scholarly journals The Platelet Function Analyser (PFA)-100 and von Willebrand disease: a story well over 16 years in the making

Haemophilia ◽  
2015 ◽  
Vol 21 (5) ◽  
pp. 642-645 ◽  
Author(s):  
E. J. Favaloro
Keyword(s):  
Platelet Function ◽  
Von Willebrand Disease ◽  
Von Willebrand

Evaluation of the Abnormal Platelet Function in von Willebrand Disease by the Blood Filtration Test

1996 ◽  
Vol 76 (03) ◽  
pp. 460-468 ◽  
Author(s):  
Francesco I Pareti ◽  
Marco Cattaneo ◽  
Luca Carpinelli ◽  
Maddalena L Zighetti ◽  
Caterina Bressi ◽  
...  
Keyword(s):  
Platelet Function ◽  
Relevant Information ◽  
Von Willebrand Disease ◽  
Type I ◽  
Cumulative Number ◽  
Primary Hemostasis ◽  
Normal Platelet ◽  
Filter Test ◽  
Type 3 ◽  
Von Willebrand

SummaryWe have evaluated platelet function in different subtypes of von Willebrand disease (vWD) by pushing blood through the capillarysized channels of a glass filter. Patients, including those with type IIB vWD, showed lower than normal platelet retention and increased cumulative number of blood drops passing through the filter as a function of time. In contrast, shear-induced platelet aggregation, measured in the cone-and-plate viscometer, was paradoxically increased in type IIB patients. Treatment with l-desamino-8-D-arginine vasopressin (DDAVP) tended to normalize the filter test in patients with type I-platelet normal and type I-platelet low vWD, but infusion of a factor VUI/von Willebrand factor (vWF) concentrate lacking the largest vWF multimers was without effect in type 3 patients. Experiments with specific monoclonal antibodies demonstrated that the A1 and A3 domains of vWF, as well as the glycoproteins Ibα and Ilb-IIIa on platelets, are required for platelet retention in the filter. Thus, the test may reflect vWF function with regard to both platelet adhesion and aggregation under high shear stress, and provide relevant information on mechanisms involved in primary hemostasis.

Platelet Disorders

2015 ◽  
Author(s):  
Lawrence L K Leung ◽  
James L. Zehnder
Keyword(s):  
Platelet Function ◽  
Clinical Manifestations ◽  
Von Willebrand Disease ◽  
Drug Induced ◽  
Excessive Bleeding ◽  
Vascular Integrity ◽  
Patient Reports ◽  
Platelet Function Disorders ◽  
Hemorrhagic Disorders ◽  
Von Willebrand

A bleeding disorder may be suspected when a patient reports spontaneous or excessive bleeding or bruising, often secondary to trauma. Possible causes can vary between abnormal platelet number or function, abnormal vascular integrity, coagulation defects, fibrinolysis, or a combination thereof. This review addresses hemorrhagic disorders associated with quantitative or qualitative platelet abnormalities, such as thrombocytopenia, platelet function disorders, thrombocytosis and thrombocythemia, and vascular purpuras. Hemorrhagic dis­orders associated with abnormalities in coagulation (e.g., von Willebrand disease and hemophilia) are not covered. An algorithm shows evidence-based practice guidelines for the management of immune thrombocytopenic purpura. Tables list questions regarding bleeding and bruising to ask patients, clinical manifestations of hemorrhagic disorders, typical results of tests for hemostatic function in bleeding disorders, causes of thrombocytopenia, other forms of drug-induced thrombocytopenia, classification of platelet function disorders, and selected platelet-modifying agents. This review contains ­1 highly rendered figure, 7 tables, and 82 references. 

The Power of a Standardized Bleeding Score in Diagnosing Pediatric Type 1 Von Willebrand Disease.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1293-1293
Author(s):  
Paul D Marcus ◽  
Kidan G Nire ◽  
Linda Grooms ◽  
Jennifer Klima ◽  
Sarah O'Brien
Keyword(s):  
Platelet Function ◽  
Predictive Value ◽  
Care Setting ◽  
Tertiary Care ◽  
Bleeding Disorder ◽  
Von Willebrand Disease ◽  
The Mean ◽  
Bleeding Score ◽  
Von Willebrand

Abstract Abstract 1293 Poster Board I-315 INTRODUCTION Type I von Willebrand disease (VWD) is the most common inherited bleeding disorder. Repetitive testing of von Willebrand factor (VWF) levels is necessary before the diagnosis can be safely ruled out, as VWF levels fluctuate in response to genetic and environmental factors. A predictive bleeding score (BS) could reveal individuals that may benefit from repetitive testing and those for whom repetitive testing is unlikely to be of benefit. While a standardized questionnaire (the Vicenza score) was developed to evaluate hemorrhagic symptoms, it was never prospectively validated for a pediatric population in a tertiary care setting. SUBJECTS The study targeted children, ages 0 to 17 years, referred to the Hemostasis and Thrombosis Center (HTC) of Nationwide Children's Hospital for a coagulation evaluation as a result of bleeding symptoms, family history of a bleeding disorder and/or abnormal coagulation labs found during pre-operative screening. Children were excluded if they had a previously diagnosed bleeding disorder, if their caregiver did not speak English or if the child did not undergo VWF:Ag and VWF:RCo testing. METHODS Prior to the diagnosis or exclusion of a bleeding disorder in the child, caregivers consented to answer the questionnaire over the telephone. Descriptions of the Vicenza score are available online (http://www.euvwd.group.shef.ac.uk/bleed_score.htm). LABORATORY TESTING A single VWF:Ag or VWF:RCo <30 IU/dL was classified as “Definite Type 1 VWD” while levels from 30-50 IU/dL were classified as “Low VWF” (http://www.nhlbi.nih.gov/guidelines/vwd). Platelet function analysis (PFA-100) screened for platelet function defects, with some patients undergoing follow-up platelet aggregation studies and/or platelet electron microscopy. Laboratory studies from other institutions were excluded from analysis. Patients' medical records were reviewed after hematologic evaluation, and the resultant data was analyzed with STATA 10.1 (Stata Corp., College Station, TX). RESULTS A total of 104 children (52 females and 52 males) with a mean age of 7.53 years (range 1 month to 17 years) were included. At least one hemorrhagic symptom was present in 99 of the 104 children (95%) with the mean number of symptoms being 2.87 (range 0 to 7). The mean Vicenza score was 3.24 (range -1 to 13). Of the 104 children, 8 met criteria for “Definite Type 1 VWD,” 23 met criteria for “Low VWF,” 14 were diagnosed with a “Platelet Function Defect,” and 2 children had bleeding secondary to Ehlers Danlos syndrome. Children with non-bleeding disorders (e.g. Factor XII deficiency) or no laboratory evidence of a bleeding disorder were classified as “No Bleeding Disorder.” In general, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and positive diagnostic likelihood ratio of the bleeding questionnaire demonstrated poor predictive value in our patient population with the exception of high specificity in ruling out “Definite Type 1 VWD” (Table). The NPV was comparably high with both qualitative (>2 bleeding symptoms) and quantitative (BS ≥2) criteria. CONCLUSIONS The Vicenza score, previously validated in adults and in a pediatric primary care setting, appears to have limited predictive value in a pediatric tertiary care setting when evaluating patients with platelet function defects or low VWF levels. While the Vicenza score has a high NPV to exclude “Definite Type 1 VWD,” the use of simpler qualitative criteria is similarly predictive. Disclosures No relevant conflicts of interest to declare.

scholarly journals Therapeutic monitoring of von Willebrand disease: interest and limits of a platelet function analyser at high shear rates

1999 ◽  
Vol 106 (3) ◽  
pp. 777-783 ◽  
Author(s):  
Edith Fressinaud ◽  
Agnès Veyradier ◽  
Marianne Sigaud ◽  
Catherine Boyer-Neumann ◽  
Cécile Le Boterff ◽  
...  
Keyword(s):  
Platelet Function ◽  
Von Willebrand Disease ◽  
Therapeutic Monitoring ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand

Utility of platelet function analyzer as a screening tool for the diagnosis of Von Willebrand disease in adolescents with menorrhagia

2013 ◽  
Vol 60 (7) ◽  
pp. 1184-1187 ◽  
Author(s):  
Swati Naik ◽  
Jun Teruya ◽  
Jennifer E. Dietrich ◽  
Purvi Jariwala ◽  
Esther Soundar ◽  
...  
Keyword(s):  
Platelet Function ◽  
Screening Tool ◽  
Von Willebrand Disease ◽  
Function Analyzer ◽  
Platelet Function Analyzer ◽  
Von Willebrand

Whole Blood Impedance Aggregometry: A New Tool for Severe Inherited Platelet Disorder Diagnosis?

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5266-5266 ◽  
Author(s):  
Celine Desconclois ◽  
Vincent Valarche ◽  
Tewfik Boutekedjiret ◽  
Martine Raphael ◽  
Marie Dreyfus ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Whole Blood ◽  
Von Willebrand Disease ◽  
Fast Method ◽  
Normal Ranges ◽  
Platelet Function Disorders ◽  
Platelet Disorder ◽  
Platelet Disorders ◽  
Von Willebrand

Abstract Abstract 5266 Diagnosis and characterization of platelet function disorders may be challenging. It requires multiple laboratory data including the assessment of platelet functions. Platelet function analysis is most commonly performed using light transmission aggregometry (LTA). LTA is a time-consuming method requiring centrifugation steps and large blood volumes. It is difficult to perform in children and in cases of thrombocytopenia. In contrast, platelet aggregation in whole blood using impedancemetry (WBI) is a fast method, allows omission of centrifugation steps and performance of platelet function studies under more physiological conditions with small samples size. It is based on the change of resistance proportional to the amount of platelets sticking to two electrodes where an alternating current is applied. Multiplate® (for “multiple electrode aggregometry”, Dynabite Medical) is a new generation of WBI aggregometer using diluted blood and single-use test cells containing twin electrodes that reduce the variation of results. We have already showed the good Multiplate® performance concerning ristocetin-induced platelet aggregation in a population of 30 patients with characterized von Willebrand disease (Valarche et al, 2011). Our aim in this ongoing study was to assess the performance of WBI in patients with inherited platelet function disorders. We tested 8 patients including 2 unrelated patients with Glanzmann Thrombasthenia (GT), 2 unrelated patients with Bernard-Soulier Syndrome (BSS), 1 patient with Gray Platelet Syndrome (GPS) and 3 patients from the same family with a platelet type von Willebrand disease (PTVWD). GT, BSS, and PTVWD diagnosis were confirmed using genotyping. BSS and GPS patients had chronic thrombocytopenia. GT, BSS, GPS and 1/3 PTVWD had platelet function tests with LTA in parallel. WBI was performed on heparinized whole blood diluted at ½ in NaCl at 37°C and triggered using high (0.77 mg/mL, WBI RH) and low (0.5 mg/mL, WBI RL) final ristocetin concentrations, ADP (6.5 Âμ Mol, WBI ADP) and collagen (3.2 Âμg/mL, WBI Coll). Results were expressed in arbitrary unit (AU) corresponding to the area under the aggregation curve observed during 6 min. Normal ranges indicated in brackets were based on the mean +/− 2 SD of 30 healthy volunteers' results. Results highlighted in grey are those out of the normal ranges (Table 1).Table 1:Results of the 8 patients with inherited platelet disorders.PatientsPlatelet count (109/L)WBI RH (AU) [>500]WBI RL (AU) [<150]WBI ADP (AU) [>550]WBI Coll (AU) [>500]GT 116923441443GT 224955417ND7BSS 134371119129BSS 230254733582GPS7916217ND42PTVWD22099493ND338PTVWD231116560ND1092PTVWD2341174168ND852 All patients except those with PTVWD had decreased results with WBI. However, as expected, patients with GT had flat traces using WBI ADP and WBI Coll but normal or only decreased curves (234 – 554 AU) using WBI RH. On the opposite, BSS patients had flat traces using WBI RH but detectable curves using WBI ADP (191 – 335 AU) despite decreased platelet count. The thrombocytopenic GPS patient has a flat trace using WBI Coll and decreased WBI RH (162 AU). Members of the PTVWD family had normal results except a slightly increased result with WBI RH in 1/3 patients. Finally, LTA results performed in 6/8 patients were all in accordance with those of the WBI. In conclusion, in 8 patients with well characterized inherited platelet disorders, WBI was able to detect all abnormalities except PTVWD. In such cases, different ristocetin concentrations use might be critical to increase sensitivity. In our hands, WBI was able to discriminate disorders involving platelet glycoprotein (GP) IIb-IIIa from GP Ib-IX-V: GT patients exhibited flat traces using WBI ADP and WBI Coll, whereas patients with BSS exhibited flat traces with ristocetin. These preliminary results need to be confirmed on a larger population of patients with various characterized platelet function disorders. They suggest that WBI using the Multiplate® analyzer, which is a fast, easy and blood-preserving test, could be a valuable extra step before or in addition to the classic LTA for the diagnosis of severe inherited platelet disorders. Disclosures: No relevant conflicts of interest to declare.

Use of a new platelet function analyzer to detect von Willebrand disease in women with menorrhagia

2004 ◽  
Vol 191 (2) ◽  
pp. 449-455 ◽  
Author(s):  
Andra H. James ◽  
Andrea S. Lukes ◽  
Leo R. Brancazio ◽  
Elizabeth Thames ◽  
Thomas L. Ortel
Keyword(s):  
Platelet Function ◽  
Von Willebrand Disease ◽  
Function Analyzer ◽  
Platelet Function Analyzer ◽  
Von Willebrand
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