The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Marco Cattaneo - One of the best experts on this subject based on the ideXlab platform.
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usefulness of the innovance pfa p2y test cartridge for the detection of patients with congenital defects of the platelet p2y12 receptor for adenosine diphosphate
Thrombosis Research, 2014Co-Authors: Mariangela Scavone, Ksenia Germanovich, Eti Alessandra Femia, Marco CattaneoAbstract:Abstract Introduction The platelet function analyzer (PFA)-100® is used in clinical practice to screen patients with bleeding diathesis and suspected defects of primary hemostasis. A new cartridge, INNOVANCE® PFA P2Y, has been specifically developed to monitor patients’ response to drugs inhibiting the platelet P2Y 12 receptor for ADP. In this study, we compared the ability of INNOVANCE® PFA P2Y to detect congenital defects of the platelet P2Y 12 receptor to that of standard cartridge formulations currently in clinical use. Materials and Methods We studied two patients with severe P2Y 12 deficiency, one patient with heterozygous P2Y 12 deficiency and one with dysfunctional P2Y 12 receptor. Closure times were measured using 3 cartridges: collagen/ADP, collagen/epinephrine, and INNOVANCE® PFA P2Y. The results obtained in the four patients with P2Y 12 defects were compared to those obtained for 20 healthy controls. Results In 2 patients with severe P2Y 12 deficiency, closure times of INNOVANCE® PFA P2Y and collagen/ADP cartridges were > 300 s, while those of collagen/epinephrine cartridge were variable (186 s and > 300 s). In the patient with dysfunctional P2Y 12 , closure time of INNOVANCE® PFA P2Y was > 300 s, while closure times of collagen/ADP and collagen/epinephrine were normal. Closure times of all cartridges were normal in the patient with heterozygous P2Y 12 deficiency. Conclusion Our study provides the first evidence that INNOVANCE® PFA P2Y cartridge is sensitive to congenital severe and moderate defects of the platelet P2Y 12 receptors.
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platelet function analyzer pfa 100 closure time in the evaluation of platelet disorders and platelet function
Journal of Thrombosis and Haemostasis, 2006Co-Authors: Catherine P M Hayward, Marco Cattaneo, Paul J Harrison, Thomas L Ortel, A K RaoAbstract:Summary. Background: Closure time (CT), measured by platelet function analyzer (PFA-100 � ) device, is now available to the clinical laboratory as a possible alternative or supplement to the bleeding time test. Aim: On behalf of the Platelet Physiology Subcommittee of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis (ISTH-SSC), a working Group was formed to review and make recommendations on the use of the PFA-100 CT in the evaluation of platelet function within the clinical laboratory. Methods: The Medline database was searched to review the published information on the PFA-100 CT in the evaluation of platelet disorders and platelet function. This information, and expert opinion, was used to prepare a report and generate consensus recommendations. Results: Although the PFA-100 CT is abnormal in some forms of platelet disorders, the test does not have sufficient sensitivity or specificity to be used as a screening tool for platelet disorders. A role of the PFA-100 CT in therapeutic monitoring of platelet function remains to be established. Conclusions: The PFA-100 closure time should be considered optional in the evaluation of platelet disorders and function, and its use in therapeutic monitoring of platelet function is currently best restricted to research studies and prospective clinical trials.
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are the pfa 100 closure time and the skin bleeding time useful in the diagnostic work up of patients with bleeding diathesis correlation with the severity of bleeding symptoms and sensitivity for known defects of primary hemostasis
Blood, 2004Co-Authors: Gian Marco Podda, Paolo Bucciarelli, Federico Lussana, Marco CattaneoAbstract:We compared the performance of PFA-100® closure time (CT) and the skin bleeding time (BT) in the diagnostic work-up of 128 consecutive patients referred to our Centre from June 2002 through June 2003 to be screened for bleeding disorders, due to the presence of bleeding symptoms or the casual finding of abnormal screening tests of hemostasis. The correlation with the severity of the bleeding symptoms and the sensitivity of BT and PFA-100® CT for known defects of primary hemostasis were evaluated. All patients underwent a careful medical interview and were assigned a “bleeding score”, based on the number, type, frequency and severity (development of anemia, need for blood transfusion and/or surgical or medical intervention) of bleeding symptoms. In addition, all patients underwent a first-line screening, which included prothrombin time, activated partial thromboplastin time (APTT), BT and PFA-100® CT (with both the collagen-ADP and the collagen-epinephrine cartridges). The search for Von Willebrand disease (VWD), platelet function disorders (PFD), clotting factor defects and abnormalities of fibrinolysis was performed according to the results of the first line screening tests and the severity and type of bleeding history. Seven (6%) patients had type-1 VWD, 12 (9%) PFD, 29 (23%) defects of clotting factors, 18 (14%) had prolongations of the APTT due to abnormalities that are not associated with bleeding (factor XII deficiency and lupus anticoagulant), while in 63 (49%) all tests gave normal results. The sensitivity of PFA-100® for VWD was 86% (both cartridges), for PFD 75% (collagen-epinephrine) and 8% (collagen-ADP). The sensitivity of BT for VWD was 29%, for PFD 33%. The CT of the PFA-100® CT collagen-epinephrine cartridge was mildly prolonged in 38% of patients with clotting factor deficiency. After dividing the patient population in four quartiles of distribution, according to the severity of the bleeding score (null, low, intermediate and severe), only the CT of the PFA-100® CT collagen-epinephrine cartridge showed a progressive and significant prolongation from the first to the fourth quartile (p=0.04). No association of BT and collagen-ADP CT with the severity of bleeding history was found. In conclusion: 1) CT of the PFA-100® collagen-epinephrine cartridge was significantly associated with the severity of the bleeding history; 2) PFA-100® CT showed a better sensitivity than BT for VWD and PFD; 3) at variance with the BT, PFA-100® could help to discriminate between VWD (prolongation of CT of both cartridges) and PFD (prolongation of CT of the collagen-epinephrine cartridge only).
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evaluation of the pfa 100 system in the diagnosis and therapeutic monitoring of patients with von willebrand disease
Thrombosis and Haemostasis, 1999Co-Authors: Marco Cattaneo, Augusto B Federici, Anna Lecchi, Barbara Agati, R Lombardi, F Stabile, Paolo BucciarelliAbstract:We have evaluated platelet function at high shear with the PFA-100 ® system in different subtypes of von Willebrand disease (vWD), before and after the intravenous infusions of desmopressin or a factor-VIII/ von Willebrand factor (vWF) concentrate. Closure times with the PFA-100 ® system were determined for both the collagen/ADP and the collagen/epinephrine cartridges in 52 patients with vWD (9 type 1 “platelet normal”, 5 type 1 “platelet-discordant”, 8 type 1 “platelet-low”, 6 type 2A, 9 type 2B, 6 type 2M Vicenza, 6 type 3 and 3 acquired vWD) and 40 controls. Measurements were repeated 1 and 4 h after the i. v. infusion of desmopressin (0.3 mg/Kg) in 26 patients with types 1, type 2M Vicenza or type 2A vWD, or of a factorVIII/vWF concentrate (Alphanate HT, 60 U/Kg) in 4 patients with type 3 vWD. At all time points, vWF plasma levels and the bleeding time (Symplate II) were also determined. Baseline closure times were longer in vWD patients than in controls with both the collagen/ADP and the collagen/ epinephrine cartridges. The sensitivity of the PFA-100 ® system (88% and 87% with the two cartridges) was higher than that of the bleeding time (65%). Treatment with desmopressin normalized the closure times in patients with type 1 “platelet-normal” or type 2M Vicenza vWD, had no significant effects in patients with type 1 “platelet-low”, type 1 “pla-telet- discordant” or type 2A vWD. Infusion of a factorVIII/vWF concentrate in patients with type 3 vWD slightly shortened their prolonged closure times. In general, changes in PFA-100 ® were paralleled by shortenings of the bleeding times and increases in plasma vWF levels. The PFA-100 ® test reflects vWF-dependent platelet function under high shear stress and could be useful in the diagnosis and therapeutic monitoring of patients with vWD.
Douglas J Christie - One of the best experts on this subject based on the ideXlab platform.
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hypersensitivity of platelets to adenosine diphosphate in patients with stable cardiovascular disease predicts major adverse events despite antiplatelet therapy
Platelets, 2008Co-Authors: Douglas J Christie, Kandice Kottkemarchant, Robert T GormanAbstract:Enhanced platelet activity correlates with early markers of myocardial damage in patients with cardiovascular disease. However, the extent to which enhanced platelet function signals subsequent adverse clinical outcomes in patients with cardiovascular disease is unknown. Blood from patients with stable cardiovascular disease receiving aspirin (325 mg/day) as the only antiplatelet therapy was tested for closure time (CT) with the Dade® PFA-100® Platelet Function Analyzer system collagen/adenosine diphosphate (ADP) [CADP] cartridge and platelet aggregometry using 10 µM ADP. This study intentionally focused on those patients defined as aspirin sensitive by previously established criteria of arachidonic acid- and ADP-induced platelet aggregometry, and separately by collagen/epinephrine (CEPI) CT using the PFA-100®. Follow up averaged 22 months for the adverse clinical events of death, myocardial infarction or cerebrovascular accident. For aspirin sensitivity determined by aggregometry, patients with CADP CT <...
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the effect of antiplatelet drugs heparin and preanalytical variables on platelet function detected by the platelet function analyzer pfa 100
Clinical and Applied Thrombosis-Hemostasis, 1999Co-Authors: Kandice Kottkemarchant, James B Powers, Linda M Brooks, Sourav Kundu, Douglas J ChristieAbstract:The platelet function analyzer (PFA)-100 is a newly developed instrument that provides a rapid, in vitro, quantitative measurement of platelet adhesion and aggregation in whole blood flowing through a small aperture under high shear conditions. Thirty patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and ten normal individuals were included in this study. In vitro and in vivo studies were conducted to discern the effect of combinations of antiplatelet drugs (aspirin, ticlopidine, abciximab) and heparin on the performance of the device as well as the effects of preanalytical variables, such as method of sample collection and ex vivo anticoagulants. Studies were also conducted examining the effect of aperture size (standard 150 microns vs. smaller 120 microns) on the ability of the device to detect the effect of antiplatelet drugs. There was no difference in mean PFA-100 closure time with citrate versus PPACK anticoagulants or with venipuncture vs. sheath sampling. Closure times did not vary with heparin administration. Closure times were slightly longer for patients taking aspirin plus ticlopidine compared to aspirin alone (p = NS). In contrast adenosine disphosphate (ADP) induced platelet aggregation was significantly less in patients that took aspirin plus ticlopidine vs. aspirin alone (p = .0005). In vitro, there was a dose-dependent increase in closure time for both aperture sizes with increasing abciximab concentration. Although both cartridges showed infinite closure times at an abciximab concentration of 2.25 micrograms/mL, there was a slight benefit to using the 120 microns aperture cartridges at abciximab concentrations of 1.75 to 2.0 micrograms/mL. In ten patients who were followed during abciximab therapy to assess the effect of aperture size, the PFA-100 was able to detect in vivo platelet inhibition by abciximab, but detection of recovery from abciximab-induced platelet dysfunction was slightly better for the PFA-100 with the 120 microns aperture compared to the standard 150 microns aperture collagen/ADP cartridge.
A K Rao - One of the best experts on this subject based on the ideXlab platform.
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platelet function analyzer pfa 100 closure time in the evaluation of platelet disorders and platelet function
Journal of Thrombosis and Haemostasis, 2006Co-Authors: Catherine P M Hayward, Marco Cattaneo, Paul J Harrison, Thomas L Ortel, A K RaoAbstract:Summary. Background: Closure time (CT), measured by platelet function analyzer (PFA-100 � ) device, is now available to the clinical laboratory as a possible alternative or supplement to the bleeding time test. Aim: On behalf of the Platelet Physiology Subcommittee of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis (ISTH-SSC), a working Group was formed to review and make recommendations on the use of the PFA-100 CT in the evaluation of platelet function within the clinical laboratory. Methods: The Medline database was searched to review the published information on the PFA-100 CT in the evaluation of platelet disorders and platelet function. This information, and expert opinion, was used to prepare a report and generate consensus recommendations. Results: Although the PFA-100 CT is abnormal in some forms of platelet disorders, the test does not have sufficient sensitivity or specificity to be used as a screening tool for platelet disorders. A role of the PFA-100 CT in therapeutic monitoring of platelet function remains to be established. Conclusions: The PFA-100 closure time should be considered optional in the evaluation of platelet disorders and function, and its use in therapeutic monitoring of platelet function is currently best restricted to research studies and prospective clinical trials.
Ravindra Sarode - One of the best experts on this subject based on the ideXlab platform.
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clopidogrel anti platelet effect an evaluation by optical aggregometry impedance aggregometry and the platelet function analyzer pfa 100
Platelets, 2007Co-Authors: Anna M Dyszkiewiczkorpanty, Horatiu Olteanu, Eugene P Frenkel, Ravindra SarodeAbstract:Platelet aggregation inhibition by clopidogrel may be suboptimal in 4-30% of patients. Traditionally, optical aggregometry is used to assess clopidogrel's anti-platelet effects by inhibition of ADP-induced aggregation in platelet rich plasma. Red blood cells are an important source of ADP and, thus, are known to modulate platelet function. Because the whole blood aggregation by impedance method assesses platelet function in a physiological milieu, we compared clopidogrel response by this method with the optical method in platelet rich plasma (PRP) and the Platelet Function Analyzer (PFA-100). Platelet function studies were performed in 17 healthy subjects at baseline and after 10 days of clopidogrel intake (75 mg/day). Optical and impedance aggregometry were performed after addition of ADP (10 and 20 microM) and collagen (1 and 2 microg/mL). For PFA-100 analysis, whole blood closure time was measured in collagen-coated cartridges with ADP and epinephrine. All subjects except one showed a decrease in ADP-induced aggregation using both aggregation methods. However, ADP-induced platelet aggregation was significantly inhibited when assessed in whole blood as compared to the optical method (71+/- 34% vs. 34.2+/- 23%, p = 0.0002); this suggests that whole blood aggregometry is more sensitive in the detection of clopidogrel effect in the presence of red cells, which are known to modulate platelet function. The PFA-100 ADP closure time was slightly prolonged above the reference interval in only 5/17 (29%) subjects, suggesting that this instrument is not able to detect clopidogrel effect. We conclude that whole blood aggregation appears to be more sensitive in detecting clopidogrel effect compared with the platelet rich plasma method; the PFA-100 was unable to detect clopidogrel effect in the majority of the subjects.
Emmanuel J Favaloro - One of the best experts on this subject based on the ideXlab platform.
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novel approaches to quality control and external quality assessment for platelet function testing with a focus on the platelet function analyser pfa 100 and pfa 200
Annals of Botany, 2019Co-Authors: Emmanuel J FavaloroAbstract:Platelet function testing is a key diagnostic activity within hematology laboratories associated with advanced hemostasis diagnostics. Platelets represent a key component of primary hemostasis, and deficiency and/or defects, either congenital or acquired, leads to bleeding diathesis in affected individuals. There are various levels of platelet function tests, from simple screens, to complex functional assays, as well as molecular analysis. Platelet function testing has evolved to now incorporate a variety of processes, such as whole blood aggregometry, light transmission aggregometry (LTA), testing by platelet function analyser (PFA) -100 (or -200), flow cytometry, and many other methodologies. Despite some of these tests being available now for decades, and/or continuously evolving, internal quality control (IQC) and external quality assessment (EQA) is limited and made difficult by the nature of the tests and test material, the latter typically representing functional cellular material (i.e., platelets). The current review looks at platelet function testing from the perspective of diagnostic screening, and highlights current limitations, as well as potential solutions that will enable more effective and accurate testing in the future. The primary focus of the review, however, is on IQC and EQA for the platelet function analyser (PFA-100 and PFA-200).
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external quality assessment proficiency testing and internal quality control for the pfa 100 and pfa 200 an update
Seminars in Thrombosis and Hemostasis, 2014Co-Authors: Emmanuel J Favaloro, Roslyn BonarAbstract:Platelet function testing is an essential component of comprehensive hemostasis evaluation within the framework of bleeding and/or bruising investigations, and it may also be performed to evaluate antiplatelet medication effects. Globally, the platelet function analyzer (PFA)-100 (Siemens Healthcare, Marburg, Germany) is the most used primary hemostasis-screening instrument and has also been recently remodeled/upgraded to the PFA-200. The PFA-100 is sensitive to a wide range of associated disorders, including platelet function defects and von Willebrand disease (VWD), as well as to various antiplatelet medications. The PFA-100 is also useful in therapy monitoring, especially in VWD. External quality assessment (EQA) (or proficiency testing) and internal quality control (IQC) are critical to ensuring quality of test practice, inclusive of all hemostasis tests. However, both EQA and IQC for platelet function testing, including the PFA-100, is logistically challenging, given theoretical requirements for production, storage, and shipment of large volumes of "stabilized" normal and pathological blood/platelets covering both normal function plus a wide variety of potential defects. We accordingly describe the development and testing of novel feasible approaches to both EQA and IQC of PFA-100/PFA-200 instruments, whereby a range of formulated "platelet function antagonist" materials are utilized. For EQA purposes, these are distributed to participants, and citrated normal whole blood collected on site is then added locally, thereby creating test material that can be locally evaluated. Several exercises have been conducted by the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) over the past 6 years. A total of 26 challenges, with most designed to mimic moderate to severe primary hemostasis defects, have been tested in 26 to 50 laboratories depending on the year of dispatch. Numerical results for PFA-100/PFA-200 closure times (CTs) and interpretive comments supplied by participants are analyzed by the RCPAQAP. During this period, reported CTs for each challenge were within limits of expectation and good reproducibility was evidenced by repeated challenges. Coefficients of variation (CVs) generated for challenges using the two major PFA-100/PFA-200 cartridge types (collagen/adenosine diphosphate and collagen/epinephrine) are always similar to those obtained using native whole blood, and in general range from 15 to 25%. Interpretations are also in general consistent with expectations and test data provided by laboratories. The EQA created material has also been assessed within the context of possible IQC material. In conclusion, EQA and IQC processes for the PFA-100/PFA-200 have been developed that include highly reproducible test challenge processes, not only supporting the concept that EQA/IQC is possible for platelet function testing but also providing a valuable mechanism for monitoring and improving laboratory performance in this area.
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sample collection and platelet function testing influence of vacuum or aspiration principle on pfa 100 test results
Blood Coagulation & Fibrinolysis, 2013Co-Authors: Giuseppe Lippi, Luigi Ippolito, Valentina Zobbi, Franca Sandei, Emmanuel J FavaloroAbstract:As for other tests of hemostasis, the investigation of platelet function is highly vulnerable to a broad series of preanalytical variables, which span from patient preparation to the final analysis of the specimen and issuance of test results. In particular, there remains much controversy about the influence of manual or vacuum aspiration of blood into primary collection tubes on platelet function testing. Accordingly, we investigated this for the PFA-100. In 12 healthy volunteers, a sample labeled as 'BD-V' was drawn into a 2.7 ml BD Vacutainer tube, whereas two additional samples were collected from the opposite arm into 5.0 ml Sarstedt S-Monovette tubes by vacuum (SD-V) or manual aspiration (SD-A). All sample were tested on PFA-100 with collagen and ADP (CADP) or collagen and epinephrine (CEPI). The values of both CEPI and CADP obtained in SD-A samples were significantly lower than those obtained in SD-V and BD-V tubes, whereas those of the two evacuated tubes did not significantly differ. On average, CEPI values were prolonged by 11% in SD-V and 13% in BD-V, whereas those of CADP were prolonged by 14% in SD-V and 10% in BD-V, respectively. These findings suggests that the lower shear stress generated by the manual aspiration of blood into the primary collection tube would prevent spurious hyper-activation of platelets, thus, preserving the integrity of their function for subsequent testing on PFA-100. This study underscores the need to define or validate local reference ranges for the PFA-100 based on the collection tube used. Different reference ranges of both CEPI and CADP may also be advisable when venous blood samples are collected with manual aspiration or vacuum principle.