Thrombosis research
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Thrombosis research · Oct 2002
Comment Review Case ReportsPerioperative anticoagulation management in patients who are receiving oral anticoagulant therapy: a practical guide for clinicians.
The management of patients who require temporary interruption of oral anticoagulant therapy because of surgery or other invasive procedures is a clinically important topic because of the increasing prevalence of patients who are receiving oral anticoagulants and the availability of low-molecular-weight heparins (LMWHs), which allow out-of-hospital perioperative anticoagulation. The optimal management of such patients has been hampered by the lack of well-designed prospective studies investigating the efficacy and safety of different perioperative management strategies. ⋯ An assessment of these factors will determine the perioperative management approach. The objectives of this review are to focus on practical issues relating to perioperative anticoagulation and the implementation of a perioperative anticoagulation management approach that can be used in everyday clinical practice.
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Thrombosis research · Sep 2002
Enhanced platelet aggregation with TRAP-6 and collagen in platelet aggregometry in patients with venous thromboembolism.
The role of platelet hyperaggregability as a possible risk factor for venous thromboembolism is not well defined. Some authors described enhanced maximal platelet aggregation in platelet aggregometry as a contributing factor for arterial and venous thrombosis. This syndrome has been termed "sticky-platelet syndrome" (SPS). ⋯ In contrast, we could not detect an increased platelet aggregation with EPI or ADP. Our results indicate that platelet hyperaggregability may represent an independent risk factor in patients with otherwise unexplained venous thromboembolism. In our study, low concentrations of TRAP-6 and collagen are superior to EPI and ADP to define platelet hyperreactivity in platelet aggregometry.
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Thrombosis research · Sep 2002
Comparative StudyIn vitro comparison of the effect of heparin, enoxaparin and fondaparinux on tests of coagulation.
Low-molecular weight heparin (LMWH) is increasingly used in place of unfractionated heparin (UFH) in patients with unstable angina, and phase II clinical trials using fondaparinux for this indication are underway. Because unstable angina patients often require urgent percutaneous coronary interventions (PCI) or aortocoronary bypass surgery, a point-of-care test is needed to monitor the anticoagulant effect of these agents. The activated clotting time (ACT) and activated partial thromboplastin time (aPTT) are the tests most often used to monitor heparin. ⋯ We determined that enoxaparin produced significantly less prolongation of both the ACT and the aPTT than heparin, whereas fondaparinux had no effect on either of these tests. Addition of enoxaparin to heparin-containing plasma did not prolong the ACT beyond that produced by heparin alone. The ACT and aPTT therefore cannot be used to monitor low-molecular weight heparin or fondaparinux, highlighting the need for a point-of-care anti-factor Xa assay.
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Thrombosis research · Apr 2002
Randomized Controlled Trial Comparative Study Clinical TrialAbsence of paradoxical thrombin activation by fibrin-specific thrombolytics in acute myocardial infarction: comparison of single-bolus tenecteplase and front-loaded alteplase.
Thrombolytic therapy in patients with acute myocardial infarction is hampered by bleeding complications and procoagulant effects favoring early reocclusion. TNK-tPA was shown in vitro to have considerable fibrin specificity. We investigated the effects of tenecteplase (TNK-tPA) and alteplase (rt-PA) on the haemostasis and fibrinolytic system. ⋯ This study indicates that tenecteplase has higher fibrin specificity not only in vitro but also in vivo versus alteplase. TNK-tPA consecutively has no paradoxical systemic procoagulant effect due to the lower extent of activation of the kallikrein-factor XII system than alteplase.
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Thrombosis research · Mar 2002
Clinical TrialReductions in platelet contractile force correlate with duration of cardiopulmonary bypass and blood loss in patients undergoing cardiac surgery.
Blood loss secondary to platelet dysfunction is known to be increased when the duration of cardiopulmonary bypass (CPB) is prolonged. The ability to correlate alterations in platelet function with the duration of bypass and early postoperative blood loss, however, has remained elusive. Platelet contractile force, a novel measure of platelet-mediated clot retraction, is known to be reduced following cardiac surgery and blockade of platelet adhesion receptors. ⋯ Reductions in platelet contractile force had a significant correlation with duration of CPB (r=0.564; P=0.002) and early blood loss (r=0.545; P=0.003). Although decreases in platelet contractile force and aggregation both correlated with CPB time in the smaller subset of patients tested, only platelet contractile force correlated with decreases in CD42b, CD61 and blood loss. The results of this study suggest that prolongation of CPB is related to increasing degrees of platelet dysfunction and that reductions in platelet contractile force are related to decreases in platelet adhesion receptors and early postoperative blood loss.