Articles: partial-thromboplastin-time.
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J. Thromb. Thrombolysis · Jul 2012
Randomized Controlled Trial Multicenter StudyActivated partial thromboplastin time measurement is not associated with clinical outcomes in patients with high-risk non-ST-segment elevation acute coronary syndromes treated with unfractionated heparin.
Our objective was to determine the association of activated partial thromboplastin time (aPTT) with recurrent ischemic events and non-coronary artery bypass surgery-related thrombolysis in myocardial infarction major bleeding. We studied 4,985 patients with high-risk non-ST-segment elevation acute coronary syndromes (NSTE ACS) participating in SYNERGY, a prospective, randomized, international trial designed to emulate contemporary practice wherein unfractionated heparin (UFH) is given intravenously and titrated according to a weight-adjusted dosing nomogram to a target aPTT of 1.5-2 times the upper limit of normal (approximately 50-70 s). Aspirin was administered to 95% of patients, clopidogrel to 63%, and glycoprotein IIb/IIIa receptor inhibitors to 58%. ⋯ No relationship was observed between clinical outcomes and aPTT values persistently above or below the designated thresholds. Measurements of aPTT were not associated with clinical outcomes among patients with NSTE ACS treated with UFH. The required intensity of anticoagulation for benefit may be relatively modest when UFH is administered concomitantly with dual or triple platelet-directed therapy, particularly in patients undergoing early coronary revascularization.
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Trans. R. Soc. Trop. Med. Hyg. · Jul 2012
The role of prothrombin time (PT) in evaluating green pit viper (Cryptelytrops sp) bitten patients.
Viper bites cause consumptive coagulopathy resulting in hypofibrinogenaemia. Whole-blood clotting time is a standard test used to assess bleeding risk. Prothrombin time (PT) and activated partial thromboplastin time (APTT) are better standardised assays that are widely available, but their diagnostic accuracy in viper bites remains unknown. ⋯ The respective specificities were 94.4%, 95.8%, 95.6% and 72.4%. Three hypofibrinogenaemic patients who did not receive antivenom because of VCT <30min had persistently normal VCT and went home without clinical bleeding. In conclusion, PT with INR can be an alternative test for evaluation of coagulopathy in green pit viper bitten patients with potentially improved inter-laboratory standardisation.
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Am. J. Clin. Pathol. · Jun 2012
Recommendations for appropriate activated partial thromboplastin time reagent selection and utilization.
The activated partial thromboplastin time (aPTT) is widely used as a screening coagulation test and for monitoring unfractionated heparin therapy. Various commercial reagents are available, with different performance characteristics, particularly responsiveness to the lupus anticoagulant (LA). ⋯ Significant misunderstanding was apparent regarding the use of appropriate aPTT reagent for routine testing and LA identification. We recommend aPTT reagents with low LA responsiveness to screen for coagulation factor deficiencies and heparin monitoring, and suggest continued education of laboratory professionals and reagent manufacturers about appropriate aPTT reagent use.
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A strategy to produce sufficient anticoagulant properties with reduced risk of bleeding may be possible through inhibition of factor XI (FXI), a component of the intrinsic coagulation cascade. The objective of this work was to determine the safety profile of ISIS 416858, a 2'-methoxyethoxy (2'-MOE) antisense oligonucleotide inhibitor of FXI, with focus on assessment of bleeding risk. Cynomolgus monkeys administered ISIS 416858 (4, 8, 12, and 40 mg/kg/wk, subcutaneous) for up to 13 weeks produced a dose-dependent reduction in FXI (mRNA in liver and plasma activity) and a concomitant increase in activated partial thromboplastin time (APTT). ⋯ The dose-dependent presence of basophilic granules in multiple tissues in ISIS 416858-treated animals was an expected histologic change for a 2'-MOE antisense oligonucleotide, and no toxicity was attributed to hepatic FXI reduction. Basophilic granules reflect cellular drug uptake and subsequent visualization on hematoxylin staining. These results suggest that ISIS 416858 has an acceptable preclinical safety profile and is a promising clinical candidate to treat thrombotic disease.
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J. Oral Maxillofac. Surg. · Mar 2012
Risk factors affecting hemorrhage after tooth extraction in patients undergoing continuous infusion with unfractionated heparin.
To identify the risk factors affecting the incidence of postoperative hemorrhage (POH) associated with tooth extraction in patients undergoing continuous infusion with unfractionated heparin. ⋯ The results of the present study suggest that POH in tooth extraction occurs often in patients with an APTT of 57 seconds or greater when the continuous heparin infusion cannot be stopped.