Publications by authors named "Barbara Zieger"

95 Publications

Hypercoagulopathy, acquired coagulation disorders and anticoagulation before, during and after extracorporeal membrane oxygenation in COVID-19: a case series.

Perfusion 2021 Mar 15:2676591211001791. Epub 2021 Mar 15.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Background: Thromboembolism and bleeding contribute to Coronavirus disease 2019 (COVID-19)'s morbidity and mortality and are also frequent complications of venovenous extracorporeal membrane oxygenation (vvECMO). As the interaction of the underlying pathologies caused by vvECMO in COVID-19 is barely understood, we designed this study to better differentiate coagulation disorders in COVID-19 patients before, during and after vvECMO-support.

Methods: Observational case series, six consecutive patients with Coronavirus acute respiratory distress syndrome supported with vvECMO treated in the anaesthesiologic ICU in a third level University ECMO-centre. We measured routine coagulation parameters and assessed coagulation factors. We also conducted advanced von Willebrand factor (VWF) multimer analysis, platelet aggregometry and immunological screening.

Results: We identified various phases of coagulation disorders: Initially, intensely activated coagulation with highly increased VWF and factor VIII activity in acute COVID-19, then severe acquired von Willebrand syndrome and platelet dysfunction during vvECMO leading to spontaneous bleeding and finally, hypercoagulopathy after vvECMO explantation. Five of six patients developed immunological abnormalities enhancing coagulation.

Conclusions: Coronavirus-induced coagulopathy and bleeding disorders during vvECMO cannot be discriminated via 'routine' coagulation tests. Precise and specific analyses followed by the appropriate treatment of coagulation disorders may help us develop tailored therapeutic concepts to better manage the phases described above.
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http://dx.doi.org/10.1177/02676591211001791DOI Listing
March 2021

Neutrophil specific granule and NETosis defects in gray platelet syndrome.

Blood Adv 2021 Jan;5(2):549-564

Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, The Netherlands.

Gray platelet syndrome (GPS) is an autosomal recessive bleeding disorder characterized by a lack of α-granules in platelets and progressive myelofibrosis. Rare loss-of-function variants in neurobeachin-like 2 (NBEAL2), a member of the family of beige and Chédiak-Higashi (BEACH) genes, are causal of GPS. It is suggested that BEACH domain containing proteins are involved in fusion, fission, and trafficking of vesicles and granules. Studies in knockout mice suggest that NBEAL2 may control the formation and retention of granules in neutrophils. We found that neutrophils obtained from the peripheral blood from 13 patients with GPS have a normal distribution of azurophilic granules but show a deficiency of specific granules (SGs), as confirmed by immunoelectron microscopy and mass spectrometry proteomics analyses. CD34+ hematopoietic stem cells (HSCs) from patients with GPS differentiated into mature neutrophils also lacked NBEAL2 expression but showed similar SG protein expression as control cells. This is indicative of normal granulopoiesis in GPS and identifies NBEAL2 as a potentially important regulator of granule release. Patient neutrophil functions, including production of reactive oxygen species, chemotaxis, and killing of bacteria and fungi, were intact. NETosis was absent in circulating GPS neutrophils. Lack of NETosis is suggested to be independent of NBEAL2 expression but associated with SG defects instead, as indicated by comparison with HSC-derived neutrophils. Since patients with GPS do not excessively suffer from infections, the consequence of the reduced SG content and lack of NETosis for innate immunity remains to be explored.
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http://dx.doi.org/10.1182/bloodadvances.2020002442DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839360PMC
January 2021

Familial Multiple Coagulation Factor Deficiencies (FMCFDs) in a Large Cohort of Patients-A Single-Center Experience in Genetic Diagnosis.

J Clin Med 2021 Jan 18;10(2). Epub 2021 Jan 18.

Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, 53127 Bonn, Germany.

Background: Familial multiple coagulation factor deficiencies (FMCFDs) are a group of inherited hemostatic disorders with the simultaneous reduction of plasma activity of at least two coagulation factors. As consequence, the type and severity of symptoms and the management of bleeding/thrombotic episodes vary among patients. The aim of this study was to identify the underlying genetic defect in patients with FMCFDs.

Methods: Activity levels were collected from the largest cohort of laboratory-diagnosed FMCFD patients described so far. Genetic analysis was performed using next-generation sequencing.

Results: In total, 52 FMCFDs resulted from coincidental co-inheritance of single-factor deficiencies. All coagulation factors (except factor XII (FXII)) were involved in different combinations. Factor VII (FVII) deficiency showed the highest prevalence. The second group summarized 21 patients with FMCFDs due to a single-gene defect resulting in combined FV/FVIII deficiency or vitamin K-dependent coagulation factor deficiency. In the third group, nine patients with a combined deficiency of FVII and FX caused by the partial deletion of chromosome 13 were identified. The majority of patients exhibited bleeding symptoms while thrombotic events were uncommon.

Conclusions: FMCFDs are heritable abnormalities of hemostasis with a very low population frequency rendering them orphan diseases. A combination of comprehensive screening of residual activities and molecular genetic analysis could avoid under- and misdiagnosis.
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http://dx.doi.org/10.3390/jcm10020347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7831305PMC
January 2021

Contact activation and acquired von Willebrand syndrome during neonatal extracorporeal circulation.

J Thromb Haemost 2020 11;18(11):3119-3121

Division of General Pediatrics, Department of Pediatrics and Adolescent Medicine, Medical University Graz, Graz, Austria.

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http://dx.doi.org/10.1111/jth.15058DOI Listing
November 2020

Acquired von Willebrand syndrome in ECMO patients: A 3-year cohort study.

Blood Cells Mol Dis 2021 Mar 10;87:102526. Epub 2020 Dec 10.

Institute of Clinical Chemistry, Univ.-Hospital Schleswig-Holstein, Kiel & Lübeck, Germany. Electronic address:

Background: Bleeding is a common but possibly underreported side effect of Extracorporeal Membrane Oxygenation (ECMO). Impairment of primary hemostasis by acquired von Willebrand syndrome (aVWS) and platelet dysfunction as well as activation and consumption of plasmatic coagulation factors contribute to hemorrhage. The aim of the present cohort study of consecutively enrolled patients admitted to our ECMO center was to collect demographic, medical and laboratory data possibly associated with i) development of clinically relevant bleeding and/or ii) death during a 12-months follow-up.

Results: Within a 3-year period 338 white patients aged 18-89 years (median: 60; male 64.5%) were enrolled. 78 of 338 patients (23%) presented with clinical relevant bleeding symptoms. The overall death rate was 74.6% within a median time of 9 days (1-229) post intervention. Logistic-regression analysis adjusted for age and gender revealed that i) the presence of blood group O versus non-O (Odds ratio (OR)/95%CI: 1.9/1.007-3.41), ECMO duration per day (1.1/1.06-1.14), veno-venous versus veno-arterial ECMO cannulation (2.33/1.2-4.5) and the overall need for blood product administered per unit (1.02/1.016-1.028) was independenly associated with bleeding in patients suffering from aVWS. ii) Older age (increase per year) at ECMO start (1.015/1.012-1.029) and an increasing amount of blood product units were significantly related with death (1.007/1.001-1.013). Patients with veno-venous versus veno-arterial cannulation survived longer (0.48/0.24-0.94).

Conclusion: In the present cohort study we found a clinical relevant bleeding rate of 23% in subjects with aVWS associated with blood group O, a longer ECMO duration and veno-venous cannulation.
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http://dx.doi.org/10.1016/j.bcmd.2020.102526DOI Listing
March 2021

Impaired Platelet Function in Sept8-Deficient Mice In Vitro.

Thromb Haemost 2021 Apr 17;121(4):484-494. Epub 2020 Nov 17.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Septins (Septs) are a widely expressed protein family of 13 mammalian members, recognized as a unique component of the cytoskeleton. In human platelets, we previously described that SEPT4 and SEPT8 are localized surrounding α-granules and move to the platelet surface after activation, indicating a possible role in platelet physiology. In this study, we investigated the impact of Sept8 on platelet function using Sept8-deficient mouse platelets. Deletion of Sept8 in mouse platelets caused a pronounced defect in activation of the fibrinogen receptor integrin αβ α-granule exocytosis, and aggregation, especially in response to the glycoprotein VI agonist convulxin. In contrast, δ-granule and lysosome exocytosis of Sept8-deficient platelets was comparable to wild-type platelets. Sept8-deficient platelet binding to immobilized fibrinogen under static conditions was diminished and spreading delayed. The procoagulant activity of Sept8-deficient platelets was reduced in response to convulxin as determined by lactadherin binding. Also thrombin generation was decreased relative to controls. Thus, Sept8 is required for efficient integrin αβ activation, α-granule release, platelet aggregation, and contributes to platelet-dependent thrombin generation. These results revealed Sept8 as a modulator of distinct platelet functions involved in primary and secondary hemostatic processes.
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http://dx.doi.org/10.1055/s-0040-1718733DOI Listing
April 2021

Novel manifestations of immune dysregulation and granule defects in gray platelet syndrome.

Blood 2020 10;136(17):1956-1967

Service d'Hématologie Biologique, Hospices Civils de Lyon, Lyon, France.

Gray platelet syndrome (GPS) is a rare recessive disorder caused by biallelic variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet α-granules, splenomegaly, and bone marrow (BM) fibrosis. Due to the rarity of GPS, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathologic features, we performed a detailed clinical genotypic and phenotypic study of 47 patients with GPS and identified 32 new etiologic variants in NBEAL2. The GPS patient cohort exhibited known phenotypes, including macrothrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. Novel clinical phenotypes were also observed, including reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4 lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One-quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data show that, in addition to the well-described platelet defects in GPS, there are immune defects. The abnormal immune cells may be the drivers of systemic abnormalities such as autoimmune disease.
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http://dx.doi.org/10.1182/blood.2019004776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582559PMC
October 2020

Impaired iloprost-induced platelet inhibition and phosphoproteome changes in patients with confirmed pseudohypoparathyroidism type Ia, linked to genetic mutations in GNAS.

Sci Rep 2020 07 9;10(1):11389. Epub 2020 Jul 9.

Department of Biochemistry, CARIM, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.

Patients diagnosed with pseudohypoparathyroidism type Ia (PHP Ia) suffer from hormonal resistance and abnormal postural features, in a condition classified as Albright hereditary osteodystrophy (AHO) syndrome. This syndrome is linked to a maternally inherited mutation in the GNAS complex locus, encoding for the GTPase subunit Gsα. Here, we investigated how platelet phenotype and omics analysis can assist in the often difficult diagnosis. By coupling to the IP receptor, Gsα induces platelet inhibition via adenylyl cyclase and cAMP-dependent protein kinase A (PKA). In platelets from seven patients with suspected AHO, one of the largest cohorts examined, we studied the PKA-induced phenotypic changes. Five patients with a confirmed GNAS mutation, displayed impairments in Gsα-dependent VASP phosphorylation, aggregation, and microfluidic thrombus formation. Analysis of the platelet phosphoproteome revealed 2,516 phosphorylation sites, of which 453 were regulated by Gsα-PKA. Common changes in the patients were: (1) a joint panel of upregulated and downregulated phosphopeptides; (2) overall PKA dependency of the upregulated phosphopeptides; (3) links to key platelet function pathways. In one patient with GNAS mutation, diagnosed as non-AHO, the changes in platelet phosphoproteome were reversed. This combined approach thus revealed multiple phenotypic and molecular biomarkers to assist in the diagnosis of suspected PHP Ia.
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http://dx.doi.org/10.1038/s41598-020-68379-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347634PMC
July 2020

Coagulation disorders in Duchenne muscular dystrophy? Results of a registry-based online survey.

Acta Myol 2020 Mar 1;39(1):2-12. Epub 2020 Mar 1.

Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany.

Different complications of hemostasis have been reported in patients with Duchenne Muscular Dystrophy (DMD). These comprise an increased rate of bleeding-symptoms during scoliosis surgery but also thromboembolic complications such as pulmonary embolism, cerebral infarction, deep vein thrombosis or cardiac thrombus. For this cross-sectional study, personalized online survey-links were forwarded to 682 registered patients with a genetically confirmed diagnosis of DMD via the German-Austrian DMD patient registry (www.dmd-register.de). The questionnaire enquired data regarding the degree of mobility, disposition to hematoma, epistaxis and gum bleeding, occurrence of peri- and postsurgical hemorrhage, stroke, deep vein thrombosis, and cardiac thromboembolism. Further data on regular medication and age were recorded. Three-hundred-fifty-one DMD-patients completed the questionnaire (response rate of 51.5%). Of those, 164 (46.7%) were ambulatory and 187 (53.3%) were non-ambulatory. Age distribution was homogeneous. Two participants had a history of thromboembolic events (0.6%). Correlations analysis revealed no coherence with the degree of mobility, age or regular medication. A bleeding tendency was reported by 76 participants (21.7%). No significant correlations with age or degree of mobility were found. We found no association with underlying genetic variants. Results of this patient registry-based survey do not indicate a distinct DMD-specific risk for thromboembolic events that exceeds the risk by typical comorbidities of chronic immobility and cardiac insufficiency in advanced stages of the disease. The results of this survey suggest a mild bleeding tendency in this DMD cohort, whereas a selection bias cannot be excluded.
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http://dx.doi.org/10.36185/2532-1900-001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315897PMC
March 2020

Acquired bleeding disorders.

Haemophilia 2021 Feb 1;27 Suppl 3:5-13. Epub 2020 Jun 1.

Surgical Research Laboratory and Section of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Acquired bleeding disorders can accompany hematological, neoplastic, autoimmune, cardiovascular or liver diseases, but can sometimes also arise spontaneously. They can manifest as single factor deficiencies or as complex hemostatic abnormalities. This review addresses (a) acquired hemophilia A, an autoimmune disorder characterized by inhibitory autoantibodies against coagulation factor VIII; (b) acquired von Willebrand syndrome in patients with cardiovascular disorders, where shear stress abnormalities result in destruction of von Willebrand factor; and (c) liver function disorders that comprise complex changes in pro- and anti-hemostatic factors, whose clinical implications are often difficult to predict. The article provides an overview on the pathophysiology, diagnostic tests and state-of-the-art treatment strategies.
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http://dx.doi.org/10.1111/hae.14033DOI Listing
February 2021

Acquired von Willebrand Syndrome and Platelet Function Defects during Extracorporeal Life Support (Mechanical Circulatory Support).

Hamostaseologie 2020 Jun 26;40(2):221-225. Epub 2020 May 26.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Patients with ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) suffer from an increased risk for thromboembolic events as well as for hemorrhages. High shear stress in the mechanical device results in acquired von Willebrand syndrome (AVWS), characterized by a loss of high-molecular-weight multimers of von Willebrand factor (VWF) leading to an increased bleeding risk. Onset of AVWS occurs within hours, persists during the whole period of mechanical support, and subsides rapidly after explantation. Patients with the older HeartMate II exhibit more severe AVWS than those with the newer HeartMate III, thanks to lower shear stress in the latter. All ECMO and VAD patients exhibit thrombocytopathia and often thrombocytopenia which further increases the bleeding risk. Etiological models for AVWS are increased cleavage by the metalloproteinase ADAMSTS13, mechanical destruction of VWF, and shear-induced VWF binding to platelets. Platelet secretion defects may be caused by transient platelet activation leading to degranulation. AVWS can be diagnosed by detection of VWF multimers using gel-electrophoresis and functional assays of varying sensitivity (VWF ristocetin cofactor activity, VWF activity, VWF collagen binding). Platelet dysfunction is monitored using light transmission aggregometry and secretion defects are detectable using flow cytometry. Modest use of anticoagulants and a target-controlled therapy based on VWF parameters and other coagulation and platelet parameters are shown to be beneficial in this patient group. Persistent hemorrhages may be controlled with tranexamic acid and platelet concentrates. Prompt weaning from the device, when indicated, is the best therapeutic option to prevent recurrent bleeding.
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http://dx.doi.org/10.1055/a-1150-2016DOI Listing
June 2020

Severe plasma prekallikrein deficiency: Clinical characteristics, novel KLKB1 mutations, and estimated prevalence.

J Thromb Haemost 2020 07 15;18(7):1598-1617. Epub 2020 May 15.

Center for Thrombosis and Hemostasis, University Medical Center Mainz, Johannes Gutenberg University, Mainz, Germany.

Background: Severe plasma prekallikrein (PK) deficiency is an autosomal-recessive defect characterized by isolated activated partial thromboplastin time prolongation. To date, no comprehensive methodologically firm analysis has investigated the diagnostic, clinical, and genetic characteristics of PK deficiency, and its prevalence remains unknown.

Patients/methods: We described new families with PK deficiency, retrieved clinical and laboratory information of cases systematically searched in the (gray) literature, and collected blood of these cases for complementary analyses. The Genome Aggregation Database (gnomAD) and the population-based Gutenberg Health Study served to study the prevalence of mutations and relevant genetic variants.

Results: We assembled a cohort of 111 cases from 89 families and performed new genetic analyses in eight families (three unpublished). We identified new KLKB1 mutations, excluded the pathogenicity of some of the previously described ones, and estimated a prevalence of severe PK deficiency of 1/155 668 overall and 1/4725 among Africans. One individual reported with PK deficiency had, in fact, congenital kininogen deficiency associated with decreased PK activity. One quarter of individuals had factor XII clotting activity below the reference range. Four major bleeding events were described in 96 individuals, of which 3 were provoked, for a prevalence of 4% and an annualized rate of 0.1%. The prevalence of cardiovascular events was 15% (6% <40 years; 21% 40-65 years; 33% >65 years) for an annualized rate of 0.4%.

Conclusions: We characterized the genetic background of severe PK deficiency, critically appraised mutations, and provided prevalence estimates. Our data on laboratory characteristics and clinical course of severe PK deficiency may have clinical implications.
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http://dx.doi.org/10.1111/jth.14805DOI Listing
July 2020

Fundamentals for a Systematic Approach to Mild and Moderate Inherited Bleeding Disorders: An EHA Consensus Report.

Hemasphere 2019 10 17;3(4):e286. Epub 2019 Sep 17.

Department of Medicine, Division of Heamtology-Oncology, University of North Carolina at Chapel Hill, NC, USA.

Healthy subjects frequently report minor bleedings that are frequently 'background noise' of normality rather than a true disorder. Nevertheless, unexpected or unusual bleeding may be alarming. Thus, the distinction between normal and pathologic bleeding is critical. Understanding the underlying pathologic mechanism in patients with an excessive bleeding is essential for their counseling and treatment. Most of these patients with significant bleeding will result affected by non-severe inherited bleeding disorders (BD), collectively denominated mild or moderate BD for their relatively benign course. Unfortunately, practical recommendations for the management of these disorders are still lacking due to the current state of fragmented knowledge of pathophysiology and lack of a systematic diagnostic approach. To address this gap, an International Working Group (IWG) was established by the European Hematology Association (EHA) to develop consensus-based guidelines on these disorders. The IWG agreed that grouping these disorders by their clinical phenotype under the single category of mild-to-moderate bleeding disorders (MBD) reflects current clinical practice and will facilitate a systematic diagnostic approach. Based on standardized and harmonized definitions a conceptual unified framework is proposed to distinguish normal subjects from affected patients. The IWG proposes a provisional comprehensive patient-centered initial diagnostic approach that will result in classification of MBD into distinct clinical-pathological entities under the overarching principle of clinical utility for the individual patient. While we will present here a general overview of the global management of patients with MBD, this conceptual framework will be adopted and validated in the evidence-based, disease-specific guidelines under development by the IWG.
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http://dx.doi.org/10.1097/HS9.0000000000000286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6919472PMC
October 2019

Novel variant in HPS3 gene in a patient with Hermansky Pudlak syndrome (HPS) type 3.

Platelets 2020 Oct 27;31(7):960-963. Epub 2019 Dec 27.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Medical Center - University of Freiburg , Germany.

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder caused by defects in 10 human genes, characterized by oculocutaneous albinism (OCA) and bleeding diathesis associated to platelet δ-storage pool defect (SPD). We report a case of 4-year-old boy from non-consanguineous parents with OCA and negative personal and familiar hemorrhagic history, referred to us for severe bleeding after mild trauma. His platelet function, studied by lumi-aggregometry, showed normal first wave of aggregation in response to exogenous agonists and impaired second wave with defective ATP release. This, in combination with impaired platelet δ-granules content (serotonin, ATP, ADP) and the OCA phenotype suggested the HPS diagnosis.

Hps3: sequencing revealed a novel pathogenic homozygous variant (NM_032383.4:c.7>T, p.Gln3*) resulting in a premature stop codon at the amino acid 3. Moreover, our report highlights the importance of evaluating platelet function in children with OCA without bleeding diathesis to identify HPS early and prevent bleeding complications.
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http://dx.doi.org/10.1080/09537104.2019.1704716DOI Listing
October 2020

Von Willebrand factor parameters as potential biomarkers for disease activity and coronary artery lesion in patients with Kawasaki disease.

Eur J Pediatr 2020 Mar 23;179(3):377-384. Epub 2019 Nov 23.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Elevated von Willebrand factor (vWF):Antigen plasma levels have been observed in conjunction with cardiovascular diseases or vasculitis. The association of Kawasaki disease, a vascular inflammatory disease and vWF:Antigen, vWF:Collagen binding activity, and vWF multimers is unknown. We therefore investigated vWF parameters in 28 patients with acute Kawasaki disease in association with disease activity and coronary artery lesions. VWF:Antigen and vWF:Collagen binding activity were assessed via enzyme-linked immunoassay. The ratio of both (vWF:Collagen binding activity and VWF:Antigen) was calculated and vWF multimeric structure analysis performed. We analyzed the association between vWF parameters and our clinical data focusing on coronary artery outcome. VWF:Antigen and vWF:Collagen binding activity levels were significantly higher in the acute than in the disease's convalescence phase, and correlated positively with CRP levels. Neither variable was associated with coronary artery lesions. The vWF:Collagen binding activity/vWF:Antigen ratio, however, was significantly decreased in patients with a coronary artery lesion (z-score > 2; N = 10; mean ratio 0.96 vs. 0.64; p = 0.031) and even more so in those with a coronary artery aneurysm (z-score > 2.5; N = 8; mean ratio 0.94 vs. 0.55; p = 0.02). In a sub-analysis, those patients with a very low ratio in the acute phase presented a persistent coronary artery aneurysm at their 1-year follow-up.Conclusion: This study suggests that comprehensive analysis of vWF parameters may help to both monitor KD inflammation and facilitate the identification of those patients carrying an increased risk for coronary artery lesion.What is Known:• Von Willebrand factor (VWF)-parameters represent surrogate markers for vascular inflammation.• Kawasaki disease is a generalized vasculitis in children, which can be complicated by coronary artery lesions.What is New:• In those Kawasaki disease patients with coronary artery lesions, the vWF:CB/vWF:Ag ratio was significantly decreased.• VWF parameters may help to identify patients at risk for coronary artery lesions.
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http://dx.doi.org/10.1007/s00431-019-03513-6DOI Listing
March 2020

Acquired von Willebrand syndrome and left ventricular assist devices.

J Heart Lung Transplant 2020 01 10;39(1):89. Epub 2019 Oct 10.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.healun.2019.09.017DOI Listing
January 2020

Antithrombotic prophylaxis for surgery-associated venous thromboembolism risk in patients with inherited platelet disorders. The SPATA-DVT Study.

Haematologica 2020 07 26;105(7):1948-1956. Epub 2019 Sep 26.

Department of Transfusion and Cell Transplantation Kitasato University School of Medicine, Sagamihara, Japan.

Major surgery is associated with an increased risk of venous thromboembolism (VTE), thus the application of mechanical or pharmacologic prophylaxis is recommended. The incidence of VTE in patients with inherited platelet disorders (IPD) undergoing surgical procedures is unknown and no information on the current use and safety of thromboprophylaxis, particularly of low-molecular-weight-heparin in these patients is available. Here we explored the approach to thromboprophylaxis and thrombotic outcomes in IPD patients undergoing surgery at VTE-risk participating in the multicenter SPATA study. We evaluated 210 surgical procedures carried out in 155 patients with well-defined forms of IPD (VTE-risk: 31% high, 28.6% intermediate, 25.2% low, 15.2% very low). The use of thromboprophylaxis was low (23.3% of procedures), with higher prevalence in orthopedic and gynecological surgeries, and was related to VTE-risk. The most frequently employed thromboprophylaxis was mechanical and appeared to be effective, as no patients developed thrombosis, including patients belonging to the highest VTE-risk classes. Low-molecular-weight-heparin use was low (10.5%) and it did not influence the incidence of post-surgical bleeding or of antihemorrhagic prohemostatic interventions use. Two thromboembolic events were registered, both occurring after high VTE-risk procedures in patients who did not receive thromboprophylaxis (4.7%). Our findings suggest that VTE incidence is low in patients with IPD undergoing surgery at VTE-risk and that it is predicted by the Caprini score. Mechanical thromboprophylaxis may be of benefit in patients with IPD undergoing invasive procedures at VTE-risk and low-molecular-weight-heparin should be considered for major surgery.
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http://dx.doi.org/10.3324/haematol.2019.227876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327644PMC
July 2020

Editorial: Hemostasis in ECMO and VAD.

Front Med (Lausanne) 2019 25;6:143. Epub 2019 Jun 25.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Freiburg, Germany.

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http://dx.doi.org/10.3389/fmed.2019.00143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6604765PMC
June 2019

Standardization of Light Transmission Aggregometry for Diagnosis of Platelet Disorders: An Inter-Laboratory External Quality Assessment.

Thromb Haemost 2019 Jul 2;119(7):1154-1161. Epub 2019 Jun 2.

Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.

Several in vitro platelet function tests are available for the diagnosis of inherited platelet function disorders. Currently, the light transmission aggregometry (LTA) is recommended as one of the first-step tests. LTA is available in most specialized hemostasis laboratories. Although the LTA is accepted as a 'gold standard' assay for the evaluation of platelet function, its standardization in the clinical practice is still challenging. The GTH-based THROMKID-Plus Study Group has performed an inter-laboratory trial in Germany and Austria. Five different agonists were selected according to the Scientific and Standardization Committee/International Society on Thrombosis and Haemostasis recommendations and shipped in 3 different sets (one should represent a healthy control and two should simulate platelet function disorders) to 15 specialized laboratories in Germany and Austria. Agonists were analyzed by APACT or PAP4/8 aggregometer using platelet-rich plasma from healthy donors. In addition, laboratory-internal platelet agonists were tested in platelet-rich plasma from a healthy donor. All laboratories (9 used APACT, 6 used PAP4/PAP8) showed very consistent data regarding the maximum percentage of aggregation induced by the tested agonists and identified the differential diagnosis of the simulated platelet function disorders with one exception, which was due to technical problems. In contrast, there was a high variability of the laboratory-internal inductors regarding reagent type, concentrations and pathological cut-off values. Our study showed that the shipment of agonists is suitable for an inter-laboratory survey of LTA. However, there is still a remarkable need for standardization of agonist reagents and their concentration as well as for definition of reference ranges.
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http://dx.doi.org/10.1055/s-0039-1688791DOI Listing
July 2019

Impaired human hematopoiesis due to a cryptic intronic splicing mutation.

J Exp Med 2019 05 26;216(5):1050-1060. Epub 2019 Mar 26.

Division of Hematology/Oncology, The Manton Center for Orphan Disease Research, Boston Children's Hospital and Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA

Studies of allelic variation underlying genetic blood disorders have provided important insights into human hematopoiesis. Most often, the identified pathogenic mutations result in loss-of-function or missense changes. However, assessing the pathogenicity of noncoding variants can be challenging. Here, we characterize two unrelated patients with a distinct presentation of dyserythropoietic anemia and other impairments in hematopoiesis associated with an intronic mutation in that is 24 nucleotides upstream of the canonical splice acceptor site. Functional studies demonstrate that this single-nucleotide alteration leads to reduced canonical splicing and increased use of an alternative splice acceptor site that causes a partial intron retention event. The resultant altered GATA1 contains a five-amino acid insertion at the C-terminus of the C-terminal zinc finger and has no observable activity. Collectively, our results demonstrate how altered splicing of GATA1, which reduces levels of the normal form of this master transcription factor, can result in distinct changes in human hematopoiesis.
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http://dx.doi.org/10.1084/jem.20181625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6504223PMC
May 2019

Acquired von Willebrand Syndrome in Patients With Ventricular Assist Device.

Front Med (Lausanne) 2019 5;6. Epub 2019 Feb 5.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Freiburg, Germany.

During the last decade the use of ventricular assist devices (VADs) for patients with severe heart failure has increased tremendously. However, flow disturbances, mainly high shear induced by the device is associated with bleeding complications. Shear stress-induced changes in VWF conformation are associated with a loss of high molecular weight multimers (HMW) of VWF and an increased risk of bleeding. This phenomenon and its cause will be elaborated and reviewed in the following.
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http://dx.doi.org/10.3389/fmed.2019.00007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371037PMC
February 2019

Increased von Willebrand factor parameters in children with febrile seizures.

PLoS One 2019 3;14(1):e0210004. Epub 2019 Jan 3.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Introduction: Primary blood coagulation and wound sealing are orchestrated by von Willebrand factor (VWF), a large multimeric glycoprotein. Upon release of arginine vasopressin (AVP), VWF containing high molecular weight multimers is secreted. By measuring copeptin, the C-terminal part of the AVP prohormone, we recently found strongly increased AVP levels in children with febrile seizures (FS) as compared to children with fever but without seizures. It is unknown if increased AVP levels in FS are of any biological function. Therefore, our a priori hypothesis was that children with FS have increased VWF parameters in parallel with higher AVP levels.

Methods: We conducted a prospective, cross-sectional study of children aged between 6 months and 5 years. Children that presented at our emergency department with fever or a recent FS (within four hours) were evaluated to be included to the study. We measured serum copeptin and VWF parameters, including analyses of VWF:Antigen (WVF:Ag), VWF:collagen binding activity (VWF:CB) and VWF multimers in children with FS, febrile infections without seizures and additionally, in a non-febrile control group.

Results: We included 54 children in our study, 30 with FS, 10 in the febrile control group, and 14 in the non-febrile control group. Serum copeptin levels were significantly higher in children with FS (median [IQR] 24.73 pmol/l [13.65-68.65]) compared to the febrile control group (5.66 pmol/l [4.15-8.07], p = 0.002) and the non-febrile control group (4.78 pmol/l [3.33-5.3], p<0.001). VWF:CB levels were also significantly higher in children with FS (VWF:CB 2.29 U/ml [1.88-2.97]) as compared to the febrile (VWF:CB 1.41 U/ml [1.27-1.93], p = 0.048) and the non-febrile control group (VWF:CB 1.15 U/ml [0.98-1.21], p<0.001). VWF:Ag tended to be higher in children with FS compared to both control groups. Multivariate regression analysis revealed FS and copeptin as major determinants of VWF:CB.

Conclusions: Our results suggest that increased secretion of AVP in children with FS is associated with higher plasma levels of VWF parameters. Especially VWF:CB may serve as additional biomarker in the diagnosis of FS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210004PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317815PMC
September 2019

Acquired von Willebrand syndrome in paediatric patients during mechanical circulatory support.

Eur J Cardiothorac Surg 2019 Jun;55(6):1194-1201

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Objectives: Bleeding signs can become life-threatening complications in patients on mechanical circulatory support (MCS). Clinical phenotyping and comprehensive analyses of the cause of bleeding are, therefore, essential, especially when risk-stratifying patients during MCS workup. We conducted coagulation analyses and determined von Willebrand factor (VWF) parameters in a paediatric cohort on temporary extracorporeal life support, extracorporeal membrane oxygenation or long-term ventricular assist device support.

Methods: We carried out an observational single-centre study including 30 children with MCS (extracorporeal life support, n = 13; extracorporeal membrane oxygenation, n = 5; and ventricular assist device, n = 12). We also assessed the acquired von Willebrand parameters of each study participant: collagen binding capacity (VWF:CB), the ratio of collagen-binding capacity to VWF antigen (VWF:CB/VWF:Ag) and high-molecular-weight VWF multimers. We also documented bleeding events, transfusion requirement, haemolysis parameters and surgical interventions.

Results: All children developed AVWS (acquired von Willebrand syndrome) during MCS, usually during the early postoperative course. They presented no AVWS after device explantation. We detected a loss of high-molecular-weight VWF multimers, decreased VWF:CB/VWF:Ag ratios and reduced VWF:CB levels. Twenty of the 30 patients experienced bleeding complications; approximately 53% of them required surgical revision. There were no deaths due to bleeding during support.

Conclusions: The AVWS prevalence in paediatric patients on MCS is 100% regardless of the types of devices tested in this study. The bleeding propensity of AVWS patients widely varies.
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http://dx.doi.org/10.1093/ejcts/ezy408DOI Listing
June 2019

Characterization of septin expression in normal and fibrotic kidneys.

Cytoskeleton (Hoboken) 2019 01 12;76(1):143-153. Epub 2018 Oct 12.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Chronic kidney disease (CKD) is characterized by the loss of nephrons and worsening organ-fibrosis that leads to deterioration and ultimately the total breakdown of kidney function. Renal fibrosis has become a major public health problem worldwide and necessitates hemodialysis and kidney transplantation in affected patients. CKD is mainly characterized by the activation and proliferation of interstitial fibroblasts and by excessive synthesis and accumulation of extracellular matrix components, causing the disruption of the normal tissue architecture of the kidney. Septins are GTPase proteins associated with membranes, actin filaments, and microtubules and are undoubtedly crucial for cytoskeleton organization. Although some septins are involved in liver fibrosis, they have not been investigated in the context of renal fibrosis. Here, we show that numerous septins are expressed in the healthy kidney and demonstrate in fibrotic mouse kidneys that various septins are remarkably up-regulated in the tubulointerstitium compared to contralateral control kidneys. We observed the same findings in human fibrotic kidneys. In both healthy and fibrotic kidneys, septins are coexpressed with extracellular matrix components, reinforcing the structural function of septins as cytoskeletal components. Furthermore, we could show in septin 8-deficient mice that septin 8 is dispensable for the formation of renal fibrosis, and that no other septin was compensatory changed in kidneys compared to wild-type mice.
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http://dx.doi.org/10.1002/cm.21473DOI Listing
January 2019

Hereditary neuralgic amyotrophy in childhood caused by duplication within the SEPT9 gene: A family study.

Cytoskeleton (Hoboken) 2019 01 10;76(1):131-136. Epub 2018 Oct 10.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, University Medical Center, Medical Faculty, University of Freiburg, Freiburg, Germany.

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant disorder associated with episodic, recurrent, and painful neuropathies affecting the nerves of the brachial plexus. In this study, we report on a family of Lebanese descent with HNA onset in early childhood. The affected family members presented with platelet dysfunction. Platelet aggregation was reduced after stimulation with the agonists ADP and epinephrine in all affected family members. Flow cytometric analyses revealed impaired platelet δ-secretion. The index patient and one brother suffered from kidney cysts. Molecular genetic analysis revealed a heterozygous duplication of exon 2 within the septin 9 (SEPT9) gene in all the affected family members. Such a young child with HNA (aged 2 years) caused by SEPT9 duplication has not been described so far.
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http://dx.doi.org/10.1002/cm.21479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6585727PMC
January 2019

CD59 deficiency presenting as polyneuropathy and Moyamoya syndrome with endothelial abnormalities of small brain vessels.

Eur J Paediatr Neurol 2018 Sep 13;22(5):870-877. Epub 2018 Apr 13.

Center for Pediatrics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; Center for Pediatrics, Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany.

CD59 is involved in lymphocyte signal transduction and regulates complement-mediated cell lysis by inhibiting the membrane attack complex. In the cases reported so far, congenital isolated CD59 deficiency was associated with recurrent episodes of hemolytic anemia, peripheral neuropathy, and strokes. Here, we report on a patient from a consanguineous Turkish family, who had a first episode of hemolytic anemia at one month of age and presented at 14 months with acute Guillain-Barré syndrome (GBS). The child suffered repeated infection-triggered relapses leading to the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). Although partly steroid-responsive, the polyneuropathy failed to be stabilized by a number of immunosuppressive agents. At the age of 6 years, he developed acute hemiparesis and showed progressive stenosis of proximal cerebral arteries, evolving into Moyamoya syndrome (MMS) with recurrent infarctions leading to death at 8 years of age. Post-mortem genetic analysis revealed a pathogenic p.(Asp49Valfs*31) mutation in CD59. Re-analysis of brain biopsy specimens showed absent CD59 expression and severe endothelial damage. Whereas strokes are a known feature of CD59 deficiency, MMS has not previously been described in this condition. Therefore, we conclude that in MMS combined with hemolysis or neuropathy CD59 deficiency should be considered. Establishing the diagnosis and targeted therapy with eculizumab might have prevented the lethal course in our patient.
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http://dx.doi.org/10.1016/j.ejpn.2018.04.003DOI Listing
September 2018

Acquired von Willebrand syndrome and impaired platelet function during venovenous extracorporeal membrane oxygenation: Rapid onset and fast recovery.

J Heart Lung Transplant 2018 08 17;37(8):985-991. Epub 2018 Mar 17.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Background: Bleeding contributes to the high mortality of venovenous extracorporeal membrane oxygenation (vvECMO). The development of acquired von Willebrand syndrome (AVWS) has been identified as relevant pathology during ECMO. This study was performed to determine the onset of AVWS after implantation and the recovery of von Willebrand factor (VWF) parameters after explantation of ECMO in a large cohort of patients.

Methods: VWF parameters of 59 patients treated with vvECMO at a university ECMO center were obtained before ECMO implantation, during therapy, and after explantation. In a subgroup of patients, light transmission aggregometry of platelets and flow-cytometric quantification of platelet granule secretion were performed.

Results: All patients developed severe AVWS hours after implantation of vvECMO. After explantation, AVWS recovered within 3 hours in 60%, within 6 hours in 86%, and in all patients within 1 day. Aggregometry showed hypoaggregability of platelets after stimulation with ADP, ristocetin, collagen, and epinephrine. Flow-cytometric platelet analyses revealed severely reduced expression of CD62 and CD63.

Conclusions: All patients during vvECMO support rapidly develop AVWS and platelet dysfunction, resulting in severe impairment of coagulation. After explantation, AVWS overwhelmingly recovers within hours, resulting in a hypercoagulative state. These findings augment the need for novel extracorporeal technologies with reduced shear stress, and shift the emphasis for intense anti-coagulation during ECMO instead to a time-point after explantation.
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http://dx.doi.org/10.1016/j.healun.2018.03.013DOI Listing
August 2018

Successful Surgical Removal of A Massive Iliopsoas Pseudotumor in a Boy With Mild Hemophilia A.

Klin Padiatr 2018 Oct 27;230(6):333-335. Epub 2018 Mar 27.

Department of Pediatric Hematology and Oncology, Medical Center - University of Freiburg, Freiburg, Germany.

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http://dx.doi.org/10.1055/a-0586-4514DOI Listing
October 2018

Platelet Secretion Defects and Acquired von Willebrand Syndrome in Patients With Ventricular Assist Devices.

J Am Heart Assoc 2018 01 13;7(2). Epub 2018 Jan 13.

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Germany

Background: The number of implanted ventricular assist devices (VADs) has increased significantly recently. Bleeding, the most frequent complication, cannot be solely attributed to anticoagulation therapy. Acquired von Willebrand syndrome (AVWS) caused by increased shear stress is frequent in VAD patients and can increase the bleeding risk. The HeartMate III (HM III) is a novel left VAD featuring potential improvements over the HeartMate II.

Methods And Results: In this study, we investigated the prevalence and onset of AVWS in 198 VAD patients. To our knowledge, this is the largest cohort of VAD patients whose longitudinal data on AVWS have been collected. We also analyzed whether AVWS is less severe in HM III patients than in HeartMate II patients. Because platelet dysfunction can raise the bleeding risk, we investigated platelet function in a subset of patients. In total, 198 VAD patients and 60 patients with heart transplants as controls were included in this study. The ratio of von Willebrand factor collagen binding capacity to von Willebrand factor:antigen, multimer analyses, and platelet function (especially secretion of α- and δ-granules) were investigated. All 198 VAD patients developed AVWS. As soon as the VAD was explanted, the AVWS disappeared within hours. AVWS was less severe in the HM III patients than in the HeartMate II patients. The HM III patients had fewer bleeding symptoms. In addition, VAD patients exhibited a platelet α- and δ-granule secretion defect.

Conclusions: AVWS develops in VAD patients and may increase the bleeding risk. The HM III device causes less severe AVWS. Platelet secretion defects should be investigated in VAD patients because they also raise the bleeding risk.

Clinical Trial Registration: https://www.drks.de/drks_web. Unique identifier: DRKS00000649.
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http://dx.doi.org/10.1161/JAHA.117.006519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5850142PMC
January 2018

Alteration of von Willebrand Factor after Transcatheter Aortic Valve Replacement in the Absence of Paravalvular Regurgitation.

Thromb Haemost 2018 01 5;118(1):103-111. Epub 2018 Jan 5.

Department of Clinical Pharmacology, University Heart Centre Freiburg, Bad Krozingen, Germany.

Moderate or severe paravalvular regurgitation after transcatheter aortic valve implantation (TAVI) is frequently associated with a loss of high-molecular-weight multimers of von Willebrand factor (VWF) and a reduced VWF collagen-binding capacity. It is unclear whether this phenomenon can also be observed in patients with mild paravalvular regurgitation, and whether there are differences between patients undergoing conventional aortic valve replacement (AVR) or TAVI. We analysed the multimeric structure of VWF and the ratio of VWF collagen-binding capacity to VWF antigen pre- and postoperatively in 12 patients scheduled for AVR and in 31 patients scheduled for TAVI. Echocardiographic examinations were performed pre-, intra- and postoperatively. Nine patients (75%) undergoing AVR and 18 patients (58%) undergoing TAVI showed pathological VWF functionality preoperatively ( = 0.48). Five to 7 days postoperatively, VWF functionality normalised in all patients with AVR, four of them with mild paravalvular regurgitation. VWF functionality was still altered in nine patients after TAVI ( = 0.044 between groups), five of them with and four without mild paravalvular regurgitation ( = 0.1).Altered VWF functionality was observed in nearly one-third of patients after TAVI, but not after AVR. This phenomenon was not related to paravalvular regurgitation, but may indicate differences in the response of the haemostatic system to the prosthetic heart valve design or the valve replacement procedure.
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http://dx.doi.org/10.1160/17-07-0506DOI Listing
January 2018