How I treat von Willebrand disease

Challenges in the management of women with type 2B von Willebrand disease during pregnancy and the postpartum period: evidence from literature and data from an international registry and physicians' survey-communication from the Scientific and Standardization Committees of the International Society on Thrombosis and Haemostasis

BACKGROUND

Management of women with type 2B von Willebrand disease (VWD) during pregnancy is challenging because of dysfunctional von Willebrand factor (VWF) and the complexity resulting from discrepant VWF/factor VIII (VWF/FVIII) levels, impaired platelet-dependent VWF activity, progressive thrombocytopenia, and risks associated with the use of desmopressin. There is a lack of high-quality evidence to support clinical decision making.

OBJECTIVES

In this study, we examined the current diagnostic and management approaches and outcomes in women with VWD during pregnancy.

METHODS

Data were collected via 3 avenues: literature review, an international registry, and an international survey on physicians' practices for the management of pregnancy in women with VWD. The registry and survey were supported by the International Society on Thrombosis and Haemostasis.

RESULTS

Data on clinical and laboratory features, management and bleeding complications, and pregnancy outcomes of a total of 55 pregnancies from 49 women across the globe (literature: 35, registry: 20) and data reported by 112 physicians were analyzed. We describe the largest dataset on pregnancies in women with type 2B VWD available to date. The data highlight the following key issues: a) bleeding complications remain a concern in these patients, b) the target safe VWF level and the ideal monitoring approach are unknown, c) there is a wide range of hemostatic management practices in the type and timing of treatment, and d) physicians have diverse views on the mode of delivery and use of neuraxial anesthesia.

CONCLUSION

We conclude that an international consensus and guidance are critically required for better care and improved outcomes in this patient cohort.

Desmopressin testing in von Willebrand disease: Lowering the burden

Background

Individuals with von Willebrand disease (VWD) require desmopressin testing because of interindividual response differences. However, testing is burdensome, while not all patients may need extensive testing.

Objectives

To provide von Willebrand factor (VWF) cutoffs that predict desmopressin nonresponse and thereby identify individuals who do not need extensive testing in a retrospective cohort. We validated these cutoffs in a prospective cohort.

Patients and Methods

We included 376 patients (Type 1 VWD with VWF activity [VWF:Act] <0.30 IU/ml: n = 112; with VWF:Act 0.30-0.50 IU/ml: n = 206; Type 2 VWD: n = 58; ages, 5-76 years) from January 2000 to July 2020. We collected VWF:Act and factor VIII activity (FVIII:C) at baseline and several time points after desmopressin (T1-T6). We defined response as VWF:Act and FVIII:C 0.50 IU/ml or greater at T1 and T4. We compared VWF:Act and FVIII:C distribution (historically lowest level, baseline, and T1) between responders and nonresponders and determined cutoffs discriminating between these groups. Results were validated in a group of 30 individuals.

Results

All individuals with Type 1 VWD and Type 2 VWD, respectively, with baseline VWF:Act 0.34 IU/ml or greater or 0.28 IU/ml or greater were responders. In individuals with T1 VWF:Act ≥0.89 IU/ml (Type 1 VWD) or T1 VWF:Act 1.10 IU/ml or greater (Type 2 VWD), response remained at T4.

Conclusion

Desmopressin testing is not needed when lowest historical VWF:Act is 0.30 IU/ml or greater. In patients with Type 1 VWD who require testing, measurements after T1 are often not needed. In patients with Type 2 VWD who require testing, we advise performing T1 and T4 measurements.

Hematologic Findings in Pregnancy: A Guide for the Internist

Hematologic changes in pregnancy are common and can potentially lead to maternal and fetal morbidity. Here, we present various hematologic manifestations seen in pregnant women. Iron deficiency anemia (IDA) is the most common cause of anemia in pregnancy. Physiologically, the state of pregnancy results in increased iron demand. Iron deficiency is important to diagnose and treat early for better maternal and fetal outcomes. An algorithmic approach is used for the repletion of iron storage, starting with oral elemental iron daily and escalating to intravenous iron if necessary. Folate and cobalamin are necessary elements for deoxyribonucleic acid (DNA) synthesis, fetal growth, and maternal tissue development, and deficiency in these elements can be a cause for anemia in pregnancy. Thrombocytopenia is currently the second most common hematologic condition in pregnancy after anemia. There is a wide range of etiology for thrombocytopenia in pregnancy from benign to life-threatening causes that require prompt diagnosis and treatment. These conditions include gestational thrombocytopenia, thrombotic thrombocytopenic purpura, pregnancy-associated atypical hemolytic-uremic syndrome, and immune thrombocytopenia. Acquired bleeding disorders that can cause major complications in pregnancy include von Willebrand disease (vWD) and coagulation factor deficiencies. Women with vWD are at increased risk of pregnancy bleeding and postpartum hemorrhage. Pregnancy can also produce a physiologic hypercoagulable state, leading to life-threatening conditions like thromboembolism. Diagnosis, treatment options, and guidelines for the management of these conditions will be explored in this review.

Obstacles to Early Diagnosis and Treatment of Inherited von Willebrand Disease: Current Perspectives

Von Willebrand disease (VWD), the most common inherited bleeding disorder, is highly heterogeneous, and its early diagnosis may be difficult, especially for mild cases and in qualitative von Willebrand factor (VWF) defects. Appropriate VWD diagnosis requires the combination of personal and/or family history of bleeding and abnormal VWF laboratory testing. The use of bleeding assessment tools has been helpful in standardizing bleeding history collection and quantification of bleeding symptoms to select patients who may benefit of further hemostatic testing. Type 1 and 3 VWD which represent quantitative VWD variants are relatively easy to diagnose. The diagnosis of type 2 VWD requires multiple assessments to evaluate the effects induced by the responsible abnormality on the heterogeneous functions of VWF. Sensitive and reproducible tests are needed to evaluate different VWF activities, starting from measuring VWF-platelet interaction. In the recent years, several increasingly sensitive, rapid and automated assays have been developed, but they are not widely available so far. Genetic testing for VWD diagnosis is not a common practice because VWF gene is very large and highly polymorphic and therefore it is used only in specific cases. It is evident that the early and correct VWD diagnosis allows optimal management of bleeding and situations at risk. Tranexamic acid, desmopressin, replacement therapy with plasma-derived concentrates with a variable content of VWF and FVIII, or the new recombinant VWF are the different therapeutic options available. Careful VWD classification guides treatment because desmopressin is widely used in type 1 while replacement therapy is the cornerstone of treatment for type 2 and 3 variants.

Pregnancy and delivery in women with von Willebrand disease

Given the wide heterogeneity of phenotypes and of the underlying pathophysiological mechanisms associated with the disorder, pregnancy and delivery in von Willebrand disease (VWD) represent a significant clinical challenge. The variable pattern of changes observed during pregnancy of von Willebrand factor (VWF) and factor VIII (FVIII), the protein carried by VWF, prompts a careful evaluation of pregnant women with VWD to plan the most appropriate treatment at the time of parturition. However, there are also instances during pregnancy (amniocentesis, vaginal bleeding associated with placental detachment, sudden abortion) that may require urgent hemostatic treatment to prevent bleeding. Thus, women with VWD should start pregnancy after being well characterised as to their type, subtype and treatments. Women with VWD who have VWF and FVIII basal levels >30 U/dL typically normalise these levels at the end of pregnancy and specific anti-haemorrhagic prophylaxis is seldom required. On the contrary, those with basal levels <20 U/dL usually show a lesser increase and specific treatment is required. Some women with DNA variants associated with increased clearance can be treated with desmopressin, while those unresponsive or with contra-indications to this agent need replacement therapy. For these latter women, the risk of vaginal bleeding during pregnancy may be increased and prophylaxis with VWF concentrates required. Similarly, women with type 2 VWD who maintain reduced VWF activity throughout pregnancy require replacement therapy with FVIII/VWF concentrates. Delayed postpartum bleeding may occur when replacement therapy is not continued for some days. Tranexamic acid is useful at discharge to avoid excessive lochia.

[Clinical observation of desmopressin in the treatment of 15 patients with DDAVP]

Objective: To assess the significance of DDAVP use in the diagnosis and treatment of VWD. Methods: An analysis of 15 VWD cases who referred to Hematology Division of First affiliated Hospital of Soochow University and treated with DDAVP from March 2016 to August 2018 was conducted. Efficacy and treatment response of DDAVP were monitored by observations of changes in factor Ⅷ procoagulant (FⅧ∶C) and von Willebrand Factor (VWF) related indicators before and 2 h after DDAVP injection. Results: Of 15 cases with VWD, 7 males and 8 females with a median age of 23 (6-46) years, 7 of 9 type I VWD patients achieved complete response (CR) , 1 type 2A VWD case CR, 5 type 3 VWD ones no response (NR) . The VWF multimer analysis in 5 patients combined with other plasma VWF values were in accordance with the known diagnosis. Conclusions: DDAVP was effective in most type 1 patients, and ineffective in some type 2 and almost all type 3 cases. It was helpful for diagnosis and subsequent treatment planning.

Zeolite-fibrin clot composite as a haemostatic agent for haemophilia A

Zeolite is a multifunctional material, which recently exhibited promising prospects in emerging biological and medical applications. This study reported a new bio-inorganic hybrid of zeolite-fibrin clot composite serving as haemostatic agent in haemophilia A. The zeolite-fibrin clot composite promoted haemocompatibility and helped to achieve short clotting time both in vitro (22 ± 3 s vs. >600 s) and in vivo (4.5 min vs. >60 min) compared to control in coagulation factor VIII deficiency bleeding model. Therefore, in situations of surgical operation or accidental injury, this effective and ready-to-use haemostatic agent may provide rapid haemostasis for haemophilia A patients.

Purification and characterization of a new highly pure, double virus inactivated von Willebrand factor concentrate

: Desmopressin-unresponsive von Willebrand disease patients are treated with substitutive therapy, with both pure von Willebrand factor (vWF) and factor VIII/vWF concentrates. We developed a new purification process, easily scalable to industrial level, to obtain a double virus inactivated highly pure vWF. VWF was purified starting from a waste fraction of already in use human plasma-derived factor VIII manufacturing procedure, using only one anionic-exchange chromatographic step. After chromatography, the product was dialyzed, lyophilized, and heat treated. The process resulted in a very highly purified vWF, with a mean specific activity of 95.3 IU of vWF:ristocetin cofactor assay/mg of total proteins. The obtained vWF had a whole structure, as showed by the triplet bands analysis. The residual content of contaminating proteins such as immonoglobulin M and factor VIII was very low. Immunoglobulin A, immunoglobulin G, and fibronectin were totally absent. Notably, the lyophilized highly pure vWF was stable, without the addition of stabilizing proteinaceous material. A new simple purification method was performed, starting from a waste fraction of in use plasma-derived factor VIII process, using one single chromatographic step to obtain a highly pure and double virus inactivated vWF.

Whole blood ristocetin-activated platelet impedance aggregometry (Multiplate) for the rapid detection of Von Willebrand disease

Von Willebrand disease (VWD) is the most common bleeding disorder, but no bedside tests specific for Von Willebrand factor are available. The objective of this study was to evaluate the diagnostic accuracy of whole blood ristocetin-induced platelet aggregometry (WB-RIPA) in VWD. WB-RIPA was performed in VWD patients (n=100) and healthy controls (n=17) using the Multiplate® platelet impedance aggregometry platform. The diagnostic properties of the test were described as sensitivity/specificity, positive and negative predictive value, and ROC area under the curve (AUC). Patients with VWD had impaired platelet aggregation by WB-RIPA. At a cut-off of 98 U, the test sensitivity and specificity of WB-RIPA for VWD was 0.95 and 0.53. A cut-off of 60 U provided a specificity of 1.00 with reduced sensitivity of 0.76. All patients with type 3 VWD and >90 % of patients with type 2 VWD were accurately distinguished from the controls. Incorrect classifications were attributable to patients with type 1 VWD, showing partly overlapping WB-RIPA results with healthy controls. Remarkably, these patients had lower bleeding scores and higher VWF activity than other type 1 VWD patients. Overall, WB-RIPA discriminated VWD patients from healthy controls accurately with a ROC AUC of 0.94. These results show that WB-RIPA is a promising diagnostic test for VWD, especially when timely results are required. Depending on the chosen test threshold, WB-RIPA could be clinically used as a rule out test, or to suggest patients in whom further testing for VWD is warranted.

Diagnosis and Treatment of von Willebrand Disease and Rare Bleeding Disorders

Along with haemophilia A and B, von Willebrand disease (VWD) and rare bleeding disorders (RBDs) cover all inherited bleeding disorders of coagulation. Bleeding tendency, which can range from extremely severe to mild, is the common symptom. VWD, due to a deficiency and/or abnormality of von Willebrand factor (VWF), represents the most frequent bleeding disorder, mostly inherited as an autosomal dominant trait. The diagnosis may be difficult, based on a bleeding history and different diagnostic assays, which evaluate the pleiotropic functions of VWF. Different treatment options are available for optimal management of bleeding and their prevention, and long-term outcomes are generally good. RBDs are autosomal recessive disorders caused by a deficiency of any other clotting factor, apart from factor XII, and cover roughly 5% of all bleeding disorders. The prevalence of the severe forms can range from 1 case in 500,000 up to 1 in 2–3 million, according to the defect. Diagnosis is based on bleeding history, coagulation screening tests and specific factor assays. A crucial problem in RBDs diagnosis is represented by the non-linear relationship between clinical bleeding severity and residual clotting levels; genetic diagnosis may help in understanding the phenotype. Replacement therapies are differently available for patients with RBDs, allowing the successful treatment of the vast majority of bleeding symptoms.

New treatment approaches to von Willebrand disease

von Willebrand disease (VWD) is the commonest inherited bleeding disorder and results from either a quantitative or qualitative deficiency in the plasma glycoprotein von Willebrand factor (VWF). Recent large cohort studies have significantly enhanced our understanding of the molecular mechanisms involved in the pathogenesis of VWD. In contrast, however, there have been relatively few advances in the therapeutic options available for the treatment of bleeding in patients with VWD. Established treatment options include tranexamic acid, 1-deamino-8-d-arginine vasopressin (DDAVP), and plasma-derived VWF concentrates. In addition, a recombinant VWF has also recently been developed. In this review, we focus on how recent insights into the clinical and molecular aspects underpinning VWD are already beginning to influence treatment in the clinic. For example, a number of different bleeding assessment tools (BATs) have been developed to objectively assess bleeding symptoms in patients with VWD. Interestingly, however, these BAT scores may also have an important role to play in predicting bleeding risk in VWD. Furthermore, recent studies have demonstrated that enhanced VWF clearance plays a critical role in the etiology of both type 1 and type 2 VWD. These findings have direct translational relevance with respect to the use of DDAVP in patients with VWD. As understanding of the mechanisms involved in VWD pathogenesis continues to advance, novel treatment options are likely to emerge. Critically, however, large adequately powered and stratified clinical trials will be required to address the outstanding questions that remain regarding VWD treatment optimization.

Human von Willebrand factor/factor VIII concentrates in the management of pediatric patients with von Willebrand disease/hemophilia A

Several plasma-derived intermediate and high-purity concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII) are currently available. The main role of these products in the management of the pediatric population is represented by the replacement therapy in patients with severe or intermediate forms of von Willebrand disease, in whom other treatments are ineffective or contraindicated. Another important role of VWF/FVIII concentrates in children may be their use in immune tolerance induction (ITI) protocols. ITI is particularly recommended for hemophilia A children who have developed an inhibitor against FVIII, currently the most serious complication of substitutive treatment in hemophilia. Although recombinant concentrates may represent the preferred option in children with hemophilia A, VWF/FVIII concentrates may offer an advantage in rescuing patients who failed previous ITI.

Practical aspects of factor concentrate use in patients with von Willebrand disease undergoing invasive procedures: a European survey

INTRODUCTION

The bleeding propensity in von Willebrand disease (VWD) is usually moderate or mild and patients with VWD do not need continuous treatment, but do require extra increased haemostatic cover when undergoing dental or surgical procedures. Desmopressin can be effective in certain patient groups and this has been considered in a previous publication.

AIM

This paper now seeks to evaluate current knowledge and practice in the use of factor concentrate in the management of VWD patients undergoing invasive procedures.

METHODS

A literature search was performed on the use of factor concentrates to cover invasive procedures and a survey of current practice in a number of specialist haematology centres across Europe represented by the European Haemophilia Strategy Board was conducted.

RESULTS

Our review of the literature and the results of the survey showed considerable heterogeneity in treatment regimens, and a lack of consistency in reporting of the variables that determine factor concentrate dosing and monitoring.

CONCLUSION

By analysing the literature, examining guidelines and using consensus deliberation, this survey allowed the group to develop recommendations for management of VWD patients undergoing invasive procedures.

Challenges of diagnosing and managing the adolescent with heavy menstrual bleeding

Unpredictable, prolonged or heavy menstrual bleeding (HMB) may be expected for many adolescents soon after menarche. A decade of clinical experience and research has now established firmly that bleeding disorders (BD) are common in adolescents with HMB. Despite these advances, many questions remain, and several aspects of the diagnosis and management of BDs in adolescents are not supported by rigorous clinical trials. In this overview, four major areas will be discussed. First, we will discuss the frequency of BDs in young women with HMB. Up to 20% of older females with HMB are thought to have an underlying BD. Estimates from retrospective studies in adolescents suggest a prevalence that varies anywhere from 10 to 62%. Prospective studies with uniform hemostatic evaluation are needed to answer this question definitively. Second, we will review existing tools that help screen and diagnose adolescents with HMB with an underlying BD. Although identification of an underlying BD in older women with HMB is relatively straight forward, uncertainties remain for adolescents. Heavy menstrual bleeding in this age group may have different pathophysiological underpinnings than those in older women and may often be disregarded as anovulatory. There is an urgent need to develop novel tools, and evaluate existing diagnostic strategies in adolescents. Third, we will discuss the optimal medical management of HMB in young adolescents. As direct evidence is largely lacking, these areas are also subject to extrapolation from older women. Lastly, an important area- prediction, and management of future bleeding in those adolescents who are diagnosed with a mild BD-will be discussed. Throughout, areas of controversy and opportunities for further research are highlighted.

Assessing the clinical severity of type 1 von Willebrand disease patients with a microchip flow-chamber system

BACKGROUND

The clinical phenotype of von Willebrand disease (VWD) is heterogeneous, and von Willebrand factor ristocetin cofactor activity (VWF:RCo) does not always reflect clinical severity, especially in VWD type 1. We have reported the potential of a microchip flow-chamber system (Total-Thrombus Formation Analysis System [T-TAS®]) for assessing physiologic hemostasis in VWD. Aim To evaluate the relationship between T-TAS, bleeding score (BS) and laboratory test results in type 1 VWD patients.

METHODS

Microchips coated with collagen (platelet chip [PL-chip]) or collagen/thromboplastin (AR-chip) were used to assess platelet thrombus formation (PTF) at high shear rates or fibrin-rich PTF at low shear rates, respectively, in whole blood from 50 patients. The times needed for the flow pressure to increase by 10 kPa and 30 kPa (T10 and T30 ) from baseline were calculated from flow pressure curves. BS was determined by the use of a standardized questionnaire.

RESULTS

PL-T10 values correlated with BS (R(2) ~ 0.45) better than VWF:RCo (R(2) ~ 0.36), irrespective of the flow rate, whereas AR-T10 showed only a weak correlation with BS (R(2) ~ 0.18). Patients with PL-T10 > 10 min or AR-T10 > 30 min had lower VWF levels and higher BS than those with PL-T10 ≤ 10 min or AR-T10 ≤ 30 min, and the greatest differences were observed with PL-T10. Clinical severity appeared to correlate best with PL-T10 > 8 min. BS was significantly higher in patients with VWF:RCo of < 10 IU dL(-1) than in those with VWF:RCo of 10 IU dL(-1) to < 25 IU dL(-1) and 25-40 IU dL(-1). In patients with VWF:RCo of < 10 IU dL(-1) , BS was significantly higher in those with PL-T10 > 8 min than in those with PL-T10 ≤ 8 min.

CONCLUSION

T-TAS could be a useful technique for discriminating and predicting BS in VWD type 1 patients.

Genotype-phenotype correlation in a cohort of Portuguese patients comprising the entire spectrum of VWD types: impact of NGS

The diagnosis of von Willebrand disease (VWD), the most common inherited bleeding disorder, is characterised by a variable bleeding tendency and heterogeneous laboratory phenotype. The sequencing of the entire VWF coding region has not yet become a routine practice in diagnostic laboratories owing to its high costs. Nevertheless, next-generation sequencing (NGS) has emerged as an alternative to overcome this limitation. We aimed to determine the correlation of genotype and phenotype in 92 Portuguese individuals from 60 unrelated families with VWD; therefore, we directly sequenced VWF. We compared the classical Sanger sequencing approach and NGS to assess the value-added effect on the analysis of the mutation distribution in different types of VWD. Sixty-two different VWF mutations were identified, 27 of which had not been previously described. NGS detected 26 additional mutations, contributing to a broad overview of the mutant alleles present in each VWD type. Twenty-nine probands (48.3 %) had two or more mutations; in addition, mutations with pleiotropic effects were detected, and NGS allowed an appropriate classification for seven of them. Furthermore, the differential diagnosis between VWD 2B and platelet type VWD (n = 1), Bernard-Soulier syndrome and VWD 2B (n = 1), and mild haemophilia A and VWD 2N (n = 2) was possible. NGS provided an efficient laboratory workflow for analysing VWF. These findings in our cohort of Portuguese patients support the proposal that improving VWD diagnosis strategies will enhance clinical and laboratory approaches, allowing to establish the most appropriate treatment for each patient.

Von Willebrand disease in the emergency department

Background

The emergency department (ED) is often the first medical contact point for von Willebrand disease (VWD) patients experiencing acute conditions, notably bleeding. However, knowledge of VWD disease types and management options by ED providers is uncertain.

Aim

To determine the scope of VWD bleeding and treatment in the ED.

Methods

We evaluated medical record data in an IRB‐approved study from 922 notes accounting for 385 ER visits by 183 VWD patients from a single large institution's emergency department.

Results

Over half the ED visits were for an active or suspected bleed, the majority of which were associated with trauma, surgery, epistaxis, gastrointestinal bleeding or gynaecologic bleeding. By treatment, only 25% of all bleeds, including 77.8% of those with menorrhagia and 50.0% of those with epistaxis, received DDAVP or von Willebrand factor concentrate (VWF). The likelihood of receiving treatment was related to referral source, with the highest rates of treatment in patients referred by a haematologist.

Conclusions

These data suggest more patient and physician education are needed in managing patients with VWD, preferably at the time of diagnosis, including confirmation of the diagnosis, response to DDAVP testing, indication for DDAVP testing and formulation of a plan for suspected or actual bleeding.

Practical aspects of DDAVP use in patients with von Willebrand Disease undergoing invasive procedures: a European survey

INTRODUCTION

Desamino D-arginine vasopressin (DDAVP or desmopressin) is a useful and effective haemostatic treatment for patients with von Willebrand Disease (VWD). However, there are still issues regarding in which subtypes of VWD DDAVP is appropriate and little consensus on its use in different surgical settings. We also lack information concerning the appropriate laboratory parameters that should be monitored.

AIM

The European Haemophilia Therapy Strategy Board (EHTSB) wished to investigate published information and clinical use of DDAVP in VWD patients.

METHODS

We conducted a literature survey on management of VWD during surgical interventions and undertook a survey of specialist haematologist centres across Europe to assess current management of VWD patients.

RESULTS

DDAVP is ineffective in type 3 VWD and its use in type 2B remains controversial due to the possibility of thrombocytopenia. It can, however, be used effectively to cover minor surgery and dental procedures in most other VWD patients. For major surgery there is wider use of factor concentrate in preference to DDAVP depending on the subtype of VWD. We give consensus recommendations on the use of DDAVP for surgical interventions in VWD including laboratory parameters that denote an adequate response and contraindications to its use.

CONCLUSIONS

DDAVP can be recommended to cover invasive procedure in selected patients with VWD, however, we need more information and systematic recording of adverse events associated with DDAVP use in VWD. A companion paper will be published covering the use of factor concentrates in VWD patients.

von Willebrand disease and platelet disorders

The diagnosis and management of bleeding disorders is made difficult by the complexity and variety of disorders, clinical symptoms and bleeding type and severity. von Willebrand disease (VWD) and platelet disorders are disorders of primary haemostasis and together represent the most common inherited bleeding disorders. In this article, we describe the diagnosis of VWD and platelet disorders and the treatment options for VWD.

How I treat type 2 variant forms of von Willebrand disease

Type 2 von Willebrand disease (VWD) includes a wide range of qualitative abnormalities of von Willebrand factor structure and function resulting in a variable bleeding tendency. According to the current classification, 4 different subtypes can be identified, each with distinctive phenotypic and therapeutic characteristics. Current available laboratory methods allow a straightforward approach to VWD subtyping, and although the precise molecular characterization remains complex, it is not required for appropriate treatment of the vast majority of cases. Desmopressin can be useful only in a few type 2 cases compared with patients with actual quantitative deficiency (type 1), most often in variants with a nearly normal multimeric pattern (type 2M). However, since no laboratory test accurately predicts response to desmopressin, a trial test should always be performed in all type 2 VWD patients, with the exception of type 2B ones. Replacement therapy with plasma-derived von Willebrand factor-factor VIII concentrates represents the safe mainstay of treatment of all patients, particularly those not responding to desmopressin or requiring a sustained hemostatic correction because of major surgery or bleeding. A significant patient bleeding history correlates with increased bleeding risk and should be considered in tailoring the optimal antihemorrhagic prophylaxis in the individual patient.

Bleeding diathesis and hemophilias

Patients with hemophilia and other congenital bleeding disorders are at risk for development of central nervous system (CNS) hemorrhage and can present with acute or chronic neurologic symptoms. These disorders are generally caused by qualitative or quantitative deficiency of components of hemostasis such as coagulation proteins, von Willebrand factor, or platelets. Rapid diagnosis and specific medical management such as coagulation factor replacement therapy are mandatory to minimize the morbidity and mortality of CNS bleeding. Therefore, the objective of this chapter is to introduce neurologists to the physiology of hemostasis and to provide an overview of the clinical presentation, and management of inherited bleeding disorders that can potentially present with CNS bleeding. Since hemophilia is the most common bleeding disorder encountered in clinical practice, more emphasis is placed on management of hemophilia. Additionally, neurologic manifestations related to the bleeding diathesis in patients with hemophilia are elaborated.

von Willebrand disease: advances in pathogenetic understanding, diagnosis, and therapy

von Willebrand disease (VWD) is the most common autosomally inherited bleeding disorder. The disease represents a range of quantitative and qualitative pathologies of the adhesive glycoprotein von Willebrand factor (VWF). The pathogenic mechanisms responsible for the type 2 qualitative variants of VWF are now well characterized, with most mutations representing missense substitutions influencing VWF multimer structure and interactions with platelet GPIbα and collagen and with factor VIII. The molecular pathology of type 3 VWD has been similarly well characterized, with an array of different mutation types producing either a null phenotype or the production of VWF that is not secreted. In contrast, the pathogenetic mechanisms responsible for type 1 VWD remain only partially resolved. In the hemostasis laboratory, the measurement of VWF:Ag and VWF:RCo are key components in the diagnostic algorithm for VWD, although the introduction of direct GPIbα-binding assays may become the functional assay of choice. Molecular genetic testing can provide additional benefit, but its utility is currently limited to type 2 and 3 VWD. The treatment of bleeding in VWD involves the use of desmopressin and plasma-derived VWF concentrates and a variety of adjunctive agents. Finally, a new recombinant VWF concentrate has just completed clinical trial evaluation and has demonstrated excellent hemostatic efficacy and safety.

Principles of care for the diagnosis and treatment of von Willebrand disease

Von Willebrand disease is a common autosomal inherited bleeding disorder caused by quantitative or qualitative defects of von Willebrand factor, a multi-adhesive protein that binds platelets to exposed subendothelium and carries factor VIII in circulation. As a result of von Willebrand factor deficiency or abnormality, levels of factor VIII, the protein deficient in hemophilia A, may be variably reduced. Clinical manifestations are mainly represented by mucous membrane and of soft tissue bleeding. Their severity is variable depending on the degree of von Willebrand factor and factor VIII reduction. While a clear-cut diagnosis is easy in severe von Willebrand factor reductions, the advantage of pursuing a definite diagnosis in mild or dubious cases should be weighed against the risk of over-medicalization. The aim of treatment is to correct the dual defect of hemostasis caused by the abnormal/reduced von Willebrand factor and the concomitant deficiency of factor VIII. Desmopressin is the treatment of choice for type 1 von Willebrand disease patients with factor VIII and von Willebrand factor levels of 10 U/dL or over who have proved responsive to a test-infusion with the compound. Von Willebrand factor/factor VIII concentrates are needed when desmopressin is ineffective (mainly type 2 and 3 von Willebrand disease).

Inherited abnormalities of coagulation: hemophilia, von Willebrand disease, and beyond

Bleeding disorders are broadly classified into primary and secondary hemostatic defects. Primary hemostatic disorders (disorders of platelets and von Willebrand factor) mainly result in mucocutaneous bleeding symptoms such as epistaxis, menorrhagia, petechiae, easy bruising, and bleeding after dental and surgical interventions. Secondary hemostatic disorders (congenital or acquired deficiencies of coagulation factors) typically manifest with delayed, deep bleeding into muscles and joints. This article provides a generalized overview of the pathophysiology, clinical manifestations, laboratory abnormalities, and molecular basis of inherited abnormalities of coagulation with a focus on hemophilia, von Willebrand disease, and rare inherited coagulation disorders.

Von Willebrand disease: pathogenesis and management

Recent studies have suggested a unifying pathophysiological concept to explain the underlying defects of von Willebrand factor (VWF) causing von Willebrand disease (VWD) and have highlighted the relevance of simple VWF related activities in producing a useful diagnosis. A standardized bleeding history condensed into a final bleeding score and few widely available laboratory tests, such as VWF ristocetin cofactor activity, VWF antigen and factor VIII (FVIII), in the index case and in his/her relatives are of critical importance. Ristocetin-induced platelet aggregation (RIPA) should also be tested. Trial with desmopressin should be carried out in patients, except those with virtual absence of VWF or with increased RIPA. Desmopressin should be used in all responsive patients as first choice. Substitutive treatment with VWF/FVIII containing products should be used in unresponsive patients, in those with heightened response to desmopressin or in those undergoing interventions requiring good hemostasis for more than 3-5 days. Special consideration should be deserved to the treatment of menorrhagia and parturition.

von Willebrand disease: advances in pathogenetic understanding, diagnosis, and therapy

von Willebrand disease (VWD) is the most common autosomally inherited bleeding disorder. The disease represents a range of quantitative and qualitative pathologies of the adhesive glycoprotein von Willebrand factor (VWF). The pathogenic mechanisms responsible for the type 2 qualitative variants of VWF are now well characterized, with most mutations representing missense substitutions influencing VWF multimer structure and interactions with platelet GPIbα and collagen and with factor VIII. The molecular pathology of type 3 VWD has been similarly well characterized, with an array of different mutation types producing either a null phenotype or the production of VWF that is not secreted. In contrast, the pathogenetic mechanisms responsible for type 1 VWD remain only partially resolved. In the hemostasis laboratory, the measurement of VWF:Ag and VWF:RCo are key components in the diagnostic algorithm for VWD, although the introduction of direct GPIbα-binding assays may become the functional assay of choice. Molecular genetic testing can provide additional benefit, but its utility is currently limited to type 2 and 3 VWD. The treatment of bleeding in VWD involves the use of desmopressin and plasma-derived VWF concentrates and a variety of adjunctive agents. Finally, a new recombinant VWF concentrate has just completed clinical trial evaluation and has demonstrated excellent hemostatic efficacy and safety.

Changes of von Willebrand Factor during Pregnancy in Women with and without von Willebrand Disease

Delivery in von Willebrand disease (VWD) represents a significant hemostatic challenge because of the variable pattern of changes observed during pregnancy of von Willebrand factor (VWF) and factor VIII (FVIII), the protein carried by VWF. Since a wide heterogeneity of phenotypes and of the underlying pathophysiological mechanisms is associated with this disorder, a prompt and careful evaluation of pregnant women with VWD is requested in order to plan the most appropriate treatment at time of parturition. VWF and FVIII increase significantly during pregnancy in normal women, already within the first trimester, reaching levels by far >100 U/dL by the time of parturition. Women with VWD, levels at baseline of VWF and FVIII >30 U/dL have us a high likelihood to achieve normal levels at the end of pregnancy; thus specific anti-hemorrhagic prophylaxis is seldom required. Women with basal level <20 U/dL usually have a poor increase since most of these women carry mutations associated with increased VWF clearance or are compound heterozygous for different VWF mutations; that prevent the achievement of satisfactory hemostatic levels. While women with mutations associated with increased clearance show a full, albeit transitory correction of their hemostatic deficiency after desmopressin administration, compound heterozygous need replacement therapy because they do not respond well to this agent. Patients with abnormal VWF:RCo/VWF:Ag ratio at baseline (e.g. <0.6), typically associated with type 2 VWD, maintain the abnormality throughout pregnancy and VWF:RCo usually does not attain safe levels ≥50 U/dL. These women require replacement therapy with VWF-FVIII concentrates. Delayed post-partum bleeding may occur when replacement therapy is not continued for some days. Tranexamic acid may be useful at discharge to avoid excessive lochia.

Bleeders, bleeding rates, and bleeding score

Bleeding symptoms are frequently reported even in otherwise healthy subjects, and differentiating a normal subject from a patient with a mild bleeding disorder (MBD) can be extremely challenging. The concept of bleeding rate, that is, the number of bleeding episodes occurring within a definite time, could be used as the unifying framework reconciling the bleeding risk observed in congenital and acquired coagulopathies into a single picture. For instance, primary prevention trials have shown that the incidence of non-major bleeding symptoms in normal subjects is around five per 100 person-years, and this figure is in accordance with the number of hemorrhagic symptoms reported by normal controls in observational studies on hemorrhagic disorders. The incidence of non-major bleeding in patients with MBDs (e.g. in patients with type 1 VWD carrying the C1130F mutation) is also strikingly similar with that of patients taking antiplatelet drugs, and the incidence in moderately severe bleeding disorders (e.g. type 2 VWD) parallels that of patients taking vitamin K antagonists. The severity of a bleeding disorder may therefore be explained by a bleeding rate model, which also explains several common clinical observations. Appreciation of the bleeding rate of congenital and acquired conditions and of its environmental/genetic modifiers into a single framework will possibly allow the development of better prediction tools in the coming years and represents a major scientific effort to be pursued.

von Willebrand factor: the old, the new and the unknown

von Willebrand factor (VWF) is a protein best known from its critical role in hemostasis. Indeed, any dysfunction of VWF is associated with a severe bleeding tendency known as von Willebrand disease (VWD). Since the first description of the disease by Erich von Willebrand in 1926, remarkable progress has been made with regard to our understanding of the pathogenesis of this disease. The cloning of the gene encoding VWF has allowed numerous breakthroughs, and our knowledge of the epidemiology, genetics and molecular basis of VWD has been rapidly expanding since then. These studies have taught us that VWF is rather unique in terms of its multimeric structure and the unusual mechanisms regulating its participation in the hemostatic process. Moreover, it has become increasingly clear that VWF is a more all-round protein than originally thought, given its involvement in several pathologic processes beyond hemostasis. These include angiogenesis, cell proliferation, inflammation, and tumor cell survival. In the present article, an overview of advances concerning the various structural and functional aspects of VWF will be provided.

Bleeding disorders in orthopedic surgery

With increasing recognition of the complications related to coagulopathies, it is of paramount importance for all orthopedic surgeons to possess a basic knowledge of common bleeding disorders. The evaluation of the coagulopathic patient requires a careful history, physical examination, and laboratory evaluation. Bleeding disorders commonly include quantitative and qualitative platelet and coagulation factor disorders and coagulation inhibitors. The management of these coagulopathies that can be encountered in elective and nonelective practice is often ignored. With appropriate knowledge and a multidisciplinary approach with hematologists and cardiologists, surgeons can perform minor and major orthopedic procedures safely and effectively.

Comparison of type I, type III and type VI collagen binding assays in diagnosis of von Willebrand disease

BACKGROUND

von Willebrand factor (VWF) plays a key role in coagulation by tethering platelets to injured subendothelium through binding sites for collagen and platelet GPIb. Collagen binding assays (VWF:CB), however, are not part of the routine work-up for von Willebrand disease (VWD).

OBJECTIVES

This study presents data on collagen binding for healthy controls and VWD subjects to compare three different collagens.

PATIENTS/METHODS

VWF antigen (VWF:Ag), VWF ristocetin cofactor activity and VWF:CB with types I, III and VI collagen were examined for samples obtained from the Zimmerman Program.

RESULTS

Mean VWF:CB in healthy controls was similar and highly correlated for types I, III and VI collagen. The mean VWF:CB/VWF:Ag ratios for types I, III and VI collagen were 1.31, 1.19 and 1.21, respectively. In type 1 VWD subjects, VWF:CB was similar to VWF:Ag with mean VWF:CB/VWF:Ag ratios for types I, III and VI collagen of 1.32, 1.08 and 1.1, respectively. For type 2A and 2B subjects, VWF:CB was uniformly low, with mean ratios of 0.62 and 0.7 for type I collagen, 0.38 and 0.4 for type III collagen, and 0.5 and 0.47 for type VI collagen.

CONCLUSIONS

Normal ranges for type I, III and VI collagen are correlated, but higher values were obtained with type I collagen as compared with types III and VI. The low VWF:CB in type 2A and 2B subjects suggests that VWF:CB may also supplement analysis of multimer distribution. However, these results reflect only one set of assay conditions per collagen type and therefore may not be generalizable to all collagen assays.

Different bleeding risk in type 2A and 2M von Willebrand disease: a 2-year prospective study in 107 patients

BACKGROUND

Type 2A and 2M von Willebrand disease (VWD2A and VWD2M) are characterized by the presence of a dysfunctional von Willebrand factor (VWF) and a variable bleeding tendency. So far, a head-to-head comparison of the clinical history and bleeding risk between VWD2A and VWD2M has never been provided in a prospective manner.

AIM OF THE STUDY

We assessed the bleeding incidence rate and clinical characteristics in two cohorts of 17 families (46 patients) with VWD2A and 15 families (61 patients) with VWD2M prospectively followed-up for 24 months. VWF gene mutations were characterized in all of them.

RESULTS

Mean bleeding score (BS) and VWF antigen at enrollment were significantly higher in VWD2A patients (P = 0.007). No correlation between VWF activity or factor VIII levels and the severity of BS was observed. The incidence rate of spontaneous bleeding requiring treatment was 107/100 patient-years (95% CI, 88.3-131) in VWD2A compared with 40/100 patient-years (95% CI, 30-53) in VWD2M (P < 0.001). The risk of bleeding was significantly higher in patients with BS ≥ 10 at enrollment compared with those with BS 0-2. Furthermore, 54 episodes of gastrointestinal bleeding occurred in 17/46 (36.9%) VWD2A patients and seven in 2/61 (3.3%) VWD2M patients (P < 0.0001).

CONCLUSION

Bleeding tendency in VWD2A is greater than that of VWD2M, is not explained by factor VIII or VWF levels and is mainly due to an increased incidence of gastrointestinal bleeding.

Menorrhagia and bleeding disorders in adolescent females

In women, von Willebrand disease (VWD) is the most common inherited bleeding disorder. Since VWD and other inherited bleeding disorders are autosomal disorders, they affect women and men. Menorrhagia, or heavy menstrual bleeding (HMB), is the most common symptom of women with bleeding disorder experience. Objectively, it is defined as bleeding that lasts for more than seven days or results in the loss of more than 80 ml of blood per menstrual cycle. The prevalence of menorrhagia in a woman with a bleeding disorder ranges from 32 to 100% in patients with VWD, from 5 to 98% in patients with a platelet dysfunction and from 35 to 70% in women with a rare factor deficiency. A detailed history and a careful physical exam are the first steps towards a diagnosis in adolescents, adding a PBAC>100 increased the sensitivity of the screening tool further to 95%. Laboratory testing should be made at the time of menstrual bleeding in an effort to capture the lowest level of VWF:Ag and FVIII:C. Treatment options for menorrhagia in VWD: (1) antifibrinolytic therapy with tranexamic acid, (2) the non-transfusional agent desmopressin (DDAVP), (3) purified blood products that contain factor VIII and VWF concentrated from plasma and (4) hormonal preparations.

Advances in the diagnosis and management of type 1 von Willebrand disease

Von Willebrand disease (VWD) is an autosomally inherited bleeding disorder caused by a deficiency and/or abnormality of von Willebrand factor (VWF). VWF is a multimeric adhesive protein that plays an important role in primary hemostasis by promoting platelet adhesion to the subendothelium at sites of vascular injury and platelet-platelet interactions at high-shear rate conditions. Furthermore, VWF is the carrier of factor VIII, thus indirectly contributing to the coagulation process. Most cases have a partial quantitative deficiency of VWF (type 1 VWD) with variable bleeding tendency, whereas qualitative variants (type 2 VWD), due to a dysfunctional VWF, are clinically more homogeneous and account for approximately 20-30% of cases. Type 3 VWD is rare and these patients have moderate-to-severe bleeding diathesis, display a recessive pattern of inheritance and virtual absence of VWF. The diagnosis of VWD may be difficult, especially in type 1 disease, since the laboratory phenotype of the disorder is very heterogeneous and confounded by the influence on VWF levels by factors outside the VWF gene (e.g., blood group). An array of tests are usually required to characterize the several types of the disorder in order to predict the best treatment modality. Desmopressin is the treatment of choice for most patients with type 1 VWD because it corrects the the dual defects of hemostasis, that is, abnormal coagulation expressed by low levels of factor VIII and abnormal platelet adhesion expressed by the reduction of VWF.

Bleeding tendency and efficacy of anti-haemorrhagic treatments in patients with type 1 von Willebrand disease and increased von Willebrand factor clearance

Accelerated clearance of von Willebrand factor (VWF) has been recently identified as a major pathophysiologic mechanism inducing low VWF in some patients with von Willebrand disease (VWD). The frequency of bleeding and the best treatment of these patients have never been evaluated prospectively in large series of patients. It was the aim of the present study to prospectively evaluate clinical events of 60 heterozygous patients with VWD Vicenza (VWD-VI) carrying R1205H VWF mutation and 23 with C1130F mutation, both characterised by markedly increased VWF clearance. During 71 months of follow-up, 65% of patients with VWD-VI and 61% with C1130F required treatment. The rate of spontaneous bleeding requiring consultation/treatment was 7.5/100 patients-year in patients with C1130F mutation vs. 1.9/100 patients-year in those with R1205H (p=0.004). This difference persisted also by multivariate analysis adjusted for sex, age and blood group (hazard ratio [HR]=3.3 for C1130F, 95% confidence interval [CI] 1.16-9.27) and females were at greater risk of bleeding (HR=3, 95%CI 1.01-9.93) because of menorrhagia. Only 3/15 (20 %) women in fertile age with VWD-VI compared to 8/9 (89 %) with C1130F mutation required consultation/treatment for menorrhagia (iron supplementation, combined oral contraceptives, tranexamic acid). Almost all dental extractions, minor surgeries and deliveries occurring during follow-up were successfully managed with desmopressin. Major surgery required factor VIII/VWF concentrates, but a few cases benefited from desmopressin. In conclusion, similar to patients with type 1 VWD, also in patients with increased VWF clearance desmopressin maintains a major therapeutic role.

von Willebrand disease in the pediatric and adolescent population

Recent studies indicate that bleeding disorders, particularly von Willebrand disease (VWD) is more prevalent than previously thought in adolescents with menorrhagia. Menorrhagia management in undiagnosed disorders of hemostasis may be associated with unwanted risks and complications. The prevalence of symptomatic VWD in the pediatric primary care setting appears to be 0.11% (95% CI, 0.04-0.25%). Studies evaluating the prevalence of VWD in adolescents with menorrhagia have included over 500 patients with a prevalence range from 3 to 36% depending on the clinical setting studied, with the highest prevalence seen in adolescents referred to an outpatient Hemophilia Center, while the lowest prevalence is seen in the acute hospital setting. Recently, the diagnosis of VWD has been facilitated by the use of pediatric bleeding questionnaires that have proved useful in quantifying the severity of bleeding symptoms. Treatment of VWD is often complex because a combination of therapies is often required. Potential treatment options include estrogen-progesterone preparations, desmopressin, antifibrinolytic agents and von Willebrand factor concentrates. More research is needed to evaluate the effectiveness of the various treatment modalities in the adolescent population.

Continuing education course #2: current understanding of hemostasis

The goal of this review is to briefly summarize the two primary pathways of hemostasis, primary hemostasis and secondary hemostasis, as well as to summarize anticoagulant mechanisms and fibrinolysis. In addition, this review will discuss pathologies of hemostasis and the mechanisms of the various drugs that are available to impact these pathways to prevent either thrombosis or bleeding. While many of the main drugs that are used to treat disorders of hemostasis have been used for decades, greater understanding of hemostasis has led to development of various new drugs that have come onto the market recently or are close to coming onto the market. Thus, improved understanding of hemostasis continues to lead to benefits for patients.