Management of inherited von Willebrand disease

Advances in the diagnosis and management of von Willebrand disease

von Willebrand disease (VWD), the most common inherited bleeding disorder, is caused by a quantitative (type 1 and 3) or qualitative (type 2) defect of von Willebrand factor (VWF). In this review, the present knowledge regarding the diagnosis and the management of VWD is briefly analyzed.

A longitudinal prospective study of bleeding diathesis in Egyptian pediatric patients: single-center experience

Keeping an updated registry of bleeding disorders is crucial for planning care and documenting prevalence. We aimed to assess the prevalence of various bleeding disorders including rare inherited coagulation and platelet disorders concerning their clinico-epidemiological, diagnostic data and bleeding manifestations severity. Patients suffering from manifestations of bleeding or coagulation disorders presented to Hematology Clinic during 16 years were included and prospectively followed up. Demographics, clinical characteristics, complete blood count, bleeding, prothrombin and activated partial thromboplastin times, platelet aggregation tests and bone marrow aspiration were recorded. Overall 687 patients with bleeding disorders from total 2949 patients were identified. Inherited coagulation defects were found in 27.2%; hemophilia A (70.6%), hemophilia B (13.9%), factor I deficiency (2.3%), factor V deficiency (1.6%), factor X deficiency (4.2%), factor VII deficiency (2.6%), factor XIII deficiency (1.1%), combined factor deficiency (2.1%) and unclassified coagulation disorders in 1.6% of studied patients. Overall 72.7% had diagnosed with platelet disorders; immune thrombocytopenia was the commonest (74.8%), and inherited conditions represent (25.2%) in the following order: Glanzman's thrombasthenia (11.2%), von Willebrand disease (6.6%), Bernard-Soulier syndrome (1%) and Chediak Higashi in 0.4% and unclassified in 6%. Median age of diagnosis of coagulation and platelet disorders were 33 and 72 months. Presenting symptoms of coagulation disorders were: 25.1% post circumcision bleeding, 22.5% ecchymosis, 20.9% hemoarthrosis and 15% epistaxis. Symptoms of rare coagulation disorders were postcircumcision bleeding (20%), bleeding umbilical stump (20%), epistaxis (12%), hemoarthrosis (8%) and hematomas (4%). Presenting symptoms in rare inherited platelet disorders were purpura, ecchymosis, epistaxis and bleeding gums, respectively. Analysis of the clinico-epidemiological data of patients with bleeding disorders is a useful tool for monitoring and improving their quality of care.

The Role Of von Willebrand Factor In Hemorrhagic And Thrombotic Disorders

von Willebrand factor (VWF) is a multimeric plasma protein that mediates platelet adhesion as well as platelet aggregation at sites of vascular injury and acts as a carrier of factor VIII. Although acquired or inherited VWF deficiency is associated with a bleeding tendency, there is increasing evidence that VWF has a pivotal role in thrombogenesis. In fact, while the presence in the plasma of unusually large VWF multimers, due to a congenital or acquired deficiency of a VWF-cleaving metalloprotease, has been implicated in the pathogenesis of thrombotic thrombocytopenic purpura, high plasma levels of VWF have been associated with an increased risk of both arterial and venous thrombosis. The role of VWF in normal and pathological hemostasis is discussed in this review, and important advances in the pathophysiology, diagnosis, and treatment of VWF-associated disorders are also described.

Clinical efficacy in bleeding and surgery in von Willebrand patients treated with Fanhdi a highly purified, doubly inactivated FVIII/VWF concentrate

Therapy with factor VIII/von Willebrand factor (FVIII/VWF) concentrate is the mainstay therapy in patients with von Willebrand disease (VWD) unresponsive to desmopressin. There are several commercially available FVIII/VWF concentrates that have been tested in VWD patients. We retrospectively analized the clinical efficacy in bleeding episodes and surgery of a highly purified FVIII/VWF complex with two inactivation steps (Fanhdi) in VWD patients. Sixty patients were included in the study. Treatment schedule consisted of one or more doses (standard dose 40 IU/kg body weight of FVIII) of Fanhdi. One hundred and fifty bleeding episodes were treated. These were: 28 serious bleedings; 92 moderate and 30 mild. An excellent clinical efficacy in almost 95% of cases was observed. Fanhdi was administered during 66 surgical procedures (38 major and 28 minor) with an overall efficacy of 98%. Fanhdi a highly purified, doubly virus-inactivated FVIII/VWF concentrate, with a high content of active VWF and an excellent record of clinical safety, is a valid choice in treating VWD.

Use of Recombinant Factor VIIa in Inherited and Acquired von Willebrand Disease

Recombinant factor VIIa (rFVIIa) is increasingly used outside the labeled indications for the treatment of life-threatening bleeding episodes after failure of respective standard therapy. In this article, the authors focus on the use of the agent in patients with inherited or acquired von Willebrand disease (vWD). Although the current experience is sparse, published cases indicate the high efficacy of rFVIIa for the treatment of patients refractory to conventional treatment. The agent may be used in patients with congenital vWD complicated by alloantibodies directed against substituted von Willebrand factor or in the presence of concomitant hemostatic defects as well as acquired vWD with hitherto limited therapeutic options. Controlled clinical studies are necessary to define the use of rFVIIa in this clinical setting.

The use of desmopressin as a hemostatic agent: a concise review

Desmopressin, a synthetic derivative of the antidiuretic hormone vasopressin, is the treatment of choice for most patients with von Willebrand disease and mild hemophilia A. Moreover, the compound has been shown to be useful in a variety of inherited and acquired hemorrhagic conditions, including some congenital platelet function defects, chronic liver disease, uremia, and hemostatic defects induced by the therapeutic use of antithrombotic drugs such as aspirin and ticlopidine. Finally, desmopressin has been used as a blood saving agent in patients undergoing operations characterized by large blood loss and transfusion requirements, but studies suggest that this is not as effective as other methods. This review briefly summarizes the current clinical indications on the use of desmopressin as a hemostatic agent.

Recent acquisitions in acquired and congenital von Willebrand disorders

von Willebrand factor is a multimeric plasma protein that mediates platelet adhesion as well as platelet aggregation at sites of vascular injury and, moreover, acts as a carrier of factor VIII. Its deficiency is associated with a bleeding tendency. The progresses in the pathophysiology, diagnosis and management of inherited von Willebrand disease and acquired von Willebrand syndrome will be discussed in this review.

Management of von Willebrand disease with factor VIII/von Willebrand factor concentrates: results from current studies and surveys

Until the mid 1980s, cryoprecipitate had been the mainstay of treatment of patients with von Willebrand disease (VWD) who were unresponsive to desmopressin. The advent of virally inactivated factor VIII/von Willebrand factor (FVIII/VWF) concentrates, originally developed for the treatment of patients with hemophilia, provided improved therapy for VWD. These products were therefore introduced in clinical practice in most European hemophilia centers; one concentrate (Humate-P) was approved for management of VWD in the USA. The 1980s saw the first clinical studies of FVIII/VWF concentrates in patients with VWD, but a standardized procedure for ex vivo effects of these virus-inactivated plasma concentrates in VWD patients became available only in 1992. Study results have shown that the commercially available VWF-containing concentrates are effective in clinical practice (bleeding and surgery), producing responses that may differ depending on the patient's VWD subtype; infusion results in correction of factor VIII activity (FVIII:C) and ristocetin cofactor activity of VWF (VWF:RCo), whereas bleeding time is not consistently corrected. Several studies have demonstrated that FVIII/VWF concentrates have variable VWF multimer patterns relative to normal human plasma. New products should be validated by current methodologies before introduction in clinical practice. Data on several intermediate-purity and high-purity FVIII/VWF concentrates have been reported, and a large prospective study of an intermediate-purity FVIII/VWF concentrate (Haemate P/Humate-P) is currently in progress. In the latter study, for the first time, the appropriate dosage to prevent bleeding during surgery is being calculated on the basis of scheduled pharmacokinetic assessments in each patient. Although thrombotic events are rare in patients with VWD receiving repeated infusions of FVIII/VWF concentrates, there is some concern that sustained high concentrations of FVIII:C may increase the risk of postoperative venous thromboembolism. On the basis of these observations, the dosage and timing of FVIII/VWF administration should be planned to keep FVIII:C concentrations between 50 U/dl and 150 U/dl in the postoperative period.

Haemostatic management of intraoral bleeding in patients with von Willebrand disease

OBJECTIVES

To develop plans for the haemostatic management of intraoral bleeding in patients with von Willebrand disease (VWD).

SUBJECTS AND METHODS

Thirty-seven episodes of haemostatic management of intraoral bleeding in 19 VWD patients were analysed retrospectively based on the medical records.

RESULTS AND CONCLUSIONS

When performing tooth extractions in patients with type 1 or 2A VWD [responsive to 1-deamino-8-D-arginine-vasopressin (DDAVP)], 0.35-0.4 microg kg(-1) of DDAVP should be administered intravenously at three times. In patients with type 2A VWD (unresponsive to DDAVP) or patients with type 2B or 2N VWD, 50-90 U [as ristocetin cofactor (VWF:RCof)] kg(-1) of a factor VIII concentrate containing von Willebrand factor (FVIII/VWF concentrate) should be administered twice in routine extractions, and four to six times in surgical extractions. Gingival bleeding related to primary teeth can be mostly managed by pressure haemostasis alone. However, when treating gingival bleeding caused by marginal periodontitis, it is often necessary to administer 0.4 microg kg(-1) of DDAVP or 40-70 U (as VWF:RCof) kg(-1) of a FVIII/VWF concentrate. As local haemostasis is difficult to achieve in bleeding from the tongue or labial or mandibular haematoma, it is necessary to administer 0.4 microg kg(-1) of DDAVP or 60-80 U (as VWF:RCof) kg(-1) of a FVIII/VWF concentrate. In addition, oral administration of 20 mg kg(-1) day(-1) of tranexamic acid should be combined with the regimens described above.

Study of human von Willebrand factor immunogenicity in pigs with severe von Willebrand disease

Replacement therapy is the treatment of choice for patients with von Willebrand disease who are unresponsive to desmopressin. In order to prevent transmission of non-enveloped viruses, a solvent/detergent-treated plasma-derived von Willebrand factor available in France since 1989 has been subjected to additional removal/inactivation steps by 35 nm filtration and dry heating for 72 h at 80 degrees C. This preclinical study evaluates the potential immunogenicity of this new product by comparing the antibodies raised in pigs affected with von Willebrand disease after intravenous injection of either a solvent/detergent-treated product or a triple-secured product. Our data showed that there is no difference between the two products in terms of the rate and intensity of the humoral response measured by both binding and neutralizing antibody levels. It was concluded that no antigenic alterations of von Willebrand factor molecules during the nanofiltration and final dry-heating steps were detected in our animal model.

Bleeding prophylaxis for major surgery in patients with type 2 von Willebrand disease with an intermediate purity factor VIII–von Willebrand factor concentrate (Haemate-P)

The parameters to diagnose von Willebrand disease (vWD) include factor VIII coagulant activity (FVIII:C), von Willebrand factor antigen (vWF:Ag), von Willebrand factor ristocetin cofactor activity (vWF:RCo), and von Willebrand factor collagen binding activity (vWF:CB). Type 2 vWD is associated with a moderate bleeding diathesis due to low levels of vWF:RCo and vWF:CB as compared with near normal or normal values for FVIII:C and vWF:Ag. As the factor VIII/von Willebrand factor (vWF) concentrate, Haemate-P, is featured by a vWF:RCo/FVIII:C ratio of about 2.2, the recommended loading dose of 50 U/kg FVIII:C followed by 25 U/kg FVIII:C every 12 h for several days for bleeding prophylaxis in type 2 vWD patients undergoing major surgery demonstrated a predicted significant over-treatment reaching vWF:RCo levels above 2 U/ml. Therefore, we restricted Haemate-P substitution for major surgery to one loading dose of 40-50 U/kg FVIII:C (88-110 U/kg vWF:RCo) followed by 15-20 U/kg FVIII:C (33-44 U/kg vWF:RCo) every 12 h for several days and evaluated this strategy in a prospective pharmacokinetic and efficacy study for bleeding prophylaxis in five type 2 vWD patients. Pre-treatment and peak levels (1 h after Haemate-P loading dose) rose from 0.43-0.66 to 1.5-2.5 U/ml for FVIII:C, from 0.23-0.45 to 1.5-2.5 U/ml for vWF:Ag, from 0.10-< 0.20 to 1.5-2.5 U/ml for vWF:RCo, and from < 0.05-0.10 to 1.0-2.0 U/ml for vWF:CB. Mean in vivo recoveries per transfused IU FVIII:C/kg body weight were 3.2% for FVIII:C, 3.9% for vWF:RCo, and 2.8% for vWF:CB. Mean in vivo recoveries per transfused IU vWF:RCo/kg were 1.45% for FVIII:C, 1.7% for vWF:RCo and 1.25% for vWF:CB. The biological half-life times after transfused Haemate-P were about 12 h for both vWF:RCo and vWF:CB. Based on these pharmacokinetic data, we propose to adapt the loading dose factor VIII/vWF concentrate (Haemate-P) to 60-80 U/kg vWF:RCo followed by 30-40 U/kg vWF:RCo every 12 h for no longer than several days (less than 1 week) for bleeding prophylaxis during major surgery or trauma, and to one loading dose of 40-60 U/kg vWF:RCo for minor surgery, trauma or mucotaneous bleedings in patients with type 2 vWD unresponsive to DDAVP.

Clinical efficacy of highly purified, doubly virus-inactivated factor VIII/von Willebrand factor concentrate (Fanhdi) in the treatment of von Willebrand disease: a retrospective clinical study

The goal of therapy in patients with von Willebrand disease (vWD) is to correct the dual defect of primary haemostasis and intrinsic coagulation reflected by low levels of von Willebrand factor (vWF) and factor VIII coagulant activity (FVIII:C). Factor VIII/von Willebrand factor (FVIII/vWF) concentrates are currently the treatment of choice in vWD patients unresponsive to desmopressin (DDAVP). However, only few studies on their clinical use are available so far. The main objective of this study was to retrospectively evaluate the clinical efficacy of a highly purified, doubly virus-inactivated FVIII/vWF concentrate with a high content of FVIII/vWF (Fanhdi). Twenty-two patients with congenital vWD have been treated from 1999 to 2001 at eight specialized centres belonging to the Italian Association of Hemophilia Centers (AICE). Ten males and 12 females, median age 28.5 years, range 5-70 years) had type 3 vWD (six cases), DDAVP-unresponsive type 1 (nine cases) and type 2B (seven cases). The study drug was given to stop or prevent 12 bleeding episodes or to prevent excessive bleeding during 14 surgical or invasive procedures. Overall, replacement therapy with the concentrate showed an excellent to good clinical efficacy in 92% of bleeding episodes and in 93% of surgical procedures. No adverse events occurred during 1,601 infusions, accounting for a total of 304,500 IU of FVIII:C administered. These results confirm the efficacy and safety of this concentrate in the management of bleeding episodes and in the prevention of excessive bleeding during major and minor surgery.

Guidelines for the diagnosis and management of von Willebrand disease in Italy

von Willebrand disease (vWD) is a bleeding disorder caused by quantitative (type 1 and 3) or qualitative (type 2) defects of von Willebrand factor (vWF). The molecular basis of type 2 and 3 vWD are now known and those of type 1 vWD are being understood. Phenotypic diagnosis is based on the measurements of plasma and platelet vWF, of the ability of vWF to interact with platelet receptors and the analysis of the multimeric structure of vWF. Due to the heterogeneity of vWF defects and the variables that interfere with vWF levels, a correct diagnosis of types and subtypes may sometimes be difficult but is very important for therapy. The aim of treatment is to correct the dual defects of haemostasis, i.e. abnormal intrinsic coagulation expressed by low levels of factor VIII (FVIII) and abnormal platelet adhesion. Desmopressin is the treatment of choice in patients with type 1 vWD, who account for approximately 70% of cases, because it corrects FVIII-vWF levels and the prolonged bleeding time (BT) in the majority of these patients. In type 3 and in severe forms of type 1 and 2 vWD patients, desmopressin is not effective and it is necessary to resort to plasma concentrates containing FVIII and vWF. Treated with virucidal methods, these concentrates are effective and safe, but they cannot always correct BT defect. Platelet concentrates or desmopressin can be used as adjunctive treatments when poor correction of BT after plasma concentrate treatment is associated with continued bleeding.

Von Willebrand factor and von Willebrand disease

von Willebrand disease (vWD) is caused by quantitative and/or qualitative defects of the von Willebrand factor (vWF), a multimeric high molecular weight glycoprotein. Typically, it affects the primary hemostatic system, which results in a mucocutaneous bleeding tendency simulating a platelet function defect. The vWF promotes its function in two ways: (i) by initiating platelet adhesion to the injured vessel wall under conditions of high shear forces, and (ii) by its carrier function for factor VIII in plasma. Accumulating knowledge of the different clinical phenotypes and the pathophysiological basis of the disease translated into a classification that differentiated between quantitative and qualitative defects by means of quantitative and functional parameters, and by analyzing the electrophoretic pattern of vWF multimers. The advent of molecular techniques provided the opportunity for conducting genotype-phenotype studies which have recently helped, not only to elucidate or confirm important functions of vWF and its steps in post-translational processing, but also many disease causing defects. Acquired von Willebrand syndrome (avWS) has gained more attention during the recent years. An international registry was published and recommendation by the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis in 2000. It concluded that avWS, although not a frequent disease, is nevertheless probably underdiagnosed. This should be addressed in future prospective studies. The aim of treatment is the correction of the impaired hemostatic system of the patient, ideally including the defects of both primary and secondary hemostasis. Desmopressin is the treatment of choice in about 70% of patients, mostly with type 1, while the others merit treatment with concentrates containing vWF.