectilinear grid and default prior emission estimates can be conducted with no significant learning curve. Users can
also configure their inversions to infer emissions for irregular regions of interest, swap in their own prior emission inventories, and modify
inversion parameters. Inversion ensembles can be generated at minimal additional cost once the Jacobian matrix for the analytical inversion has been
constructed. A preview feature allows users to determine the TROPOMI information content for their region and time period of interest before
actually performing the inversion. The IMI is heavily documented and is intended to be accessible by researchers and stakeholders with no expertise
in inverse modelling or high-performance computing. We demonstrate the IMI's capabilities by applying it to estimate methane emissions from the US
oil-producing Permian Basin in May 2018.</p
Left and right ventricular longitudinal strain-volume/area relationships in elite athletes.
We propose a novel ultrasound approach with the primary aim of establishing the temporal relationship of structure and function in athletes of varying sporting demographics. 92 male athletes were studied [Group IA, (low static-low dynamic) (n = 20); Group IC, (low static-high dynamic) (n = 25); Group IIIA, (high static-low dynamic) (n = 21); Group IIIC, (high static-high dynamic) (n = 26)]. Conventional echocardiography of both the left ventricles (LV) and right ventricles (RV) was undertaken. An assessment of simultaneous longitudinal strain and LV volume/RV area was provided. Data was presented as derived strain for % end diastolic volume/area. Athletes in group IC and IIIC had larger LV end diastolic volumes compared to athletes in groups IA and IIIA (50 ± 6 and 54 ± 8 ml/(m(2))(1.5) versus 42 ± 7 and 43 ± 2 ml/(m(2))(1.5) respectively). Group IIIC also had significantly larger mean wall thickness (MWT) compared to all groups. Athletes from group IIIC required greater longitudinal strain for any given % volume which correlated to MWT (r = 0.4, p < 0.0001). Findings were similar in the RV with the exception that group IIIC athletes required lower strain for any given % area. There are physiological differences between athletes with the largest LV and RV in athletes from group IIIC. These athletes also have greater resting longitudinal contribution to volume change in the LV which, in part, is related to an increased wall thickness. A lower longitudinal contribution to area change in the RV is also apparent in these athletes
Effects of fatigue on trunk stability in elite gymnasts
The aim of the present study was to test the hypothesis that fatigue due to exercises performed in training leads to a decrement of trunk stability in elite, female gymnasts. Nine female gymnasts participated in the study. To fatigue trunk muscles, four series of five dump handstands on the uneven bar were performed. Before and after the fatigue protocol, participants performed three trials of a balancing task while sitting on a seat fixed over a hemisphere to create an unstable surface. A force plate tracked the location of the center of pressure (CoP). In addition, nine trials were performed in which the seat was backward inclined over a set angle and suddenly released after which the subject had to regain balance. Sway amplitude and frequency in unperturbed sitting were determined from the CoP time series and averaged over trials. The maximum displacement and rate of recovery of the CoP location after the sudden release were determined and averaged over trials. After the fatigue protocol, sway amplitude in the fore-aft direction was significantly increased (p = 0.03), while sway frequency was decreased (p = 0.005). In addition, the maximum displacement after the sudden release was increased (p = 0.009), while the rate of recovery after the perturbation was decreased (p = 0.05). Fatigue induced by series of exercises representing a realistic training load caused a measurable decrement in dynamic stability of the trunk in elite gymnasts
Genes as Tags: The Tax Implications of Widely Available Genetic Information
This paper examines how progress in genetics\u27 specifically, the proliferation of knowledge about the human genome\u27 may influence the feasibility and desirability of a tax that is based on individual human endowments or ability. The paper explores various forms that such a genetic endowment tax-and-transfer regime might take and identifies some of the benefits and costs of such a regime. The authors take no position on whether a genetic endowment tax would be desirable or not. However, one contribution of the paper is to observe that current law in the U.S., which restricts the use of genetic information by insurers and employers, is equivalent to a form of genetic endowment tax. The paper also notes that, in the absence of a government-mandated transfer policy with respect to genetic endowments, private insurance markets may arise to fill the gap, allowing individuals to purchase insurance against the possibility of a bad genetic draw
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