Fibrinolytic Potential Research Articles

Effects of Extracellular DNA on Plasminogen Activation and Fibrinolysis

The increased levels of extracellular DNA found in a number of disorders involving dysregulation of the fibrinolytic system may affect interactions between fibrinolytic enzymes and inhibitors. Double-stranded (ds) DNA and oligonucleotides bind tissue-(tPA) and urokinase (uPA)-type plasminogen activators, plasmin, and plasminogen with submicromolar affinity. The binding of enzymes to DNA was detected by EMSA, steady-state, and stopped-flow fluorimetry. The interaction of dsDNA/oligonucleotides with tPA and uPA includes a fast bimolecular step, followed by two monomolecular steps, likely indicating slow conformational changes in the enzyme. DNA (0.1-5.0 μg/ml), but not RNA, potentiates the activation of Glu- and Lys-plasminogen by tPA and uPA by 480- and 70-fold and 10.7- and 17-fold, respectively, via a template mechanism similar to that known for fibrin. However, unlike fibrin, dsDNA/oligonucleotides moderately affect the reaction between plasmin and α(2)-antiplasmin and accelerate the inactivation of tPA and two chain uPA by plasminogen activator inhibitor-1 (PAI-1), which is potentiated by vitronectin. dsDNA (0.1-1.0 μg/ml) does not affect the rate of fibrinolysis by plasmin but increases by 4-5-fold the rate of fibrinolysis by Glu-plasminogen/plasminogen activator. The presence of α(2)-antiplasmin abolishes the potentiation of fibrinolysis by dsDNA. At higher concentrations (1.0-20 μg/ml), dsDNA competes for plasmin with fibrin and decreases the rate of fibrinolysis. dsDNA/oligonucleotides incorporated into a fibrin film also inhibit fibrinolysis. Thus, extracellular DNA at physiological concentrations may potentiate fibrinolysis by stimulating fibrin-independent plasminogen activation. Conversely, DNA could inhibit fibrinolysis by increasing the susceptibility of fibrinolytic enzymes to serpins.

Hypofibrinolysis and the Risk of Recurrent Venous Thromboembolism: A Prospective Cohort Study,

Abstract 3331Hypercoagulability reflected by enhanced activity of clotting factors or a natural inhibitor deficiency is a risk factor of venous thromboembolism (VTE). Whether defects in the fibrinolytic system confer an increased risk of VTE is unclear. We assessed the relationship between fibrinolytic system activity (reflected by clot lysis time [CLT]) and the risk of recurrent VTE.We followed 704 patients (378 women; mean age 48 years) with a first unprovoked VTE for an average of 46 months after anticoagulation withdrawal. Patients with a natural coagulation inhibitor deficiency, lupus anticoagulant, cancer, female hormone use, homozygosity or double heterozygosity for factor V Leiden or prothrombin mutation, or requirement for indefinite anticoagulation were excluded. The fibrinolytic potential was assessed using a plasma based clot-lysis assay according to Lisman et al. (1). A tissue factor-induced clot was lysed by adding tissue-type plasminogen activator and the optical density was measured at 405 nm in an absorbance microplate reader every 30 seconds in order to get a clot-lysis turbidity profile. Study end point was symptomatic recurrent VTE.135 (19%) patients had recurrent VTE. Recurrence was unprovoked in 117 patients and was more frequent in men (97/326, 29.8%) than in women (38/378, 10.1%). When CLT was entered as continuous variable in a Cox proportional hazards model, hazard ratio (HR) for recurrence was 1.13 (95% CI 1.02–1.25; p=0.02) for each 10 minutes prolongation. The HR for recurrence was 1.11 (95% CI 1.11–1.24; p=0.046) after adjustment for age and 1.08 (95% CI 0.98–1.20; p=0.13) after additional adjustment for sex. After 5 years, the likelihood of recurrence was 23.8% (95% CI 19.3%-28.3%) in patients with a CLT longer than 63.5 minutes (25th percentile) as compared with 14.1% (95% CI 7.4%-20.8%; p=0.04) among those with a shorter CLT. Men and women differed with regard to CLT (76.1±16.2 vs. 71.5±13.6 sec, p<0.001). After adjustment for age, the HR was 1.04 (95% CI 0.92–1.18; p=0.54) among men and 1.14 (95% CI 0.93–1.14; p=0.22) among women.Hypofibrinolysis confers an increased risk of recurrent VTE. The effect was more pronounced in women than in men. Disclosures:No relevant conflicts of interest to declare.

Clot lysis time and the risk of myocardial infarction and ischaemic stroke in young women; results from the RATIO case–control study

Reduced overall fibrinolytic capacity increases the risk of myocardial infarction (MI), as demonstrated in studies with predominantly male participants. We determined the influence of altered fibrinolysis on the risk of MI and ischaemic stroke (IS) in young women. The RATIO (Risk of Arterial Thrombosis In relation to Oral contraceptives) study is a population-based case-control study including young women with MI (n=203), IS (N=175) and 638 matched healthy controls. Fibrinolytic potential was determined with a tissue factor/tissue plasminogen activator induced clot-lysis assay. Odds ratios (OR) adjusted for cardiovascular risk factors were obtained with logistic regression. Clot-lysis time (CLT) was divided into tertiles based on the control group (T1-T3), with T2 as reference. Hypofibrinolysis (prolonged CLT) was associated with an increase in risk of MI (T3 vs. T2, OR 2·8; 95%confidence interval [CI] 1·7-4·7). Hyperfibrinolysis (decreased CLT) had no clear effect (T1 vs. T2, OR 1·6; 95% CI 0·9-2·9). Hypofibrinolysis did not affect the risk of IS (T3 vs. T2, OR 1·5; 95% CI 0·7-3·0), whereas hyperfibrinolysis increased this risk (T1 vs. T2, OR 4·1; 95% CI 2·1-8·0). Oral contraceptive use and smoking further increased these risks. Hypofibrinolysis increases the risk for MI in young women, a finding similar to previous studies. Counter-intuitively, hyperfibrinolysis increased the risk of IS four-fold, which suggests that MI and IS have different aetiologies.

Effect of fibrinolysis on bleeding phenotype in moderate and severe von Willebrand disease

Patients with von Willebrand disease (VWD), the most common inherited bleeding disorder, display large variation in bleeding tendency, which is not completely related to VWF levels. The cause of variability in clinical expression is largely unknown. The effect of plasma fibrinolytic capacity on bleeding tendency in VWD patients has not been investigated. We hypothesized that enhanced fibrinolysis may result in a more severe bleeding phenotype. Therefore, we measured the fibrinolytic potential in patients with moderate or severe VWD to investigate the contribution of fibrinolysis to the bleeding tendency. Fibrinolytic potential was measured as plasma clot lysis time (CLT) with and without addition of potato carboxypeptidase inhibitor (PCI) in 638 patients with moderate or severe VWD who participated in a nationwide multicentre cross-sectional study. Bleeding severity was measured using the Bleeding Score (BS).The CLTs were significantly longer, indicative of hypofibrinolysis, in men compared to women with VWD [106.2 (IQR 95.7-118.1) vs. 101.9 (IQR 92.8-114.0) min]. The CLTs prolonged with increasing age. No association was found between VWF or FVIII levels and CLT, or between VWF or FVIII levels and CLT(+PCI) . No association was observed for BS in a model with 10log-transformed CLT, adjusted for age, gender, VWF:Act and FVIII [b = 6.5 (95%CI -0.3 to 13.4)]. Our study showed that the plasma fibrinolytic potential does not influence bleeding tendency in VWD patients and therefore does not explain the variability in bleeding phenotype in VWD.

Fibrinolytic activity of kaempferol isolated from the fruits of Lagenaria siceraria (Molina) Standley

This study was undertaken to isolate a flavonol, kaempferol, from the fruits of Lagenaria siceraria (bottle gourd) as a sole compound and to explore the fibrinolytic potential of the methanolic extract of the fruits of L. siceraria and the isolated compound using their in vitro activity. The fibrinolytic activity in terms of percentage of plasma clot liquefaction was determined by plasma clot lysis at 37°C in 24 h. The fibrinolytic activity of both substances was compared to the well-known thrombolytic agent streptokinase (30,000 IU). The percentage of fibrinolytic activity of the extract and isolated compound were found to be 54.72 ± 0.7210 and 77.37 ± 1.3010, respectively. Streptokinase was considered as the standard fibrinolytic enzyme for comparative purposes and had 91.46 ± 0.7625% fibrinolytic activity. The conclusion drawn in our study after testing the hypothesis by experimental procedures is that in vitro fibrinolytic activity on plasma clots is an inherent property of kaempferol isolated from the fruits of L. siceraria, and its comparison with streptokinase is a new aspect for further study.

Future Perspectives on the Fibrinolytic Therapy of Intracerebral Hemorrhages

Intracerebral hemorrhage (ICH) is associated with a high mortality and severe disability. Whereas a classical open craniotomy for hematoma removal may further traumatize brain tissue, minimally invasive surgery combines benefits of surgical clot removal with limited tissue damage and shorter surgery duration. Evacuation is often hampered by clot retraction, thus, advocating clot liquefaction to facilitate complete evacuation. The use of urokinase or recombinant tissue plasminogen activator (rtPA) alone and in combination with neuroprotective drugs in experimental studies and clinical trials is reviewed with respect to efficacy in hematoma reduction and effects on secondary brain injury. Whereas rtPA promotes delayed edema formation and inflammation after local fibrinolysis, desmoteplase (DSPA), a highly fibrin-selective plasminogen activator derived from vampire bat saliva, combines high fibrinolytic potential with lack of excitotoxicity, thus representing a novel, promising candidate for fibrinolytic therapy of ICH.

Gender-Specific Association of the Plasminogen Activator Inhibitor-1 4G/5G Polymorphism With Central Arterial Blood Pressure

The functional plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism has previously been associated with hypertension. In recent years, central blood pressure, rather than brachial has been argued a better measure of cardiovascular damage and clinical outcome. The aim of this study was to investigate the possible influence of the 4G/5G polymorphism on central arterial blood pressure in a cohort of elderly individuals. We studied 410 individuals, 216 men and 194 women, aged 70-88. Central pressures and pulse waveforms were calculated from the radial artery pressure waveform by the use of the SphygmoCor system and a generalized transfer function. Brachial pressure was recorded using oscillometric technique (Dinamap, Critikon, Tampa, FL). PAI-1 antigen was determined in plasma. The results showed that central pressures were higher in women carrying the PAI-1 4G/4G genotype compared to female carriers of the 5G/5G genotype, (P = 0.025, P = 0.002, and P = 0.002 for central systolic-, diastolic-, and mean arterial pressure, respectively). The association remained after adjustment for potentially confounding factors related to hypertension. No association of the PAI-1 genotype with blood pressure was found in men. Multiple regression analysis revealed an association between PAI-1 genotype and plasma PAI-1 levels (P = 0.048). Our findings show a gender-specific association of the PAI-1 4G/5G polymorphism with central arterial blood pressure. The genotype effect was independent of other risk factors related to hypertension, suggesting that impaired fibrinolytic potential may play an important role in the development of central hypertension in women.

Simultaneous thrombin and plasmin generation capacities in normal and abnormal states of coagulation and fibrinolysis in children and adults

Introduction Thrombin and plasmin are the key enzymes involved in coagulation and fibrinolysis, respectively. Plasma coagulative and fibrinolytic potentials in normal children and adults, and in representative pathologically altered hemostatic states, were evaluated via simultaneous assessment of thrombin and plasmin generation. Materials and Methods An assay of Simultaneous Thrombin and Plasmin generation (STP) was developed to measure thrombin and plasmin in plasma using individual fluorometric substrates. Coagulation is initiated with dilute tissue factor, phospholipid, and calcium in platelet-poor plasma; fibrinolysis is accelerated via tissue plasminogen activator (tPA). Abnormal states of hemostasis were investigated. Results STP assay reproducibility and normal adult and pediatric values for measured and calculated parameters have been established. Onset of both thrombin and plasmin generation was significantly delayed in children relative to adults (p < 0.001) and the maximum amplitudes of thrombin and plasmin generation were less in children than adults (p < 0.01). No significant differences were measured among pediatric age groups. The most profound impairments in thrombin generation were observed for extrinsic and common pathway factor deficiencies, with the exception of afibrinogenemia. Plasmin generation was severely impaired in deficiencies of fibrinogen and plasminogen as well as with decreased tPA reagent concentration and addition of aminocaproic acid. Plasmin generation was greatly enhanced by alpha-2-antiplasmin deficiency and excess tPA reagent. Conclusion Simultaneous assessment of thrombin and plasmin generation in plasma shows promise for affording an enhanced understanding of overall coagulative and fibrinolytic functions in physiological and pathologically altered states of hemostasis in children and adults.

Hemostatic Disorders in Type 1 Diabetes Mellitus

This review summarizes current knowledge of the adverse effects of type 1 diabetes mellitus on coagulation and fibrinolysis. Although further larger studies are needed to provide more definitive information, patients with type 1 diabetes exhibit a proinflammatory/procoagulant condition deriving from increased platelet adhesiveness, activation of the coagulation system, and decreased plasma fibrinolytic potential. This review also focuses on recent data from large prospective studies suggesting a strong association between procoagulant imbalance and development of chronic vascular complications in people with type 1 diabetes. It is likely that a greater appreciation of the intimate interactions between endothelial integrity, coagulation and fibrinolytic factors, and platelets in type 1 diabetes will provide a greater understanding of the risk of developing cardiovascular disease and microvascular complications such as nephropathy and retinopathy in this patient population.

Reduced plasma fibrinolytic potential in patients with recurrent implantation failure after IVF and embryo transfer

Recurrent implantation failure (RIF) following embryo transfer (ET) is a major continuing problem in IVF. Women with haemostatic defects may be at increased risk of miscarriage and preclinical pregnancy loss. The fibrinolytic system is considered, at present, the key to new thrombotic pathogenic mechanisms. Patients with unexplained recurrent miscarriage have an impairment of fibrinolysis, as demonstrated by prolonged clot lysis time (CLT) in association with increased plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI). In this study, we investigated fibrinolytic potential in patients with RIF. Three groups of patients were studied: 30 women with RIF (RIF group), 60 patients undergoing a first successful IVF-ET cycle (IVF group) and 60 healthy fertile women (FER group). Plasma CLT was measured using a global fibrinolysis assay. TAFI antigen plasma levels and polymorphisms in the TAFI gene (+505A/G and +1542C/G) were analysed using enzyme-linked immunosorbent assay and allele-specific PCR, respectively. CLT was significantly longer (P < 0.0001 and P < 0.0009, respectively) and TAFI antigen levels were significantly higher (both P < 0.0001) in the RIF versus the IVF and FER groups. A direct relationship between CLT and TAFI antigen levels (r = 0.40; P = 0.001) was detected in the whole study population. There were no differences in distribution of TAFI polymorphisms between groups. Patients with RIF have reduced plasma fibrinolytic potential, as shown by a prolonged CLT, and this may be explained, at least in part, by increased TAFI antigen levels.

A Novel Assay to Detect Alterations of Coagulation and Fibrinolysis after Coronary Artery Bypass Surgery

Background: A fine balance between pro- and anti-coagulant factors is required to prevent bleeding and graft (or other) thrombosis in the period that follows coronary artery bypass grafting (CABG). The majority of routinely available tests can adequately detect clinical states of hypocoagulability but fail to detect states of hypercoagulability. The overall haemostatic potential (OHP) assay, which measures coagulation and fibrinolysis, has been used to detect the presence and cause of hypercoagulable states in a variety of patients – those with arterial and venous thromboembolism, autoimmune disease and disorders of pregnancy. We performed the assay on the plasma of patients before and after CABG. Methods: Plasma was collected from patients before and on days 1, 3 and 5 after both CABG and off-pump CABG (OPCAB). An anti-fibrinolytic agent was given routinely during CABG. By adding a combination of tissue factor and tissue plasminogen activator to plasma and buffer, the formation and degradation of fibrin clot was measured by spectrophotometry. Results: There was significant increase in the coagulation potential on days 3 and 5 after surgery in both groups (p < 0.0001 for both groups, no difference between groups). Fibrinolysis was significantly impaired after CABG on days 1, 3 and 5 but not after OPCAB (p < 0.0001, p = 0.57 respectively). Conclusion: Patients in the period after CABG are in a hypercoagulable state. This is a result of both an increase in coagulation potential and impairment of fibrinolysis.

Cross-talk Between Statins and the Renin-angiotensin System

Hypercholesterolaemia and hypertension are major public health problems that are frequently treated with statins and renin-angiotensin system (RAS) blockades. Although the mechanisms of action for these two classes of drugs differ, both classes have beneficial effects on the vasculature. Experimental and clinical studies demonstrated that combined statins and RAS blockades improve endothelial function as reflected by improved flow-mediated dilation, improved fibrinolysis potential and reduced oxidant stress, inflammatory markers and insulin sensitivity. There is a strong scientific rationale for recommending combination therapy, especially statins and RAS blockades, to treat or prevent atherosclerosis and coronary heart disease. In this article, we address the mechanisms on the cross-talk between statins and RAS and discuss the rationale and importance of combination therapy with statins and RAS blockades in treating and preventing cardiovascular events.

The Overall Hemostasis Potential: A Laboratory Tool for the Investigation of Global Hemostasis

A simple and rapid global haemostatic assay for determination of the overall hemostasis potential (OHP) in plasma represents a new approach in detecting alterations in the delicate balance between coagulation and fibrinolysis. The assay is based on repeated spectrophotometric registration of the fibrin-aggregation curve in platelet-poor plasma containing small amounts of exogenous thrombin, tissue-type plasminogen activator, and calcium. The overall coagulation potential and overall fibrinolytic potential are supplementary parameters of OHP, providing details of underlying changes in coagulation and/or fibrinolysis. The OHP assay was evaluated in connection with hypercoagulation in normal pregnancy, preeclampsia, some thrombophilias, coronary heart disease, diabetes, stroke, and vascular surgery as well as with hypocoagulability, especially in patients with hemophilia A or B. Preliminary results also indicate the possible usefulness of the assay in monitoring anticoagulant treatments. Large prospective clinical trials are needed before the method can be recommended for routine clinical application.

Tissue plasminogen activator induced fibrinolysis: standardization of method using thromboelastography

Fibrinolysis is a complex physiological process that involves the interaction of several anticoagulant proteins. Defects of the fibrinolytic system are extremely difficult to diagnose and study because there are no standardized tests available. Thromboelastography is a novel method that allows the study of both coagulation and fibrinolysis using one sample of whole blood, thereby allowing a more physiologic assessment of the coagulation process. Several in-vitro studies have been attempted to determine whether thromboelastography would be a useful assay for the study of fibrinolysis but have reported problems with reproducibility and reliability. Here we report the process involved in developing a thromboelastographic assay in which tissue plasminogen activator (t-PA) is used to induce fibrinolysis. The assay was standardized to ensure that the concentration of the coagulation inducer (tissue factor) and fibrinolytic agent (t-PA) was adequate to induce a clot with lysis parameters that were reproducible and reliable. This method can be used to rapidly assess the intrinsic fibrinolytic potential of whole blood. Our assay showed that it could rapidly predict high levels of plasminogen activator inhibitor, and this information would be beneficial in patients with acute stroke or myocardial infarction.

Use of Terahertz Electromagnetic Waves for Correcting Hemostasis Functions

The influence of terahertz range waves at 129.0 GHz (frequency of the molecular spectrum of radiation and absorption of atmospheric oxygen) on faulty coagulation hemostasis and its fibrinolysis potential was studied under conditions of experimental stress. Considerable hypercoagulation and the suppression of fibrinolysis of blood were observed in experimental animals exposed to experimental stress. The influence of 129.0 GHz radiation was studied in animals under conditions of immobilizing stress. No considerable changes in the faulty indicators of hemostasis and fibrinolysis were observed for 5-min exposure duration. In case of 15-min exposure, partial normalization of indicators characterizing the coagulation cascade and fibrinolysis was observed. The influence of terahertz radiation on the specified frequencies within 30 min caused full normalization of hemocoagulation and fibrinolysis as the studied indicators of a coagulation link of the system of hemostasis and fibrinolysis. Thus, on the basis of the presented data it is possible to draw a conclusion about positive effect of terahertz radiation at the frequency of the molecular spectrum of radiation and absorption of atmospheric oxygen (129.0 GHz) on the coagulation properties and fibrinolysis of blood in animals under conditions of immobilizing stress. A 30-min exposure proved to be especially effective for restoration of the indicators of hemocoagulation and fibrinolysis activity of blood.

Impaired fibrinolysis as a risk factor for Budd-Chiari syndrome

AbstractIn Budd-Chiari syndrome (BCS), thrombosis develops in the hepatic veins or inferior vena cava. To study the relationship between hypofibrinolysis and BCS, we measured plasma levels of fibrinolysis proteins in 101 BCS patients and 101 healthy controls and performed a plasma-based clot lysis assay. In BCS patients, plasminogen activator inhibitor 1 (PAI-1) levels were significantly higher than in controls (median, 6.3 vs 1.4 IU/mL, P < .001). Thrombin-activatable fibrinolysis inhibitor and plasmin inhibitor levels were lower than in controls (13.8 vs 16.9 μg/mL and 0.91 vs 1.02 U/L, both P < .001). Median plasma clot lysis time (CLT) was 73.9 minutes in cases and 73.0 minutes in controls (P = .329). A subgroup of cases displayed clearly elevated CLTs. A CLT above the 90th or 95th percentile of controls was associated with an increased risk of BCS, with odds ratios of 2.4 (95% confidence interval, 1.1-5.5) and 3.4 (95% confidence interval, 1.2-9.7), respectively. In controls, only PAI-1 activity was significantly associated with CLT. Analysis of single nucleotide polymorphisms of fibrinolysis proteins revealed no significant differences between cases and controls. This case-control study provides the first evidence that an impaired fibrinolytic potential, at least partially caused by elevated PAI-1 levels, is related to the presence of BCS.

Age-related changes in fibrin networks and platelets of individuals over 75: a scanning electron microscopy study showing “thrombotic preparedness”

During aging, changes in vasculature, haemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur. Research has also reported that healthy, aged individuals have heightened coagulation enzyme activity, accompanied by signs of enhanced formation of fibrin and secondary hyperfibrinolysis. It is now believed that the impaired fibrinolytic potential in old age results in a condition that has previously been described as a systemic state of "thrombotic preparedness". This state is far out of proportion to the physiological needs of the person. In the current research we investigate whether this apparent changed thrombotic profile in healthy aged individuals (over the age of 75), is evident in their platelet and fibrin network ultrastructure, when compared to healthy individuals under 25 years. The main differences among young and older individuals were found in the fibrin network ultrastructure. It is concluded that with age, major fibers seem to become thinner and more sparsely arranged and that minor, thin fibers dominate it the coagulum, forming a fine netlike structure. At irregular intervals in the coagulum, thicker, fibrin fiber lattices are present; this is not found in healthy individuals. This might be due to the previously suggested enhanced fibrin formation and heightened coagulation enzyme activity. Here we therefore provide ultrastructural evidence for the thrombotic preparedness previously suggested after studying biochemistry of fibrinolysis and coagulation factors in the elderly.

The effect of ethanol and its metabolism on fibrinolysis

The role of ethanol metabolism in possible haemostatic cardioprotective effects has not yet been determined. To this end, we investigated the effect of a moderate dose of ethanol (35 g) and its metabolism, on haemostatic variables over 14 hours (h). Eighteen Caucasian males participated in a placebo-controlled, randomised, cross-over study. Blood was collected prior to alcohol consumption, and at 10 time points for 14 h. Blood ethanol peaked at 1 h and was cleared after 8 h following ethanol consumption, significantly increasing plasma acetate (p=0.0028). Ethanol did not influence the coagulation factors significantly. PAI-1act increased (p<0.0001) and tPAact (p=0.047) decreased following alcohol consumption, reaching maximum (0.69 to 22.2 IU/ml) and minimum (0.88 to 0.33 IU/ml) levels at 5 h, respectively. Significantly increased plasma clot lysis times (46.8 to 67.6 minutes) and reduced global fibrinolytic capacity of whole blood, measured as D-dimer production during incubation of blood clots (2.26 to 0.29 μg/ml), were found at 5 h. Except for PAI-1act (borderline significance; p=0.05), there was no significant difference in the fibrinolytic markers between the two groups the following morning. Moderate ethanol consumption resulted in a significant temporary fibrinolysis inhibition. Any protective effects of moderate ethanol consumption on cardiovascular disease do not appear to be due to improvement in fibrinolytic potential within the first 14 h following consumption. The use of global fibrinolytic assays is recommended for determining the true effect of ethanol on fibrinolysis.

Correction of Hypercoagulation in Pregnant Women, by Using Intermittent Plasmapheresis in Combination with 10% HES

Objective: to evaluate the impact of intermittent plasmapheresis in combination with 10% HES (Refortan® HES 10%, Berlin-Chemie AG) on hemostatic parameters in pregnant women with hypercoagulation syndrome. Subjects and methods. One hundred and forty pregnant women at 25-to-34 weeks gestational age with significant hypercoagulation as shown by hemostasiograms, who received a course of intermittent plasmapheresis for correction of hemostasis, were followed up. Plasma exchange using 10% HES (Refortan®) 500 ml was performed in 80 pregnant women. That with 0.9% NaCl 800 ml was carried out in 60 pregnant women. Results. There were substantial shifts towards a reduced coagulation potential in both groups. When a control hemostasiogram was recorded after 14 days, no negative changes were found in the former group whereas in the latter group all the study indices returned to the values obtained before a course of intermittent plasma-pheresis with plasma exchange using 0.9% NaCl. Conclusion. The performed analysis of hemostatic changes in pregnant women from the study and control groups leads to the conclusion that the use of HES (Refortan® 10%) as a plasma-substituting solution during intermittent plasmapheresis results in a more considerable and longer stabilization of the blood coagulation potential at the expense of the plasma and platelet links of hemostasis and the increased blood fibrinolytic potential, as suggested by the indicators of decreased intravascular coagulation processes. Furthermore, these positive effects persist for at least two weeks, which promotes a more effective prevention of placental insufficiency and gives grounds to substantially reduce a medical burden in pregnant women with hypercoagulation syndrome and to prolong pregnancy in these women. Key words: pregnancy, miscarriage, hypercoagulation, plasmapheresis, hydroxyethyl starch.

Assessment of Global Hypercoagulability and Fibrinolytic Potential in Pediatric VTE: Findings From A Single-Institutional Prospective Inceptional Cohort Study.

Abstract 2988Poster Board II-964 BACKGROUND:In pediatric venous thromboembolism (VTE), duration of hypercoagulability—which has implications for recurrence risk and duration of therapy–is not readily assessed despite a battery of laboratory assays for comprehensive thrombophilia testing. Global clotting assays offer the possibility to better understand duration of hypercoagulability on an individualized basis. OBJECTIVE:We sought to evaluate overall coagulability and fibrinolytic potential over time in children with acute VTE and to compare these findings with D-dimer and established thrombophilia traits. METHODS:The Clot Formation and Lysis (CloFAL) global assay was performed in platelet-poor plasma in 58 children enrolled in a single-institutional prospective inceptional cohort study of VTE at The Children's Hospital, Colorado, between March 2006 and June 2009. This spectrophotometric fibrin registration assay employing clotting activation with dilute tissue factor and phospholipid and fibrinolytic enhancement with tissue plasminogen activator has been previously shown analytically sensitive to physiologic and pathologic alterations in multiple components of the coagulation and fibrinolytic systems (Goldenberg et al., Thromb Res 2005). Hypercoagulability was defined by an area under the curve (AUC) of the CloFAL waveform that exceeded the upper limit of age-appropriate reference values established in healthy children (n=26) using the non-parametric method of Tukey, and hypofibrinolysis was similarly defined as a fibrinolytic index (FI, which relates to the slope of decline in absorbance over the period of 30 minutes following maximal amplitude of clot formation) that was below the lower limit of normal. Coagulation index (CI, measured as the AUC over the first 30 minutes of the assay, indexed to the pooled normal plasma standard) was also evaluated, and compared to established reference ranges. Analyses were grouped by period post-diagnosis, as follows: acute (0-1 month; n=10), subacute (1-3 months; n=12), early chronic (3-6 months; n=10), late chronic (≥1 year; n=32). Comprehensive testing for genetic and acquired thrombophilia states was performed in all subjects, along with serial assessment of D-dimer and automated euglobulin lysis time (ELT). RESULTS:Of the 58 children with VTE evaluated for global coagulative and fibrinolytic capacity, 25% underwent repeat testing in follow-up. A positive relationship with factor VIII activity (FVIII) was demonstrated for both CI and AUC (r=0.37, P=0.006 and r=0.52, P<0.0001). In addition, AUC correlated inversely with FI and directly with ELT (r=-0.58, P<0.0001 and r=0.40, P=0.003), underscoring the interrelatedness between the coagulative and fibrinolytic systems (as has been previously shown, for example, via thrombin-activatable fibrinolytic inhibitor). Figure 1 demonstrates a decreasing trend in values over time post-diagnosis for CloFAL AUC, D-dimer, and FVIII, and increasing trend in CloFAL FI. The proportion of patients with abnormally elevated values for AUC, D-dimer, and FVIII, and abnormally low values for FI, also progressively decreased with time (Figure 2). Notably, however, persistent hypercoagulability was demonstrated in 28% , and hypofibrinolysis in 12.5%, of patients studied ≥1 year post-event (n=32). CONCLUSIONS:These findings demonstrate net hypercoagulability and hypofibrinolysis acutely in the majority of children with VTE, with a trend toward normalization in hemostasis over time across the study population. Further prospective studies are underway to determine whether persistence of hypercoagulability and/or hypofibrinolysis (as observed by global clotting assay in a subset of patients studied here), serves as a prognostic factor for recurrent VTE, and hence may contribute to future risk-stratified approaches to anticoagulant therapy duration. [Display omitted] [Display omitted] Disclosures:Off Label Use: The presentation refers to the use of anticoagulants as a drug class in general in the treatment of venous thromboembolism (VTE) in children. Despite their use in the standard care for pediatric VTE, all anticoagulants remain off-label for this indication in children.