Vol

Distribution by Scientific Domains


Selected Abstracts


Oxovanadium(IV) Complexes with Pyrazinecarboxylic Acids:The Coordinating Properties of Ligands with the (Naromatic, COO,) Donor Set

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006
Eugenio Garribba
Abstract Complex formation between the VIVO ion and four pyrazine derivatives, 2-pyrazinecarboxylic acid (pzc), 5-methyl-2-pyrazinecarboxylic acid (5-Mepzc), 2,3-pyrazinedicarboxylic acid (3-COOHpzc) and 5-hydroxy-2-pyrazinecarboxylic acid (5-OHpzc), was studied in aqueous solution and in the solid state through the combined application of potentiometric and spectroscopic (EPR and FT-IR) techniques. The results indicate that in acidic and neutral aqueous solution all theligands form mono(chelated), bis(chelated) and dinuclear species of composition VOL, VOL2 and (VO)2L2H,2. Hexacoordinated VOL2 complexes are characterised by a cis/trans isomerism, where cis and trans are the species with a water molecule bound in the cis or trans position with respect to the V=O group. The trans arrangement is favoured over the cis arrangement. Three solid derivatives, [VO(5-Mepzc)2] (1), cis -[VO(pzc)2(H2O)] (2) and cis -[VO(3-COOHpzc)2(H2O)] (3), were isolated and characterised. Based on the experimental results and on the data in the literature, the stability of cis and trans isomers in aqueous solution and in the solid state has been discussed, showing that with ligands of comparable basicity and size of the chelate ring the hydrophilicity favours the cis species and determines the relative amount of the two isomers. The analysis of the magnetic properties of the hydroxo-bridged VIVO dimers suggests that for the (VO)2L2H,2 species the anti -coplanar arrangement is realised. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Response of methanogen populations to organic load increase during anaerobic digestion of olive mill wastewater

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2006
Aurora Rizzi
Abstract Process performances of an upflow anaerobic filter treating olive mill wastewater and the response of methanogenic Archaea to increasing volumetric organic load (VOL) were studied. At a VOL of 15 g chemical oxygen demand (COD) L,1 day,1, 90% of the influent COD was removed. Following a VOL increase from 6 to 15 g COD L,1 day,1, the polymerase chain reaction (PCR) titre of hydrogenotrophic Methanobacterium, determined by magnetic capture of the target DNA and group-specific PCR based on the 16S rRNA gene, decreased from 1011 to 108 cells g,1 sludge, while that of Methanomicrobiaceae and relatives increased from 104 to 106 cells g,1 sludge. Methanosaeta -like acetoclastic methanogens were less affected by VOL variation and dominated at high VOL with a 16S rRNA gene PCR titre of 109 cells g,1 sludge. Single-strand conformation polymorphism analysis of the PCR-amplified archaeal 16S rRNA gene showed a stable band pattern, indicating that VOL variation affected the methanogen PCR titre but not the archaeal community structure. Copyright © 2006 Society of Chemical Industry [source]


Chemistry, Urease Inhibition, and Phytotoxic Studies of Binuclear Vanadium(IV) Complexes

CHEMISTRY & BIODIVERSITY, Issue 1 2007
Rifat Ara
Abstract Vanadium plays an important role in biological systems and exhibits a variety of bioactivities. In an effort to uncover the chemistry and biochemistry of vanadium with nitrogen- and oxygen-containing ligands, we report herein the synthesis and spectroscopic characterization of vanadium(IV) complexes with hydrazide ligands. Substituents on these ligands exhibit systematic variations of electronic and steric factors. Elemental and spectral data indicate the presence of a dimeric unit with two vanadium(IV) ions coordinated with two hydrazide ligands along with two H2O molecules. The stability studies of these complexes over time in coordinating solvent, DMSO, indicates binding of the solvent molecules to give [V2O2L2(H2O)2(DMSO)2]2+ (L=hydrazide ligand) and then conversion of it to a monomeric intermediate species, [VOL(DMSO)3]1+. Hydrazide ligands are inactive against urease, whereas vanadium(IV) complexes of these ligands show significant inhibitory potential against this enzyme and are found to be non-competitive inhibitors. These complexes also show low phytotoxicity indicating their usefulness for soil ureases. Structure,activity relationship studies indicate that the steric and/or electronic effects that may change the geometry of the complexes play an important role in their inhibitory potential and phytotoxicity. [source]


On the impact of the solution representation for the Internet Protocol Network Design Problem with max-hop constraints

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2004
L. De Giovanni
Abstract The IP (Internet Protocol) Network Design Problem can be shortly stated as follows. Given a set of nodes and a set of traffic demands, we want to determine the minimum cost capacity installation such that all the traffic is routed. Capacity is provided by means of links of a given capacity and traffic must be loaded on the network according to the OSPF-ECM (Open Shortest Path First,Equal Commodity Multiflow) protocol, with additional constraints on the maximum number of hops. The problem is strongly NP-Hard, and the literature proposes local search-based heuristics that do not take into account max-hop constraints, or assume a simplified OSPF routing. The core in a local search approach is the network loading algorithm for the evaluation of the neighbor solutions costs. It presents critical aspects concerning both computational efficiency and memory requirements. Starting from a tabu search prototype, we show how these aspects deeply impact on the design of a local search procedure, even at the logical level. We present several properties of the related network loading problem, that allow to overcome the critical issues and lead to an efficient solution evaluation. © 2004 Wiley Periodicals, Inc. NETWORKS, VoL. 44(2), 73,83 2004 [source]


Has repetitive transcranial magnetic stimulation (rTMS) treatment for depression improved?

ACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2007
A systematic review, meta-analysis comparing the recent vs. the earlier rTMS studies
Objective:, To investigate whether the recent repetitive transcranial magnetic stimulation (rTMS) studies on depression using new parameters of stimulation have shown improved clinical results. Method:, We performed a systematic review and a meta-analysis of the rTMS studies on depression published in the past 12 months comparing these results with an earlier meta-analysis that analyzed the results of the initial rTMS studies on depression. Results:, Using our inclusion criteria, we selected the meta-analysis of Martin [Br J Psychiatry (2003) Vol. 182, 480,491] that included 13 studies (324 patients) and five studies for the recent meta-analysis (274 patients). The pooled effect size (standardized mean difference between pretreatment vs. post-treatment) from the random effects model was ,0.76 (95% confidence interval, CI, ,1.01 to ,0.51). This result was significantly larger than that of the earlier meta-analysis (,0.35, 95% CI ,0.66 to ,0.04). Conclusion:, Our findings suggest that recent rTMS clinical trials have shown larger antidepressant effects when compared with the earlier studies. [source]


Corrigendum to "Existence and Uniqueness of Solutions to the Bellman Equation in the Unbounded Case" Econometrica, Vol.

ECONOMETRICA, Issue 1 2009
2003), No. 5 (September
No abstract is available for this article. [source]


THE IMPORTANCE OF PRIVATE PROPERTY RIGHTS FOR ECONOMIC GROWTH: THE CASE OF RURAL CHINA, 1979,1987

ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 2 2006
IAN WILLS
This is an extended and slightly revised version of an article by Wills and Yang published in Policy, Vol. 9, No. J, Autumn 1993. The article was derived from a paper by Yang, Wang and Wills published in the China Economic Review in 1992. The idea for the empirical study, the analytical model and the procedure for quantifying changes in property rights came from Xiaokai Yang. The study illustrates his ability to apply inframarginal concepts to real problems. [source]


Clarification on Rejoinder: Evaluating Standard Setting Methods Using Error Models by Schulz in Vol.

EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 4 2006
No.
No abstract is available for this article. [source]


Further to Clinical Quiz, Volume 13 (5) 2001 and Vol.

EQUINE VETERINARY EDUCATION, Issue 4 2002
14 (2) 200
No abstract is available for this article. [source]


Correction: Association of CTLA4 polymorphism with regulatory T cell frequency, Vol.

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2005
35 (7) 200, DOI 10.1002/eji.20052616
No abstract is available for this article. [source]


Correction: Immunodominance of cytotoxic T lymphocyte epitopes co-injected in vivo and modulation by interleukin-12, Vol 26 (11) 1996, 2709,2716

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2005
Eberl
No abstract is available for this article. [source]


Thirty years on from the paper ,Gust Spectrum Fatigue Crack Propagation in Candidate Skin Materials', Fatigue of Engineering Materials and Structures, Vol.

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2009

IMPACT OF THE PAPER This paper1 addressed a very specific topic and by itself would not have had much impact in the intervening years. However, most of the paper's content was subsequently included in an extensive report on the Damage Tolerance (DT) properties of aluminium alloys.2 This report enabled guidelines for flight simulation fatigue crack growth testing to be formulated.3,4 [source]


Hygrocybe rigelliae (Velen.) E.Ludwig comb. nov. und Hygrocybe roseascens sp. nova, eine nahestehende Art aus der Untergattung Cuphophyllus (Agaricales, Hygrophoraceae, Tricholomataceae),

FEDDES REPERTORIUM, Issue 1-2 2004
E. Ludwig
Die Literatur zu Hygrophorus rigelliaeVelen. wird diskutiert, die Art wird zu Hygrocybe umkombiniert. Eine eng verwandte, neue Spezies , Hygrocybe roseascens , mit (nach Entwässerung) auffallenden rosa Tönen auf dem teilweise schuppigen Hut, 1,4-sporigen Basidien und kleinen, (sub)globosen Sporen wird beschrieben. Die Unterschiede zu anderen Arten werden diskutiert. Eine Tafel mit Habituszeichnungen und den mikroskopischen Merkmalen wird beigegeben. Eine Farbtafel der neuen Art wird im Band III meines Pilzkompendiums veröffentlicht werden, steht aber bereits jetzt im Internet unter http://www.pabb-web.de ("Pilzbilder") zur Verfügung. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Hygrocybe rigelliae (Velen.) E.Ludwig comb. nov. and Hygrocybe roseascens sp. nova, a tiny related species from the subspecies Cuphophyllus (Agaricales, Hygrophoraceae, Tricholomataceae) The literature on Hygrophorus rigelliaeVelen. is studied and the species is transferred to Hygrocybe. A related tiny wax gill, Hygrocybe roseascens, likewise belonging to subgenus Cuphophyllus is described as a new one. It is characterised by partly squamulose pileus with conspicuously pinkish hues when dry, 1,4-spored basidia and small, (sub)globose spores. The differences between the new species and similar taxa are discussed. A plate with drawings of its habit and microscopic features is given. A coloured plate will be published in Vol. III of my "Pilzkompendium" but is already available at http://www.pabb-web.de ("Pilzbilder"). [source]


Joseph S. Takahashi, Fred W. Turek and Robert Y.Moore (eds): Circadian Clocks (Handbook of Behavioral Neurobiology, Vol 12)

GENES, BRAIN AND BEHAVIOR, Issue 3 2002
W.J. Schwartz
[source]


Isotopic and petrological evidence of fluid,rock interaction at a Tethyan ocean,continent transition in the Alps: implications for tectonic processes and carbon transfer during early ocean formation

GEOFLUIDS (ELECTRONIC), Issue 4 2007
A. ENGSTRÖM
Abstract We report overprinting stable isotope evidence of fluid,rock interaction below two detachment faults along which mantle rocks were exhumed to the seafloor, between the respective landward and seaward limits of oceanic and continental crust, at a Tethyan ocean,continent transition (OCT). This OCT, which is presently exposed in the Tasna nappe (south-eastern Switzerland) is considered an on-land analogue of the well-studied Iberian OCT. We compare our results with the fault architecture (fault core,damage zone,protolith) described by Caine et al. [Geology (1996) Vol. 24, pp. 1025,1028]. We confirm the existence of a sharp boundary between the fault core and damage zone based on isotopic data, but the boundary between the damage zone and protolith is gradational. We identify evidence for: (1) pervasive isotopic modification to 8.4 ± 0.1, which accompanied or post-dated serpentinization of these mantle rocks at an estimated temperature of 67,109°C, (2) either (i) partial isolation of some highly strained regions [fault core(s) and mylonite] from this pervasive isotopic modification, because of permeability reduction (Caine et al.) or (ii) subsequent isotopic modification caused by structurally channelled flow of warm fluids within these highly strained regions, because of permeability enhancement, and (3) isotopic modification, which is associated with extensive calcification at T = 54,100°C, primarily beneath the younger of the two detachment faults and post-dating initial serpentinization. By comparing the volumetric extent of calcification with an experimentally verified model for calcite precipitation in veins, we conclude that calcification could have occurred in response to seawater infiltration, with a calculated flux rate of 0.1,0.2 m year,1 and a minimum duration of 0.2,4.0 × 104 years. The associated time-averaged uptake flux of carbon during this period was 8,120 mol m,2 year,1. By comparison with the estimated area of exhumed mantle rocks at the Iberian OCT, we calculate a maximum annual uptake flux for carbon of 2,30 Tg year,1. This is an order of magnitude greater than that for carbon exchange at the mid-ocean ridges and 0.1,1.4% of the global oceanic uptake flux for carbon. [source]


Author, book review and key word indexes Vol 45, 2007

GEOGRAPHICAL RESEARCH, Issue 4 2007
Article first published online: 1 NOV 200
First page of article [source]


Integrating Efficient Grassland Farming and Biodiversity (Grassland Science in Europe, Vol.

GRASS & FORAGE SCIENCE, Issue 3 2006

No abstract is available for this article. [source]


Segmenting youth voting behaviour through trusting,distrusting relationships: a conceptual approach

INTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 3 2004
Janine Dermody
This paper reviews current evidence on the declining political engagement of British youth. What emerges is that causes of their political disaffection are manifold and complex, but trust, distrust and cynicism feature strongly. Traditional approaches to trust and distrust fail to recognise this complexity; consequently this paper offers a more sophisticated conceptual framework that examines trust and distrust as separate but linked dimensions, as advocated by Lewicki, McAllister and Bies.[Lewicki, R. J., McAllister D. J. and Bies R. J. (1998) ,Trust and distrust: New relationships and realities', Academy of Management Review, Vol. 23, No. 3, pp. 438,458.] From the analysis four segments of ,voter' types are identified. By segmenting voters in this way, marketers can design strategies to help increase young people's trust and reduce their distrust, thereby increasing their propensity to vote in future elections. A synopsis of marketing aims to stimulate the ,youth vote' is presented along with areas for further research. Copyright © 2004 Henry Stewart Publications [source]


Long-Term Outcome of Atrial Fibrillation Ablation: Impact and Predictors of Very Late Recurrence

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
ANITA WOKHLU M.D.
Long-Term Outcome of AF Ablation. Introduction: Ablation eliminates atrial fibrillation (AF) in studies with 1 year follow-up, but very late recurrences may compromise long-term efficacy. In a large cohort, we sought to describe the determinants of delayed recurrence after AF ablation. Methods and Results: Seven hundred and seventy-four patients with AF (428 paroxysmal [PAF, 55%] and 346 persistent or longstanding persistent [PersAF, 45%]) underwent wide area circumferential ablation (WACA, 62%) or pulmonary vein isolation (38%). Over 3.0 ± 1.9 years, there were 135 recurrences in PAF patients and 142 in PersAF patients. AF elimination was achieved in 61% of patients with PersAF at 2 years after last ablation and in 71% of patients with PAF (P = 0.04). This finding was related to a higher initial rate of very late recurrence in PersAF. From 1.0 to 2.5 years, the recurrence increased by 20% (from 37% to 57%) in PersAF patients versus only 12% (from 27% to 39%) in PAF patients. Independent predictors of overall recurrence included diabetes (HR 1.9 [1.3,2.9], P = 0.002) and PersAF (HR 1.6 [1.2,2.0], P < 0.001). Independent predictors of very late recurrence included PersAF (HR 1.7 [1.1,2.7], P = 0.018) and WACA (HR 1.8 [1.1,2.7], P = 0.018), while diabetes came close to significance. In PAF patients, left atrial size >45 mm was identified as an AF-type specific predictor (HR 2.4 [1.3,4.7], P = 0.009), whereas in PersAF patients, no unique predictors were identified. Conclusion: Late recurrences reduced the long-term efficacy of AF ablation, particularly in patients with PersAF and underlying cardiovascular diseases. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1071-1078) [source]


Persistence of Pulmonary Vein Isolation After Robotic Remote-Navigated Ablation for Atrial Fibrillation and its Relation to Clinical Outcome

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
STEPHAN WILLEMS M.D.
Robotic Remote Ablation for AF. Aims: A robotic navigation system (RNS, HansenÔ) has been developed as an alternative method of performing ablation for atrial fibrillation (AF). Despite the growing application of RNS-guided pulmonary vein isolation (PVI), its consequences and mechanisms of subsequent AF recurrences are unknown. We investigated the acute procedural success and persistence of PVI over time after robotic PVI and its relation to clinical outcome. Methods and Results: Sixty-four patients (60.7 ± 9.8 years, 53 male) with paroxysmal AF underwent robotic circumferential PVI with 3-dimensional left atrial reconstruction (NavXÔ). A voluntary repeat invasive electrophysiological study was performed 3 months after ablation irrespective of clinical course. Robotic PVI was successful in all patients without complication (fluoroscopy time: 23.5 [12,34], procedure time: 180 [150,225] minutes). Fluoroscopy time demonstrated a gradual decline but was significantly reduced after the 30th patient following the introduction of additional navigation software (34 [29,45] vs 12 [9,17] minutes; P < 0.001). A repeat study at 3 months was performed in 63% of patients and revealed electrical conduction recovery in 43% of all PVs. Restudied patients without AF recurrence (n = 28) showed a significantly lower number of recovered PVs (1 (0,2) vs 2 (2,3); P = 0.006) and a longer LA-PV conduction delay than patients with AF recurrences (n = 12). Persistent block of all PVs was associated with freedom from AF in all patients. At 3 months, 67% of patients were free of AF, while reablation of recovered PVs led to an overall freedom from AF in 81% of patients after 1 year. Conclusion: Robotic PVI for PAF is safe, effective, and requires limited fluoroscopy while yielding comparable success rates to conventional ablation approaches with PV reconduction as a common phenomenon associated with AF recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1079-1084) [source]


Long-Term Mechanical Consequences of Permanent Right Ventricular Pacing: Effect of Pacing Site

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
DARRYL P. LEONG M.B.B.S.
Optimal Right Ventricular Pacing,Introduction: Long-term right ventricular apical (RVA) pacing has been associated with adverse effects on left ventricular systolic function; however, the comparative effects of right ventricular outflow tract (RVOT) pacing are unknown. Our aim was therefore to examine the long-term effects of septal RVOT versus RVA pacing on left ventricular and atrial structure and function. Methods: Fifty-eight patients who were prospectively randomized to long-term pacing either from the right ventricular apex or RVOT septum were studied echocardiographically. Left ventricular (LV) and atrial (LA) volumes were measured. LV 2D strain and tissue velocity images were analyzed to measure 18-segment time-to-peak longitudinal systolic strain and 12-segment time-to-peak systolic tissue velocity. Intra-LV synchrony was assessed by their respective standard deviations. Interventricular mechanical delay was measured as the difference in time-to-onset of systolic flow in the RVOT and LV outflow tract. Septal A' was measured using tissue velocity images. Results: Following 29 ± 10 months pacing, there was a significant difference in LV ejection fraction (P < 0.001), LV end-systolic volume (P = 0.007), and LA volume (P = 0.02) favoring the RVOT-paced group over the RVA-paced patients. RVA-pacing was associated with greater interventricular mechanical dyssynchrony and intra-LV dyssynchrony than RVOT-pacing. Septal A' was adversely affected by intra-LV dyssynchrony (P < 0.05). Conclusions: Long-term RVOT-pacing was associated with superior indices of LV structure and function compared with RVA-pacing, and was associated with less adverse LA remodeling. If pacing cannot be avoided, the RVOT septum may be the preferred site for right ventricular pacing. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1120-1126) [source]


Increased Right Ventricular Repolarization Gradients Promote Arrhythmogenesis in a Murine Model of Brugada Syndrome

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
CLAIRE A. MARTIN M.R.C.P.
Repolarization Gradients in Brugada Syndrome.,,Introduction: Brugada syndrome (BrS) is associated with loss of Na+ channel function and increased risks of a ventricular tachycardia exacerbated by flecainide but reduced by quinidine. Previous studies in nongenetic models have implicated both altered conduction times and repolarization gradients in this arrhythmogenicity. We compared activation latencies and spatial differences in action potential recovery between different ventricular regions in a murine Scn5a+/, BrS model, and investigated the effect of flecainide and quinidine upon these. Methods and Results: Langendorff-perfused wild-type and Scn5a+/, hearts were subjected to regular pacing and a combination of programmed electrical stimulation techniques. Monophasic action potentials were recorded from the right (RV) and left ventricular (LV) epicardium and endocardium before and following flecainide (10 ,M) or quinidine (5 ,M) treatment, and activation latencies measured. Transmural repolarization gradients were then calculated from the difference between neighboring endocardial and epicardial action potential durations (APDs). Scn5a+/, hearts showed decreased RV epicardial APDs, accentuating RV, but not LV, transmural gradients. This correlated with increased arrhythmic tendencies compared with wild-type. Flecainide increased RV transmural gradients, while quinidine decreased them, in line with their respective pro- and antiarrhythmic effects. In contrast, Scna5+/, hearts showed slowed conduction times in both RV and LV, exacerbated not only by flecainide but also by quinidine, in contrast to their differing effects on arrhythmogenesis. Conclusion: We use a murine genetic model of BrS to systematically analyze LV and RV action potential kinetics for the first time. This establishes a key role for accentuated transmural gradients, specifically in the RV, in its arrhythmogenicity. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1153-1159) [source]


Acidosis Impairs the Protective Role of hERG K+ Channels Against Premature Stimulation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
B.Sc., CHUN YUN DU M.B.
Acidosis and the hERG K+ Channel.,Introduction: Potassium channels encoded by human ether-à-go-go-related gene (hERG) underlie the cardiac rapid delayed rectifier K+ channel current (IKr). Acidosis occurs in a number of pathological situations and modulates a range of ionic currents including IKr. The aim of this study was to characterize effects of extracellular acidosis on hERG current (IhERG), with particular reference to quantifying effects on IhERG elicited by physiological waveforms and upon the protective role afforded by hERG against premature depolarizing stimuli. Methods and Results: IhERG recordings were made from hERG-expressing Chinese Hamster Ovary cells using whole-cell patch-clamp at 37°C. IhERG during action potential (AP) waveforms was rapidly suppressed by reducing external pH from 7.4 to 6.3. Peak repolarizing current and steady state IhERG activation were shifted by ,+6 mV; maximal IhERG conductance was reduced. The voltage-dependence of IhERG inactivation was little-altered. Fast and slow time-constants of IhERG deactivation were smaller across a range of voltages at pH 6.3 than at pH 7.4, and the contribution of fast deactivation increased. A modest acceleration of the time-course of recovery of IhERG from inactivation was observed, but time-course of activation was unaffected. The amplitude of outward IhERG transients elicited by premature stimuli following an AP command was significantly decreased at lower pH. Computer simulations showed that after AP repolarization a subthreshold stimulus at pH 7.4 could evoke an AP at pH 6.3. Conclusion: During acidosis the contribution of IhERG to action potential repolarization is reduced and hERG may be less effective in counteracting proarrhythmogenic depolarizing stimuli. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1160-1169) [source]


Role of Residual Potentials Inside Circumferential Pulmonary Veins Ablation Lines in the Recurrence of Paroxysmal Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2010
Ph.D., YONG-HYUN KIM M.D.
Residual Potentials After Pulmonary Vein Isolation. Background: Residual gaps due to incomplete ablation lines are known to be the most common cause of recurrent atrial fibrillation (AF) after catheter ablation. We hypothesized that any residual potentials at the junction of the left atrium and pulmonary vein (PV), inside the circumferential PV ablation (CPVA) lines, would contribute to the recurrence of AF or post-AF ablation atrial flutter (AFL); therefore, the elimination of these potentials increases AF-/AFL-free survival rates. Methods and Results: One hundred and two patients with paroxysmal AF (PAF) were enrolled and prospectively randomized to a group with ablation of residual potentials as add-on therapy to CPVA + PV electrical isolation (PVI) (group 1, n = 49), or a group without ablation of the residual potentials (group 2, n = 53). Post-CPVA residual potentials, inside the ablation lines, were identified by contact bipolar electrode mapping catheter and a detailed 3-dimensional voltage map. Twenty-three patients in group 1 and 18 patients in group 2 had post-CPVA residual potentials (46.9% vs 34.0%, P = 0.182). The AF-/AFL-free survival rate during follow-up of 23.3 ± 7.9 months was not different in comparisons between the 2 groups (P = 0.818), and 79.6% and 81.1% of the patients in groups 1 and 2 maintained a sinus rhythm (P = 0.845), respectively. Conclusions: Residual potentials inside CPVA were commonly found in the patients with PAF after CPVA + PVI. Further ablation of residual potentials did not increase the efficacy of catheter ablation in patients with PAF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 959-965, September 2010) [source]


The Impact of Age on the Electroanatomical Characteristics and Outcome of Catheter Ablation in Patients with Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2010
TA-CHUAN TUAN M.D.
Age and Atrial Fibrillation.,,Background: Previous studies have indicated that atrial fibrillation (AF) in patients over the age of 60 at diagnosis is a risk factor for a substantial increase in cardiovascular events. However, information about the impact of age on the atrial substrate and clinical outcome after catheter ablation of AF is limited. Methods: This study included 350 patients (53 ± 12 years, 254 males) who underwent circumferential pulmonary vein isolation (CPVI) of AF, guided by a NavX mapping system. The subjects were divided into three groups according to their age, as follows: Group I: age ,50 (n = 141), Group II: age = 51,64 (n = 149) and Group III: age ,65 years old (n = 60). The mean voltage and total activation time of the individual atria were obtained by using a NavX mapping system before ablation. Several parameters, including the gender, AF duration, and left atrial (LA) diameter were analyzed. Results: The younger age group had a significantly smaller LA diameter (Group I vs Group II vs Group III, 36.89 ± 7.11 vs 39.16 ± 5.65 vs 40.77 ± 4.95 mm, P = 0.002) and higher LA bipolar voltage (2.09 ± 0.83 vs 1.73 ± 0.73 vs 1.86 ± 0.67 mV, respectively, P = 0.024), compared with the older AF patients. The LA bipolar voltage exhibited a significant reduction when the patients became older, however, that did not occur in the right atrium. The incidence of an AF recurrence was higher in the older age group than in the younger age groups. A subgroup of patients with lone AF was analyzed and age was found to be an independent predictor of the AF recurrence after receiving the first CPVI in the multivariable model (P < 0.05). Conclusions: Age has a significant impact on the LA substrate properties and outcome of the catheter ablation of AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 966-972, September 2010) [source]


Microvolt T-Wave Alternans Testing: Renewed Hope?

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2010
M.P.H., SANDEEP BANSAL M.D.
J Cardiovasc Electrophysiol, Vol. 21, pp. 1015-1016, September 2010. [source]


Successful Catheter Ablation and Documentation of the Activation and Propagation Pattern During a Left Atrial Focal Tachycardia in a Patient with Cor Triatriatum Sinister

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2010
KOICHIRO EJIMA M.D.
Atrial Tachycardia in Cor Triatriatum. We report a case of an atrial tachycardia (AT) originating from the left atrium (LA) associated with cor triatriatum sinister. Electroanatomical mapping of the 2 subdivided chambers of the LA during the AT revealed a centrifugal activation pattern from the posterior wall of the accessory chamber near the left superior pulmonary vein. The propagation map on the CARTO system revealed that the AT wave front spread centrifugally over the "accessory chamber," turned around the edge of the membrane subdividing the LA, and then spread over the "main chamber." A single radiofrequency application successfully abolished the AT. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1050-1054, September 2010) [source]


Lobectomy for Pulmonary Vein Occlusion Secondary to Radiofrequency Ablation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2010
MATTHEW A. STELIGA M.D.
Pulmonary Vein Occlusion After RF Ablation., Pulmonary vein stenosis, a recognized complication of transcatheter radiofrequency ablation in the left atrium, is often asymptomatic. Significant stenosis is commonly treated with percutaneous balloon dilation with or without stenting. We encountered a case of complete pulmonary vein occlusion that caused lobar thrombosis, pleuritic pain, and persistent cough. Imaging studies revealed virtually no perfusion to the affected lobe. A lobectomy was performed, resolving the persistent cough and pain. Pulmonary vein occlusion should be suspected in patients who present with pulmonary symptoms after having undergone ablative procedures for atrial fibrillation. This condition may necessitate surgical intervention if interventions such as balloon dilation or stenting are not possible or are ineffective.,(J Cardiovasc Electrophysiol, Vol. 21, pp. 1055-1058, September 2010) [source]


Capsule Endoscopy in Examination of Esophagus for Lesions After Radiofrequency Catheter Ablation: A Potential Tool to Select Patients With Increased Risk of Complications

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2010
LUIGI DI BIASE M.D.
Capsule Endoscopy in Examination of Esophagus.,Background: Esophageal injury can result from left atrial radiofrequency ablation (RFA) therapy, with added concern because of its possible relationship to the development of atrial-esophageal (A-E) fistulas. Objective: Evaluate utility of esophageal capsule endoscopy to detect esophageal lesions as a complication of RFA therapy in the treatment of atrial fibrillation (AF). Methods: Consecutive patients with AF who underwent left atrial RFA therapy and received capsule endoscopy within 48 hours postablation. Video was reviewed by a single gastroenterologist. The medical records were also reviewed for symptoms immediately postablation and at the 3-month follow-up. Results: A total of 93 consecutive patients were included and 88 completed the study and were analyzed. The prevalence of esophageal lesions was 17% (15/88 patients). Nine percent (8/88) of these patients had lesions anatomically consistent with the location of the ablation catheter. Six patients with positive capsule findings had symptoms of chest pain (3/6, 50%), throat pain (2/6, 33%), nausea (1/6, 17%), and abdominal pain (1/6, 17%). An additional 24 patients were symptomatic postablation, but with normal capsule findings. All patients with identified lesions by capsule endoscopy received oral proton pump inhibitor therapy, and were instructed to contact the Cleveland Clinic in the event of worsening symptoms. No delayed complications were reported at the 3-month follow-up. Conclusion: This study supports the use of capsule endoscopy as a tool for the detection of esophageal injury post-RFA therapy. PillCam ESO is well tolerated and provides satisfactory images of the areas of interest in the esophagus without potential risk related to insufflation with regular esophagogastroduodenoscopy. (J Cardiovasc Electrophysiol, Vol. 21, pp. 839-844, August 2010) [source]


A Short-Term, Randomized, Double-Blind, Parallel-Group Study to Evaluate the Efficacy and Safety of Dronedarone versus Amiodarone in Patients with Persistent Atrial Fibrillation: The DIONYSOS Study

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2010
JEAN-YVES LE HEUZEY M.D.
Dronedarone versus Amiodarone in Patients with AF.,,Introduction: We compared the efficacy and safety of amiodarone and dronedarone in patients with persistent atrial fibrillation (AF). Methods: Five hundred and four amiodarone-naïve patients were randomized to receive dronedarone 400 mg bid (n = 249) or amiodarone 600 mg qd for 28 days then 200 mg qd (n = 255) for at least 6 months. Primary composite endpoint was recurrence of AF (including unsuccessful electrical cardioversion, no spontaneous conversion and no electrical cardioversion) or premature study discontinuation. Main safety endpoint (MSE) was occurrence of thyroid-, hepatic-, pulmonary-, neurologic-, skin-, eye-, or gastrointestinal-specific events, or premature study drug discontinuation following an adverse event. Results: Median treatment duration was 7 months. The primary composite endpoint was 75.1 and 58.8% with dronedarone and amiodarone, respectively, at 12 months (hazard ratio [HR] 1.59; 95% confidence interval [CI] 1.28,1.98; P < 0.0001), mainly driven by AF recurrence with dronedarone compared with amiodarone (63.5 vs 42.0%). AF recurrence after successful cardioversion was 36.5 and 24.3% with dronedarone and amiodarone, respectively. Premature drug discontinuation tended to be less frequent with dronedarone (10.4 vs 13.3%). MSE was 39.3 and 44.5% with dronedarone and amiodarone, respectively, at 12 months (HR = 0.80; 95% CI 0.60,1.07; P = 0.129), and mainly driven by fewer thyroid, neurologic, skin, and ocular events in the dronedarone group. Conclusion: In this short-term study, dronedarone was less effective than amiodarone in decreasing AF recurrence, but had a better safety profile, specifically with regard to thyroid and neurologic events and a lack of interaction with oral anticoagulants. (J Cardiovasc Electrophysiol, Vol. 21, pp. 597-605, June 2010) [source]