Establishing Expectancy Values for Fibrin Monomer in Uncomplicated Pregnancy.

Background During pregnancy, a physiological increase of molecular activation markers (MAM) of hemostasis such as prothrombin fragments 1 + 2, thrombin-antithrombin complex, and D-dimers (DD) occurs. Therefore, monitoring MAM levels during pregnancy to evaluate the risk of venous thromboembolism (VTE) may be unreliable; nevertheless, DD analysis in pregnancy is widely performed. In contrast to DD, fibrin monomer (FM) levels have been reported to remain stable during pregnancy. Objectives The main aim of this study was to define the expected range for FM levels in pregnant outpatients. In addition, we examined the impact of the individual VTE risk, as calculated by the pregnancy risk score of the Royal College of Obstetricians and Gynaecologists (RCOG), as well as that of antithrombotic treatment on FM levels. Methods A total of 342 pregnant women seen at our hemostasis unit were included throughout 350 pregnancies in 899 samples. Results Low-risk thrombophilia, but not the RCOG score itself, was found to influence all MAM levels, whereas antithrombotic treatment had only an impact on DD. For FM, a reference range could be calculated irrespective of the pregnancy term, in contrast to other MAMs, which fluctuated throughout pregnancy. Conclusions Our findings suggest a stronger impact of inherited thrombophilia on hemostasis activity during pregnancy as compared with acquired or other predisposing thrombophilic risk factors. FM levels showed a marginal increase during pregnancy in contrast to other MAM and remain a potential candidate to improve the laboratory assessment of VTE risk during pregnancy. Further prospective studies in pregnant patients with suspicion of VTE are needed.

Evaluation of a tryptase depletion index for better pathologic identification of mast cell activation syndrome.

BACKGROUND: Laboratory evidence supporting diagnosis of the prevalent condition of mast cell activation syndrome (MCAS) currently includes elevated levels in blood or urine of mediators relatively specific to mast cells (MCs) and/or increased numbers of MCs in luminal gastrointestinal (GI) tract tissues. However, identification of elevated mediators is technically challenging and expensive, and controversy persists regarding the normal ranges of numbers/counts of MCs in various GI tract segments, let alone challenges in determining how many of the visualized MCs are activated. To aid diagnosis of MCAS, we developed a potential new approach for the pathologist to identify the extent of GI tract MC activation easily and inexpensively. PARTICIPANTS AND METHODS: Visualization of MCs in gastrointestinal biopsies from 251 patients vs. 95 controls using antibodies against CD117 and tryptase; MC counting per mm2; calculation of the difference between the CD117-positive MCs (identifying all MCs) vs. tryptase-positive MCs (identifying non-activated tryptase-containing MCs), which we define as the tryptase depletion index (TDI). RESULTS: Mean total MC counts did not differ significantly between patients and controls, but mean TDIs differed significantly. Non-overlapping confidence intervals at the 99.9% level identified cut-offs of TDIs between patients vs. controls of 26, 45 and 32 MCs/mm2 in gastric antrum, duodenum, and colon, respectively. CONCLUSIONS: The TDI may discriminate between MCAS patients vs. controls. If this preliminary work can be independently confirmed, the TDI may become a useful additional minor diagnostic criterion for MCAS.

Effects of Primary Mast Cell Disease on Hemostasis and Erythropoiesis.

Mast cell disease is an epigenetically and genetically determined disease entity with very diverse clinical manifestations in potentially every system and tissue due to inap pro priate release of variable subsets of mast cell mediators together with accumulation of either morphologically normal or altered mast cells. Easy bruising, excessive bleeding, and aberrancies of erythropoiesis can frequently be observed in patients with mast cell disease. A thorough history, including a family history, will guide the appropriate work-up, and laboratory evaluations may provide clues to diagnosis. In recent years, our understanding of the involvement of coagulation and anticoagulant pathways, the fibrinolytic system, and erythropoiesis in the pathophysiology of mast cell disease has increased considerably. This review summarizes current knowledge of the impact of the disturbed hemostatic and erythropoietic balance in patients with mast cell disease and describes options of treatment.

Lower prevalence of vitamin D insufficiency in German patients with systemic mast cell activation syndrome compared with the general population.

Introduction The common mastocytosis variant systemic mast cell activation syndrome (MCAS) may underlie at least a subset of patients with irritable bowel syndrome (IBS). A critical role of vitamin D (VD) in the stabilization of mast cells (MCs) with deficiency of VD resulting in MC activation has been demonstrated. If so, supplementation of VD would be a potential therapeutic approach in the treatment of those IBS patients. Methods We investigated in the present study for the first time systematically whether the VD level in 100 MCAS patients differed from that in the German general population (Ggp) and made a first attempt to elucidate potential reasons for possible differences by simultaneously determining the blood levels of heparin and cholesterol. Results In contrast to the Ggp, the VD level was detected in a sufficient range (> 30 ng/mL) in 53 % of the MCAS patients (Ggp 8 %), and only 34 % had values in the range of deficiency (< 20 ng/mL; GgP 75 %). There was no correlation between VD blood level and heparin and cholesterol blood levels. Conclusions The demonstration that in the majority of MCAS patients the VD level is not in a deficient range argues against an essential contribution of VD deficiency to the high prevalence of MCAS in Germany. Our findings do not exclude the possibility of smaller effects of VD level on MC activation in vivo. However, if such effects are present, the effect sizes seem to be too small to become identifiable in the multifactorial process of disease development.

Transcatheter aortic valve implantation leads to a restoration of von Willebrand factor (VWF) abnormalities in patients with severe aortic stenosis - Incidence and relevance of clinical and subclinical VWF dysfunction in patients undergoing transfemoral TAVI.

BACKGROUND: In this study, we sought to analyze the incidence and relevance of von Willebrand factor (VWF) abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI), especially on perioperative bleeding. Furthermore, we hypothesized that, similar to aortic valve surgery, TAVI results in a restoration of VWF abnormalities. METHODS AND RESULTS: We performed a prospective analysis of periinterventional VWF parameters in 74 patients (80±7years, female in 37.5%) undergoing transfemoral TAVI for severe symptomatic aortic valve stenosis. At baseline, VWF:Ag was 210±90IU/dl with a mean VWF activity of 166±106IU/dl; activity-to-antigen ratio was 0.85±0.45. Heyde's syndrome (severe aortic stenosis plus GI bleeding from angiodyplasia) was observed in 2/74 (2.7%). Whereas preprocedural loss of high-molecular-weight (HMW) VWF multimers was found in thirty-six patients (48.6%), none of the patients fulfilled criteria for possible acquired VW syndrome. After TAVI, an increase of both VWF:Ag and activity compared to baseline was observed (p<0.01). In patients with HMW multimer loss, post-interventional recovery of multimers occurred in all cases. In the two patients with Heyde's syndrome, a trend towards reduced VWF:Ag was seen, with loss of HMW multimers in one patient. Of interest, all patients suffering from periprocedural major bleeding (5/74; 6.8%) exhibited activity-to-antigen ratios <0.7, indicating subclinical VWF dysfunction. CONCLUSION: Whereas clinically relevant VWF dysfunction is rare, loss of HMW VWF multimers is common in TAVI patients. Similar to surgery, TAVI leads to a restoration of this loss. Furthermore, VWF parameters may be useful parameter to evaluate risk of periprocedural bleeding.

Case Report: Treatment of systemic mastocytosis with sunitinib.

Mast cell activation disease typically presents as chronic multisystem polymorbidity of generally inflammatory ± allergic theme.  Presently, treatment of the rare, cytoproliferative variant systemic mastocytosis employs empirically selected therapies to impede mast cell mediator production and action and, when necessary, inhibition of proliferation. Some tyrosine kinase inhibitors (TKIs) have been used successfully in uncommon cases of systemic mastocytosis not bearing that disease's usual imatinib-resistant KIT D816V mutation. Recently, sunitinib, a multi-targeted TKI, had been successful in a case of systemic mast cell activation syndrome. In addition, most allergy is principally a mast cell activation phenomenon, and sunitinib has been shown helpful in controlling a murine model of oral allergy syndrome. Here, we present the first use of sunitinib in systemic mastocytosis.

Determination of plasma heparin level improves identification of systemic mast cell activation disease.

Diagnosis of mast cell activation disease (MCAD), i.e. systemic mastocytosis (SM) and idiopathic systemic mast cell activation syndrome (MCAS), usually requires demonstration of increased mast cell (MC) mediator release. Since only a few MC mediators are currently established as biomarkers of MCAD, the sensitivity of plasma heparin level (pHL) as an indicator of increased MC activation was compared with that of serum tryptase, chromogranin A and urinary N-methylhistamine levels in 257 MCAD patients. Basal pHL had a sensitivity of 41% in MCAS patients and 27% in SM patients. Non-pharmacologic stimulation of MC degranulation by obstruction of venous flow for 10 minutes increased the sensitivity of pHL in MCAS patients to 59% and in SM patients to 47%. In MCAS patients tryptase, chromogranin A, and N-methylhistamine levels exhibited low sensitivities (10%, 12%, and 22%, respectively), whereas sensitivities for SM were higher (73%, 63%, and 43%, respectively). Taken together, these data suggest pHL appears more sensitive than the other mediators for detecting systemic MC activity in patients with MCAS. The simple, brief venous occlusion test appears to be a useful indicator of the presence of pathologically irritable MCs, at least in the obstructed compartment of the body.

Genetic variants of the vitamin K dependent coagulation system and intraventricular hemorrhage in preterm infants.

BACKGROUND: Pathogenesis of intraventricular hemorrhage (IVH) in premature infants is multifactorial. Little is known about the impact of genetic variants in the vitamin K-dependent coagulation system on the development of IVH. METHODS: Polymorphisms in the genes encoding vitamin K epoxide reductase complex 1 (VKORC1 -1639G>A) and coagulation factor 7 (F7 -323Ins10) were examined prospectively in 90 preterm infants <32 weeks gestational age with respect to coagulation profile and IVH risk. RESULTS: F7-323Ins10 was associated with lower factor VII levels, but not with individual IVH risk. In VKORC1-wildtype infants, logistic regression analysis revealed a higher IVH risk compared to carriers of the -1639A allele. Levels of the vitamin K-dependent coagulation parameters assessed in the first hour after birth did not differ between VKORC1-wildtype infants and those carrying -1639A alleles. CONCLUSIONS: Our data support the assumption that genetic variants in the vitamin K-dependent coagulation system influence the coagulation profile and the IVH risk in preterm infants. Further studies focussing on short-term changes in vitamin K-kinetics and the coagulation profile during the first days of life are required to further understand a possible link between development of IVH and genetic variants affecting the vitamin K-metabolism.

ATZ11 recognizes not only Z-α1-antitrypsin-polymers and complexed forms of non-Z-α1-antitrypsin but also the von Willebrand factor.

AIMS: The ATZ11 antibody has been well established for the identification of α1-anti-trypsin (AAT) molecule type PiZ (Z-AAT) in blood samples and liver tissue. In this study, we systematically analyzed the antibody for additional binding sites in human tissue. METHODS AND RESULTS: Ultrastructural ATZ11 binding was investigated immunoelectron microscopically in human umbilical vein endothelial cells (HUVECs) and in platelets of a healthy individual. Human embryonic kidney (HEK293) cells were transiently transfected with Von Willebrand factor (VWF) and analyzed immunocytochemically using confocal microscopy and SDS-PAGE electrophoresis followed by western blotting (WB). Platelets and serum samples of VWF-competent and VWF-deficient patients were investigated using native PAGE and SDS-PAGE electrophoresis followed by WB. The specificity of the ATZ11 reaction was tested immunohistochemically by extensive antibody-mediated blocking of AAT- and VWF-antigens. ATZ11-positive epitopes could be detected in Weibel-Palade bodies (WPBs) of HUVECs and α-granules of platelets. ATZ11 stains pseudo-WBP containing recombinant wild-type VWF (rVWF-WT) in HEK293 cells. In SDS-PAGE electrophoresis followed by WB, anti-VWF and ATZ11 both identified rVWF-WT. However, neither rVWF-WT-multimers, human VWF-multimers, nor serum proteins of VWF-deficient patients were detected using ATZ11 by WB, whereas anti-VWF antibody (anti-VWF) detected rVWF-WT-multimers as well as human VWF-multimers. In human tissue specimens, AAT-antigen blockade using anti-AAT antibody abolished ATZ11 staining of Z-AAT in a heterozygous AAT-deficient patient, whereas VWF-antigen blockade using anti-VWF abolished ATZ11 staining of endothelial cells and megakaryocytes. CONCLUSIONS: ATZ11 reacts with cellular bound and denatured rVWF-WT and human VWF as shown using immunocytochemistry and subsequent confocal imaging, immunoelectron microscopy, SDS-PAGE and WB, and immunohistology. These immunoreactions are independent of the binding of Z-AAT-molecules and non-Z-AAT complexes.

[Hemostasis and antifibrinolytic therapy in major pediatric surgery]. / Antifibrinolytika und Blutgerinnung in der Kinderchirurgie - Was ist anders als beim erwachsenen Patienten?

More than 30 years ago the pioneering work of Andrew and co-workers showed that the coagulation system of children is different than from adult. They have introduced the term of "developmental hemostasis" to describe this phenomenon. They were able to show that the concentration of coagulation factors and inhibitors are age-dependent and therefore reference limits from adult practice cannot be transferred to children one to one. Numerous studies showed that the perioperative loss of blood, and thus the use of homologous blood could be limited by administering antifibrinolytic substances such as aprotinin. Other antifibrinolytics acting substances like Epsilon-aminocaproic acid (EACA) or tranexamic acid (TXA) tended to be misfits in routine clinical practice. In 2006, the publication of a retrospective study carried out by Mangano et al, in which considerable safety concerns were expressed with regard to aprotinin led to a significant rethinking of its clinical use. Two years later the results of the BART (Blood Conservation using antifibrinolytics in a Randomized Trial) study confirmed that there was an increased postoperative mortality associated with the use of aprotinin compared to TXA and EACA. In a few adult studies so far tranexamic acid was found to be comparably as effective as aprotinin. Although TXA is a long known drug available on the market for more than 50 years, the studies connecting factors of indication, dosage regimen and safety are limited especially in children and infants. This article highlights the differences in the coagulation system in children compared to adult as well as indication, dosage regimens and possible side effects of antifibrinolytic agents in children.

Mutation distribution in the von Willebrand factor gene related to the different von Willebrand disease (VWD) types in a cohort of VWD patients.

Von Willebrand disease (VWD) is the most common inherited bleeding disorder caused by quantitative or qualitative defects of the von Willebrand factor (VWF). VWD is classified into three types--type 1 (partial quantitative deficiencies), type 2 (qualitative defects) and type 3 (complete deficiency of VWF). In this study we explored genotype and phenotype characteristics of patients with VWD with the aim of dissecting the distribution of mutations in different types of VWD. One hundred fourteen patients belonging to 78 families diagnosed to have VWD were studied. Mutation analysis was performed by direct sequencing of the VWF . Large deletions were investigated by multiplex ligation-dependent probe amplification (MLPA) analysis. The impact of novel candidate missense mutations and potential splice site mutations was predicted by in silico assessments. We identified mutations in 66 index patients (IPs) (84.6%). Mutation detection rate was 68%, 94% and 94% for VWD type 1, 2 and 3, respectively. In total, 68 different putative mutations were detected comprising 37 missense mutations (54.4%), 10 small deletions (14.7%), two small insertions (2.9%), seven nonsense mutations (10.3%), five splice-site mutations (7.4%), six large deletions (8.8%) and one silent mutation (1.5%). Twenty-six of these mutations were novel. Furthermore, in type 1 and type 2 VWD, the majority of identified mutations (74% vs. 88.1%) were missense substitutions while mutations in type 3 VWD mostly caused null alleles (82%). Genotyping in VWD is a helpful tool to further elucidate the pathogenesis of VWD and to establish the relationship between genotype and phenotype.

Elevated interleukin-6 concentration and alterations of the coagulation system are associated with the development of intraventricular hemorrhage in extremely preterm infants.

BACKGROUND: Pathogenesis of intraventricular hemorrhage (IVH) in premature infants is multifactorial. Little is known about the influence of pro-inflammatory cytokine activation on the coagulation system in extremely preterm infants and its impact on the development of IVH. OBJECTIVE: To determine the interaction between serum interleukin-6 (IL-6) and the coagulation system in preterm infants predisposed to the development of IVH. METHODS: Vitamin K-dependent coagulation factors were examined retrospectively in 132 extremely preterm infants prior to vitamin K administration at the first day of life. Patients were grouped according to the occurrence of IVH and serum concentration of IL-6 >/<100 pg/ml. RESULTS: Occurrence of IVH was associated with clinical diagnosis of chorioamnionitis, low gestational age, high CRIB score, air leak, catecholamine treatment, low initial hematocrit and increased serum concentration of IL-6. Infants developing IVH showed a diminished coagulation profile. Multivariable logistic regression analysis revealed decreased activity of coagulation factor VII, development of pneumothorax and low hematocrit as independent risk factors for the development of IVH. An increased IL-6 serum concentration was associated with a significantly decreased activity of coagulation factor VII and increased levels of fibrinogen. CONCLUSIONS: The association of elevated IL-6 levels with alterations of the coagulation profile and development of IVH found in our study supports the assumption of a close pathophysiological relation between inflammation and IVH.

Perioperative monitoring of primary and secondary hemostasis in coronary artery bypass grafting.

On-pump cardiac surgery is accompanied by complex alterations of hemostasis. The excessive postoperative bleeding has been attributed to acquired platelet dysfunction, impaired plasmatic coagulation, and increased fibrinolysis. The characterization of the hemostatic defects responsible for bleeding is crucial for specific treatment and optimal clinical management of the patient. For rapid determination of platelet-dependent primary hemostatic capacity (PHC), the Platelet Function Analyzer PFA-100 system is available. To evaluate the PFA performance in perioperative monitoring, a study was performed in 49 patients selected for low bleeding risk undergoing selective primary coronary artery bypass grafting (CABG). We compared PHC with Simplate bleeding time (BT) and platelet aggregometry. Furthermore, we analyzed global hemostasis by thromboelastography (TEG) and plasmatic coagulation by standard clotting tests prothrombin time (PT, Quick), activated partial thromboplastin time (aPTT), thrombin time (TT) and clotting factors and fibrinolysis by batroxobin (reptilase) time (RT). In all patients BT was postoperatively increased by 1.5- to 2-fold irrespective of perioperative complications and decreased to mildly prolonged values on the first postoperative day (1st day). In patients without complications, PHC in both collagen-adenosine diphosphate closure time (CADP-CT: 83 seconds preop, 78 seconds postop, and 74 seconds 1st day) and collagen-epinephrine closure time (CEPI-CT: 98 seconds preop, 95 seconds postop, 85 seconds 1st day) remained nearly stable. Apart from a patient with postoperative moderate thrombocytopenia, in bleeding patients no other significant defect of postoperative platelet hemostatic capacity was observed. However, on 1st day, the PHC of those patients was significantly reduced compared with non-bleeding patients. In patients with postoperative myocardial ischemia, increased PHC was identified by significantly shorter postoperative CADP-CT (66 seconds vs. 83 seconds) than in uncomplicated patients. By aggregometry, partial platelet dysfunction was observed in some patients without correlation to bleeding complications. In seven of 9 patients the postoperative bleeding complication was attributed to prolonged heparin anticoagulation and/or mildly enhanced fibrinogenolysis/fibrinolysis by TEG and standard plasmatic coagulation tests (TEG: k time 18 minutes vs. 8 minutes; aPTT: 47 seconds vs. 32 seconds; TT: 18.0 seconds vs. 12.3 seconds) and (RT: 19.5 seconds vs. 17.7 seconds). The impairment of PHC, platelet aggregation, and clotting factors observed on the 1st day in bleeding and in intra-aortic balloon pump (IABP) patients are most likely secondary effects, for example, loss of active platelets and clotting factors, to the primary postoperative bleeding or implantation of the IABP. In conclusion, our data indicate that in standard CABG procedures highly variable alterations of the hemostatic system occur after cardiopulmonary bypass (CPB) even in patients with assumed low operative risks. For identification of post-CPB bleeding complications, thromboelastography, aPTT, and TT and heparin and batroxobin (reptilase) time as fibrinolysis-sensitive assays are useful. Platelet function appears to be rapidly restored in uncomplicated CABG. PHC determination by PFA-100 demonstrates a high specificity for adequate platelet function and, therefore, could be beneficial in improved transfusion of platelet concentrates. PHC testing by PFA-100 may help identify postoperative platelet hyper-reactivity associated with myocardial lesion.