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Query: UMLS:C0034065 (pulmonary embolism)
 14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombolytic therapy is rarely used in venous thromboembolism because of the fear of hemorrhagic complications. Preliminary clinical experiences with recombinant tissue-type plasminogen activator (rt-PA) in patients with deep vein thrombosis have shown that even this fibrin-specific plasminogen activator causes an unacceptable rate of hemorrhagic complications. Theoretical considerations and the available experimental and clinical data suggest that infusion of rt-PA over a short period of time would result in a more favorable risk-benefit ratio. Shortening the period of rt-PA infusion results in higher peak plasma levels, thus allowing a higher concentration of the plasminogen activator on the surface and inside the occluding thrombus. In addition, a bolus infusion can prevent or minimize the interaction between rt-PA and the hemostatic system, reducing the likelihood of a systemic lytic state, of a platelet function defect, and, possibly, of bleeding side effects. In venous thromboembolism animal models, the efficacy of bolus rt-PA can be further increased by the adjunctive administration of an effective antithrombotic treatment. This is because the accretion of new fibrin on the thrombi counteracts the lysis of preformed fibrin and influences negatively the final thrombus size. Effective adjunctive antithrombotic treatment includes either high doses of heparin, producing an unclottable activated partial thromboplastin time (aPTT), or doses of recombinant hirudin, doubling the aPTT. When used as an alternative to rt-PA, bolus doses of a hybrid plasminogen activator with prolonged half-life efficiently reduce thrombus size by lysing preformed and newly formed fibrin. Preliminary clinical experience in patients with pulmonary embolism seems to confirm that rt-PA infused as a bolus is at least as effective as, and probably more effective than, rt-PA infused over a longer period.
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PMID:Bolus thrombolysis in venous thromboembolism. 155 82

The standard treatment of deep vein thrombosis is given by continuous intravenous infusion of unfractionated heparin. This entails hospitalisation, nursing care, immobility and repeated laboratory tests (e.g. activated partial thromboplastin time [APTT], platelet count). In addition approximately 10% of patients suffer major haemorrhages. The potential advantages of a low molecular weight heparin (CY 216) given subcutaneously were explored in a randomised trial with blind quantitative evaluation of venograms. The study included 166 patients and both "therapeutic efficacy" and "intention to-treat" analyses showed that subcutaneous CY 216 in fixed doses based only on body weight was more effective on the Arnesen and Marder phlebographic scores than continuous i.v. standard heparin with daily dose adjustment according to results of coagulation tests. There was no increase in the risks of pulmonary embolism, haemorrhage or clot extension.
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PMID:A randomised trial of subcutaneous low molecular weight heparin (CY 216) compared with intravenous unfractionated heparin in the treatment of deep vein thrombosis. A collaborative European multicentre study. 164 90

The indications, efficacy, dosage, administration, and monitoring of heparin and warfarin therapy for acute thromboembolic events are reviewed, with emphasis on recent changes in treatment recommendations. High-dose heparin therapy is indicated for acute deep-vein thrombosis and pulmonary embolism. Heparin therapy as an adjunct to thrombolytic agents for acute myocardial infarction is becoming increasingly accepted. Heparin therapy for acute thromboembolic events consists of a dosage that elevates the activated partial thromboplastin time to 1.5 to 2.0 times the control value; formerly, 1.5 to 2.5 times control was considered therapeutic. The recommended heparin dosage is a bolus dose of 70-100 units/kg followed by an infusion of 15-25 units/kg/hr. To prevent recurrent thromboembolism, most patients require long-term therapy following acute treatment; this typically consists of warfarin, which should be initiated on day 1 or 2 of heparin therapy whenever possible. For most indications, the intensity of warfarin has been reduced to a dosage that elevates the prothrombin time to 1.3 to 1.5 times control. Alternative therapies (low-molecular-weight heparins) and routes (subcutaneous heparin) should be further investigated. Current recommendations for heparin and warfarin therapy of acute thromboembolism include reduced intensity of both drugs and shortened duration of therapy. Since the therapeutic ranges for both heparin and warfarin therapy have been compressed, closer monitoring may be necessary to achieve and maintain adequate anticoagulation.
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PMID:Therapy of acute thromboembolism with heparin and warfarin. 179 18

Plasma levels of prothrombin fragment 1 + 2 (F 1 + 2), of thrombin-antithrombin III complexes (TAT) and of D-dimers were evaluated at several time intervals in 15 patients affected by acute proximal deep vein thrombosis, complicated or not by pulmonary embolism, and treated by conventional heparin therapy for 9 d. The mean levels of the three markers remained significantly increased throughout the period of observation, except for F 1 + 2 on day 9, when compared to normal values established in a population of normal healthy blood donors. However, whereas heparin significantly decreased the plasma levels of F 1 + 2 and of TAT complexes in less than 3 d. D-dimer levels were not significantly altered. Significant correlations were observed between the plasma levels of the three markers but they were not correlated to the actual intensity of heparin treatment evaluated as the activated partial thromboplastin time prolongation. These results indicate that heparin improves the hypercoagulable state associated with a deep vein thrombosis within the first days of treatment as indicated by TAT and F 1 + 2. They also account for the performances of D-dimer assay for the diagnosis of deep vein thrombosis in patients already receiving heparin, a common situation in routine hospital practice.
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PMID:Prothrombin fragment 1 + 2, thrombin-antithrombin III complexes and D-dimers in acute deep vein thrombosis: effects of heparin treatment. 187 25

To examine the diagnostic work-up and subsequent management of patients with pulmonary embolism, we retrospectively reviewed the medical records of 60 patients who had arteriographically proven pulmonary embolism. Ventilation-perfusion scans were utilized in 47 patients and were classified as showing a high (55.3%), moderate (14.9%), low (8.5%), or indeterminate (21.3%) probability of pulmonary embolism. Of the 33 patients treated with anticoagulation, complications occurred in 10 (30.3%). Of the 39 patients treated with inferior vena cava filters, complications occurred in 16 (41.0%) patients, with the most clinically significant complication being recurrent pulmonary embolism, found to occur in one (2.6%) patient. For patients treated with anticoagulation, heparin was started an average of 0.3 (+/- 0.5) days following the initial suspicion of a pulmonary embolism. The average time to reach a therapeutic partial thromboplastin time level was 2.0 (+/- 1.8) days, and warfarin was started an average of 6.2 (+/- 4.1) days after heparin was begun. Among the 60 patients, five (8.3%) died from the pulmonary embolism, and two of these had at least a five day delay before diagnosis was made by pulmonary arteriography. Since the ventilation-perfusion scan had a sensitivity of 70.2% and a false negative rate of 8.5%, it is not always sufficiently accurate in making final treatment decisions, so there should be less hesitation in attaining pulmonary arteriograms. Therapeutic partial thromboplastin time levels should be more aggressively sought. Warfarin should be started within the first few days of heparin therapy. Inferior vena cava filters should be utilized in patients who have a contraindication to anticoagulation therapy or a complication from anticoagulation therapy.
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PMID:Physician practices in the diagnosis and management of patients with pulmonary embolism. 187 91

Heparin and warfarin sodium (Coumadin, Panwarfin, Sofarin) are used most often to treat acute and recurrent venous thromboembolic disease, arterial disease, valvular heart disease, and atrial fibrillation. These agents along with dextran, pneumatic compression devices, and gradient stockings are also used to prevent deep venous thrombosis and pulmonary embolism in patients at high risk (eg, those with venous stasis, lower limb or spinal cord trauma, clotting abnormalities). Anticoagulation therapy is monitored by maintaining the activated partial thromboplastin time and the prothrombin time in the therapeutic range.
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PMID:Using anticoagulants safely. Guidelines for therapeutic and prophylactic regimens. 188 10

A young man who had suffered several episodes of deep-vein thrombosis of the legs since the age of 20 had a myocardial infarction at the age of 33, at which time both a prolonged partial thromboplastin time (PTT), compatible with a lupus anticoagulant (LA), and decreased fibrinolytic capacity (FC) were found. His sister presented with deep-vein thrombosis of a leg and subsequent pulmonary embolism when she was 18 years old. She had a miscarriage three years later and developed a hemolytic-uremic syndrome at the age of 35. The PT and FC were normal. Laboratory investigations of the parents revealed positive antinuclear antibodies in the mother's serum but no anomaly in the father. This study suggests a familial tendency to develop autoimmune disorders associated with LA and thromboembolic complications related to decreased FC.
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PMID:Different clinical presentations of a lupus anticoagulant in the same family. 190 97

Standard unfractionated heparin is a mixture of mucopolysaccharide chains of various length that may vary from 5000 to 30,000 daltons. Heparin is only effective as an anticoagulant in the presence of a plasma protein termed antithrombin III, with which it forms a complex. High- and low-affinity heparin are 2 types that readily bind or do not bind, respectively, to antithrombin III. The pharmacokinetics of unfractionated heparin are compatible with a model based on the combination of a saturable and a linear mechanism. The primary indication for intravenous infusion of conventional heparin is to prevent extension of an established arterial, venous or intracardiac thrombus. The average requirement is 400 U/kg/24h. Subcutaneous administration of 5000U of concentrated unfractionated heparin, administered every 8 or 12 hours, is effective and safe in the prevention of postoperative venous thrombosis and pulmonary embolism in patients at medium thrombotic risk. Adequate prophylaxis is also obtained in patients at high thrombotic risk if 5000U of heparin combined with 0.5mg dihydroergotamine is given subcutaneously 3 times daily, or by monitoring the 3 subcutaneous doses of heparin in order to maintain an adjusted activated partial thromboplastin time (APTT) of around 50 to 70 seconds. Low molecular weight heparins have been produced by a variety of techniques and their molecular weights range from 3000 to 9000 daltons. These preparations have a ratio of anti-factor Xa activity to anti-factor IIa activity of about 4, while the ratio for unfractionated heparin is 1. After intravenous administration of low molecular weight heparin, the half-life of the anti-factor Xa activity is considerably longer than for unfractionated heparin, while the anti-factor IIa half-lives are similar. In contrast to unfractionated heparin, low molecular weight heparin is completely absorbed after subcutaneous administration and its biological half-life is almost twice as long. In spite of certain differences with regard to the ratio between factor Xa and IIa inhibition, the various low molecular weight preparations show a rather similar absorption pattern. The bioavailability of all low molecular weight heparin fractions is substantially higher than that of unfractionated heparin, which renders their use more simple. Low molecular weight heparins less readily enhance platelet aggregation although there is no evidence that low molecular weight heparins are less antigenic or that they do not interact with platelet IgGFc receptor. A lower bleeding incidence for equivalent antithrombotic efficacy of fractionated heparins when compared to unfractionated heparins has yet to be established in humans.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pharmacotherapeutic aspects of unfractionated and low molecular weight heparins. 196 34

Fifty patients presenting with acute deep-vein thrombosis were randomized in a prospective, controlled study to determine the safety and efficacy of a treatment with low-molecular-weight (LMW) heparin compared with unfractionated heparin. LMW heparin (n = 24) was administered twice daily subcutaneously at a dose of 2 X 150 anti-Xa units/kg body weight, and unfractionated heparin (n = 26) was given intravenously by continuous infusion at a dose of 450 anti-Xa units/kg body weight daily for 10 days. Doses were adjusted to maintain peak anti-Xa levels between 0.5 and 1.0 anti-Xa units per milliliter. One patient in the unfractionated heparin group and 2 patients in the LMW heparin group suffered from bleeding complications. Two patients on LMW heparin and on unfractionated heparin had high evidence of pulmonary embolism based on defects on ventilation-perfusion scintigraphy. Control phlebography and duplex sonography demonstrated a significant improvement during both treatment regimens. Reperfusion of the deep-vein system was 70% with LMW heparin and 75% with unfractionated heparin. The anti-Xa levels were significantly higher in the LMW heparin group, and activated partial thromboplastin and thrombin clotting times were significantly higher in the group receiving unfractionated heparin. Thrombin-antithrombin III complexes and D-dimer concentration decreased during the treatment, but did not differ between the two regimens. At the end of the treatment period with LMW heparin, protein C and antithrombin III were significantly higher.
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PMID:Therapeutic application of subcutaneous low-molecular-weight heparin in acute venous thrombosis. 196 63

271 patients with acute symptomatic deep venous thrombosis of lower limbs, confirmed by strain-gauge plethysmography and/or venography, were randomly assigned to receive intermittent subcutaneous heparin calcium or heparin sodium by continuous intravenous infusion for 6-10 days. Heparin dosage was adjusted to maintain activated partial thromboplastin time values (Thrombofax reagent) at 1.3-1.9 times the basal ones. Strain-gauge plethysmography was repeated at the end of heparin treatment, and evaluation of therapy was performed by comparing the indexes of venous hemodynamics and by assessing the incidence of pulmonary embolism and of bleeding complications. In the intravenous group, Maximal Venous Outflow (MVO) increased from 20.8 +/- 12.8 to 28.4 +/- 17.5 ml/min per 100 ml of tissue and Venous Capacitance (VC) from 1.39 +/- 0.92 to 1.94 +/- 1.0 ml/100 ml of tissue (mean +/- SD). In the subcutaneous group, MVO increased from 21.0 +/- 12.7 to 27.5 +/- 18.1 and VC from 1.60 +/- 0.86 to 2.06 +/- 1.0. The median improvement of MVO and VC were 22% and 36% respectively in the IV group and 20% and 24% in the SC group. Clinical pulmonary embolism occurred in 2 patients in the intravenous group (1 fatal) and in 4 in the subcutaneous group (1 fatal). 9 major bleeding complications occurred in the intravenous group (1 fatal) and 5 in the subcutaneous group (1 fatal). The differences were not significant at the statistical analysis. The results suggest that subcutaneous intermittent heparin has a comparable efficacy to continuous intravenous heparin in the treatment of deep venous thrombosis. To the same conclusion points an overview of the seven randomized trials which compared these treatment modalities.
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PMID:Subcutaneous vs intravenous heparin in the treatment of deep venous thrombosis--a randomized clinical trial. 227 May 31


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