1,720,972 research outputs found
Improving outcomes with antiplatelet therapies in percutaneous coronary intervention and stenting
No full textPercutaneous closure of coronary artery fistulae: is it time for a UK registry?
No full textMost coronary artery fistulae are asymptomatic but there may be complications such as rupture and myocardial infarction. Percutaneous intervention is an attractive alternative to open surgical repair that offers lower procedural risk.
Increasing numbers of fistulae are being discovered incidentally during angiography. They present challenges in assessment and management. For example, there is poor correlation between symptoms and the size and flow rate of fistulae
Should We Interrupt Oral Anticoagulation Before Percutaneous Coronary Intervention? A National Survey of UK Interventional Cardiologists
No full textEffects of clopidogrel on "aspirin specific" pathways of platelet inhibition
No full textThe most widely accepted methods of assessing response to clopidogrel involve isolated ADP-induced platelet aggregation. Whilst poor response determined by these assays correlates with adverse clinical events, the number of “poor responders” is far higher than the number of events attributed to treatment failure. Clopidogrel may have effects that cannot be assessed using isolated ADP-induced aggregation. We have investigated the effect of clopidogrel on Arachidonic Acid (AA) induced platelet activation-an “aspirin specific” pathway using a novel near patient assay. Thirty four volunteers on no medication and 36 patients, on maintenance therapy with aspirin 75 mg daily, were recruited. Blood tests for Thrombelastogram PlateletMapping were taken immediately prior to and 6 hours after administration of a 600 mg clopidogrel loading dose. Changes in the area under the response curve at 15 minutes (AUC15) with both ADP- and AA-stimulation were calculated as were the corresponding percentage platelet and percentage clotting inhibition (%PIn and %CIn). There were predictable and significant changes in the AUC15 of the ADP channel in response to clopidogrel and the corresponding %PIn and %CIn in both volunteers and patients. There were also significant reductions in the AUC15 of the AA channel (presented as Mean +/- 95%CI), by 27.2 +/- 11.8%, p = 0.005 in volunteers and 35.0 +/- 8.2%, p < 0.001 in patients) and increases in the %PIn and %CIn calculated using the AA channel in volunteers (by 20.0 +/- 11.4%, p + 0.02 and 32.3 +/- 12.8%, p < 0.001 respectively) and patients (by 24.2 +/- 8.6%, p < 0.001 and by 18.0 +/- 8.6, p < 0.001 respectively). Clopidogrel has both independent and aspirin-synergistic effects on AA-induced platelet activation suggesting potentiation of the antiplatelet activity of aspirin. This effect may be clinically important and is not detected by current “gold standard” methods of assessing response to clopidogrel
"Short" thrombelastography as a test of platelet reactivity in response to antiplatelet therapy: validation and reproducibility
No full textBACKGROUND: A significant proportion of patients receiving dual antiplatelet therapy following percutaneous coronary intervention experience recurrent ischaemic events despite standard doses of treatment. Although clinical studies show significant heterogeneity in antiplatelet therapy responses, routine testing is not undertaken due to (i) lack of a standardized test, and (ii) poor clarity with regards to definition of abnormal responses. Short Thrombelastography (s-TEG) is a validated test that allows rapid measurement of clotting responses to antiplatelet therapy.OBJECTIVES: This study sought to determine the reproducibility of s-TEG and to compare s-TEG with VerifyNow in assessment of responses to antiplatelet therapy.METHODS: (i) intra-individual variability was assessed using s-TEG Area Under the Curve (AUC15) and maximum amplitude (MA) in one volunteer at 20 time-points on no medication and at 10 time-points pre and post 300?mg aspirin treatment (ii) inter-individual variability was determined from a retrospective analysis of data on MA and AUC15 obtained from 56 volunteers on no medication, 25 volunteers pre and post 300?mg aspirin treatment and 28 patients pre and post 600?mg clopidogrel treatment (iii) a comparison between AUC15 arachidonic-acid (AA) channel and VerifyNow aspirin response units (VN ARU) and between AUC15 adenosine diphosphate (ADP) channel and VerifyNow P2Y12 reactivity units (VN PRU) was obtained from retrospective analysis of data at 370 and 296 time-points respectively.RESULTS: There was minimal intra-and inter-individual variability in MA and AUC15 in the AA, ADP and thrombin channels. There was a good correlation between AA AUC15 and VN ARU (r?=?0.701, p?<?0.001) and between ADP AUC15 and VN PRU (r?=?0.609, p?<?0.001).CONCLUSIONS: s-TEG is a reproducible and reliable near-patient test that correlates well with VerifyNow. Large scale studies are needed to determine its potential role in individually tailored antiplatelet therapy
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
A novel fifteen minute test for assessment of individual time-dependent clotting responses to aspirin and clopidogrel using modified thrombelastography
No full textBACKGROUND: A rapid, reliable, point of care test reflecting patient specific responses to antiplatelet therapy would be of great clinical value in percutaneous coronary intervention (PCI). The aim of this study was to establish whether modified thrombelastography (TEG) can be employed as a 15 minute test of individual patient responses to aspirin and clopidogrel using a novel parameter, percentage clotting inhibition (%CIn). METHODS AND RESULTS: Thirty healthy volunteers and 10 patients undergoing elective PCI were recruited into four groups: 10 volunteers received a single 300 mg dose of aspirin [A1]: 10 volunteers received aspirin 75 mg daily for 7 days [A2]: 10 volunteers received a 600 mg dose of clopidogrel [C1]: 10 patients received a 600 mg loading dose of clopidogrel prior to elective PCI [C2]. In all cases the area under the clotting response curve was measured at 15 minutes (AUC15) and used to calculate a novel parameter, percentage clotting inhibition (%CIn). Large differences were demonstrated in both aspirin and clopidogrel groups in response to therapy as assessed by both the area under the curve at 15 minutes and %CIn. Furthermore, the technique demonstrated important heterogeneity of time-dependent responses between individuals. CONCLUSION: Modified TEG, employing AUC15 and %CIn, is a promising tool for assessing responses to aspirin and clopidogrel. Further data are now required to assess the potential of this test to optimise individual therapy in PCI patients in order to detect and treat those patients with relative hypo-responsiveness to anti-platelet drugs
Point-of-care platelet function assays demonstrate reduced responsiveness to clopidogrel, but not aspirin, in patients with Drug-Eluting Stent Thrombosis whilst on dual antiplatelet therapy
No full textBackgroundTo test the hypothesis that point-of-care assays of platelet reactivity would demonstrate reduced response to antiplatelet therapy in patients who experienced Drug Eluting Stent (DES) ST whilst on dual antiplatelet therapy compared to matched DES controls. Whilst the aetiology of stent thrombosis (ST) is multifactorial there is increasing evidence from laboratory-based assays that hyporesponsiveness to antiplatelet therapy is a factor in some cases.MethodsFrom 3004 PCI patients, seven survivors of DES ST whilst on dual antiplatelet therapy were identified and each matched with two patients without ST. Analysis was performed using (a) short Thrombelastogram PlateletMapping™ (TEG) and (b) VerifyNow Aspirin and P2Y12 assays. TEG analysis was performed using the Area Under the Curve at 15 minutes (AUC15) as previously described.ResultsThere were no differences in responses to aspirin. There was significantly greater platelet reactivity on clopidogrel in the ST group using the Accumetrics P2Y12 assay (183 ± 51 vs. 108 ± 31, p = 0.02) and a trend towards greater reactivity using TEG AUC15 (910 ± 328 vs. 618 ± 129, p = 0.07). 57% of the ST group by TEG and 43% of the ST cases by Accumetrics PRU had results > two standard deviations above the expected mean in the control group.ConclusionThis study demonstrates reduced platelet response to clopidogrel in some patients with DES ST compared to matched controls. The availability of point-of-care assays that can detect these responses raises the possibility of prospectively identifying DES patients at risk of ST and manipulating their subsequent risk
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