Clinical and Applied Thrombosis/Hemostasis current issue

Anticoagulant Therapy for Acute Venous Thromboembolism: What We Think We Know and What the Data Show for the Timing of Recurrent Events

Stein, P. D., Hull, R. D., Matta, F., Yaekoub, A. Y. — Wed, 18 Nov 2009 21:33:27 PST

Although heparin is administered to prevent early recurrences of venous thromboembolism (VTE) by preventing new thrombi, allowing old thrombi to attach to venous walls, and covering warfarin until it is therapeutic, heparin largely prevents late recurrences of VTE (after 5 days). The dreaded early occurrence of pulmonary embolism (PE) (on or before day 5) while waiting for the vitamin K antagonist to become antithrombotic did not occur among patients with deep venous thrombosis (DVT), who received acencoumarol alone. Fewer total recurrences resulted if a therapeutic level of heparin was reached within the first 24 hours of treatment of DVT. Fewer total recurrences also resulted if heparin was consistently maintained at therapeutic levels. A recurrent VTE within 5 days, however, occurred infrequently in those in whom heparin was not given, or therapeutic levels were delayed or not maintained. The incidence of early recurrent VTE was not lower in those who received adequate heparin than in those who did not, although the data are sparse. The true incidence of early recurrent VTE is uncertain due to the broad confidence intervals for the observed frequency of early recurrent events. Later recurrences are the norm and may be reduced by early treatment with adequate heparin.

Rivaroxaban in Orthopedic Surgery -- A Change of Paradigm?

Schulman, S. — Wed, 18 Nov 2009 21:33:27 PST

Two selective, orally available anticoagulant agents, although with different targets in the coagulation cascade, have recently been approved in many countries on the indication of prophylaxis against venous thromboembolism (VTE) after major joint arthroplasty. This review discusses mainly the antifactor Xa drug, rivaroxaban, with a focus on the orthopedic trials. Pharmacokinetic characteristics and other clinical development programs with rivaroxaban are briefly reviewed. Although the aim of this article is not to review the direct thrombin inhibitor, dabigatran etexilate, some comparisons are made. For clinical results, these are obviously indirect and conclusions must be drawn with caution until head-to-head comparisons are performed. Whether the introduction of rivaroxaban is a change of paradigm will ultimately be decided in the eyes and mind of the beholder.

Unexplained Discrepancies in the Activity--Antigen Ratio in Congenital FX Deficiencies With Defects in the Catalytic Domain

Wed, 18 Nov 2009 21:33:27 PST

Studies on molecular biology have considerably enhanced our understanding of congenital coagulation disorders but have failed so far to supply tools for an adequate classification of defects. In fact, mutations in the same domain may give rise to different phenotypes. Conversely, mutations in different domains, controlled by different exons, may cause similar patterns. The 37 kindreds with congenital factor X (FX) deficiency, known to have a defect in the catalytic domain, have been evaluated in an attempt to investigate the genotype—phenotype relation. Discrepant results were obtained because about half kindreds showed a type I pattern, namely a concomitant decrease in FX activity and antigen. The other half showed a type II pattern, namely a decrease in FX activity with a normal or near normal FX antigen. In a few instances, the allocation of the kindred either to type I or to type II defect could not be reached, due to the lack of information about the antigen.

The comparison of the kindreds in which the same mutation has been discovered by different investigations is not always possible also for lack of information.

The study analyzes the need to have a multipronged approach to the study of congenital FX deficiency. The indication of a mutation in a given domain does not provide clear information about the phenotype.

Effect of Recombinant Activated Factor VII in Critical Bleeding: Clinical Experience of a Single Center

Wed, 18 Nov 2009 21:33:27 PST

Recombinant activated factor VII (rFVIIa) has been successfully used ‘‘off-label’’ in patients with refractory life-threatening hemorrhage. Intravenous rFVIIa was given to 31 patients unresponsive to standard therapy with blood products and surgical reexploration, who were bleeding due to trauma, surgery, organ transplantation, liver cirrhosis, ruptured uterus. We recorded their coagulation and hematologic profiles, acid-base balance, blood loss, number of red blood cells (RBC), plasma and platelet transfusions, complications, and survival. rFVIIa (mean dose 132.2 ± 56.3 µg/kg) effectively contained the hemorrhage in 28/31 (90.3%) cases, with a mean reduction in blood loss from 12.4 ± 10.2 to 2.7 ± 2.2 L (P < .0001). The need for RBC, platelet, and plasma transfusion decreased significantly after rFVIIa, with a consequent significant improvement in clotting of test hematocrit, pH, and bicarbonates. Four patients had adverse events potentially related to rFVIIa. The survival rates after 1 and 30 days were 48.4% and 29.1%, respectively.

Use of Heparin in Women With Early and Late Miscarriages With and Without Thrombophilia

Monien, S., Kadecki, O., Baumgarten, S., Salama, A., Dorner, T., Kiesewetter, H. — Wed, 18 Nov 2009 21:33:27 PST

Objective: In women with a history of recurrent miscarriage, the risk of miscarriage in a subsequent pregnancy is about 30% to 40%. In patients with thrombophilia, the risk is even higher. Placental thrombosis has been found in women with unexplained recurrent miscarriage independent of thrombophilia. In addition, proinflammatory changes, for example, altered Th1 to Th2 cytokine ratio and complement activation, have been repeatedly demonstrated in these women. Because of the fact that heparin has both anticoagulative and anti-inflammatory effects, the current study evaluated the efficacy of low-molecular-weight heparin (LMWH) in unexplained abortions. Study Design: A total of 164 women with unexplained early and late miscarriages presented in our hemostaseological clinic for thrombophilia screening. For these 164 women, 82 subsequent pregnancies in 79 patients were treated with subcutaneous LMWH independently of thrombophilia. In 54/82 unselected pregnancies, 100 mg aspirin was administered in addition to LMWH. Two patients were excluded due to termination of pregnancy. Results: Overall, 83.8% (67/80) of pregnancies resulted in live births. In 22/79 women (27.8%), thrombophilia markers were positive. Most noteworthy, patients with thrombophilia markers had live births at a similar frequency as patients without those parameters. No severe side effects of LMWH were seen. Conclusions: Our data support the notion that LMWH is efficacious in patients with recurrent abortions and thrombophilia. We demonstrated the same effect of LMWH in women with unexplained abortions without thrombophilia. The potential mechanism of action of LMWH in early and late abortions warrants further study.

European Community and US-FDA Approval of Recombinant Human Antithrombin Produced in Genetically Altered Goats

Adiguzel, C., Iqbal, O., Demir, M., Fareed, J. — Wed, 18 Nov 2009 21:33:27 PST

Thrombin and factor Xa play a central role in thrombogenesis in both medical and surgical patients. Antithrombin (AT) is the key inhibitor, which controls the action of these enzymes in hypercoagulable states. The AT concentrates prepared from human blood have been used to treat patients with thrombotic disorders and heparin resistance. The AT concentrates are prepared from pooled human plasma and beside limited supply, suffer from viral and other biological contaminants. The availability of recombinant human AT (rhAT) obtained from genetically engineered goats provide a biologically equivalent product that can be used in practically all indications where human AT is indicated including heparin resistance. Moreover, because of its high affinity to heparin and related drugs, recombinant AT can also be developed in further indications. On review of the preclinical and clinical data on the safety and efficacy, the European Union and U.S. Food and Drug Administration (US-FDA) have recently approved the use of rhAT in specified clinical indications.

Utility of the PFA-100 Instrument and the Novel Multiplate Analyzer for the Assessment of Aspirin and Clopidogrel Effects on Platelet Function in Patients With Cardiovascular Disease

Mueller, T., Dieplinger, B., Poelz, W., Haltmayer, M. — Wed, 18 Nov 2009 21:33:27 PST

This study evaluated the utility of the PFA-100 and the Multiplate analyzer for the assessment of aspirin and clopidogrel effects on platelet function in patients with cardiovascular disease. Platelet function was determined with the PFA-100 using collagen+epinephrine (CEPI) and collagen+adenosine-5’-diphosphate (CADP) cartridges, and with whole blood impedance aggregometry using the Multiplate ASPI and ADP+PG tests (aggregation triggered with arachidonic acid and ADP+ prostaglandin E1, respectively). Four study groups were identified from the 154 patients enrolled: patients without antiplatelet therapy, patients with 100 mg aspirin daily but without clopidogrel treatment, patients with 75 mg clopidogrel daily but without aspirin treatment, and patients with both 100 mg aspirin daily plus 75 mg clopidogrel daily. It was found that the PFA-100 instrument is useful for detection of aspirin but not for detection of a clopidogrel effect, while the Multiplate analyzer is useful for specific detection of both aspirin and clopidogrel effects on platelet function.

The Impact of Prothrombotic Mutations on Factor Consumption in Adult Patients with Severe Hemophilia

Ar, M. C., Baykara, O., Buyru, A. N., Baslar, Z. — Wed, 18 Nov 2009 21:33:27 PST

About 10% of patients with severe hemophilia exhibit a milder clinical phenotype with less frequent bleeds. Among many other factors, coinheritance of prothrombotic mutations have been proposed to act as modulators of clinical severity in severe hemophilia. We conducted a study to evaluate the impact of 3 prothrombotic mutations (factor V Leiden, factor II, and methylenetetrahydrofolate reductase mutations) on clinical phenotype of patients with severe hemophilia in our institution. For this purpose we compared the average annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. A total of 38 hemophilia A and B patients with factor levels less than 1 were recruited between October 2006 and October 2007. Prothrombotic mutations were detected in venous blood using polymerase chain reaction amplification technique. Eighteen patients (47%) carried no prothrombotic mutations. The remaining 20 patients (53%) were found to be carriers of either 1 or 2 mutations. Median age in both carrier and the non-carrier groups was 27 years. None of the patients in either group gave a history of thromboembolic event. Median annual factor concentrate consumptions in carriers and noncarriers were 610 ± 530 units/kg and 770 ± 670 units/kg, respectively (P = .203). Our results demonstrated no significant difference in annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. Considering that average annual factor consumption is a surrogate indicator of clinical phenotype, we concluded that coinheritance of prothrombotic mutations was not associated with occurrence of different clinical phenotypes in severe hemophilia.

D-Dimers, Thrombin--Antithrombin Complexes, and Risk Factors for Thromboembolism in Hospitalized Patient

Pottier, P., Fouassier, M., Hardouin, J.-B., Volteau, C., Planchon, B. — Wed, 18 Nov 2009 21:33:27 PST

Introduction There is lack of data about the correlation between hemostatic markers and the clinical and biological risk factors (RFs) for venous thromboembolism (VTE) in medical inpatients without suspicion of acute VTE. Material and methods To evaluate the coagulation activation status in patients with current known RFs for VTE, the authors measured 2 markers of hypercoagulability, thrombin antithrombin (TAT) complexes and D-dimers, at day 1 in 165 patients hospitalized in internal medicine wards without suspected acute VTE. All known RFs for VTE were systematically assessed at admission and classified in a chronological way as permanent or transient. Results Surprisingly, TAT values followed a multimodal distribution. D-dimers showed a normal distribution after a logarithmic transformation (P = .34, Shapiro—Wilk test). Interestingly, a significant progression in D-dimer levels was found according to the chronological classification of RFs. D-dimer variations on multivariate analysis (not applicable for TAT because of the multimodal distribution) correlated independently with a recent inability to walk and an increase in C reactive protein level more than 10 mg/L. Conclusions (a) this study is the first to describe the variations of hypercoagulability markers according to a systematic screening of RFs for VTE in inpatients without suspicion of acute VTE, (b) TAT appeared as a less relevant marker of hypercoagulability than D-dimers in internal medicine inpatients, (d) the chronological classification of RFs identified clearly groups at risk for the prethrombotic state, and (d) an increased hypercoagulability state was demonstrated in patients with an association between a recent immobility and increased inflammatory markers.

Venous Thromboembolism in Patients Hospitalized With Thyroid Dysfunction

Wed, 18 Nov 2009 21:33:27 PST

The objective of this investigation is to explore a possible role of thyroid dysfunction in venous thromboembolism (VTE). The number of patients discharged from short-stay nonfederal hospitals in the United States, from 1979 to 2005, with a diagnostic code for hypothyroidism or hyperthyroidism, pulmonary embolism (PE), and deep venous thrombosis (DVT) was obtained from the National Hospital Discharge Survey (NHDS). Among 19 519 000 hospitalized patients discharged with a diagnosis of hypothyroidism from 1979 to 2005, 119 000 (0.61%) had PE. Among patients with no thyroid dysfunction, PE was diagnosed in 3 372 000 of 908 805 000 patients (0.37%; relative risk = 1.64, 95% CI 1.63-1.65). Deep venous thrombosis was diagnosed in 1.36% of hypothyroid patients and in 0.84% of patients with no thyroid dysfunction (relative risk = 1.62, 95% CI 1.61-1.62). The relative risk of PE in patients with hypothyroidism was highest in patients <40 years of age (relative risk = 3.99) and the relative risk of DVT was also highest in patients <40 years (relative risk = 2.25). Hyperthyroidism was not associated with an increased risk of VTE (relative risk = 0.98, 95% CI = 0.96-1.01). In conclusion, an increased risk of PE, DVT, and VTE was shown in patients with hypothyroidism but not hyperthyroidism. Antithrombotic prophylaxis in patients with severe hypothyroidism, however, should be viewed with caution because of a possible hyperfibrinolytic state in such patients.

Relative Purity of Different Bovine Thrombin Preparations

Zhu, H., Hoppensteadt, D., Iqbal, O., Litinas, E., Adiguzel, C., Fareed, J. — Wed, 18 Nov 2009 21:33:27 PST

The aim of this study was to compare the relative purity of bovine crude thrombin and its purified forms, namely, thrombin 4A and thrombin 4B (the products of King Pharma, Middleton, Wisconsin) by virtue of the detection of bovine prothrombin-related antigens in these preparations. Bovine prothrombin was administered intravenously to 3 individual rabbits on days 0, 21, 42, 91, 123, and 151 using standard immunologic method. Blood was drawn from each rabbit on days 30, 50, 105, 137, and 165, and the pooled antisera from 3 rabbits were purified to isolate immunoglobulin G (IgG) using protein G affinity columns. Using Western blotting method, serially diluted bovine crude thrombin, thrombin 4A, and 4B preparations were probed using the prothrombin IgGs obtained from each time point to explore prothrombin-related antigens in these preparations. The results revealed that compared with the prothrombin IgG collected on day 30, the IgGs collected on days 50 to 165 showed a time-dependent increase in their ability to detect the prothrombin-related antigens in 3 bovine thrombin preparations studied. The lowest amount of crude thrombin, thrombin 4A, and 4B preparations that prothrombin IgG could detect was 0.125, 10, and 20 U, respectively. The rank order of the number of immunoreactive bands detectable in 3 bovine thrombin preparations probed by the prothrombin IgGs collected from any given time point was always the same: crude thrombin > thrombin 4A > thrombin 4B. The results indicate that thrombin 4B preparation contains the least amount of antigens detectable by prothrombin IgG, suggesting that relatively thrombin 4B represents the most purified thrombin preparation among the 3 thrombin preparations studied.

Effects of rhG-CSF Plus Dexamethasone on Hemostatic Parameters in Healthy Granulocyte Donors: Role of u-PA and Nitric Oxide

Wed, 18 Nov 2009 21:33:27 PST

Granulocyte colony-stimulating factor (G-CSF) is widely used to reduce the risk of infection resulting from neutropenias and to mobilize and collect CD34+ hematopoetic progenitor cells (HPCs) for autologous and allogenic transplantation. The safety of recombinant human G-CSF (rhG-CSF) administration in healthy donors has been investigated in several studies. However, there are limited cumulative data about the effects of rhG-CSF on hemostasis. Hemostatic parameters, including urokinase-type plasminogen activator antigen (u-PA:Ag) and nitric oxide in 17 healthy granulocyte apheresis donors who donated for neutropenic patients were evaluated. rhG-CSF (single dose, 10 µg/kg subcutaneously) and dexamethasone (8 mg, single dose oral) were given to donors 12 hours before granulocyte apheresis. Two blood samples were drawn at time 0 (T₀) before rhG-CSF and dexamethasone administration and at time 1 (T1), immediately before the apheresis. A statistically significant rise in coagulant factor VIII (FVIII) and von Willebrand factor (vWF), and slightly rise in u-PA:Ag were observed after G-CSF plus dexamethasone administration. In addition, there were positive correlations between vWF-D-dimer and FVIII-D-dimer. A significant decrease in mean total nitric oxide (NOx), nitrite, and nitrate levels was also found after G-CSF plus dexamethasone administration. Moreover, there was a strong negative correlation between nitrite and D-dimer levels (r = –0.611; P = .009). Even if partially compensated with u-PA and protein C, increased FVIII and vWF activity, and decreased nitric oxide levels may still partially contribute to progress of thrombosis risk in rhG-CSF plus dexamethasone administered healthy granulocyte donors. Large numbers of healthy donors exposed to G-CSF plus dexamethasone will be needed to evaluate the risk of thrombosis in this population.

Oxidative Stress and Total Antioxidant Capacity in Diabetic and Nondiabetic Acute Ischemic Stroke Patients

Guldiken, B., Demir, M., Guldiken, S., Turgut, N., Turgut, B., Tugrul, A. — Wed, 18 Nov 2009 21:33:27 PST

Free radical formation is the pivotal mechanism of neuronal injury of ischemic and reperfused brain tissue. In healthy individuals, antioxidant activity counterbalances free radical production, but in the case of ischemia, the balance between reactive oxygen species and antioxidant activity is shifted toward free radicals, causing oxidative stress. The aim of this study is to assess total antioxidant capacity (TAC) and oxidative stress in diabetic and nondiabetic acute stroke patients with 2 different stroke subtypes: large and small vessel disease stroke. Sixty-five acute ischemic stroke patients (29 diabetic and 36 nondiabetic) and 20 age-matched healthy control subjects were recruited in the study. Plasma TAC and nitric oxide (NO) metabolite levels (nitrite and nitrate) were measured by enzyme-linked immunosorbent assay. The subtypes of stroke were defined according to Trial of Org 10172 in Acute Stroke Treatment criteria. The main findings of this study are that the TAC and NO levels were significantly higher in diabetic acute stroke patients than in nondiabetic patients and control cases (P < .001 and P < .001, respectively). The TAC and NO levels were higher also in nondiabetic stroke patients than in controls, but the difference did not reach any significance. No difference was found between NO and TAC levels in large and small vessel stroke subtypes of diabetic and nondiabetic patients. The authors conclude that oxidative stress and counterbalancing antioxidant capacity are more pronounced in diabetic acute stroke patients than in nondiabetic acute stroke patients.

Single Nucleotide Polymorphisms That Affect Homocysteine Levels in Turkish Population

Koc, Y. L., Akar, N. — Wed, 18 Nov 2009 21:33:27 PST

In this study, single nucleotide polymorphisms (SNPs) involved in homocysteine metabolism such as CT replacement in the 677th nucleotide in 5,10-methylenetetrahydrofolate reductase (MTHFR) enzyme; 68-bp insertion in the 844th nucleotide of cystathionine β-synthase (CBS) enzyme; 6-bp insertion/deletion in the region of 3'UTR in thymidylate synthase (TYMS) enzyme and 19-bp deletion in dihydrofolate reductase (DHFR) enzyme were investigated. The effects of these mutations on homocysteine levels were studied. As a result; we found that TT genotype of MTHFR 677 CT is an influencing factor on homocysteine levels in Turkish population. Furthermore, there seems to be another MTHFR 677 TT haplotype, which does not have an effect on homocysteine levels .Our data revealed that other SNPs did not have any influence on homocysteine levels.

Diffuse Cerebral Infarct Associated With Factor V Leiden and Prothrombin 20210A Mutations in a Patient With Tetralogy of Fallot

Sipahi, T., Karademir, S., Kuybulu, A., Akar, N. — Wed, 18 Nov 2009 21:33:27 PST

A 2-year-old girl with tetralogy of Fallot presented with diffuse cranial infarct after cardiac angiography. Heterozygosity for factor V Leiden and prothrombin 20210A mutations were detected. The authors suggest that if thrombosis develops in patients with congenital heart disease, genetic risk factors should be evaluated.

Acute Massive Pulmonary Embolism With Hemodynamic Compromise Treated Successfully With Thrombolytic Therapy Selcuk

Pala, S., Kahveci, G., Bozok, S. — Wed, 18 Nov 2009 21:33:27 PST

A 78 year-old woman presented with a history of 15 days of dyspnea and tachypnea at rest. A distended right ventricle with free-wall hypokinesis and displacement of the interventricular septum toward the left ventricle were shown on echocardiography. The patient suddenly arrested. She underwent cardiac catheterization and selective pulmonary angiography for suspected pulmonary embolism while undergoing cardiopulmonary resuscitation. With the diagnosis of pulmonary embolism confirmed, recombinant tissue plasminogen activator was given immediately in the catheterization room. This case shows how pulmonary embolism can be diagnosed with pulmonary angiography during cardiopulmonary resuscitation and the life-saving result from rapid thrombolysis with recombinant tissue plasminogen activator.

A Woman With Rectal Sinus and Left Transversal Sinus Thrombosis After Ovarian Stimulation: Case Report

Santoro, R. — Wed, 18 Nov 2009 21:33:27 PST

Thromboembolic events are an infrequent complication of hormonal treatment for infertility and are generally related to the ovarian hyperstimulation syndrome. The presence of factor V Leiden and a mutation of G20210A prothrombin mutation are further risk factors for thromboembolic events. We describe a case of dual cerebral vein thrombosis in a woman with prothrombin mutation homozygosity and ovarian hyperstimulation syndrome.

Book Review: Coagulation in Cancer. David Green and Hau C. Kwaan, Editors. New York, NY: Springer Science + Business Media LCC, 2009. 339 pp. Price $129.00

Messmore, H. L., Wehrmacher, W. H. — Wed, 18 Nov 2009 21:33:27 PST

Book Review: New Therapeutic Agents in Thrombosis and Thrombolysis. Jane E. Freedman and Joseph Loscalzo, Editors. 3rd ed. New York, London: Informa Healthcare, 2009. 690 pp. $299.95. USBM 13 1420069235. Illustrated

Messmore, H. L., Wehrmacher, W. H. — Wed, 18 Nov 2009 21:33:27 PST

A Platelet Defect Modulates Bleeding in Mild Hemophilia: The Tale of 2 Brothers

Wed, 18 Nov 2009 21:33:27 PST

Clinical and Applied Thrombosis/Hemostasis: Instructions for Authors

Wed, 18 Nov 2009 21:33:27 PST