Acquired von Willebrand syndrome in adult patients with congenital heart disease.

OBJECTIVES: Postoperative bleeding is common in patients with congenital heart disease (CHD). However, little is known about the role and prevalence of acquired von Willebrand syndrome (AVWS). METHODS: We evaluated the prevalence of AVWS in relation to underlying cardiac defects, operative procedures and the presence of Eisenmenger syndrome. The prothrombin time, aPTT, platelet function analysis (PFA-100), von Willebrand factor antigen (VWF:Ag), VWF activity, VWF collagen binding activity (VWF:CB), factor VIII activity and multimeric analysis were measured in addition to tests evaluating heart, liver and kidney functions. RESULTS: A total of 221 patients were screened and 192 patients were included in the study. The overall prevalence of AVWS was 20.8%. AVWS was identified across all of the cardiac defects, with the highest prevalence in the defects of great complexity (38.6% compared to 9.4% in patients with CHD of simple/moderate complexity, p<0.001), Eisenmenger syndrome (p<0.001) and more severe heart failure symptoms (NYHA III/IV vs. NYHA I, p<0.001; NYHA III/IV vs. NYHA II, p=0.044). A combination of multimeric analysis, VWF:CB to VWF:Ag ratio (sensitivity: 77.5%, specificity: 93.3%) and PFA-100 (PFA Col/Epi sens.: 77%, spec.: 52%; PFA Col/ADP sens.: 75%, spec.: 74.3%) were used to detect AVWS. CONCLUSIONS: This study demonstrated that AVWS occurred in patients with various congenital cardiac defects, but the highest prevalence occurred in the patients with complex CHD and Eisenmenger syndrome. We, therefore, suggest preoperative screening for AVWS in all of the patients with CHD, particularly in the patients with CHD of greater complexity and suffering from Eisenmenger syndrome.

The use of recombinant activated factor VII in neurosurgery.

BACKGROUND: Bleeding complications in neurosurgery often take alarming proportions without major hemodynamic effect or impairment of coagulation physiology because severe neurologic deficits are to be expected. Any measures used to stabilize or normalize coagulation are therefore of great interest. Administration of packed red cells, fresh frozen plasma, and platelet concentrates is associated with volume loading, which is suspected to multiply the secondary brain damage, for example, by the development of an edema. In this respect, the administration of rFVIIa may develop into a new option associated with low-volume administration. CASE DESCRIPTIONS: We report on 5 neurosurgical patients to whom rFVIIa was given at doses of 51 to 202 microg/kg of body weight for the treatment of severe intraoperative bleeding (n = 3) or as prophylaxis of bleeding (n = 2). The operation was completed successfully in all patients after administration of rFVIIa, with stabilization of the coagulation status. CONCLUSION: Therefore, reported cases constitute an approach in treatment and prophylaxis of bleeding complications in neurosurgery. There are reports of thromboembolic events in use of rFVIIa, particularly in unlabeled use. But according to our findings and current literature, there is no evidence of higher risk of thromboembolic adverse events in treatment with rFVIIa. However, the number of patients presented does not allow any final assessment to be made as to whether the properties of rFVIIa are of particular benefit for neurosurgical patients. Further studies with appropriate study design are required to verify effects observed in this investigation.

Antithrombin alfa in hereditary antithrombin deficient patients: A phase 3 study of prophylactic intravenous administration in high risk situations.

During surgery and childbirth, patients with hereditary antithrombin (AT) deficiency are at high risk for thrombosis, and heparin prophylaxis may not be sufficiently efficacious. In these patients, exogenous AT may be used in association with heparin. A recombinant human AT (generic name: antithrombin alfa) has been developed. This multi-center study assessed the efficacy and safety of prophylactic intravenous administration of antithrombin alfa to hereditary AT deficient patients in high risk situations, including elective surgery, childbirth, or cesarean section. Antithrombin alfa was administered prior to and during the high risk period for restoration and maintenance of AT activity at 100% of normal. Heparin, low-molecular-weight heparin, and/or vitamin K antagonists were used according to standard of care. The primary efficacy endpoint was the incidence of acute deep vein thrombosis (DVT) from baseline up to day 30 post dosing as assessed by independent central review of duplex ultrasonograms and/or venograms. Safety was assessed based on adverse events (AEs) and laboratory evaluations. Five surgical and nine obstetrical hereditary AT deficiency patients received antithrombin alfa for a mean period of seven days. No clinically overt DVT occurred. Central review of ultrasonograms identified signs of acute DVT in two out of 13 evaluable patients. No antithrombin alfa-related AEs were reported. No patient developed anti-antithrombin alfa antibodies. In conclusion, this study suggests that antithrombin alfa is a safe and effective alternative to human plasma-derived AT for treating hereditary AT deficiency patients at high risk for thromboembolic events.

The use of recombinant-activated factor VII in von Willebrand disease: a case series.

Spontaneous and surgery-associated bleeding in patients with von Willebrand disease (vWD) cannot always be controlled with desmopressin or replacement therapy. This paper presents results on the use of recombinant-activated factor VII (rFVIIa) in patients with vWD included in the internet registry Haemostasis.com. Twenty-eight reports on the use of rFVIIa in vWD were identified from the database and included in this analysis. The bleeding episodes were classified as mild (n = 7), moderate (n = 16), or severe (n = 2), and were unspecified in three cases. The median dose of rFVIIa administered was 94 microg/kg body weight (40-127.3 microg/kg). Bleeding stopped in 23 of 27 evaluable patients (85%) and markedly decreased in three patients; the total response rate was 96% (26/27 patients). Response did not correlate with the type of vWD, the site or severity of the initial bleed, or the rFVIIa dose. Other replacement therapies were infrequently used, and their use was similar in the 24 h before and after rFVIIa administration. Eighteen patients also received antifibrinolytic treatment, but its impact on response was not recorded. Only one adverse event (mild fever) was observed. These cases suggest a role for rFVIIa as a safe and effective therapy for vWD.

Combined aspirin and clopidogrel resistance associated with recurrent coronary stent thrombosis.

We report about a 72-year-old woman who was admitted to our hospital because of an acute ST-elevation myocardial infarction (STEMI). At admission, she received a loading dose of 300 mg Clopidogrel and 500 mg aspirin (ASA) prior to angioplasty with stenting of a 90% diameter stenosis of the proximal right coronary artery. After intervention, 75 mg Clopidogrel and 300 mg ASA OD were continued. Three days later, she developed a recurrent acute STEMI due to stent thrombosis and a second stent implantation was performed. The dose of Clopidogrel and ASA remained unchanged. Three days later, the patient suffered a third STEMI due to a restent thrombosis and additional stent implantation was performed. The dose of Clopidogrel and ASA was increased to 75 mg BD and 500 mg OD. Platelet function analysis and aggregation studies demonstrated dose-independent ASA resistance. ADP-induced aggregation showed a short-term platelet inhibition with subsequent rapid normalisation, thus suggesting Clopidogrel resistance. Therefore, the treatment was changed to coumadin and ASA 100 mg OD. Since then, the patient has been clinically stabile. Our case indicates for the first time the existence of a subgroup of patients with combined Clopidogrel and ASA resistance. We conclude that identification of these patients is required and alternative therapeutic options have to be considered.

Clinical and prognostic role of plasma coagulation factor XIII activity for bleeding disorders and 6-year survival in patients with chronic liver disease.

BACKGROUND/AIMS: Alterations of plasma coagulation factor XIII may contribute to bleeding disorders in patients with liver cirrhosis. As standard clotting tests such as prothrombin time or activated thromboplastin time (aPTT) cannot detect factor XIII deficiency, this may often be overlooked in clinical practice. We aimed to define factor XIII's clinical and prognostic role in chronic liver disease. PATIENTS AND METHODS: Factor XIII activities were assessed among various other parameters in 111 patients with chronic liver diseases during evaluation for liver transplantation in a prospective study. RESULTS: Unlike coagulation factors II, V or VII, factor XIII activity was maintained in the majority of patients with liver cirrhosis. However, although rarely, factor XIII deficiencies (<50%) occurred, especially in Child C cirrhosis. Factor XIII levels correlated with liver's biosynthetic capacity (cholinesterase activity, albumin, total protein) as well as with platelet count, global coagulation tests and other single coagulation factors. Patients reporting a current systemic bleeding tendency at study entry had significantly reduced factor XIII. In a 6-year follow-up, patients with factor XIII<50% had a significantly increased risk of severe upper gastrointestinal bleed, and reduced factor XIII (<50%, 50-75% vs. normal) was associated with increased mortality. CONCLUSIONS: Factor XIII deficiency is rare in patients with liver cirrhosis, but is associated with a clinical bleeding tendency and an unfavorable prognosis for future hemorrhages and survival.

Clinical perspectives of emerging pathogens in bleeding disorders.

As a result of immunological and nucleic-acid screening of plasma donations for transfusion-transmissible viruses, and the incorporation of viral reduction processes during plasma fractionation, coagulation-factor concentrates (CFC) are now judged safe in terms of many known infectious agents, including hepatitis B and C viruses, HIV, and human T-cell lymphotropic virus. However, emerging pathogens could pose future threats, particularly those with blood-borne stages that are resistant to viral-inactivation steps in the manufacturing process, such as non-lipid-coated viruses. As outlined in this Review, better understanding of infectious diseases allows challenges from newly described agents of potential concern in the future to be anticipated, but the processes of zoonotic transmission and genetic selection or modification ensure that plasma-derived products will continue to be subject to infectious concerns. Manufacturers of plasma-derived CFC have addressed the issue of emerging infectious agents by developing recombinant products that limit the need for human plasma during production. Such recombinant products have extended the safety profile of their predecessors by ensuring that all reagents used for cell culture, purification steps, and stabilisation and storage buffers are completely independent of human plasma.

Immune tolerance therapy in patients with acquired hemophilia.

Acquired hemophilia is a rare disorder with an estimated annual incidence of 0.2-1 cases per million individuals. The etiology of the disorder remains obscure, although approximately half of all cases are associated with other underlying conditions. In acquired hemophilia, the severe hemorrhagic diathesis is caused by the development of autoantibodies directed against a clotting factor, most commonly factor VIII. These autoantibodies inhibit normal coagulation and lead to bleeding complications, which can be life-threatening in a high percentage of cases. Prompt diagnosis and appropriate management of the disorder enable effective control; the short- and long-term aims of therapy are to terminate the acute bleed and eliminate or reduce the inhibitor, respectively. Immune tolerance therapy has been shown to successfully eradicate or suppress inhibitors in patients with congenital hemophilia A and may be applicable to patients with acquired hemophilia. Here we present preliminary data on the use of immune tolerance therapy in patients with acquired hemophilia and discuss possible treatment strategies.

Plasma P-selectin levels are elevated in patients with chronic liver disease.

P-selectin is a leukocyte receptor and platelet activation marker that has been shown to be involved in thrombogenesis as well as bleeding disorders and may represent a possible link between inflammation and thrombosis. In animal models, high plasma levels correlated with a procoagulant tendency. In acute liver damage models such as hepatic ischaemia-reperfusion-injury, P-selectin was found to be a key mediator of liver injury. In order to investigate the clinical and pathogenetic role of P-selectin in chronic liver diseases, plasma P-selectin levels were measured in 111 patients with chronic liver diseases. P-Selectin was significantly elevated in patients (median 56 ng/ml, range 0-180) compared with controls (n = 38, median 20 ng/ml, range 3.3-42, P < 0.001). Current clinical bleeding symptoms were common, whereas thrombotic events occurred rarely. P-selectin levels were not associated with haemorrhagic or thromboembolic complications. P-selectin correlated with platelet and white-blood-cell counts, but not with endothelial injury markers thrombomodulin and tissue factor or coagulation factors. Interestingly, P-selectin levels were not associated with Child's stage of cirrhosis or disease aetiology, but were generally elevated in chronic liver diseases. Severe hepatic leukocyte infiltration in liver histology was associated with a tendency towards higher P-selectin levels. In line with its role in acute liver damage, P-selectin elevation in chronic liver disease may suggest a possible pathogenetic role in the course of liver cirrhosis.

The deletion polymorphism in the angiotensin-converting enzyme gene is a moderate risk factor for venous thromboembolism.

ACE displays potent vasoconstrictive effects, attenuation of fibrinolysis, and platelet activation and aggregation, thus possibly promoting venous thromboembolism (VTE). The ACE gene contains an insertion (I) or deletion (D) polymorphism accounting for 50% of the variation in serum ACE concentration. To evaluate the role of the I/D polymorphism in VTE, its prevalence was determined in 931 patients with VTE and 432 blood donors. The prevalence of the DD genotype was 27.6% in patients and 21.3% in controls (OR 1.4; p < 0.02). In multivariate analysis there was a trend of the DD genotype to be an independent risk factor (OR 1.4; p = 0.08). No differences in DD genotype prevalence according to exogenous risk factors were found. Coinheritance of FV G1691A, PT G20210A mutation, and PS deficiency with the DD genotype increased the relative risk of VTE. Thus, the ACE DD genotype is a moderate risk factor of hereditary thrombophilia. Exogenous risk factors did not alter the manifestation of VTE among carriers of the DD genotype, whereas coinheritance of the DD genotype with the aforementioned defects increased the risk for VTE considerably.

NovoSeven: mode of action and use in acquired haemophilia.

Recombinant activated factor VII (rFVIIa, 'NovoSeven') is indicated for the treatment of spontaneous and surgical bleeding in patients with haemophilia A or B with antibodies to factors VIII or IX (FVIII or FIX) worldwide, and in patients with acquired haemophilia in Europe. In vitro cell models have demonstrated that rFVIIa can bind to activated platelets and generate small amounts of Fxa, independent of the presence of tissue factor. The amount of platelet-surface Fxa formed increases with rising concentrations of FVIIa and, at levels of rFVII a that are effective in patients, sufficient platelet surface Fxa is generated partially to restore platelet surface thrombin generation. Acquired haemophilia is a rare but potentially life-threatening condition, caused by the autoimmune reduction of clotting factor levels as a result of the spontaneous development of auto-antibodies directed against the deficient factor. Bleeding into the skin or muscles is common in acquired haemophilia and the associated mortality rate is approximately 20%. rFVIIa has reported efficacy in the treatment of major bleeding episodes in patients with acquired haemophilia, which may be explained by its distinct mechanism of action that induces haemostasis at the site of injury, independent of the presence of FVIII or FIX. Also, the localisation of the action of rFVIIa at the site of injury may explain why it is well tolerated in these patients.

Plasminogen activator inhibitor-1 mRNA expression in cultured pigmented ciliary epithelial cells of the porcine eye.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) is a main regulator of the fibrinolytic system. PAI-1 inhibits tissue plasminogen activator and urokinase-type plasminogen activator, resulting in reduced plasminogen activity and attenuated fibrinolysis and proteolysis. The present study was performed to determine the gene expression encoding for PAI-1 in cultured pigmented ciliary epithelial cells of the porcine eye and to detect PAI-1 activity in cell culture supernatants. METHODS: Total mRNA of respective confluent primary cultures of porcine ciliary epithelial cells, porcine liver cells and porcine kidney cells was isolated. Reverse transcribed PAI-1 mRNA was measured by real-time polymerase chain reaction (TaqMan PCR) with PAI-1 primers and probes deduced from the human PAI-1 gene. PAI-1 activity in supernatants of the cell cultures was determined by a specific chromogenic test (Coatest PAI). RESULTS: PAI-1 mRNA was localized in all samples of primary cultures of porcine pigmented ciliary epithelial cells. As a negative control we analyzed total mRNA of porcine kidney cells. PAI-1 mRNA was not detectable in these cells. On the other hand, we established PAI-1 mRNA in porcine liver cells as a positive control. High levels of PAI-1 activity were found in all samples of cell culture supernatants. CONCLUSIONS: Our results indicate that PAI-1 is produced and secreted by the porcine ciliary epithelium. We suggest that PAI-1 together with components of the fibrin/fibrinolytic system may be involved in aqueous humor outflow. Overproduction of PAI-1 may induce less fibrinolysis and extracellular proteolysis in aqueous humor and trabecular meshwork, which could result in an elevated intraocular pressure by increasing the outflow obstruction. Therefore stimulation of PAI-1 production may perhaps contribute to the pathogenesis of primary open-angle glaucoma.