Four Decades of Carrier Detection and Prenatal Diagnosis in Hemophilia A: Historical Overview, State of the Art and Future Directions.

Hemophilia A (HA), a rare recessive X-linked bleeding disorder, is caused by either deficiency or dysfunction of coagulation factor VIII (FVIII) resulting from deleterious mutations in the F8 gene encoding FVIII. Over the last 4 decades, the methods aimed at determining the HA carrier status in female relatives of HA patients have evolved from phenotypic studies based on coagulation tests providing merely probabilistic results, via genetic linkage studies based on polymorphic markers providing more accurate results, to next generation sequencing studies enabling highly precise identification of the causative F8 mutation. In parallel, the options for prenatal diagnosis of HA have progressed from examination of FVIII levels in fetal blood samples at weeks 20-22 of pregnancy to genetic analysis of fetal DNA extracted from chorionic villus tissue at weeks 11-14 of pregnancy. In some countries, in vitro fertilization (IVF) combined with preimplantation genetic diagnosis (PGD) has gradually become the procedure of choice for HA carriers who wish to prevent further transmission of HA without the need to undergo termination of pregnancies diagnosed with affected fetuses. In rare cases, genetic analysis of a HA carrier might be complicated by skewed X chromosome inactivation (XCI) of her non-hemophilic X chromosome, thus leading to the phenotypic manifestation of moderate to severe HA. Such skewed XCI may be associated with deleterious mutations in X-linked genes located on the non-hemophilic X chromosome, which should be considered in the process of genetic counseling and PGD planning for the symptomatic HA carrier. Therefore, whole exome sequencing, combined with X-chromosome targeted bioinformatic analysis, is highly recommended for symptomatic HA carriers diagnosed with skewed XCI in order to identify additional deleterious mutations potentially involved in XCI skewing. Identification of such mutations, which may profoundly impact the reproductive choices of HA carriers with skewed XCI, is extremely important.

The hemostatic efficacy of chitosan-pads in hemodialysis patients with significant bleeding tendency.

BACKGROUND: Patients on chronic hemodialysis often have acquired coagulopathy that can aggravate bleeding from puncture site after needle extraction. Chitosan-based pads have been reported to accelerate hemostasis even in the presence of coagulopathy. The aim of this study was to evaluate the hemostatic efficacy of the chitosan pads compared to gauze pads, applied for local hemostasis. METHODS: A crossover study in a cohort of patients on hemodialysis with extended time to hemostasis after needle extraction. At the end of each dialysis, either gauze or chitosan pad was applied on both access points (arterial and venous). The type of pad was changed in the next dialysis all together 5 times in each patient (10 applications per patient for every pad). RESULTS: A total of 288 applications, 144 for each type of pad, were performed in 15 patients. The average time to hemostasis for the entire group was significantly shorter with the chitosan pads compared to the regular gauze pads ("arterial" point 3 vs. 18.5 min, p<0.001 "venous" access 2.8 vs. 13.2 min, p<0.001, respectively). CONCLUSIONS: Chitosan pads significantly reduce time to hemostasis and should be considered for the treatment of accessible bleeds in patients with coagulopathy.

Long-acting recombinant coagulation factor IX albumin fusion protein (rIX-FP) in hemophilia B: results of a phase 3 trial.

A global phase 3 study evaluated the pharmacokinetics, efficacy, and safety of recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP) in 63 previously treated male patients (12-61 years) with severe hemophilia B (factor IX [FIX] activity ≤2%). The study included 2 groups: group 1 patients received routine prophylaxis once every 7 days for 26 weeks, followed by either 7-, 10-, or 14-day prophylaxis regimen for a mean of 50, 38, or 51 weeks, respectively; group 2 patients received on-demand treatment of bleeding episodes for 26 weeks and then switched to a 7-day prophylaxis regimen for a mean of 45 weeks. The mean terminal half-life of rIX-FP was 102 hours, 4.3-fold longer than previous FIX treatment. Patients maintained a mean trough of 20 and 12 IU/dL FIX activity on prophylaxis with rIX-FP 40 IU/kg weekly and 75 IU/kg every 2 weeks, respectively. There was 100% reduction in median annualized spontaneous bleeding rate (AsBR) and 100% resolution of target joints when subjects switched from on-demand to prophylaxis treatment with rIX-FP (P< .0001). The median AsBR was 0.00 for all prophylaxis regimens. Overall, 98.6% of bleeding episodes were treated successfully, including 93.6% that were treated with a single injection. No patient developed an inhibitor, and no safety concerns were identified. These results indicate rIX-FP is safe and effective for preventing and treating bleeding episodes in patients with hemophilia B at dosing regimens of 40 IU/kg weekly and 75 IU/kg every 2 weeks. This trial was registered at www.clinicaltrials.gov as #NCT0101496274.

The impact of thrombin generation and rotation thromboelastometry on assessment of severity of factor XI deficiency.

The phenotype of bleeding in patients with severe FXI deficiency is unpredictable and unlike other bleeding disorders, it is not directly correlated with levels of FXI. In this study we analyzed whether the global coagulation assays can serve as a clinical tool in predicting bleeding tendency in patients with severe FXI deficiency undergoing surgery, taking into account the large inter-individual variability of FXI levels and genotypes. Thrombin generation (TG) was measured in 39 platelet-poor plasma with or without tissue factor (TF) and in the presence or absence of corn trypsin inhibitor (CTI). Rotation thromboelastometry (ROTEM) was performed with fresh whole blood of 26 patients applying NATEM and INTEM tests. TG induced by recalcification can distinguish between bleeding and non-bleeding patients with severe FXI deficiency particularly among those with FXI activity of 2-20IU/dl. The addition of TF or TF and CTI to the TG assay masked the ability to differentiate between XI activity, genotype as well as bleeding and non-bleeding patients. ROTEM assays failed to distinguish bleeding from non-bleeding patients but could do so between different FXI activity levels and genotypes. In conclusion, in the current study we found a sensitive tool to distinguish between bleeding and non-bleeding patients. In order to recommend TG as a predictive tool for treatment tailoring, a larger patient group is required.

Survival of hepatitis C-infected haemophilia patients is predicted by presence of cirrhosis but not by anti-viral treatment.

BACKGROUND/PURPOSE: Hepatitis C (HCV) is a major cause of morbidity and mortality in haemophilia patients who received clotting factor concentrates before the availability of virus-inactivated factors in the mid-1980s. Recently, it has been suggested that anti-HCV treated patients, particularly those achieving a sustained virological response (SVR) have an improved outcome. We sought to examine the survival of treated and untreated HCV-infected haemophilia patients. MATERIAL AND METHODS: We studied overall and liver-related survival of patients with haemophilia and other congenital bleeding disorders between 2000 and 2010. The outcome was compared in 3 sub-groups: HCV mono-infected (N = 127), HCV/HIV co-infected (N = 28), and patients with either HCV-antibodies negative or persistent HCV RNA-negative (referred to as non-infected) (N = 45). Sixty-two (40%) (HCV and HCV/HIV) patients underwent anti-HCV treatment with an SVR rate of 40.3%. RESULTS: Overall and liver-related 10-year survival were: 82.1 and 89.3%, 95.3 and 99.2 and 100% for HCV/HIV co-infected, HCV mono-infected and non-infected haemophilia patients, respectively (p = 0.015 and 0.023 for comparisons of HCV/HIV vs. HCV; p = 0.003 for comparison of HCV/HIV and non-infected). One HCV mono-infected and 3 co-infected patients died of end-stage liver disease (2 underwent liver transplantation). There was no survival benefit from anti-HCV treatment or from attaining of an SVR. Only clinically suspected cirrhosis remained as an independent predictor of survival. CONCLUSION: The prognosis of haemophilia patients who acquired HCV/HIV co-infection is worse than that of HCV mono-infected or non-infected or haemophiliacs. This is mainly due to liver-related mortality. Anti-HCV treatment or SVR had no observable impact on survival rate.

Surfactant impairs coagulation in-vitro: a risk factor for pulmonary hemorrhage?

BACKGROUND: Pulmonary hemorrhage (PHEM) complicates the hospital course of 3-5% of preterm infants with respiratory distress syndrome (RDS), and bears a high mortality rate. Impaired thrombin generation and poor clot formation in premature neonates affect PHEM severity. OBJECTIVES: We evaluated the impact of surfactant upon in-vitro clot formation in order to assess the role of surfactant in the pathogenesis of PHEM. METHODS: Blood samples were obtained from healthy volunteers for measuring complete blood count, PT, PTT, and platelet function. Surfactant at increasing concentrations was added to blood samples, and whole blood clotting assays were performed using rotation thromboelastogram (ROTEM®, Pentapharm Munich, Germany) and whole blood platelet adhesion and aggregation (Impact-R®, Diamed, Switzerland). RESULTS: The mean PT level increased from 10.05 ± 033 to 11.64 ± 0.85 sec (p=0.06) in the presence of surfactant. Platelet aggregation with the agonists adenosine diphosphate and epinephrine significantly decreased with escalating surfactant concentration (p<0.001). Adhesion, manifested by surface coverage (SC), significantly decreased with increasing surfactant concentration: mean SC 9.25 ± 2.96 compared to 6.1 ± 0.96 and 0.05 ± 0.058 with 0/0.1/5mg/ml surfactant, respectively, p<0.001 Whole blood ROTEM studies showed a trend towards lengthening of clotting time with increased surfactant concentration and lower clot strength. CONCLUSION: The presence of surfactant impairs coagulation in-vitro. The risk of PHEM may therefore be greater in extremely premature infants. Future studies are required to assess the clinical significance and relevance of our preliminary findings.

Phase I/II, open-label, multicenter, safety, efficacy and PK study of a recombinant coagulation factor IX albumin fusion protein (rIX-FP) in subjects with hemophilia B.

Recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP) is a novel recombinant albumin fusion protein designed to extend the half-life of recombinant factor IX (rFIX), which is used in the management of hemophilia B. Clinical evaluation of rIX-FP in humans is underway, including a recently completed phase I/II, open-label, multicenter, study that assessed the safety, pharmacokinetics, and efficacy of rIX-FP in patients with severe hemophilia B. A total of 17 patients received rIX-FP (25 IU/kg) as either on-demand therapy (n = 4) for 20 weeks or weekly prophylaxis (n = 13) for up to 44 weeks. Preliminary results confirm that rIX-FP has an excellent safety profile and a pharmacokinetic profile highlighted by a marked extended half-life, suggesting that weekly prophylaxis with rIX-FP at a dose of 25 IU/kg may be appropriate in patients with severe hemophilia B, and that extended dosing intervals (10-14 days) may be feasible in some patients. A phase II/III study evaluating the safety and efficacy of rIX-FP in patients with hemophilia B is underway.

Percutaneous coronary intervention in patients with haemophilia presenting with acute coronary syndrome: an interventional dilemma: case series, review of the literature, and tips for management.

Since the introduction of clotting factor concentrates over 50 years ago the life expectancy of patients with hemophilia (PWH) has increased to over 70 years. Consequently, diseases of the ageing population, including coronary artery disease, are increasingly being encountered. These patients present a unique therapeutic problem due to their greatly increased bleeding risk. Randomized controlled studies specific to PWH are lacking, emphasizing the need for case series. We present three cases of acute coronary syndrome in PWH who underwent urgent percutaneous coronary intervention at our institution, and summarize the available literature on the topic. We describe their management and outcome and provide points to consider when treating these complex patients.

Efficacy and safety of prophylaxis with once-weekly BAY 79-4980 compared with thrice-weekly rFVIII-FS in haemophilia A patients. A randomised, active-controlled, double-blind study.

The benefits of prophylaxis of haemophilia A patients regarding joint health and quality-of-life are well established. However, adherence to an up to every-other-day infusion regimen is a barrier to widespread adoption of prophylaxis. BAY 79-4980 is an investigational drug consisting of rFVIII-FS (sucrose-formulated recombinant FVIII) reconstituted with liposome solvent. Previous clinical studies showed extended protection from bleeding after a single injection of BAY 79-4980 (13.3 ± 6.2 days) compared with rFVIII-FS (7.2 ± 1.7 days). The effect of once-a-week prophylaxis with BAY 79-4980 (35 IU/kg) compared with three times-per-week rFVIII-FS (25 IU/kg) in previously treated, severe haemophilia A patients was evaluated in a 52-week, double-blind, two-arm, randomised, controlled study. The primary and secondary endpoints were protection from total bleeds and joint bleeds, respectively. Short- and long-term safety and tolerability of BAY 79-4980 including effects on lipid levels were assessed. A total of 139 and 131 subjects were evaluable for safety and efficacy analyses, respectively. A large difference in efficacy between treatment groups was observed with 72.1% (49/68) in the rFVIII-FS control group demonstrating <9 bleeds/year compared with 38.1% (24/63) of BAY 79-4980-treated subjects. A similar difference was seen in annualised joint bleeds, with 43 subjects (63.2%) in the control group demonstrating <5 joint bleeds/year compared with 24 subjects (38.1%) treated with BAY 79-4980. The distribution of bleeds seven days post-prophylactic treatment with BAY 79-4980 showed that 61% of bleeds occurred after day 4 post dosing. There were no safety concerns identified. The investigational treatment arm was prematurely discontinued due to failure to achieve the primary endpoint.

[Trauma-induced coagulopathy--mechanisms and state of the art treatment].

Uncontrolled bleeding is a major cause for early death in both military and civilian trauma. The process of massive bleeding which begins as "surgical bleed" from injured vessels may rapidly evolve into a complex coagulopathy that can be detected early, sometimes within minutes of injury. The magnitude of coagulopathy is directly related to the severity of the injury and its presence is also an independent predictor of early mortality. Therefore, an early "hemostatic resuscitation" is now the "state of the art" in trauma management. Combined mechanisms contribute to the complex coagulopathy as described herein: excessive consumption of coagulation factors and platelets, dilutional coagulopathy due to administration of large volumes of fluids, especially high molecular solutions such as Hydroxyethyl starch (HES); the use of multiple red blood cells (RBC) transfusion without sufficient fresh frozen plasma (FFP) and platelets; acidosis that markedly attenuates thrombin generation and platelets function; hypothermia that slows down enzymatic reactions and platelets function and hyperfibrinolysis which accelerates the degradation of fibrin and might cause platelet dysfunction. An important breakthrough was the understanding that abnormal coagulation tests early in the process of trauma are not the consequences of disseminated intravascular coagulation (DIC). Supported by these new data, an aggressive approach to hemostatic resuscitation was developed which is based on the following principles: permissive hypotension to avoid "dilutional" coagulopathy, awareness of the prevention of hypothermia and acidosis and the use of hemostatic agents such as rFVIIa, fibrinogen concentrate and tranexamic acid early in the course of trauma. Importantly, the common practice of blood component therapy was revised and it is recommended that RBC, FFP and platelets will be transfused early and preferably in 1:1:1 ratio.

Differential roles of fibrinogen and von Willebrand factor on clot formation and platelet adhesion in reconstituted and immune thrombocytopenia.

BACKGROUND: Bleeding tendencies in immune thrombocytopenia (ITP) do not always correlate with the number of platelets, suggesting platelet function variation. We used a model of normal whole blood thrombocytopenia to compare platelet function and other hemostatic variables with ITP patients. We further investigated the effect of in vitro spiking with von Willebrand factor (vWF) and fibrinogen on platelet function and hemostatic variables. METHODS: The Cone and Plate(let) Analyzer was used to measure platelet adhesion (surface coverage [SC], %) and aggregation (average size, µm(2)) under defined shear rate (1200 s(-1)). Rotational thromboelastometry was used to determine variables of clot formation triggered by CaCl(2) and tissue factor. RESULTS: In both the model of thrombocytopenia as well as in ITP, the SC and to some extent the average size were correlated to the platelet number over a range of 5 to 80 × 10(6)/mL. The results obtained for most ITP samples were within the boundaries of the lower and upper limits set by the whole blood model of thrombocytopenia. The addition of 2 U/mL vWF (Haemate-P) to whole blood (calculated to plasma volume) results in an increase in the SC and average size without affecting clot formation. Spiking with fibrinogen (100 and 300 mg/dL) did not affect platelet deposition but improved clot formation. CONCLUSIONS: Using a model of whole blood thrombocytopenia enables us to establish reference variables for the Cone and Plate(let) Analyzer and rotational thromboelastometry and to assess platelet function and clot formation in the presence of severe thrombocytopenia. We demonstrated that in most cases of ITP, platelet function is comparable to normal platelets. This work also suggests that vWF and fibrinogen differentially affect primary and secondary hemostasis and therefore both may perform a function in the bleeding phenotype and possibly may be considered for treatment in patients with ITP.

A highly sensitive thrombin generation assay for assessment of recombinant activated factor VII therapy in haemophilia patients with an inhibitor.

Bypass agents are the common treatment for haemophilia patients who develop inhibitory antibodies. Laboratory assessment of the efficacy of bypassing agent therapy is a challenge. In the present work we modified the conditions triggering thrombin generation (TG) assay in order to find the most sensitive assay for detection of rFVIIa and its analogue NN1731 in haemophilic plasma. TG was measured in samples of normal plasma, plasma of haemophilia patient with inhibitors, as well as haemophilia induced plasma. Recalcification-induced TG was compared to tissue factor (TF) -induced TG in the presence and absence of rFVIIa and NN1731. Recalcification-induced TG (without TF) in haemophilic plasma yielded baseline flat curves, with increased TG as a consequence of spiking the plasma rFVIIa. Using our system, we observed both dose-dependence and time-dependence of rFVIIa effect on TG. Elevated concentrations of TF mask the difference between rFVIIa-treated and non-treated haemophilic plasma. NN1731 yielded normalisation of recalcification-induced TG curves (without TF) which may reflect high potency. In conclusion, we suggest that triggering TG by recalcification-only may be the most sensitive assay for determining the impact of bypassing agents in haemophilic plasma, and may serve as a caution surrogate safety marker in future studies.

Enhancement of pig embryonic implants in factor VIII KO mice: a novel role for the coagulation cascade in organ size control.

Very little is known about the mechanisms that contribute to organ size differences between species. In the present study, we used a mouse model of embryonic pig tissue implantation to define the role of host Factor VIII in controlling the final size attained by the implant. We show here that pig embryonic spleen, pancreas, and liver all grow to an increased size in mice that are deficient in the Factor VIII clotting cascade. Similar results were obtained using the transplantation model after treatment with the low molecular weight heparin derivative Clexane which markedly enhanced transplant size. Likewise, enhanced size was found upon treatment with the direct thrombin inhibitor Dabigatran, suggesting that organ size regulation might be mediated by thrombin, downstream of Factor VIII. Considering that thrombin was shown to mediate various functions unrelated to blood clotting, either directly by cleavage of protease-activated receptors (PARs) or indirectly by cleaving osteopontin (OPN) on stroma cells, the role of PAR1 and PAR4 antagonists as well as treatment with cleaved form of OPN (tcOPN) were tested. While the former was not found to have an impact on overgrowth of embryonic pig spleen implants, marked reduction of size was noted upon treatment with the (tcOPN). Collectively, our surprising set of observations suggests that factors of the coagulation cascade have a novel role in organ size control.

A rapidly progressive, life-threatening postpartum hemorrhage: successful treatment with anti-CD-20 monoclonal antibody.

BACKGROUND: Postpartum hemorrhage may be a life-threatening event and may result from coagulation defects. CASE: We report a case of a multigravida woman who developed rapidly progressive postpartum bleeding as a result of acquired factor VIII inhibitors. Repeated laparotomies and massive transfusions failed to achieve adequate control of bleeding. Laboratory studies revealed a prolonged activated partial thromboplastin time, and the presence of specific inhibitors was soon established. The patient responded only partially to steroids and immunotherapy. Upon administration of rituximab, an anti-CD-20 monoclonal antibody, control of bleeding was achieved. CONCLUSION: Early diagnosis of acquired hemophilia as a rare cause of postpartum hemorrhage is crucial, because specific therapy may be life saving.

Single-dose recombinant activated factor VII therapy in hemophilia patients with inhibitors.

Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) is well established as an effective hemostatic agent for the management of hemorrhage in hemophilia patients with inhibitors. Its use in prophylaxis is currently being investigated. On-demand treatment schedules usually involve multiple bolus doses of 90 to 120 microg/kg administered every 2 to 3 hours, but recent evidence from randomized controlled trials suggests that the use of higher single doses is equally safe and effective when used for the home treatment of hemarthroses. Consequently, the use of a single dose of 270 microg/kg rFVIIa for the treatment of bleeds in inhibitor patients has recently been approved by the European Medicines Agency (EMEA). Such high-dose regimens may overcome the rapid clearance rate observed in pediatric patients, and may be more convenient for patients with poor venous access. It also has been suggested that individually tailored single-dose therapies might be beneficial in selected groups of patients, although proper monitoring of such patients is advised. Further research should contribute towards more effective dose optimization of rFVIIa in hemophilic inhibitor patients.

Phacoemulsification of cataract in patients receiving Coumadin therapy: ocular and hematologic risk assessment.

PURPOSE: To assess the risks of intra- and postoperative bleeding tendency associated with uncomplicated cataract surgery by phacoemulsification in patients receiving Coumadin treatment. DESIGN: Prospective, nonrandomized, interventional, consecutive case series. METHODS: Sixty-three consecutive patients underwent cataract extraction with lens implantation in 75 eyes. All patients were receiving Coumadin therapy at the time of surgery, and nine patients (14.3%) were also taking antiaggregants. The operations were performed by phacoemulsification technique under topical anesthesia. All patients underwent a hemostatic work-up before intervention. Structured questionnaires were completed by the surgeon immediately after the operation. In 18 (24%) eyes, the surgery was videotaped, and the tapes were reviewed subsequently for any bleedings by an independent observer. RESULTS: Twelve patients (19%) underwent surgery in both eyes, not simultaneously. The mean prothrombin time international normalized ratio (INR) was 2.03 at the time of the surgery. No significant intraoperative bleeding occurred. Four (6.3%) patients had minor postoperative ocular bleeding. A microscopic hyphema and a dot retinal hemorrhage were each seen in one eye on the first postoperative day, and small iris hemorrhages were identified in two additional eyes at the one-week visit. All bleedings disappeared within one week without affecting the visual acuity. The mean INR of the four patients with minor bleedings was 2.1. CONCLUSIONS: Cataract surgery by phacoemulsification in uncomplicated eyes can be performed safely in patients receiving Coumadin treatment. However, a large clinical trial is required to assess the safety of continuous Coumadin treatment associated with phacoemulsification in eyes with complicated cataract.

Correction of hemophilia as a proof of concept for treatment of monogenic diseases by fetal spleen transplantation.

Previous clinical attempts to correct genetic deficiencies such as hemophilia or Gaucher disease by transplantation of allogeneic spleen were associated with aggressive graft versus host disease, mediated by mature T cells derived from the donor spleen. We show that a fetal pig spleen harvested at the embryonic day 42 stage, before the appearance of T cells, exhibited optimal growth potential upon transplantation into SCID mice, and the growing tissue expressed factor VIII. Transplantation of embryonic day 42 spleen tissue into hemophilic SCID mice led to complete alleviation of hemophilia within 2-3 months after transplant, as demonstrated by tail bleeding and by assays for factor VIII blood levels. These results provide a proof of principle to the concept that transplantation of a fetal spleen, obtained from a developmental stage before the appearance of T cells, could provide a novel treatment modality for genetic deficiencies of an enzyme or a factor that can be replaced by the growing spleen tissue.

Continuous infusion of coagulation factors: current opinion.

PURPOSE OF REVIEW: To review the most recent reports on continuous infusion of coagulation factors, focusing on the current issues relating to this mode of therapy. RECENT FINDINGS: Continuous infusion has been extensively used as an alternative to intermittent bolus factor replacement since the 1990s. To date, more than 100 reports comprising more than 800 continuous infusion treatments in various clinical situations have been published, with an increase in the current utilization of recombinant coagulation factors. An excellent hemostatic efficacy of continuous infusion has been reported. Continuous infusion protocols, however, still vary widely in terms of the different hemostatic levels targeted, dosage regimens, modes of continuous infusion and duration of therapy, which obviously result in variations in the cost-effectiveness reported by different centers. SUMMARY: Continuous infusion has been shown to be a safe and cost-effective mode of replacement for treatment of hemophilia. The lack of evidence-based information on the hemostatic levels to be maintained in specific clinical situations, and recent concerns regarding the development of inhibitors, particularly in patients with mild hemophilia treated with continuous infusion, need to be addressed by prospective, randomized studies that compare traditional intermittent injections and the continuous infusion mode of factor replacement.

Effects of increasing doses of activated recombinant factor VII on haemostatic parameters in swine.

This study examined dose-response relationships between activated recombinant factor VII (rFVIIa) and (1) in vivo haemostasis and (2) in vitro measures of coagulation and platelet function. Anesthetized swine were used. Ear bleeding time (BT) was measured and blood was sampled following increasing doses of rFVIIa (0, 90, 180, 360 and 720 microg/kg; n=6) or saline (n=6). BT was not altered by rFVIIa. Prothrombin time (PT) using standard or pig-specific methods was decreased by rFVIIa. Activated clotting time (ACT) was decreased by rFVIIa. Thromboelastography using collagen (COLL) or pig thromboplastin (p-ThP) as agonist demonstrated shorter reaction times, shortened time to reach maximum velocity of clot formation, and increased alpha-angle in the presence of rFVIIa. rFVIIa dosing increased maximum velocity of clot formation when p-ThP was used to initiate the reaction but not when COLL was used. rFVIIa at the highest concentration increased maximum amplitude when COLL was used to initiate the reaction. Platelet aggregation was not altered by rFVIIa. Following completion of the dose escalation phase, a severe liver injury was produced. rFVIIa altered neither blood loss nor survival time following injury but improved mean arterial pressure. A small increase in systemic thrombin-antithrombin III complex occurred after administration of rFVIIa at doses of 180 microg/kg and above. However, there was no histological evidence of intravascular coagulation after rFVIIa administration. In summary, rFVIIa activity was detectable in vitro but did not change haemostasis in normal swine.

Continuous infusion of recombinant factor VIIa for surgery in patients with deficiency of factor VII.

The administration of recombinant activated factor VII (rFVIIa) by continuous infusion has provided a safe and convenient alternative to bolus injections in haemophiliacs with inhibitors, but it has only been reported in a single case with congenital factor VII (FVII) deficiency. The results of 12 consecutive surgical procedures in 7 patients with congenital FVII deficiency are reported here. rFVIIa was always given in continuous infusion,aiming at plasma FVII activity of 0.5 IU/mL. Treatment was given for 2 to 7 days with a mean total dose of 7.8 mg rFVIIa. Blood loss was as expected from the different types of procedures and the only thromboembolic complication was a superficial thrombophlebitis at the infusion site. This mode of substitution was therefore safe, effective and well tolerated.