Acquired von Willebrand syndrome: is it an extremely rare disorder or do we see only the tip of the iceberg?

Pilot Assessment of Platelet Thrombus Area and Contractile Force in Pediatric Congenital Heart Surgery Patients Using a Microfluidic Device

OBJECTIVES

This work was designed to evaluate maximum platelet contractile force and thrombus area before and after cardiopulmonary bypass (CPB) in pediatric patients having congenital heart disease (CHD) surgery using a microfluidic device.

DESIGN

A prospective cohort study was designed.

SETTING

The work took place at an academic medical center.

PARTICIPANTS

Twenty pediatric CHD patients ≤8 years of age with expected CPB time >30 minutes were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood was collected at baseline and post-CPB. Maximum platelet contractile force and thrombus area were evaluated in vitro using a microfluidic device (ATLAS PST). Post-CPB samples were supplemented with recombinant von Willebrand factor (rVWF) to explore the impact on contractile force and thrombus area. At baseline, the maximum thrombus area was 0.06 (0.05, 0.07), and the maximum force was 123.3 nN (68.4, 299.5). Linear mixed-effects regression models showed that the maximum thrombus area was larger post-CPB and post-CPB + rVWF compared with pre-CPB (estimated coefficient [Est] = 0.04, p = 0.002; Est = 0.09, p < 0.001, respectively). The maximum thrombus area was also larger post-CPB + rVWF compared with post-CPB (Est = 0.04, p = 0.001). Force was higher post-CPB + rVWF compared with pre-CPB (Est = 173.32, p = 0.044).

CONCLUSIONS

In pediatric CHD patients, microfluidic testing demonstrated that platelet thrombus area increased slightly after CPB, while platelet contractile force did not change. In vitro addition of rVWF further increased thrombus area, suggesting augmentation of primary hemostasis. Microfluidic assessment of platelet contractile force and thrombus area in pediatric CHD patients appears feasible and can demonstrate changes after CPB. Further studies are needed to determine its accuracy, clinical utility, and normal values for pediatric patients.

Rediscovering hemostasis abnormalities in multiple myeloma: The new era

Multiple myeloma (MM) is a malignancy arisen from the abnormal proliferation of clonal plasma cells. It has a high risk of developing bleeding and thrombotic complications, which are related to poor prognosis and decreased survival. Multiple factors are involved in the breaking of the hemostasis balance, including disease specific factors, patient-specific factors, and drug factors that change pro-and anticoagulant and fibrinolysis. Recently, with the introduction of new treatments such as monoclonal antibodies, chimeric antigen receptor modified T-cell therapy, antibody-drug conjugates directed against BCMA, programmed death-1 inhibitor, export protein 1 inhibitors, histone deacetylase inhibitors, immunomodulatory drugs, proteasome inhibitors and Bcl-2 inhibitors, the therapy of MM patients has entered into a new era. Furthermore, it arouses a question whether these new treatments would alter the hemostasis balance in MM patients, which highlights the importance of the underlying pathophysiology of hemostasis abnormalities in MM, and on prophylaxis approaches. In this review, we updated the mechanisms of hemostasis abnormalities in MM, the impact of the new drugs on hemostasis balance and reliable therapeutic strategies.

Von Willebrand factor in diagnostics and treatment of cardiovascular disease: Recent advances and prospects

Von Willebrand factor (VWF) is a large multimeric glycoprotein involved in hemostasis. It is essential for platelet adhesion to the subendothelium of the damaged endothelial layer at high shear rates. Such shear rates occur in small-diameter arteries, especially at stenotic sites. Moreover, VWF carries coagulation factor VIII and protects it from proteolysis in the bloodstream. Deficiency or dysfunction of VWF predisposes to bleeding. In contrast, an increase in the concentration of high molecular weight multimers (HMWM) of VWF is closely associated with arterial thrombotic events. Severe aortic stenosis (AS) or hypertrophic obstructive cardiomyopathy (HOCM) can deplete HMWM of VWF and lead to cryptogenic, gastrointestinal, subcutaneous, and mucosal bleeding. Considering that VWF facilitates primary hemostasis and a local inflammatory response at high shear rates, its dysfunction may contribute to the development of coronary artery disease (CAD) and its complications. However, current diagnostic methods do not allow for an in-depth analysis of this contribution. The development of novel diagnostic techniques, primarily microfluidic, is underway. Such methods can provide physiologically relevant assessments of VWF function at high shear rates; however, they have not been introduced into clinical practice. The development and use of agents targeting VWF interaction with the vessel wall and/or platelets may be reasonable in prevention of CAD and its complications, given the prominent role of VWF in arterial thrombosis.

Immune complications and their management in inherited and acquired bleeding disorders

Disorders of coagulation, resulting in serious risks for bleeding, may be caused by autoantibody formation or by mutations in genes encoding coagulation factors. In the latter case, antidrug antibodies (ADAs) may form against the clotting factor protein drugs used in replacement therapy, as is well documented in the treatment of the X-linked disease hemophilia. Such neutralizing antibodies against factors VIII or IX substantially complicate treatment. Autoantibody formation against factor VIII leads to acquired hemophilia. Although rare, antibody formation may occur in the treatment of other clotting factor deficiencies (eg, against von Willebrand factor [VWF]). The main strategies that have emerged to address these immune responses include (1) clinical immune tolerance induction (ITI) protocols; (2) immune suppression therapies (ISTs); and (3) the development of drugs that can improve hemostasis while bypassing the antibodies against coagulation factors altogether (some of these nonfactor therapies/NFTs are antibody-based, but they are distinct from traditional immunotherapy as they do not target the immune system). Choice of immune or alternative therapy and criteria for selection of a specific regimen for inherited and autoimmune bleeding disorders are explained. ITI serves as an important proof of principle that antigen-specific immune tolerance can be achieved in humans through repeated antigen administration, even in the absence of immune suppression. Finally, novel immunotherapy approaches that are still in the preclinical phase, such as cellular (for instance, regulatory T cell [Treg]) immunotherapies, gene therapy, and oral antigen administration, are discussed.

Acquired von Willebrand syndrome: Five cases report and literature review

Acquired von Willebrand syndrome is a rare bleeding disorder with laboratory findings similar to those of inherited von Willebrand disease. Principal factors distinguishing acquired von Willebrand syndrome from the latter condition include lack of prior bleeding disorders, diagnosis at older age, negative family history and association with underlying conditions.

METHODS

Retrospective, monocentric descriptive case series of acquired von Willebrand syndrome diagnosed between 2010 and 2020. Diagnostic criteria included a recent history of bleeding, a negative family history and a presence of underlying disorders.

RESULTS

Five men were diagnosed with acquired von Willebrand syndrome. All of them presented with recent mucocutaneous bleeding. The biological phenotype was a type 2 von Willebrand disease in all cases, with decreased VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag ratios (<0.7). Lymphoproliferative, autoimmune and cardiovascular diseases were the main underlying conditions identified. Screening for an anti-von Willebrand factor inhibitor was positive in two patients. Four patients received treatment for the underlying disorder. High-dose intravenous immunoglobulins were the most frequent treatment administrated. Improvement of plasma von Willebrand factor levels was observed in four cases.

CONCLUSION

Acquired von Willebrand syndrome is a rare but potentially serious disease. The diagnostic should be suspected in adults with unusual mucocutaneous bleeding associated with lymphoproliferative, myeloproliferative, autoimmune and cardiovascular disorders.

A Review of Autoimmune Acquired von Willebrand Factor Deficiency in Japan

von Willebrand factor (VWF) forms high-molecular-weight multimers and plays an essential role in hemostasis, and thus its deficiency leads to bleeding symptoms. Acquired von Willebrand syndrome (AVWS) is rare, but potentially underdiagnosed, and develops in various underlying disorders. AVWS caused by anti-VWF autoantibodies is a rare subcategory of AVWS that can also be referred to as autoimmune VWF deficiency (AiVWFD). We performed a search of patients with autoimmune coagulation factor deficiencies in our nationwide survey in Japan. Among these, suspected cases of AiVWFD were extremely few, with only 11 case consultations in the last 10 years. Of these, three and five were respectively positive for anti-VWF autoantibodies (anti-VWF-Ab) and VWF inhibitor (VWF-inh). We also performed an extensive literature search of other cases from Japan, and in total, 40 cases were finally identified to have AiVWFD, with mean age of 55.0 years. Most underlying disorders were lympho- or myeloproliferative diseases, followed by autoimmune diseases. The major bleeding sites were subcutaneous and mucosal, the bleeding severity was moderate, and there were no hemorrhagic deaths. Bleeding time was prolonged; factor VIII activity, VWF antigen, and VWF activity were decreased, and high-molecular-weight VWF multimers were absent or decreased. These are similar to the common abnormal laboratory findings observed among general AVWS cases. Hemostatic therapy often involved VWF concentrates and vasopressin, and antibody eradication therapy often included corticosteroids and achieved remission. Notably, of all cases, 68% had anti-VWF-Abs, and 83% of anti-VWF-Ab-positive patients were also VWF-inh positive. To accumulate precise clinical information on AiVWFD, it is necessary to verify and improve the measurement methods for both anti-VWF-Ab and anti-VWF-inh. These findings from Japan should be confirmed in other geographic localities.

The Intriguing Connections between von Willebrand Factor, ADAMTS13 and Cancer

von Willebrand factor (VWF) is a complex and large protein that is cleaved by ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and together they serve important roles in normal hemostasis. Malignancy can result in both a deficiency or excess of VWF, leading to aberrant hemostasis with either increased bleeding or thrombotic complications, as respectively seen with acquired von Willebrand syndrome and cancer-associated venous thromboembolism. There is emerging evidence to suggest VWF also plays a role in inflammation, angiogenesis and tumor biology, and it is likely that VWF promotes tumor metastasis. High VWF levels have been documented in a number of malignancies and in some cases correlate with more advanced disease and poor prognosis. Tumor cells can induce endothelial cells to release VWF and certain tumor cells have the capacity for de novo expression of VWF, leading to a proinflammatory microenvironment that is likely conducive to tumor progression, metastasis and micro-thrombosis. VWF can facilitate tumor cell adhesion to endothelial cells and aids with the recruitment of platelets into the tumor microenvironment, where tumor/platelet aggregates are able to form and facilitate hematogenous spread of cancer. As ADAMTS13 moderates VWF level and activity, it too is potentially involved in the pathophysiology of these events. VWF and ADAMTS13 have been explored as tumor biomarkers for the detection and prognostication of certain malignancies; however, the results are underdeveloped and so currently not utilized for clinical use. Further studies addressing the basic science mechanisms and real word epidemiology are required to better appreciate the intriguing connections between VWF, ADAMTS13 and malignancy. A better understanding of the role VWF and ADAMTS13 play in the promotion and inhibition of cancer and its metastasis will help direct further translational studies to aid with the development of novel cancer prognostic tools and treatment modalities.

Thrombocytapheresis for acquired von Willebrand syndrome in a patient with essential thrombocythemia and recent multivisceral transplantation

BACKGROUND

Essential thrombocythemia (ET) is associated with increased risk of bleeding secondary to acquired von Willebrand syndrome (AVWS). Bleeding in ET requires urgent platelet reduction by cytoreductive therapy such as hydroxyurea or thrombocytapheresis. We report on the efficacy and safety of thrombocytapheresis in managing AVWS in a patient with ET and multivisceral transplantation.

CASE REPORT

The patient was a 51-year-old female who underwent multivisceral transplantation. Her postoperative course was complicated by bleeding from oral cavity, IV lines, gastrointestinal and upper respiratory tracts as well as vaginal bleeding, which coincided with ET flare with a platelet count of 1512 × 10⁹ /L. Coagulation studies including von Willebrand factor (vWF) antigen and activity, vWF propeptide antigen, and vWF multimer analysis were consistent with AVWS. Hydroxyurea was initiated. However, due to major bleeding, rapidly increasing platelet count, and uncertainty of response to hydroxyurea being given through the enteral tube, thrombocytapheresis was initiated for rapid platelet reduction. The patient tolerated the procedure well. Platelet count was reduced from 1636 × 10⁹ /L to 275 × 10⁹ /L with rapid cessation of bleeding. The patient's condition stabilized over the next few days; however, bleeding recurred with increasing platelet count, which required a second thrombocytapheresis 8 days after the first one. The patient was maintained on hydroxyurea 500 mg twice/day. At 11-month follow-up, she had a normal platelet count and no recurrence of bleeding.

DISCUSSION

Thrombocytapheresis is safe and efficient in managing postoperative bleeding due to ET/AVWS in solid organ transplant patients. The procedure can be an adjunct to bridging therapy before response to hydroxyurea is achieved.

A Case of Acquired von Willebrand Syndrome Complicated by Acute Myelomonocytic Leukemia

We here report a 21-year-old male who presented with acute myelomonocytic leukemia (AMML) associated with acquired von Willebrand syndrome (AVWS). To our knowledge, this is the first case of AVWS caused by AMML. In our case, following remission-induction chemotherapy combined with idarubicin and cytarabine, the patient showed remarkable improvement of bleeding symptoms due to AVWS. Moreover, after an allogeneic stem cell transplantation from a sibling donor, both AMML and AVWS maintain complete remission.

Acquired von Willebrand syndrome and factor VIII in patients with moderate to severe mitral regurgitation undergoing transcatheter mitral valve repair

Background and Hypothesis

The acquired von Willebrand syndrome (AvWS), which predisposes to bleeding events, is often related to valvular heart diseases. We investigated possible implications of AvWS and factor VIII levels in patients with moderate to severe mitral regurgitation (MR) undergoing transcatheter mitral valve repair (TMVR).

Methods and Results

123 patients with moderate to severe MR were prospectively enrolled. Complete measurements of von Willebrand Factor activity (vWFAct), von Willebrand Factor antigen (vWFAg), and factor VIII expression before and 4 weeks after TMVR were available in 85 patients. At baseline, seven patients had a history of gastrointestinal bleeding, two patients suffered bleeding events during their hospital stay, and one patient had a bleeding 4 weeks after TMVR. Even though vWFAct, vWFAct/vWFAg ratio and vWFAg values did not change after TMVR, we observed a significantly lower vWFAct/vWFAg ratio in patients with primary MR as compared to patients with secondary MR both at baseline (p = 0.022) and 4 weeks following the TMVR procedure (p = 0.003). Additionally, patients with a mean mitral valve gradient ≥4 mmHg after TMVR had significantly lower vWFAct/vWFAg ratios as compared to patients with a mean mitral valve gradient <4 mmHg (p = 0.001).

Conclusions

MR of primary etiology was associated with lower vWFAct/vWFAg ratio, hinting toward HMWM loss due to shear stress caused by eccentric regurgitation jets. In addition, morphological changes leading to postprocedural transmitral gradients ≥4 mmHg were related to lower vWFAct/vWFAg ratio 4 weeks after the procedure. Alterations of the vWFAct/vWFAg ratio in turn did not translate into a greater risk for bleeding events.

Shear Stress-Induced Activation of von Willebrand Factor and Cardiovascular Pathology

The von Willebrand factor (vWF) is a plasma protein that mediates platelet adhesion and leukocyte recruitment to vascular injury sites and carries coagulation factor VIII, a building block of the intrinsic pathway of coagulation. The presence of ultra-large multimers of vWF in the bloodstream is associated with spontaneous thrombosis, whereas its deficiency leads to bleeding. In cardiovascular pathology, the progression of the heart valve disease results in vWF deficiency and cryptogenic gastrointestinal bleeding. The association between higher plasma levels of vWF and thrombotic complications of coronary artery disease was described. Of note, it is not the plasma levels that are crucial for vWF hemostatic activity, but vWF activation, triggered by a rise in shear rates. vWF becomes highly reactive with platelets upon unfolding into a stretched conformation, at shear rates above the critical value (more than 5000 s⁻¹), which might occur at sites of arterial stenosis and injury. The activation of vWF and its counterbalance by ADAMTS-13, the vWF-cleaving protease, might contribute to complications of cardiovascular diseases. In this review, we discuss vWF involvement in complications of cardiovascular diseases and possible diagnostic and treatment approaches.

Acquired von Willebrand syndrome: focused for hematologists

The acquired von Willebrand syndrome (AvWS) is a rare bleeding disorder with laboratory findings similar to those of inherited von Willebrand disease. However, unlike the inherited disease, AvWS occurs in persons with no personal and family history of bleeding and is often associated with a variety of underlying diseases, most frequently lymphoproliferative, myeloproliferative and cardiovascular disorders. After the presentation of a typical case, in this narrative review we discuss the more recent data on the pathophysiology, clinical, laboratory and therapeutic aspects of this acquired bleeding syndrome. We chose to focus particularly on those aspects of greater interest for the hematologist.

Good Profile of Efficacy/Tolerance of Bortezomib or Idelalisib in Waldenström Macroglobulinemia Associated with Acquired Von Willebrand Syndrome

Acquired von Willebrand syndrome (AVWS) in the setting of Waldenström macroglobulinemia (WM) is a challenging condition. No real standard of care is recommended for these patients, although the therapeutic strategy should include a rapid approach to the emergency bleeding events and to the underlying malignant lymphoid disorder. We report here our experience treating three elderly patients with these concomitant hematologic entities. The use of a bortezomib-based chemotherapy regimen showed a good profile of tolerance and efficacy even in a long-term follow-up period. These patients were treated for several years before switching their therapy to idelalisib, a targeted oral therapy that inhibits phosphatidylinositol 3-kinase isoform-delta (PI3KD), which is part of the signaling pathway downstream B-cell receptor. This approach was well tolerated and efficacious, although some adverse effects were observed, particularly at hepatic levels, but were all reversible. The same profile of tolerance/efficacy was observed in one very old patient who received idelalisib as a first-line therapy. We think that bortezomib-based therapy could be considered in refractory patients with AVWS associated with WM.

Bleeding signs due to acquired von Willebrand syndrome at diagnosis of chronic myeloid leukaemia in children

A considerable proportion of patients with chronic myeloid leukaemia (CML) may present at diagnosis with high platelet counts. This may result in thrombosis or bleeding complications due to binding of von Willebrand factor (VWF) multimers to platelets. Paediatric CML is very rare and no systematic investigation on clinical complications of elevated platelets has been reported. Data on platelet count and associated haemostaseological complications were retrospectively analysed in a cohort of 156 children with CML. Fifty-one percent (81/156) patients presented with thrombocytosis (platelet count> 500 × 10⁹ /l), and were extreme (>1 000 × 10⁹ /l) in 23/156 (16%). There were no cases of thrombosis but mild bleeding signs were present in 12% (n = 9) children with thrombocytosis. Bleeding occurred without correlation to elevated platelet counts and was associated with reduced large VWF multimers, indicating a diagnosis of acquired von Willebrand syndrome (AVWS), which resolved after initiation of CML treatment. Patients with paediatric CML frequently exhibit high platelet counts not resulting in thrombosis. In patients with thrombocytosis mild bleeding signs due to a low percentage of large VWF multimers can be demonstrated. AVWS may be underdiagnosed in paediatric CML (Clinical-Trials.gov NCT00445822, 9 March 2007).

Combination of acquired von Willebrand syndrome (AVWS) and Glanzmann thrombasthenia in monoclonal gammopathy of uncertain significance (MGUS), a case report

Background

Autoimmune paraphenomena, are associated with B-cell lymphoproliferative disorders, including monoclonal gammopathy of uncertain significance. These paraphenomena can rarely include acquired bleeding disorders.

Case presentation

This case study reports an unusual clinical presentation of 2 acquired bleeding disorders, Acquired von Willebrand syndrome (disease) and Acquired Glanzmann's thrombasthenia, in an elderly patient with monoclonal gammopathy of uncertain significance.

Conclusions

Acquired bleeding disorders are often underdiagnosed and a high degree of clinical suspicion is required. The patient in this study demonstrated platelet aggregometry which was atypical for isolated Glanzmann's thrombosthenia because of the severe concomitant endogenous decrease in von Willebrand factor. There was an absence of platelet aggregation to all tested agonists including ristocetin. Once the diagnosis was made, however, the patient showed a partial response to intravenous immunoglobulin confirming the immunological pathogenesis in this case. This case highlights the need to consider acquired bleeding disorders in patients with a possible predisposing factor.

Von Willebrand Factor as a Novel Player in Valvular Heart Disease: From Bench to Valve Replacement

von Willebrand Factor (vWF) is a well-known mediator of hemostasis and vascular inflammation. Its dynamic modulation in the bloodstream, according to hemodynamic conditions, makes it an appealing biomarker in patients with valvular heart disease (VHD). Recent studies highlight the close connection between vWF and VHD, with possible implications in the pathogenesis of VHD, promoting valve aging and calcification or favoring the development of infective endocarditis. Moreover, vWF has been recently proposed as a new diagnostic and prognostic tool in patients with valve stenosis or regurgitation, showing a strict correlation with severity of valve disease, outcome, and bleeding (Heyde syndrome). A novel role for vWF is also emerging in patients undergoing percutaneous or surgical valve repair/replacement to select and stratify patients, evaluate periprocedural bleeding risk, and detect procedural complications. We also report our single-center experience, suggesting, for the first time, possible clinical implications for vWF in percutaneous mitral valve repair (MitraClip). This review summarizes recent advances in the role of vWF in VHD with an updated overview going from bench to operating room.

What have we learned from large population studies of von Willebrand disease?

Von Willebrand factor (VWF) is a critical regulator of hemostatic processes, including collagen binding, platelet adhesion, and platelet aggregation. It also serves as a carrier protein to normalize plasma factor VIII synthesis, release, and survival. While VWF protein measurements by immunoassay are reasonably comparable between institutions, the measurement of VWF ristocetin cofactor activity (VWF:RCo) has significant variability. Other tests of VWF function, including collagen binding or platelet glycoprotein IIb-IIIa binding, are not universally available, yet these functional defects may cause major bleeding even with normal VWF antigen (VWF:Ag) and VWF:RCo assays. This results in both the overdiagnosis and underdiagnosis of VWD. Newer assays of VWF function (using recombinant glycoprotein Ib rather than whole platelets) have been developed that may improve interlaboratory variability. Some of these tests are not uniformly available and may not be licensed in the United States. Large longitudinal studies of VWF in von Willebrand disease (VWD) patients are not available. Patients are sometimes diagnosed with a single diagnostic VWF panel. Plasma VWF levels increase with age, but it is not clear if this results in less bleeding or whether different normal ranges should be used to identify age-related decreases in VWF. In order to quantitatively compare bleeding symptoms in VWD patients and normal individuals, recent studies in the European Union, Canada, United Kingdom, Holland, and the United States have used semiquantitative bleeding assessment tools (BATs). Even with careful centralized testing, including functional assays of VWF, addition of a BAT does not solve all of the problems with VWD diagnosis. No matter where the line is drawn for diagnosis of VWD, VWF is still a continuous variable. Thus, VWD can be a severe hemorrhagic disease requiring frequent treatment or a mild condition that may not be clinically relevant. As will be discussed by Dr. Goodeve in her presentation, genetics has helped us to diagnose type 2 functional variants of VWD but has not been helpful for the many patients who are at the interface of normal and low VWF and carry the possible diagnosis of type 1 VWD. The hematologist's management of patients with reduced levels of VWF still requires both the art and science of clinical medicine.

Acquired Von Willebrand's Syndrome in Systemic Lupus Erythematosus

Acquired von Willebrand syndrome (AVWS) is an uncommon, underdiagnosed, and heterogeneous disease which is increasingly recognized as a cause of bleeding diatheses. Systemic lupus erythematosus (SLE) is an infrequent cause of AVWS. Herein, we report a case of AVWS diagnosed during the initial presentation of SLE in a previously healthy young man with no family history of bleeding diathesis who presented with worsening epistaxis, gastrointestinal bleeding, and anasarca. He was found to have severe anemia and prolonged activated partial thromboplastin time (aPTT) with severely decreased levels of von Willebrand factor (VWF) measurements in addition to markedly decreased factor VIII levels. Further evaluation revealed nephrotic syndrome and interstitial lung disease due to SLE. He initially received combination therapy with intravenous immunoglobulin (IVIG) and von Willebrand factor/factor VIII concentrates without significant improvement. Treatment with steroids, cyclophosphamide, and rituximab was followed by clinical improvement evidenced by cessation of bleeding. The short follow-up did not allow us to definitely prove the therapeutic effect of immunosuppressive treatment on AVWS in SLE patients. This case adds to the literature supporting the relationship between AVWS and SLE and highlights the importance of combination therapy in the treatment of severe AVWS as well as the role of IVIG, cyclophosphamide, and rituximab in AVWS associated with SLE.

Acquired von Willebrand syndrome: von Willebrand factor propeptide to von Willebrand factor antigen ratio predicts remission status

We investigated a case of acquired von Willebrand syndrome (AVWS) secondary to a nonneutralizing anti-von Willebrand factor (VWF) antibody associated with an autoimmune disorder. At diagnosis, VWF activity (VWF:Act), antigen (VWF:Ag), multimers, and factor VIII coagulant activity were virtually absent. VWF propeptide (VWFpp) was elevated with an infinitely high VWFpp to VWF:Ag ratio (VWFpp:Ag) consistent with rapid VWF clearance. Immunosuppressive treatment resulted in phenotypic remission 1 with normalization of VWF/factor VIII levels and multimer pattern. However, VWFpp:Ag remained elevated (∼2× normal), consistent with ongoing VWF clearance by the remaining anti-VWF antibody still present by enzyme-linked immunosorbent assay. This suggests that increased VWF secretion was compensating for the incomplete remission state. Relapse occurred when VWFpp:Ag was again infinitely high, with associated decreased VWFpp but unchanged anti-VWF titers; switching the balance to favor VWF clearance over secretion. Complete remission with undetectable anti-VWF occurred only when VWFpp:Ag was normal. This case of relapsing-remitting AVWS demonstrates the use of VWFpp:Ag for predicting remission status.

Salvage therapy with high dose Intravenous Immunoglobulins in acquired Von Willebrand Syndrome and unresponsive severe intestinal bleeding

A 91-year-old woman affected with acquired Von Willebrand (VW) syndrome and intestinal angiodysplasias presented with severe gastrointestinal bleeding (hemoglobin 5 g/dl). Despite replacement therapy with VW factor/factor VIII concentrate qid, bleeding did not stop (eleven packed red blood cell units were transfused over three days). High circulating levels of anti-VW factor immunoglobulin M were documented immunoenzimatically. Heart ultrasound showed abnormalities of the mitral and aortic valves with severe flow alterations. When intravenous immunoglobulins were added to therapy, prompt clinical and laboratory responses occurred: complete cessation of bleeding, raise in hemoglobin, VW factor antigen, VW ristocetin cofactor and factor VIII levels as well as progressive reduction of the anti-VWF autoantibody levels.

Update on von Willebrand factor multimers: focus on high-molecular-weight multimers and their role in hemostasis

Normal hemostasis requires von Willebrand factor (VWF) to support platelet adhesion and aggregation at sites of vascular injury. VWF is a multimeric glycoprotein built from identical subunits that contain binding sites for both platelet glycoprotein receptors and collagen. The adhesive activity of VWF depends on the size of its multimers, which range from 500 to over 10 000 kDa. There is good evidence that the high-molecular-weight multimers (HMWM), which are 5000-10 000 kDa, are the most effective in supporting interaction with collagen and platelet receptors and in facilitating wound healing under conditions of shear stress. Thus, these HMWM of VWF are of particular clinical interest. The unusually large multimers of VWF are, under normal conditions, cleaved by the plasma metalloproteinase ADAMTS13 to smaller, less adhesive multimers. A reduction or lack of HMWM, owing to a multimerization defect of VWF or to an increased susceptibility of VWF for ADAMTS13, leads to a functionally impaired VWF and the particular type 2A of von Willebrand disease. This review considers the biology and function of VWF multimers with a particular focus on the characterization of HMWM - their production, storage, release, degradation, and role in normal physiology. Evidence from basic research and the study of clinical diseases and their management highlight a pivotal role for the HMWM of VWF in hemostasis.

Treatment of acquired von Willebrand syndrome in childhood

A 3-1/2-year-old male with no personal or family history of bleeding disorders presented with abdominal distension, epistaxis, and anemia (hemoglobin 8.2 g/dL). A magnetic resonance imaging scan of the abdomen demonstrated a mass arising from the left kidney. Preoperative laboratory studies revealed a prolonged activated partial thromboplastin time of 49.2 seconds, a normal prothrombin time of 12.4 seconds, and a platelet count of 230 000/μL. Further testing revealed factor VIII (FVIII) activity of 16%, factor IX (FIX) activity of 74%, von Willebrand factor (VWF) activity of 12%, VWF antigen activity of 31%, and decreased high-molecular-weight VWF multimers consistent with acquired von Willebrand syndrome (AVWS). What is the best treatment for this child?

Markers of coagulation activation, endothelial stimulation, and inflammation in dogs with babesiosis

BACKGROUND

Babesia infections in dogs can result in a wide range of clinical and laboratory presentations, including coagulopathy. Expression of intercellular adhesion molecule-1 (ICAM-1) and von Willebrand factor (vWF) in dogs with babesiosis is unknown.

OBJECTIVES

Whether inflammation in babesiosis triggers activation of ICAM-1 and the coagulation system.

ANIMALS

Twelve and 10 dogs with naturally occurring babesiosis before and after antiparasitic treatment, respectively, were compared with 10 healthy dogs.

METHODS

In this prospective study, diagnosis was made by blood smear examination and confirmed by PCR. C-reactive protein (CRP), soluble intercellular adhesion molecule 1 (sICAM-1), and von Willebrand factor (vWF) levels were measured by a canine ELISA kit, fibrinogen (FIB) and factor VIII activity levels were measured by coagulometric methods, and blood cell counts (WBC, RBC, PLT) were determined with an automatic analyzer.

RESULTS

Compared to healthy dogs, the CRP, sICAM-1, and FIB concentrations were significantly increased before therapy and remained high for 3 days after therapy in dogs with babesiosis. vWF activity was significantly decreased in dogs with babesiosis before treatment. FVIII activity did not differ between dogs with babesiosis and healthy dogs. WBC; RBC and PLT were significantly lower before treatment and normalized by 3 days after treatment.

CONCLUSION AND CLINICAL IMPORTANCE

A proinflammatory condition in babesiosis appears to influence endothelial dysfunction and hemostatic activity. Although clearly beneficial for the parasite, sequestered blood cells can obstruct blood flow in small vessels, promote an inflammatory state, and could increase the severity of babesiosis.

Acquired von Willebrand syndrome associated with Hashimoto's thyroiditis and subcutaneous mucosa-associated lymphoid tissue lymphoma

Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder with laboratory findings similar to those of congenital von Willebrand disease. We herein report a case of AVWS associated with Hashimoto's thyroiditis and subcutaneous mucosa-associated lymphoid tissue lymphoma. An IgG autoantibody against von Willebrand factor (VWF) was detected. The antibody bound to VWF but did not inhibit VWF activity. Rapid clearance of VWF seemed to be the cause of AVWS in the present case. VWF-containing concentrates stopped the bleeding. Even if such a complication is rare, for AVWS patients, prompt recognition of the underlying mechanism can save lives.

Thrombosis in hematologic malignancies: risks and consequences

SUMMARY Thrombotic complications in hematologic malignancies have been found to be high among the various forms of cancer. Thrombosis not only increases the morbidity, but also has an adverse impact on survival. The pathogenesis among the different forms of hematologic malignancies is reviewed in this article. The thrombogenicity of the individual malignant cells, the tumor burden, treatment modalities and presence of comorbidities are among the major risk factors. These factors vary with the acute leukemias, lymphomas, multiple myeloma and myeloproliferative neoplasms. The thrombogenetic factors in the more common hematologic malignancies are discussed. Results of recent randomized controlled clinical trials are beginning to provide data for meaningful therapeutic guidelines on thromboprophylaxis. They also enable the clinician to assess the risk factors in each individual patient. More clinical trials are needed to provide better risk stratification and to devise risk-adapted treatment regimens.

Acquired von Willebrand syndrome associated with monoclonal gammopathy: a single-center study of 36 patients

In this single-center retrospective study, we evaluated the accuracy of laboratory tests in diagnosing acquired von Willebrand syndrome associated with lymphoproliferative disorders in 36 consecutive patients diagnosed at the University Hospital of Nantes, France. We also compared hemostatic treatments in the following groups: 21 patients with Waldenström macroglobulinemia (WM), 14 with monoclonal gammopathy of undetermined significance (MGUS) (10 with IgG-MGUS and 4 with IgM-MGUS), and 1 with IgA multiple myeloma (IgA-MM). The diagnosis was made in 18 (50%) patients during systematic screening, in 6 (17%) during active mild hemorrhage, and in 12 (33%) during an active, severe bleed. Of the laboratory tests studied, only closure times measured on the Platelet Function Analyzer (PFA)-100 device reliably diagnosed the hemostatic problem. There was no relationship between the factor VIII activity (FVIII:C) or von Willebrand factor activity (VWF:RCo) levels and the previous history of hemorrhage described by patients.We studied hemostatic treatment in most patients: IgG-MGUS patients responded well to high-dose intravenous immunoglobulin (IVIg) infusions (1 g/kg per d), although patients with IgM-MGUS did not. Desmopressin infusions were effective in 3 patients with IgG-MGUS and 2 patients with IgM-MGUS when the baseline values were above 10 IU/dL, but levels soon returned to the baseline. The 7 WM patients had a good response to desmopressin. These results confirm the efficacy of IVIg in IgG-MGUS patients and the prominent role of closure time in the diagnosis of acquired von Willebrand syndrome.

Pathophysiology of acquired von Willebrand disease: a concise review

Acquired von Willebrand disease (AVWD) is a rare, underdiagnosed hemorrhagic disorder, which is similar to congenital VWD with regard to the clinical and laboratory parameters; however, it is found in individuals with no positive family history and has no genetic basis. The etiology is varied, the commonest being hematoproliferative disorders and cardiovascular disorders. Other disorders associated with AVWD are autoimmune disorders such as systematic lupus erythematosus, hypothyroidism, and neoplasia, or it may also be drug induced. In quite a few cases, the etiology is unknown. The pathogenic mechanisms are different in different underlying disorders or they may be overlapping among these disorders. Some of the proposed mechanisms include the development of autoantibodies, selective absorption of high molecular weight von Willebrand factor (VWF) multimers, non-selective absorption of VWF, mechanical destruction of VWF under high shear stress, and increased proteolysis. This report presents a concise review of the pathophysiological mechanisms of AVWD in these various underlying conditions.

Acquired von Willebrand syndrome and mitral valve prosthesis leakage. A pilot study

BACKGROUND

Of patients with severe aortic stenosis, 15-25% present with bleeding episodes possibly attributable to acquired von Willebrand syndrome (AVWS). AVWS associated with mitral valve prosthesis leakage has not been reported.

METHODS AND RESULTS

Five patients receiving appropriate oral anticoagulation showed mitral valve prosthesis leakage and bleeding episodes; all of them required hospitalization and two blood transfusions, and a von Willebrand factor (VWF) analysis was performed. Two patients with normal functioning metallic prosthesis valves were included as controls. Before surgery, after cessation of acenocumarol, the patients had prolonged activated partial thromboplastin time; four had prolonged closure time (CT) from the platelet function analyzer. Factor VIII procoagulant activity (FVIII:C), VWF ristocetin cofactor activity (VWF:RCo), and VWF collagen binding (VWF:CB) were considerably elevated, while VWF antigen (VWF:Ag) was most elevated. Disproportionate VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag ratios were seen with the loss of large VWF multimers. Following surgery, all parameters were markedly increased and the ratios, CT, and multimeric VWF profile became normal.

CONCLUSIONS

Acquired VWF qualitative alterations in mitral valve prosthesis leakage may be associated with or contribute to bleeding diathesis. AVWS should be taken into consideration in patients with mitral valve prosthesis leakage with bleeding diathesis not explained by excessive oral anticoagulation.

How I treat the acquired von Willebrand syndrome

The acquired von Willebrand syndrome (AVWS) is a bleeding disorder that is frequently unrecognized or is misdiagnosed as von Willebrand disease. AVWS is characterized by structural or functional defects of von Willebrand factor (VWF) that are secondary to autoimmune, lymphoproliferative or myeloproliferative, malignant, cardiovascular, or other disorders. VWF abnormalities in these disorders can result from (1) antibody-mediated clearance or functional interference, (2) adsorption to surfaces of transformed cells or platelets, or (3) increased shear stress and subsequent proteolysis. Diagnosis can be challenging as no single test is usually sufficient to prove or exclude AVWS. Furthermore, there are no evidence-based guidelines for management. Treatments of the underlying medical condition, including chemo/radiotherapy, surgery, or immunosuppressants can result in remission of AVWS, but is not always feasible and successful. Because of the heterogeneous mechanisms of AVWS, more than one therapeutic approach is often required to treat acute bleeds and for prophylaxis during invasive procedures; the treatment options include, but are not limited to, desmopressin, VWF-containing concentrates, intravenous immunoglobulin, plasmapheresis or recombinant factor VIIa. Here, we review the management of AVWS with an overview on the currently available evidence and additional considerations for typical treatment situations.

Bleeding from gastrointestinal angioectasias is not related to bleeding disorders - a case control study

BACKGROUND

Angioectasias in the gastrointestinal tract can be found in up to 3% of the population. They are typically asymptomatic but may sometimes result in severe bleeding. The reasons for why some patients bleed from their angioectasias are not fully understood but it has been reported that it may be explained by an acquired von Willebrand syndrome (AVWS). This condition has similar laboratory findings to congenital von Willebrand disease with selective loss of large von Willebrand multimers. The aim of this study was to find out if AVWS or any other bleeding disorder was more common in patients with bleeding from angioectasias than in a control group.

METHODS

We compared bleeding tests and coagulation parameters, including von Willebrand multimers, from a group of 23 patients with anemia caused by bleeding from angioectasias, with the results from a control group lacking angioectasias.

RESULTS

No significant differences between the two groups were found in coagulation parameters, bleeding time or von Willebrand multimer levels.

CONCLUSION

These results do not support a need for routine bleeding tests in cases of bleeding from angioectasias and do not show an overall increased risk of AVWS among these patients.

Acquired von Willebrand disease secondary to hypothyroidism: a rare cause for postextraction hemorrhage

Acquired von Willebrand's Disease (AvWD) is a rare disease with a clinical pattern similar to the congenital disorder that typically presents later in life in patients with no prior history of prolonged bleeding. It has been shown to be related to a number of common medical conditions including lymphoproliferative and myeloproliferative diseases, cardiovascular disease, immunological disorders, neoplasia, drugs, and miscellaneous disorders. We present 2 cases where post- and interoperative hemorrhage were the initial sign of AvWD and a previously undiagnosed hypothyroid condition was the precipitating factor. There are no similar cases reported within the dental literature. We highlight the importance of taking a medical history and bleeding history in all patients about to undergo oral surgery, periodontal surgery, or implant placement. Increased vigilance is suggested when patients, who have been otherwise well, present with abnormal bleeding problems as this may be a manifestation of an underlying undiagnosed disease.

Hematological issues in critically ill patients with cancer

Patients with solid and hematologic malignancies presenting with major bleeding or thrombotic complications, potentially life-ending events in a cancer patient's clinical course, usually require admission to an intensive care unit (ICU), making their diagnosis and management even more important for the intensivist. Given the significant advances in the diagnosis and treatment of almost all types of cancers in recent years, the intensivist is likely to encounter an ever-increasing number of cancer patients in the ICU setting with these complications. Abnormal hemostasis can occur as a consequence of both the pathology and treatment of cancer. Because cancer can have multiple effects on hemostatic equilibrium, treatment of these complications can be more complex than in the general population. This article reviews the physiology of coagulation and fibrinolysis, with special attention to those aspects that are most frequently altered in the setting of malignancy. The pathophysiology of bleeding and thrombotic complications specific to critically ill cancer patients are then detailed, and the diagnostic and therapeutic strategies are discussed. Special emphasis is placed on new cancer medications that have an effect on hemostasis, and on novel clotting and anticoagulant agents that are available to the intensivist for the management of these patients.

Acquired von Willebrand syndrome in a 10-year-old girl with acute lymphoblastic leukaemia

Following diagnosis of acute lymphoblastic leukaemia (ALL) in a 10-year-old girl, routine coagulation screening including von Willebrand factor antigen (VWF:Ag), ristocetin cofactor activity (VWF:RCo) and factor VIIIC (FVIII:C) detected no pathological findings. After the first HR2' element of the high-risk group of the ALL-BFM 2000 protocol, the patient demonstrated extensive bleeding symptoms and acquired von Willebrand syndrome was diagnosed. VWF:Ag (13%), VWF:RCo (13%) and FVIII:C (27%) were decreased. Multimer analysis showed a loss of large multimers and a loss in triplet structures. The observed pattern was thought to be typical for monoclonal IgG gammopathy; however, in this case, unexpectedly, biclonal IgM gammopathy (κ and λ) was detected. After treatment with intravenous immunoglobulin over 5 days, coagulation factors increased to normal levels. Although this effect was assumed to be at best only temporary, especially in a case of IgM gammopathy, no further bleeding symptoms have been observed.

TRIAL REGISTRATION NUMBER

M208.