352 research outputs found
Reliability Of A Novel Intracardiac Electrogram Method For AV And VV Delay Optimization And Comparability To Echocardiography Procedure For Determining Optimal Conduction Delays In CRT Patients
Background: Echocardiography is widely used to optimize CRT programming. A novel intracardiac electrogram method (IEGM) was recently developed as an automated programmer-based method, designed to calculate optimal atrioventricular (AV) and interventricular (VV) delays and provide optimized delay values as an alternative to standard echocardiographic assessment.Objective: This study was aimed at determining the reliability of this new method. Furthermore the comparability of IEGM to existing echocardiographic parameters for determining optimal conduction delays was verified.Methods: Eleven patients (age 62.9± 8.7; 81% male; 73% ischemic), previously implanted with a cardiac resynchronisation therapy defibrillator (CRT-D) underwent both echocardiographic and IEGM-based delay optimization.Results: Applying the IEGM method, concordance of three consecutively performed measurements was found in 3 (27%) patients for AV delay and in 5 (45%) patients for VV delay. Intra-individual variation between three measurements as assessed by the IEGM technique was up to 20 ms (AV: n=6; VV: n=4). E-wave, diastolic filling time and septal-to-lateral wall motion delay emerged as significantly different between the echo and IEGM optimization techniques (p < 0.05). The final AV delay setting was significantly different between both methods (echo: 126.4 ± 29.4 ms, IEGM: 183.6 ± 16.3 ms; p < 0.001; correlation: R = 0.573, p = 0.066). VV delay showed significant differences for optimized delays (echo: 46.4 ± 23.8 ms, IEGM: 10.9 ± 7.0 ms; p <0.01; correlation: R = -0.278, p = 0.407).Conclusion: The automated programmer-based IEGM-based method provides a simple and safe method to perform CRT optimization. However, the reliability of this method appears to be limited. Thus, it remains difficult for the examiner to determine the optimal hemodynamic settings. Additionally, as there was no correlation between the optimal AV- and VV-delays calculated by the IEGM method and the echo optimization, the use of the IEGM method and the comparability to the echo has not been definitely clarified
Levo-α-acetylmethadol (LAAM) induced QTc-prolongation - results from a controlled clinical trial
<p>Abstract</p> <p>Background</p> <p>Due to potential proarrhythmic side-effects levo-α-Acetylmethadol (LAAM) is currently not available in EU countries as maintenance drug in the treatment of opiate addiction. However, recent studies and meta-analyses underline the clinical advantages of LAAM with respect to the reduction of heroin use. Thus a reappraisal of LAAM has been demanded. The aim of the present study was to evaluate the relative impact of LAAM on QTc-interval, as a measure of pro-arrhythmic risk, in comparison to methadone, the current standard in substitution therapy.</p> <p>Methods</p> <p>ECG recordings were analysed within a randomized, controlled clinical trial evaluating the efficacy and tolerability of maintenance treatment with LAAM compared with racemic methadone. Recordings were done at two points: 1) during a run-in period with all patients on methadone and 2) 24 weeks after randomisation into methadone or LAAM treatment group. These ECG recordings were analysed with respect to QTc-values and QTc-dispersion. Mean values as well as individual changes compared to baseline parameters were evaluated. QTc-intervals were classified according to CPMP-guidelines.</p> <p>Results</p> <p>Complete ECG data sets could be obtained in 53 patients (31 LAAM-group, 22 methadone-group). No clinical cardiac complications were observed in either group. After 24 weeks, patients receiving LAAM showed a significant increase in QTc-interval (0.409 s ± 0.022 s versus 0.418 s ± 0.028 s, p = 0.046), whereas no significant changes could be observed in patients remaining on methadone. There was no statistically significant change in QTc-dispersion in either group. More patients with borderline prolonged and prolonged QTc-intervals were observed in the LAAM than in the methadone treatment group (n = 7 vs. n = 1; p = 0.1).</p> <p>Conclusions</p> <p>In this controlled trial LAAM induced QTc-prolongation in a higher degree than methadone. Given reports of severe arrhythmic events, careful ECG-monitoring is recommended under LAAM medication.</p
How much of the intraaortic balloon volume is displaced toward the coronary circulation?
This is a post-print version of the published article. Copyright @ 2010 The American Association for Thoracic Surgery.This article has been made available through the Brunel Open Access Publishing Fund.Objective: During intraaortic balloon inflation, blood volume is displaced toward the heart (Vtip), traveling retrograde in the descending aorta, passing by the arch vessels, reaching the aortic root (Vroot), and eventually perfusing the coronary circulation (Vcor). Vcor leads to coronary flow augmentation, one of the main benefits of the intraaortic balloon pump. The aim of this study was to assess Vroot and Vcor in vivo and in vitro, respectively.
Methods: During intraaortic balloon inflation, Vroot was obtained by integrating over time the aortic root flow signals measured in 10 patients with intraaortic balloon assistance frequencies of 1:1 and 1:2. In a mock circulation system, flow measurements were recorded simultaneously upstream of the intraaortic balloon tip and at each of the arch and coronary branches of a silicone aorta during 1:1 and 1:2 intraaortic balloon support. Integration over time of the flow signals during inflation yielded Vcor and the distribution of Vtip.
Results: In patients, Vroot was 6.4% ± 4.8% of the intraaortic balloon volume during 1:1 assistance and 10.0% ± 5.0% during 1:2 assistance. In vitro and with an artificial heart simulating the native heart, Vcor was smaller, 3.7% and 3.8%, respectively. The distribution of Vtip in vitro varied, with less volume displaced toward the arch and coronary branches and more volume stored in the compliant aortic wall when the artificial heart was not operating.
Conclusion: The blood volume displaced toward the coronary circulation as the result of intraaortic balloon inflation is a small percentage of the nominal intraaortic balloon volume. Although small, this percentage is still a significant fraction of baseline coronary flow.This article is available through the Open Access Publishing Fund
The propargyl rearrangement to functionalised allyl-boron and borocation compounds
A diverse range of Lewis acidic alkyl, vinyl and aryl boranes and borenium compounds that are capable of new carbon–carbon bond formation through selective migratory group transfer have been synthesised. Utilising a series of heteroleptic boranes [PhB(C6F5)2 (1), PhCH2CH2B(C6F5)2 (2), and E-B(C6F5)2(C6F5)C=C(I)R (R=Ph 3 a, nBu 3 b)] and borenium cations [phenylquinolatoborenium cation ([QOBPh][AlCl4], 4)], it has been shown that these boron-based compounds are capable of producing novel allyl- boron and boronium compounds through complex rearrangement reactions with various propargyl esters and carbamates. These reactions yield highly functionalised, synthetically useful boron substituted organic compounds with substantial molecular complexity in a one-pot reaction
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Los Alamos Plutonium Facility Waste Management System
This paper describes the new computer-based transuranic (TRU) Waste Management System (WMS) being implemented at the Plutonium Facility at Los Alamos National Laboratory (LANL). The Waste Management System is a distributed computer processing system stored in a Sybase database and accessed by a graphical user interface (GUI) written in Omnis7. It resides on the local area network at the Plutonium Facility and is accessible by authorized TRU waste originators, count room personnel, radiation protection technicians (RPTs), quality assurance personnel, and waste management personnel for data input and verification. Future goals include bringing outside groups like the LANL Waste Management Facility on-line to participate in this streamlined system. The WMS is changing the TRU paper trail into a computer trail, saving time and eliminating errors and inconsistencies in the process
Probing fibronectin adsorption on chemically defined surfaces by means of single molecule force microscopy
Atomic force microscope (AFM) based single molecule force spectroscopy (SMFS) and a quartz crystal microbalance (QCM) were respectively employed to probe interfacial characteristics of fibronectin fragment FNIII8–14 and full-length fibronectin (FN) on CH3–, OH–, COOH–, and NH2-terminated alkane-thiol self-assembled monolayers (SAMs). Force-distance curves acquired between hexahistidine-tagged FNIII8–14 immobilised on trisNTA-Ni2+ functionalized AFM cantilevers and the OH and COOH SAM surfaces were predominantly ‘loop-like’ (76% and 94% respectively), suggesting domain unfolding and preference for ‘end-on’ oriented binding, while those generated with NH2 and CH3 SAMs were largely ‘mixed type’ (81% and 86%, respectively) commensurate with unravelling and desorption, and ‘side-on’ binding. Time-dependent binding of FN to SAM-coated QCM crystals occurred in at least two phases: initial rapid coverage over the first 5 min; and variably diminishing adsorption thereafter (5–70 min). Loading profiles and the final hydrated surface concentrations reached (~ 950, ~ 1200, ~ 1400, ~ 1500 ng cm−2 for CH3, OH, COOH and NH2 SAMs) were consistent with: space-filling ‘side-on’ orientation and unfolding on CH3 SAM; greater numbers of FN molecules arranged ‘end-on’ on OH and especially COOH SAMs; and initial ‘side-on’ contact, followed by either (1) gradual tilting to a space-saving ‘end-on’ configuration, or (2) bi-/multi-layer adsorption on NH2 SAM
Long-term left ventricular remodelling after revascularisation for ST-segment elevation myocardial infarction as assessed by cardiac magnetic resonance imaging
Objective Left ventricular remodelling following a ST-segment elevated myocardial infarction (STEMI) is an adaptive response to maintain the cardiac output despite myocardial tissue loss. Limited studies have evaluated long term ventricular function using cardiac magnetic resonance imaging (CMR) after STEMI. Methods Study population consisted of 155 primary percutaneous coronary intervention treated first STEMI patients. CMR was performed at 4±2 days, 4 months and 24 months follow-up. Patients were treated with beta-blockers, ACE-inhibitors or AT-II-inhibitors, statins and dual antiplatelet according to c
Long-Term Outcomes of External Dacryocystorhinostomy in the Age of Transcanalicular Microendoscopic Techniques
Purpose. This study aimed to evaluate long-term results of external dacryocystorhinostomy (DCR) at a tertiary eye care center specializing in lacrimal duct surgery in Germany. Methods. The medical records of 1010 patients with acquired nasolacrimal duct obstruction (NLDO), who had undergone lacrimal duct surgery at a tertiary eye care center, were reviewed. Only adult patients who had undergone external DCR were included. The evaluation included the following parameters: age, gender, duration of symptoms, patient satisfaction, previous dacryocystitis, complication rates, and surgical outcome. Results. 154 eyes of 146 patients (14.5%) could be included in the study. The average age was 64.1±29.7 years. 66.4% of patients were females and 33.6% were males. Acute or chronic dacryocystitis was found in 81 patients (55.5%). Overall, 82.8% of patients had full resolution of symptoms. The success rate of external DCR for patients with previous episodes of dacryocystitis was 82.7% compared to 83.4% for patients without dacryocystitis in their medical history. Conclusion. In cases in which transcanalicular microendoscopic techniques are contraindicated (e.g., after dacryocystitis) or in complex cases where microendoscopic procedures have failed (revision surgery), external DCR is still the surgical treatment of choice with very good postoperative success
3D Fluid Flow Estimation with Integrated Particle Reconstruction
The standard approach to densely reconstruct the motion in a volume of fluid
is to inject high-contrast tracer particles and record their motion with
multiple high-speed cameras. Almost all existing work processes the acquired
multi-view video in two separate steps, utilizing either a pure Eulerian or
pure Lagrangian approach. Eulerian methods perform a voxel-based reconstruction
of particles per time step, followed by 3D motion estimation, with some form of
dense matching between the precomputed voxel grids from different time steps.
In this sequential procedure, the first step cannot use temporal consistency
considerations to support the reconstruction, while the second step has no
access to the original, high-resolution image data. Alternatively, Lagrangian
methods reconstruct an explicit, sparse set of particles and track the
individual particles over time. Physical constraints can only be incorporated
in a post-processing step when interpolating the particle tracks to a dense
motion field. We show, for the first time, how to jointly reconstruct both the
individual tracer particles and a dense 3D fluid motion field from the image
data, using an integrated energy minimization. Our hybrid Lagrangian/Eulerian
model reconstructs individual particles, and at the same time recovers a dense
3D motion field in the entire domain. Making particles explicit greatly reduces
the memory consumption and allows one to use the high-res input images for
matching. Whereas the dense motion field makes it possible to include physical
a-priori constraints and account for the incompressibility and viscosity of the
fluid. The method exhibits greatly (~70%) improved results over our recently
published baseline with two separate steps for 3D reconstruction and motion
estimation. Our results with only two time steps are comparable to those of
sota tracking-based methods that require much longer sequences.Comment: To appear in International Journal of Computer Vision (IJCV
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Proposal to process RTNS-II accelerator targets for LLL
This proposal is submitted in response to a programmatic need at LLL for a supplier of 50-cm targets (tritided) for the new RTNS-II facility. Previous letters of inquiry to Mound also delineate a need for recovery of tritium from expended RTNS-II targets. As explained in this proposal, the tritided target manufacturing and tritium recovery can be accomplished in an efficient and timely manner at Mound Facility. Mound has been a major tritium handling facility for over 20 yr. Multigram quantities of tritium are routinely handled in various production, recovery, research, and development processes. Mound is widely recognized as a leader in the design, installation, and operation of high-purity glovebox atmosphere systems, and tritium containment, effluent control, and waste packaging systems. Demonstrated performance and experience in these strategic technology areas makes this facility ideally suited for meeting LLL`s tritided accelerator target needs. After consolidation and evaluation of various inputs of information, the authors feel confident that Mound can fabricate and recover RTNS-II targets to meet LLL requirements. This proposal, therefore, outlines their plan for performing this work and requests that Mound Facility be designated by LLL as the fabrication and recovery site for large-diameter fully tritided accelerator targets
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