Angiodysplasia in von Willebrand Disease: Understanding the Clinical and Basic Science

Refractory Iron-Deficiency Anemia and Vascular Malformation Concomitant with Aortic Stenosis: Heyde Syndrome

BACKGROUND Heyde syndrome is characterized by anemia due to angiodysplasia, aortic valve stenosis, and acquired von Willebrand syndrome. However, the awareness regarding Heyde syndrome in clinical practice is low. We report the case of an older woman with severe refractory iron-deficiency anemia and severe aortic stenosis who was diagnosed with Heyde syndrome. CASE REPORT A 70-year-old woman who had been experiencing exertional dyspnea for 3 months prior to presentation was diagnosed with iron-deficiency anemia, with a hemoglobin level of 69 g/L. She did not experience any episodes of bleeding, such as nosebleeds, gum bleeding, abnormal bleeding, or melena. Upper and lower gastrointestinal endoscopy revealed no evidence of bleeding, and oral iron supplementation failed to improve the anemia. Auscultation of the chest identified an ejection systolic murmur. Chest and abdominal computed tomography showed no significant lesions or active bleeding. Capsule endoscopy of the small intestine revealed capillary dilation. Echocardiography detected severe aortic valve stenosis. Blood test results revealed a deficiency in large von Willebrand factor multimers. Therefore, Heyde syndrome was diagnosed. Aortic valve replacement surgery was performed, which resulted in an improvement in anemia and the associated symptoms. CONCLUSIONS In cases of unexplained and treatment-resistant iron-deficiency anemia, especially if careful auscultation detects aortic stenosis, Heyde syndrome should be considered a differential diagnosis. Furthermore, screening for angiodysplasia in the gastrointestinal tract and prompt diagnosis through measurement of large von Willebrand factor multimers are imperative when investigating potential sources of bleeding.

Retrospective chart review of GI bleeding in people with von Willebrand disease

INTRODUCTION

Gastrointestinal (GI) bleeding events (BEs) in von Willebrand disease (VWD) are difficult to diagnose and often recurrent. Limited data from clinical trials has led to lack of consensus on treatment options.

AIM

Describe current treatments and outcomes for GI BEs in people with VWD.

METHODS

This retrospective, observational, multicentre chart review study was conducted from January 2018 through December 2019 and included patients with inherited VWD with ≥1 GI BE in the preceding 5 years. Baseline characteristics, number and aetiology of BEs, associated GI-specific morbidities/lesions, treatment and outcomes were analysed descriptively.

RESULTS

Sixty bleeds were reported in 20 patients with type 1 (20%), type 2 (50%) and type 3 (30%) VWD. During the 5-year study period, 31 (52%) BEs had one identified or suspected cause; multiple causes were reported in 11 (18%). Most GI BEs (72%) were treated with a combination of von Willebrand factor (VWF), antifibrinolytics and/or other haemostatic or non-haemostatic treatments. Time to resolution did not differ by VWF treatment use; however, BEs treated with non-VWF treatments tended to resolve later. In patients with GI-specific morbidities/lesions, 84% resolved with first-line treatment; time to resolution tended to be longer than in patients without such morbidities/lesions. Thirteen BEs occurred in patients receiving prophylaxis and 47 in patients receiving on-demand treatment; 18 BEs resulted in a switch to prophylaxis after bleed resolution.

CONCLUSIONS

This study confirms the unmet need for the management of recurrent GI BEs in people with VWD and the need for prospective data, especially on prophylaxis.

Progress in von Willebrand Disease Treatment: Evolution towards Newer Therapies

von Willebrand disease (VWD) is a very heterogenous disease, resulting in different phenotypes and different degrees of bleeding severity. Established therapies (i.e., desmopressin, antifibrinolytic agents, hormone therapy for heavy menstrual bleeding, and von Willebrand factor [VWF] concentrates) may work in some subtypes, but not in all patients. In recent years, progress has been made in improving the diagnosis of VWD subtypes, allowing for more specific therapy. The impact of VWD on women's daily lives has also come to the fore in recent years, with hormone therapy, tranexamic acid, or recombinant VWF as treatment options. New treatment approaches, including the replacement of lacking factor VIII (FVIII) function, may work in those subgroups affected by severe FVIII deficiency. Reducing the clearance of VWF is an alternative treatment pathway; for example, rondaptivon pegol is a VWFA1 domain-binding aptamer which not only improves plasma VWF/FVIII levels, but also corrects platelet counts in thrombocytopenic type 2B VWD patients. These approaches are currently in clinical development, which will be the focus of this review. In addition, half-life extension methods are also important for the improvement of patients' quality of life. Targeting specific mutations may further lead to personalized treatments in the future. Finally, a few randomized controlled trials, although relatively small, have been published in recent years, aiming to achieve a higher level of evidence in future guidelines.

The Impact of Acute Exercise on Hemostasis and Angiogenesis Mediators in Patients With Continuous-Flow Left Ventricular Assist Devices: A Prospective Observational Pilot Study

Impaired primary hemostasis and dysregulated angiogenesis, known as a two-hit hypothesis, are associated with gastrointestinal (GI) bleeding in patients with continuous-flow left ventricular assist devices (CF-LVADs). Exercise is known to influence hemostasis and angiogenesis in healthy individuals; however, little is known about the effect in patients with CF-LVADs. The objective of this prospective observational study was to determine whether acute exercise modulates two-hit hypothesis mediators associated with GI bleeding in patients with a CF-LVAD. Twenty-two patients with CF-LVADs performed acute exercise either on a cycle ergometer for approximately 10 minutes or on a treadmill for 30 minutes. Blood samples were taken pre- and post-exercise to analyze hemostatic and angiogenic biomarkers. Acute exercise resulted in an increased platelet count (p < 0.00001) and platelet function (induced by adenosine diphosphate, p = 0.0087; TRAP-6, p = 0.0005; ristocetin, p = 0.0009). Additionally, high-molecular-weight vWF multimers (p < 0.00001), vWF collagen-binding activity (p = 0.0012), factor VIII (p = 0.034), angiopoietin-1 (p = 0.0026), and vascular endothelial growth factor (p = 0.0041) all increased after acute exercise. This pilot work demonstrates that acute exercise modulated two-hit hypothesis mediators associated with GI bleeding in patients with CF-LVADs.

Evidence That Anemia Accelerates AS Progression Via Shear-Induced TGF-β1 Activation: Heyde's Syndrome Comes Full Circle

The severity of aortic stenosis (AS) is associated with acquired von Willebrand syndrome (AVWS) and gastrointestinal bleeding, leading to anemia (Heyde's syndrome). We investigated how anemia is linked with AS and AVWS using the LA100 mouse model and patients with AS. Induction of anemia in LA100 mice increased transforming growth factor (TGF)-β1 activation, AVWS, and AS progression. Patients age >75 years with severe AS had higher plasma TGF-β1 levels and more severe anemia than AS patients age <75 years, and there was a correlation between TGF-β1 and anemia. These data are compatible with the hypothesis that the blood loss anemia of Heyde's syndrome contributes to AS progression via WSS-induced activation of platelet TGF-β1 and additional gastrointestinal bleeding via WSS-induced AVWS.

Real-world healthcare costs and resource utilization in patients with von Willebrand disease and angiodysplasia

OBJECTIVE

To describe the economic burden among VWD patients with angiodysplasia compared to VWD patients without angiodysplasia and the general population.

METHODS

This was a retrospective analysis using the Merative MarketScan Commercial and Medicare Databases® (January 2011-September 2020). Selected patients had ≥1 medical claim for VWD or low VWF, ≥1 medical claim for AGD, and ≥3 GI-related bleeding episodes within a year. HCRU and all-cause costs were compared with the VWD (only) and the general cohorts.

RESULTS

The mean total all-cause costs were $150,101 among patients with VWD and angiodysplasia (n = 34), higher compared to $48,249 among matched VWD patients without angiodysplasia (n = 136) and $31,029 among matched individuals of the general population [n = 136; p-value < 0.0001]. The differences in costs between groups were primarily due to inpatient care. During the 12-month follow-up, VWD patients with symptomatic (n = 35), asymptomatic (n = 81), and suspected (n = 378) angiodysplasia had an average of 4.1, 0.6, and 3.8 gastrointestinal (GI) bleeds, respectively. Desmopressin, VWF concentrates, and aminocaproic acid were the most frequent treatments used. The most frequent procedures to treat GI-related bleeding and underlying lesions were blood transfusion and laser therapy.

CONCLUSIONS

Despite recent therapeutic advances, there is room for considerable reduction of the disease burden in patients with VWD and angiodysplasia.

Vascular Function in Continuous Flow LVADs: Implications for Clinical Practice

Left ventricular assist devices (LVADs) have been increasingly used in patients with advanced heart failure, either as a destination therapy or as a bridge to heart transplant. Continuous flow (CF) LVADs have revolutionized advanced heart failure treatment. However, significant vascular pathology and complications have been linked to their use. While the newer CF-LVAD generations have led to a reduction in some vascular complications such as stroke, no major improvement was noticed in the rate of other vascular complications such as gastrointestinal bleeding. This review attempts to provide a comprehensive summary of the effects of CF-LVAD on vasculature, including pathophysiology, clinical implications, and future directions.

Special considerations in GI bleeding in VWD patients

Gastrointestinal (GI) bleeding is an important cause of morbidity and mortality in von Willebrand disease (VWD). It has been noted that GI bleeding caused by angiodysplasia is overrepresented in VWD patients compared to other causes. The bleeding from angiodysplasia is notoriously difficult to treat; recurrences and rebleeds are common. A growing body of basic science evidence demonstrates that von Willebrand factor negatively regulates angiogenesis through multiple pathways. VWD is clinically highly associated with angiodysplasia. The predisposition to angiodysplasia likely accounts for many of the clinical difficulties related to managing GI bleeding in VWD patients. Diagnosis and treatment are challenging with the current tools available, and much further research is needed to further optimize care for these patients with regard to acute treatment, prophylaxis, and adjunctive therapies. In this review we provide an overview of the available literature on GI bleeding in VWD and explore the molecular underpinnings of angiodysplasia-related GI bleeding. Considerations for diagnostic effectiveness are discussed, as well as the natural history and recurrence of these lesions and which therapeutic options are available for acute and prophylactic management.

Translating the success of prophylaxis in haemophilia to von Willebrand disease

INTRODUCTION

There is limited awareness of von Willebrand disease (VWD), leading to challenges in both diagnosis and defining the optimal treatment approach for these patients. Patients with VWD are typically treated on-demand, with short-term prophylaxis used during surgery. In contrast, early initiation, and long-term use of prophylaxis is the standard of care in patients with severe haemophilia and can be successfully used to prevent joint bleeding and reduce chronic arthropathy.

AIM

To provide an understanding of the current evidence for the prophylactic treatment of patients with VWD and compare this to the management of patients with haemophilia.

METHODS

Review of published literature using a non-systematic search of PubMed and reference lists of sourced articles.

RESULTS

The successes seen with prophylaxis in haemophilia provide the rationale for long-term prophylaxis in patients with severe forms of VWD; preventing spontaneous, excessive and sometimes life-threatening bleeding, and reducing chronic joint disease. Currently, there are a few clinical trials assessing the long-term benefits of prophylaxis in VWD, and guidelines for the optimal prophylaxis treatment approach are lacking. Greater attempts to provide comprehensive, long-term care for patients with VWD are needed but still lacking within the community. This review highlights the success of prophylaxis in haemophilia and how this knowledge might be applied and translated to patients with VWD.

CONCLUSIONS

Lessons can be learned from the use of prophylaxis in haemophilia and prophylaxis should be considered the standard of care for a subgroup of patients with severe VWD.

Ex vivo Improvement of a von Willebrand Disease Type 2A Phenotype Using an Allele-Specific Small-Interfering RNA

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is mainly caused by dominant-negative mutations in the multimeric protein von Willebrand factor (VWF). These mutations may either result in quantitative or qualitative defects in VWF. VWF is an endothelial protein that is secreted to the circulation upon endothelial activation. Once secreted, VWF multimers bind platelets and chaperone coagulation factor VIII in the circulation. Treatment of VWD focuses on increasing VWF plasma levels, but production and secretion of mutant VWF remain uninterrupted. Presence of circulating mutant VWF might, however, still affect normal hemostasis or functionalities of VWF beyond hemostasis. We hypothesized that inhibition of the production of mutant VWF improves the function of VWF overall and ameliorates VWD phenotypes. We previously proposed the use of allele-specific small-interfering RNAs (siRNAs) that target frequent VWF single nucleotide polymorphisms to inhibit mutant VWF . The aim of this study is to prove the functionality of these allele-specific siRNAs in endothelial colony-forming cells (ECFCs). We isolated ECFCs from a VWD type 2A patient with an intracellular multimerization defect, reduced VWF collagen binding, and a defective processing of proVWF to VWF. After transfection of an allele-specific siRNA that specifically inhibited expression of mutant VWF, we showed amelioration of the laboratory phenotype, with normalization of the VWF collagen binding, improvement in VWF multimers, and enhanced VWF processing. Altogether, we prove that allele-specific inhibition of the production of mutant VWF by siRNAs is a promising therapeutic strategy to improve VWD phenotypes.

Expression of angiogenic factors in the uteroplacental unit is altered at time of placentation in a porcine model of von Willebrand disease type 1

Von Willebrand disease (VWD) affects blood coagulation and correlates with angiodysplasia. Data on VWD-affected women point to slightly increased miscarriage rates. We aimed to investigate the impact of VWD on angiogenesis in the uteroplacental unit of pregnant pigs of a model of VWD type 1 (T1). Uteri, placentae, and embryos were harvested at time of placentation (day 29 to 31) from four sows (two wildtype (WT) and two heterozygous for a von Willebrand factor (VWF) mutation diagnosed with T1). T1 sows were bred to a T1 boar creating embryos of three different genotypes: WT, T1 or homozygous for the VWF mutation corresponding with VWD type 3 (T3). Uteroplacental tissues were examined histologically. Embryos were genotyped. Gene expression of angiogenic factors possibly related to VWF was determined by quantitative real-time PCR. Corresponding protein expression was analyzed by immunohistochemistry. Genotyping revealed 35.3% WT, 52.9% T1 and 5.9% T3 embryos (5.9% not classified confidently). No histological alterations were found. Gene expression of VEGF was significantly increased in T1 placentae while expression of ANG1, ANG2, TIE2, and ITGB3 was significantly reduced, confirmed on protein level for different cell types. TIE2/TIE1 ratios were significantly lower in T1 placentae. Distribution of embryo genotypes indicates selection favoring the WT. Significant expression differences of angiogenic factors in placentae suggest influence of VWF on these factors during placentation, although angiodysplasia was not observed. The alterations concerning VEGF/VEGFR-2 signaling, integrin expression and the ANG/TIE system may influence angiogenesis and vascular adaptation during placentation and thus the overall outcome of pregnancy.

Characterization of a Porcine Model for Von Willebrand Disease Type 1 and 3 Regarding Expression of Angiogenic Mediators in the Nonpregnant Female Reproductive Tract

Von Willebrand disease (VWD), a blood coagulation disorder, is also known to cause angiodysplasia. Hitherto, no animal model has been found with angiodysplasia that can be studied in vivo. In addition, VWD patients tend to have a higher incidence of miscarriages for reasons unknown. Thus, we aimed to examine the influence of von Willebrand factor (VWF) on the female reproductive tract histology and the expression and distribution of angiogenic factors in a porcine model for VWD types 1 and 3. The disease-causing tandem duplication within the VWF gene occurred naturally in these pigs, making them a rare and valuable model. Reproductive organs of 6 animals (2 of each mutant genotype and 2 wildtype (WT) animals) were harvested. Genotype plus phenotype were confirmed. Several angiogenic factors were chosen for possible connections to VWF and analyzed alongside VWF by immunohistochemistry and quantitative gene expression studies. VWD type 3 animals showed angiodysplasia in the uterus and shifting of integrin α_Vβ₃ from the apical membrane of uterine epithelium to the cytoplasm accompanied by increased vascular endothelial growth factor (VEGF) expression. Varying staining patterns for angiopoietin (Ang)-2 were observed among the genotypes. As compared with WT, the ovaries of the VWD type 3 animals showed decreased gene expression of ANG2 and increased gene expression of TIE (tyrosine kinase with immunoglobulin and epidermal growth factor homology domains) 2, with some differences in the ANG/TIE-system among the mutant genotypes. In conclusion, severely reduced VWF seems to evoke angiodysplasia in the porcine uterus. Varying distribution and expression of angiogenic factors suggest that this large animal model is promising for investigation of influence of VWF on angiogenesis in larger groups.

Variability of von Willebrand factor-related parameters in endothelial colony forming cells

Essentials Endothelial colony forming cells (ECFCs) are a powerful tool to study vascular diseases ex vivo. Separate ECFC lines show variations in morphology and von Willebrand factor-related parameters. Maximum cell density is correlated with von Willebrand factor expression in ECFCs. Variations in ECFC lines are dependent on the age and mesenchymal state of the cells. ABSTRACT: Background Endothelial colony forming cells (ECFCs) are cultured endothelial cells derived from peripheral blood. ECFCs are a powerful tool to study pathophysiological mechanisms underlying vascular diseases, including von Willebrand disease. In prior research, however, large variations between ECFC lines were observed in, among others, von Willebrand factor (VWF) expression. Objective Understand the relation between phenotypic characteristics and VWF-related parameters of healthy control ECFCs. Methods ECFC lines (n = 16) derived from six donors were studied at maximum cell density. Secreted and intracellular VWF antigen were measured by ELISA. The angiogenic capacity of ECFCs was investigated by the Matrigel tube formation assay. Differences in expression of genes involved in angiogenesis, aging, and endothelial to mesenchymal transition (EndoMT) were measured by quantitative PCR. Results Different ECFC lines show variable morphologies and cell density at maximum confluency and cell lines with a low maximum cell density show a mixed and more mesenchymal phenotype. We identified a significant positive correlation between maximum cell density and VWF production, both at protein and mRNA level. Also, significant correlations were observed between maximum cell density and several angiogenic, aging and EndoMT parameters. Conclusions We observed variations in morphology, maximum cell density, VWF production, and angiogenic potential between healthy control ECFCs. These variations seem to be attributable to differences in aging and EndoMT. Because variations correlate with cell density, we believe that ECFCs maintain a powerful tool to study vascular diseases. It is however important to compare cell lines with the same characteristics and perform experiments at maximum cell density.

Significant gynecological bleeding in women with low von Willebrand factor levels

Gynecological bleeding is frequently reported in women with von Willebrand disease (VWD). Low von Willebrand factor (VWF) may be associated with significant bleeding phenotype despite only mild plasma VWF reductions. The contribution of gynecological bleeding to this phenotype has yet to be described. The optimal clinical bleeding assessment tool (BAT) to evaluate bleeding remains unclear. Using a standardized approach to phenotypic assessment, we evaluated gynecological bleeding and directly compared the Condensed Molecular and Clinical Markers for the Diagnosis and Management of type 1 VWD (Condensed MCMDM-1 VWD) and International Society on Thrombosis and Haemostasis (ISTH) BAT scores in 120 women enrolled in the Low von Willebrand in Ireland Cohort study. Heavy menstrual bleeding (HMB) was reported in 89% of female participants; 45.8% developed iron deficiency. Using identical data, Condensed MCMDM-1 VWD menorrhagia domain scores were significantly lower than ISTH BAT scores (2 vs 3; P < .0001), the discrepant results related to 40% of women not seeking medical consultation for HMB, reducing the sensitivity of the Condensed score. For those who reported HMB to physicians, the low VWF diagnosis was not expedited (age at diagnosis 34.2 vs 33.4 years in women failing to present; P = .7). Postpartum hemorrhage (PPH) was self-reported in 63.5% of parous women (n = 74); 21.6% required transfusion, critical care, radiological, or surgical intervention. Our data demonstrate that gynecological bleeding is frequently reported in women with low VWF; despite pregnancy-related increases in plasma VWF levels, these women may experience PPH. Defining the optimal management approach for these patients requires further research. This trial was registered at www.clinicaltrials.gov as #NCT03167320.