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Hematologic Disorders and Stroke. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00042-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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2
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Loberg LI, Chhaya M, Ibraghimov A, Tarcsa E, Striebinger A, Popp A, Huang L, Oellien F, Barghorn S. Off-target binding of an anti-amyloid beta monoclonal antibody to platelet factor 4 causes acute and chronic toxicity in cynomolgus monkeys. MAbs 2021; 13:1887628. [PMID: 33596779 PMCID: PMC7894423 DOI: 10.1080/19420862.2021.1887628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/26/2021] [Accepted: 02/04/2021] [Indexed: 11/30/2022] Open
Abstract
ABT-736 is a humanized monoclonal antibody generated to target a specific conformation of the amyloid-beta (Aβ) protein oligomer. Development of ABT-736 for Alzheimer's disease was discontinued due to severe adverse effects (AEs) observed in cynomolgus monkey toxicity studies. The acute nature of AEs observed only at the highest doses suggested potential binding of ABT-736 to an abundant plasma protein. Follow-up investigations indicated polyspecificity of ABT-736, including unintended high-affinity binding to monkey and human plasma protein platelet factor 4 (PF-4), known to be involved in heparin-induced thrombocytopenia (HIT) in humans. The chronic AEs observed at the lower doses after repeat administration in monkeys were consistent with HIT pathology. Screening for a backup antibody revealed that ABT-736 possessed additional unintended binding characteristics to other, unknown factors. A subsequently implemented screening funnel focused on nonspecific binding led to the identification of h4D10, a high-affinity Aβ oligomer binding antibody that did not bind PF-4 or other unintended targets and had no AEs in vivo. This strengthened the hypothesis that ABT-736 toxicity was not Aβ target-related, but instead was the consequence of polyspecificity including PF-4 binding, which likely mediated the acute and chronic AEs and the HIT-like pathology. In conclusion, thorough screening of antibody candidates for nonspecific interactions with unrelated molecules at early stages of discovery can eliminate candidates with polyspecificity and reduce potential for toxicity caused by off-target binding.
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MESH Headings
- Alzheimer Vaccines/immunology
- Alzheimer Vaccines/pharmacokinetics
- Alzheimer Vaccines/toxicity
- Amyloid beta-Peptides/antagonists & inhibitors
- Amyloid beta-Peptides/immunology
- Animals
- Antibodies, Monoclonal, Humanized/immunology
- Antibodies, Monoclonal, Humanized/pharmacokinetics
- Antibodies, Monoclonal, Humanized/toxicity
- Antibody Specificity
- Blood Platelets/drug effects
- Blood Platelets/immunology
- Blood Platelets/metabolism
- Female
- Humans
- Immunity, Heterologous
- Macaca fascicularis
- Male
- Mice, Inbred BALB C
- No-Observed-Adverse-Effect Level
- Platelet Activation/drug effects
- Platelet Factor 4/antagonists & inhibitors
- Platelet Factor 4/immunology
- Purpura, Thrombocytopenic, Idiopathic/blood
- Purpura, Thrombocytopenic, Idiopathic/chemically induced
- Purpura, Thrombocytopenic, Idiopathic/immunology
- Risk Assessment
- Time Factors
- Toxicity Tests, Acute
- Toxicity Tests, Chronic
- Mice
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Affiliation(s)
- Lise I. Loberg
- Development Sciences, AbbVie Inc., North Chicago, IL, USA
| | - Meha Chhaya
- Global Biologics, AbbVie Inc., Worcester, MA, USA
| | | | | | | | - Andreas Popp
- Preclinical Safety, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany
| | - Lili Huang
- Global Biologics, AbbVie Inc., Worcester, MA, USA
| | - Frank Oellien
- Discovery Chemistry, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany
| | - Stefan Barghorn
- Discovery Biology, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany
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3
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Navaratnam M, Williams GD, Shuttleworth P, Almond C, Maeda K. Epoprostenol Therapy for a Pediatric Patient With Subacute Heparin-Induced Thrombocytopenia and a Ventricular Assist Device Undergoing Heart Transplant: A Case Report. A A Pract 2018; 11:329-331. [PMID: 29985837 DOI: 10.1213/xaa.0000000000000818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Concerns remain regarding the use of direct thrombin inhibitors for cardiopulmonary bypass anticoagulation in pediatric patients with heparin-induced thrombocytopenia undergoing complex cardiac surgery. We describe the safe and effective use of epoprostenol sodium as an alternative therapy before heparin exposure for a pediatric patient with subacute heparin-induced thrombocytopenia and a ventricular assist device undergoing heart transplant.
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Affiliation(s)
| | - Glyn D Williams
- From the Department of Anesthesiology, Perioperative and Pain Medicine
| | - Paul Shuttleworth
- Department of Cardiovascular Perfusion, Stanford Hospital and Clinics
| | - Chris Almond
- Division of Cardiology, Department of Pediatrics
| | - Katsuide Maeda
- Department of Cardiothoracic Surgery, Stanford Children's Hospital, Stanford University Medical Center, Palo Alto, California
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4
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Kannan M, Ahmed R, Kale S, Ahmad S, Fareed J, Saxena R. Laboratory Diagnosis of Heparin-Induced Thrombocytopenia in Asian Indians as Investigated With Functional and Immunologic Methods. Clin Appl Thromb Hemost 2016; 10:51-4. [PMID: 14979405 DOI: 10.1177/107602960401000108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) was looked for in 33 Indian patients undergoing cardiovascular surgery who received unfractionated heparin (UFH). Platelet counts were performed before the initiation of UFH therapy and 5 to 16 days after administration of the therapy. A decrease in patients' platelet count >35% of the baseline value or <100,000/μL was considered to be suggestive of HIT syndrome. Heparin-induced platelet aggregation (HIPA) and enzyme-linked immunosorbent assay (ELISA) tests were performed in all the patients to detect antibodies against heparin/PF4 complex. Thrombocytopenia was found to be present in 10 (30%) patients. Of these, two patients were found to be positive as detected by HIPA and ELISA tests. These two patients were considered to have classic HIT syndrome. One of these had bleeding while the other was asymptomatic. Among the 23 non-thrombocytopenic patients and controls, HIT antibodies were not detectable by HIPA test in all but absent by ELISA in only 21 of them. Two of 23 non-thrombocytopenic patients had positive results on the ELISA test. Because the latter had negative test results on HIPA, they were considered to be false-positive results. Thus, HIT syndrome develops in approximately 6% of Indian patients treated with UFH.
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Affiliation(s)
- Meganathan Kannan
- Department of Haematology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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5
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Hematologic Disorders and Stroke. Stroke 2016. [DOI: 10.1016/b978-0-323-29544-4.00042-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Bueno PV, Souza PR, Follmann HD, Pereira AG, Martins AF, Rubira AF, Muniz EC. N,N-Dimethyl chitosan/heparin polyelectrolyte complex vehicle for efficient heparin delivery. Int J Biol Macromol 2015; 75:186-91. [DOI: 10.1016/j.ijbiomac.2015.01.030] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/29/2022]
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7
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Abstract
Heparin is widely used for the prevention and treatment of thrombotic and particularly cardiovascular disorders. Unfortunately, 0.5 to 3.0% of patients given heparin develop an immune reaction, commonly termed Type II heparin-induced thrombocytopenia (HIT). This is characterized by a moderate thrombocytopenia and in some patients, a venous or arterial thrombosis. This frequently leads to disastrous sequelae, such as limb amputation and death. The pathophysiological basis of this serious adverse drug reaction is the production of an immunoglobulin G antibody that reacts with an antigenic complex consisting of heparin and platelet factor 4. A significant risk factor for the development of HIT is recent surgery, and the frequency of developing an antiheparin-platelet factor 4 or HIT antibody is particularly high in cardiac surgery patients, although surprisingly, only a few of these patients actually develop the clinical syndrome of HIT. This review will discuss the frequency, pathophysiology, clinical features, diagnosis and management of HIT.
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Affiliation(s)
- Beng H Chong
- Department of Medicine, St George Clinical School and Centre of Vascular Research, University of New South Wales, Sydney, New South Wales, USA.
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8
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Shaikh N, Rahman MA, Nayeemuddin M, Maudali IN, Matthias R, Al Thani H. Heparin-induced Thrombocytopenia: A known rare complication of heparin therapy. Qatar Med J 2012. [DOI: 10.5339/qmj.2012.1.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a rare clinico-pathological abnormality. It is characterized by the development of thrombocytopenia, resulting from heparin administration, which leads to a decrease in platelet count by 50%, or to less than 1 0 0 x 1 0 3 M within 5 to 14 days. HIT causes increased morbidity and mortality, thus it is of vital importance that acute care physicians, surgeons and intensivist should be aware of this clinical entity. We report a case of heparin-induced thrombocytopenia and review of its management, including alternatives to heparin therapy.
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Affiliation(s)
- N. Shaikh
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
| | - M. A. Rahman
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
| | - M. Nayeemuddin
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
| | - I. N. Maudali
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
| | - R. Matthias
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
| | - H. Al Thani
- Department of Anesrthesia/ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
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9
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Hüser N, Aßfalg V, Reim D, Novotny A, Thorban S, Cheng Z, Kornberg A, Friess H, Büchler P, Matevossian E. Heparin-induced thrombocytopenia (HIT II) in liver transplant recipients: a retrospective multivariate analysis of prognostic factors. Transpl Int 2012; 25:739-47. [PMID: 22548256 DOI: 10.1111/j.1432-2277.2012.01486.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We investigated the prevalence of HIT II in liver transplant recipients and analysed associated factors. In recipients with clinically suspected HIT II in the 4Ts pretest clinical scoring system HIPA-assay was performed. Next, 37 clinical variables were analysed retrospectively for their association with HIT II. Factors significantly correlated to our findings in univariate analysis were included in a multivariate model and binary logistic regression analysis. Among 46 recipients 21 patients were suspicious in the 4Ts pretest and 14 of them (30.4%) were diagnosed HIT-antibody positive. Patient's age (P = 0.001), postoperative dialysis (P = 0.028), and postoperative hospital stay (P = 0.035) were significantly associated with development of HIT-antibodies in univariate analysis. Postoperative dialysis and postoperative hospital stay turned out as epiphenomena of patient's age, the only independent predictor (P = 0.021). Using multiple χ(2) -testing, a cut-off could be calculated, assigning patients younger than 59 years to a low risk group and patients of 59 years and older to a high risk group. High incidence of peri-operative HIT II seroconversion in liver transplant recipients is not associated with factors known to induce thrombocyte activation, like blood products or cell-saver. Only patients' age was identified as independent predictor.
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Affiliation(s)
- Norbert Hüser
- Department of Surgery, Munich Transplant Centre, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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10
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Griffin JW, Hopkinson WJ, Lassen MR, Thethi I, Litinas E, Fareed J. Assessment of HIT antibody complex in hip fracture patients receiving enoxaparin or unfractionated heparin. Clin Appl Thromb Hemost 2012; 17:567-71. [PMID: 22345625 DOI: 10.1177/1076029611398121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Thromboembolic disease is a common complication of hip fracture in the elderly. Anticoagulants represent a standard of care in preventing postoperative thrombotic complications following surgical fixation. We asked whether levels of antibody to heparin-platelet factor 4 (PF4) complex were differentially present in unfractionated heparin (UFH) versus Enoxaparin, following hip fracture and whether one particular subtype of antibodies was more prevalent. Plasma samples from elderly patients sustaining a hip fracture treated with either enoxaparin or UFH were collected pre- and postoperatively and analyzed using enzyme-linked immunosorbent assay (ELISA) sandwich method for the prevalence of antiheparin-PF4 antibodies and later subtyped. The prevalence of antiheparin-PF4 antibodies was higher in the UFH group especially on postoperative day 7. Patients treated with UFH showed a greater prevalence of antiheparin-PF4 antibodies and a greater prevalence of immunoglobulin G (IgG) subtype. Heparin and enoxaparin are capable of generating heparin-induced thrombocytopenia (HIT) antibodies in elderly patients undergoing orthopedic surgery but perhaps not to the same extent. When comparing low-molecular-weight heparin (LMWH) with UFH, the incidence of new antiheparin-PF4 antibody production is higher in patients treated with UFH.
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Affiliation(s)
- Justin W Griffin
- Loyola University Chicago Stritch School of Medicine, 2160 S First Ave, Maywood, IL, USA
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11
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Vakil NH, Kanaan AO, Donovan JL. Heparin-induced thrombocytopenia in the pediatric population: a review of current literature. J Pediatr Pharmacol Ther 2012; 17:12-30. [PMID: 23118656 PMCID: PMC3428184 DOI: 10.5863/1551-6776-17.1.12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Heparin-induced thrombocytopenia is a rare and serious reaction to unfractionated heparin and low-molecular-weight heparins in children. Quick recognition, discontinuation of heparin, and subsequent treatment with an alternative anticoagulant are essential steps to prevent serious complications such as thrombus and limb amputation. The purpose of this review is to describe the clinical features of heparin-induced thrombocytopenia in children and to summarize the data available for its management. This paper summarizes data and relates the use of direct thrombin inhibitors with clinical outcomes. A literature search was conducted with Ovid, using the key terms argatroban, bivalirudin, hirulog, danaparoid, lepirudin, direct thrombin inhibitor, heparin-induced thrombocytopenia, thrombosis, warfarin, and fondaparinux. Articles were excluded if they were classified as editorials, review articles, or conference abstracts or if they involved patients 18 years of age or older or described disease states not related to thrombosis. Nineteen articles containing 33 case reports were identified and evaluated for this review. Of the 33 cases, 14, 10, 4, and 2 cases described the use of lepirudin, danaparoid, argatroban, and bivalirudin, respectively. Two cases did not report the type of anticoagulant used, and 1 case used aspirin. The most commonly reported complication was bleeding.
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Affiliation(s)
- Niyati H. Vakil
- Massachusetts College of Pharmacy and Health Sciences, Worcester, Massachusetts
| | - Abir O. Kanaan
- Massachusetts College of Pharmacy and Health Sciences, Worcester, Massachusetts
| | - Jennifer L. Donovan
- Massachusetts College of Pharmacy and Health Sciences, Worcester, Massachusetts
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12
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Shaikh N. Heparin-induced thrombocytopenia. J Emerg Trauma Shock 2011; 4:97-102. [PMID: 21633576 PMCID: PMC3097589 DOI: 10.4103/0974-2700.76843] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 10/12/2010] [Indexed: 11/04/2022] Open
Abstract
In the last 7 decades heparin has remained the most commonly used anticoagulant. Its use is increasing, mainly due to the increase in the number of vascular interventions and aging population. The most feared complication of heparin use is heparin-induced thrombocytopenia (HIT). HIT is a clinicopathologic hypercoagulable, procoagulant prothrombotic condition in patients on heparin therapy, and decrease in platelet count by 50% or to less than 100,000, from 5 to 14 days of therapy. This prothrombotic hypercoagulable state in HIT patient is due to the combined effect of various factors, such as platelet activation, mainly the formation of PF4/heparin/IgG complex, stimulation of the intrinsic factor, and loss of anticoagulant effect of heparin. Diagnosis of HIT is done by clinical condition, heparin use, and timing of thrombocytopenia, and it is confirmed by either serotonin release assay or ELISA assay. Complications of HIT are venous/arterial thrombosis, skin gangrene, and acute platelet activation syndrome. Stopping heparin is the basic initial treatment, and Direct Thrombin Inhibitors (DTI) are medication of choice in these patients. A few routine but essential procedures performed by using heparin are hemodialysis, Percutaneous Coronary Intervention, and Cardiopulmonary Bypass; but it cannot be used if a patient develops HIT. HIT patients with unstable angina, thromboembolism, or indwelling devices, such as valve replacement or intraaortic balloon pump, will require alternative anticoagulation therapy. HIT can be prevented significantly by keeping heparin therapy shorter, avoiding bovine heparin, using low-molecular weight heparin, and stopping heparin use for flush and heparin lock.
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Affiliation(s)
- Nissar Shaikh
- Department of Anaesthesia, ICU and Pain Management, Hamad Medical Corporation, Doha, Qatar
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13
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Alaraj A, Wallace A, Mander N, Aletich V, Charbel FT, Amin-Hanjani S. Risk Factors for Heparin-Induced Thrombocytopenia Type II in Aneurysmal Subarachnoid Hemorrhage. Neurosurgery 2011; 69:1030-6. [DOI: 10.1227/neu.0b013e3182284a81] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
BACKGROUND
Heparin-induced thrombocytopenia type II (HIT II) correlates with a higher incidence of thromboembolic complications and unfavorable outcome.
OBJECTIVE
To examine the risk factors and outcomes for patients with HIT II with aneurysmal subarachnoid hemorrhage.
METHODS
Demographics, risk factors, treatments, and outcomes data of 600 aneurysmal subarachnoid hemorrhage patients admitted to the University of Illinois Medical Center in Chicago between June 2002 and July 2007 were retrospectively reviewed. Patients meeting the clinical criteria for HIT II were compared with those who did not develop thrombocytopenia.
RESULTS
Twenty-five patients (6%) met the clinical criteria for HIT II, and 396 (94%) did not develop thrombocytopenia. Both groups were the same with respect to age, Hunt-Hess score and Fisher grade on admission, medical conditions, and social risk factors. The HIT II patients had significantly more unfavorable outcomes (modified Rankin Scale score >3), deep vein thrombosis, stroke, pulmonary embolism, and death. Development of HIT II was strongly associated with symptomatic vasospasm (odds ratio, 5.7; 95% confidence interval, 2.5-13.1; P < .001) and number of angiographic procedures (odds ratio, 1.7; 95% confidence interval, 1.3-2.2; P < .001). Forward buildup selection modeling demonstrated the latter to be the strongest predictor for HIT II development (odds ratio, 2.3; 95% confidence interval, 1.7-3.2; P = .02).
CONCLUSION
Heparin-induced thrombocytopenia type II correlates with a worse outcome and higher risk of thromboembolic complications in aneurysmal subarachnoid hemorrhage patients. In addition, HIT II was strongly associated with the number of angiographic procedures performed during the same hospitalization.
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Affiliation(s)
- Ali Alaraj
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
| | - Adam Wallace
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
| | - Navneet Mander
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
| | - Victor Aletich
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
| | - Fady T. Charbel
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
| | - Sepideh Amin-Hanjani
- University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois
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Okamura T, Shin'oka T, Ishibashi N, Ishii H, Kurosawa H. Simultaneous use of argatroban and heparin during cardiopulmonary bypass. Asian Cardiovasc Thorac Ann 2010; 18:22-6. [PMID: 20124292 DOI: 10.1177/0218492309352034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Heparin is the routine anticoagulant for cardiopulmonary bypass, but complications due to heparin are often reported. This study assessed argatroban as an alternative to heparin. Normothermic cardiopulmonary bypass with hemodilution was performed for 2 h in 15 dogs (mean weight, 9.8 kg) randomly assigned to 3 groups of 5 each. The controls were given heparin 200 IU x kg(-1) before cardiopulmonary bypass; group A had argatroban infused continuously at a rate of 20 microg x kg(-1) x min(-1); group H/A had half doses of both heparin (100 IU x kg(-1)) and argatroban (10 microg x kg(-1) x min(-1)). Blood samples were collected at 5 time points during the experiment. Activated clotting time, hemoglobin level, platelet counts, and serum concentrations of fibrinogen, antithrombin III, and thrombin-antithrombin III complex were measured. The platelet count was reduced significantly, and the production of thrombin-antithrombin III complex was inhibited in group H/A. Activated clotting time remained <300 sec at all time points in group A, but it was maintained at approximately 400 sec in group H/A. Fibrinogen and antithrombin III levels were reduced to half in all groups after initiation of cardiopulmonary bypass. The simultaneous use of heparin and argatroban infusion might be useful for cardiopulmonary bypass with hemodilution.
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Affiliation(s)
- Toru Okamura
- Department of Cardiovascular Surgery, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjyuku, Tokyo 162-8666, Japan.
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15
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Geninatti M, Frouge C. Hard-hearted "HITT" to the heart (mural thrombus from heparin-induced thrombocytopenia with thrombosis syndrome). J Emerg Med 2009; 36:298-299. [PMID: 17961957 DOI: 10.1016/j.jemermed.2007.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 02/13/2007] [Accepted: 03/22/2007] [Indexed: 05/25/2023]
Affiliation(s)
- Marilyn Geninatti
- Department of Emergency Medicine, Paradise Valley Hospital, Phoenix, Arizona 85032, USA
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16
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Heparin-Induced Thrombocytopenia. AACN Adv Crit Care 2009; 20:5-9; quiz 10-1. [DOI: 10.1097/nci.0b013e318194351f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Hueser CN, Patel AJ. Intraoperative Thrombosis From a Heparin-Containing Irrigation Solution in a Patient With Heparin-Induced Thrombocytopenia. J Cardiothorac Vasc Anesth 2008; 22:797-9. [DOI: 10.1053/j.jvca.2007.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Indexed: 01/27/2023]
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18
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Demir M, Duran E, Yigitbasi O, Vural O, Kurum T, Yuksel M, Turgut B, Walenga JM, Fareed J. Incidence of antiheparin-platelet factor 4 antibodies and heparin-induced thrombocytopenia in Turkish patients undergoing cardiac surgery. Clin Appl Thromb Hemost 2007; 13:279-84. [PMID: 17636189 DOI: 10.1177/1076029607299987] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The frequency of antiheparin-platelet factor 4 antibodies by means of antigenic and functional assays ((14) C-serotonin release assay and citrated plasma platelet aggregation) was determined in 115 Turkish patients undergoing cardiac surgery. Blood samples were taken immediately before surgery and on days 5 and 10 +/- 2. Platelet counts were recorded and thrombotic events were determined by clinical methods. Antibody generation measured by enzyme-linked immunosorbent assay before surgery (n = 44) and on days 5 (n = 44) and 10 (n = 115) was 15.9%, 34.1%, and 65.2%, respectively. Positive samples from functional assays were 4.4% on day 0 and 7.0% on day 10. All positive samples had been negative on day 0. A high frequency of antiheparin-platelet factor 4 antibody generation and a low frequency of clinical heparin-induced thrombocytopenia were determined in these patients. These results obtained for Turkish patients are similar to those of other studies of heparin-induced thrombocytopenia.
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Affiliation(s)
- Muzaffer Demir
- Department of Hematology, Trakya University School of Medicine, Edirne, Turkey.
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19
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Mousa SA, Ahmad S. Platelet GPIIb/IIIa antagonist, XV459, in heparin-induced thrombocytopenia. Am J Hematol 2007; 82:276-82. [PMID: 17039513 DOI: 10.1002/ajh.20801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is a serious, immune-related complication of heparin therapy. One of the most severe manifestations of HIT is the development of thromboembolic events, which is based on platelet activation and aggregation caused by HIT-associated antibodies. Therapeutic options for patients with HIT are limited despite advancement toward the development of alternative (nonheparin) anticoagulants, such as direct thrombin inhibitors and indirect anti-factor Xa agents. Platelet GPIIb/IIIa receptor antagonists have been shown to be the final common pathway for platelet aggregation regardless of the use of activator or anticoagulant. In this study, the ability of a novel platelet GPIIb/IIIa antagonist, a free acid form of roxifiban (XV459), to block platelet activation/aggregation in response to highly characterized heparin-PF4 antibody-positive plasma/heparin was examined using light transmittance aggregometry, serotonin release, and (125)I-fibrinogen binding assays to human platelets. XV459 at 20 nM maximally inhibited (P < 0.001) the platelet-activation/aggregation responses as mediated by the HIT antibody-positive plasma (in the presence of therapeutic heparin concentrations). Compared with controls, both HIT antibodies/heparin and TEAC (a mixture of thrombin [0.1 IU/ml], epinephrine [1 microg/ml], arachidonate [0.1 mM], and collagen [10 microml]) resulted in significantly higher levels of fibrinogen binding to human platelets (5-7-fold increase; P < 0.001). Concentration-dependent profiles of XV459 on the mean percent inhibition of (125)I-fibrinogen binding in the presence of HIT antibodies and TEAC were achieved ( approximately 50% inhibition at 10 nM XV459). The platelet GPIIb/IIIa receptor antagonist (XV459) might be of potential benefit in the management of thrombotic thrombocytopenia produced by heparin and/or related glycosaminoglycans.
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Affiliation(s)
- Shaker A Mousa
- Pharmaceutical Research Institute, Albany College of Pharmacy, Albany, New York 12208, USA.
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Napolitano LM, Warkentin TE, Almahameed A, Nasraway SA. Heparin-induced thrombocytopenia in the critical care setting: Diagnosis and management^. Crit Care Med 2006; 34:2898-911. [PMID: 17075368 DOI: 10.1097/01.ccm.0000248723.18068.90] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Thrombocytopenia is a common occurrence in critical illness, reported in up to 41% of patients. Systematic evaluation of thrombocytopenia in critical care is essential to accurate identification and management of the cause. Although sepsis and hemodilution are more common etiologies of thrombocytopenia in critical illness, heparin-induced thrombocytopenia (HIT) is one potential etiology that warrants consideration. OBJECTIVE This review will summarize the pathogenesis and clinical consequences of HIT, describe the diagnostic process, and review currently available treatment options. DATA SOURCE MEDLINE/PubMed search of all relevant primary and review articles. DATA SYNTHESIS AND CONCLUSIONS HIT is a clinicopathologic syndrome characterized by thrombocytopenia (>/=50% from baseline) that typically occurs between days 5 and 14 after initiation of heparin. This temporal profile suggests a possible diagnosis of HIT, which can be supported (or refuted) with a strong positive (or negative) laboratory test for HIT antibodies. When considering the diagnosis of HIT, critical care professionals should monitor platelet counts in patients who are at risk for HIT and carefully evaluate for, a) temporal features of the thrombocytopenia in relation to heparin exposure; b) severity of thrombocytopenia; c) clinical evidence for thrombosis; and d) alternative etiologies of thrombocytopenia. Due to its prothrombotic nature, early recognition of HIT and prompt substitution of heparin with a direct thrombin inhibitor (e.g., argatroban or lepirudin) or the heparinoid danaparoid (where available) reduces the risk of thromboembolic events, some of which may be life-threatening.
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Affiliation(s)
- Lena M Napolitano
- Acute Care Surgery, Trauma, Burn, Critical Care, Emergency Surgery, Department of Surgery, University of Michigan Health System, Ann Arbor, MI, USA
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Hörl WH. [Thrombocytopathy and blood complications in uremia]. Wien Klin Wochenschr 2006; 118:134-50. [PMID: 16773479 DOI: 10.1007/s00508-006-0574-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 02/15/2006] [Indexed: 01/19/2023]
Abstract
Bleeding diathesis and thrombotic tendencies are characteristic findings in patients with end-stage renal disease. The pathogenesis of uremic bleeding tendency is related to multiple dysfunctions of the platelets. The platelet numbers may be reduced slightly, while platelet turnover is increased. The reduced adhesion of platelets to the vascular subendothelial wall is due to reduction of GPIb and altered conformational changes of GPIIb/IIIa receptors. Alterations of platelet adhesion and aggregation are caused by uremic toxins, increased platelet production of NO, PGI(2), calcium and cAMP as well as renal anemia. Correction of uremic bleeding is caused by treatment of renal anemia with recombinant human erythropoietin or darbepoetin alpha, adequate dialysis, desmopressin, cryoprecipitate, tranexamic acid, or conjugated estrogens. Thrombotic complications in uremia are caused by increased platelet aggregation and hypercoagulability. Erythrocyte-platelet-aggregates, leukocyte-platelet-aggregates and platelet microparticles are found in higher percentage in uremic patients as compared to healthy individuals. The increased expression of platelet phosphatidylserine initiates phagocytosis and coagulation. Therapy with antiplatelet drugs does not reduce vascular access thrombosis but increases bleeding complications in endstage renal disease patients. Heparin-induced thrombocytopenia (HIT type II) may develop in 0-12 % of hemodialysis patients. HIT antibody positive uremic patients mostly develop only mild thrombocytopenia and only very few thrombotic complications. Substitution of heparin by hirudin, danaparoid or regional citrate anticoagulation should be decided based on each single case.
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Affiliation(s)
- Walter H Hörl
- Klinische Abteilung für Nephrologie und Dialyse, Medizinische Universitätsklinik III, Medizinische Universität Wien, Austria.
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Tóth O, Szabó C, Kecskés M, Pótó L, Nagy A, Losonczy H. In vitro effect of the potent poly(ADP-ribose) polymerase (PARP) inhibitor INO-1001 alone and in combination with aspirin, eptifibatide, tirofiban, enoxaparin or alteplase on haemostatic parameters. Life Sci 2006; 79:317-23. [PMID: 16480745 DOI: 10.1016/j.lfs.2006.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 11/25/2005] [Accepted: 01/08/2006] [Indexed: 11/23/2022]
Abstract
It has been shown that PARP inhibition is protective in several models of ischemia-reperfusion injury including cardiac, cerebral and renal ones. Due to their ability to reduce myocardial necrosis and to improve myocardial function PARP inhibitors emerged as candidates for treating various cardiovascular diseases including acute myocardial ischemia. Since the pathophysiology of acute ischemic cardiac diseases involves haemostatic impairment and the therapeutic regimen includes antithrombotic drugs, we investigated the effect of the potent poly(ADP-ribose) polymerase (PARP) inhibitor INO-1001 alone and in combination with platelet aggregation inhibitors (aspirin, eptifibatide and tirofiban), unfractionated heparin, low molecular weight heparin (enoxaparin) or the recombinant fibrinolytic drug (alteplase), on various haemostatic parameters in vitro. ADP- and epinephrine-induced platelet aggregation was evaluated by optical aggregometry in the presence or absence of different concentrations of INO-1001, in combination with aspirin, tirofiban, eptifibatide or saline on ten healthy volunteers' platelet rich plasma (PRP). Activated partial thromboplastin time, Anti-Xa activity and euglobulin lysis time were determined in the presence or absence of different concentrations of INO-1001, in combination with sodium heparin, enoxaparin or alteplase, respectively. INO-1001, on its own does not affect the measured platelet, and haemostatic functions, i.e. does not reduce the respective anti-platelet, anti-coagulant and thrombolytic activity of therapeutically relevant concentrations of aspirin, tirofiban, eptifibatide, enoxaparin and alteplase in vitro. INO-1001 enhanced the effects of heparins above therapeutic ranges; the magnitude of this effect was negligible. Consequently, the PARP inhibitor INO-1001 can be safely applied together with the drugs tested.
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Affiliation(s)
- Orsolya Tóth
- 1st Department of Medicine, University of Pécs, Hungary, 13. Ifjúság út, Pécs, 7624 Hungary.
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Abstract
Heparin, employed clinically for more than 50 years, is still a widely used anticoagulant. Unfortunately, some patients given this agent develop thrombocytopenia and thrombosis. Because this side effect can have catastrophic consequences, it is imperative that all clinicians caring for patients who receive heparin have at least a basic understanding of its pathogenesis, diagnosis, and management.
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Affiliation(s)
- A Davoren
- The Blood Research Institute, Blood Center of Southeastern Wisconsin, Milwaukee, WI 53201-2178, USA
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Kannan M, Ahmad S, Ahmad F, Kale S, Hoppensteadt DA, Fareed J, Saxena R. Functional characterization of antibodies against heparin–platelet factor 4 complex in heparin-induced thrombocytopenia patients in Asian-Indians: relevance to inflammatory markers. Blood Coagul Fibrinolysis 2005; 16:487-90. [PMID: 16175007 DOI: 10.1097/01.mbc.0000178829.31902.0a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Occurrence of heparin-induced thrombocytopenia (HIT) was investigated for 33 Indian patients undergoing cardiovascular surgery who received unfractionated heparin (UFH). Platelet counts were performed prior to the initiation of UFH therapy and 5-16 days post therapy. Heparin-induced platelet aggregation, C-serotonin release assay, and enzyme-linked immmunosorbent assay (ELISA) tests were performed in all the patients to detect the antibodies formed against the complex of heparin and platelet factor 4 (HPF4). Levels of inflammatory markers/mediators such as CD40 ligand (CD40L) and C-reactive protein (CRP) were also measured in the patient plasmas utilizing ELISA tests. Based on clinical observations and laboratory diagnoses, five patients (15%) were considered to have confirmed HIT. Despite wide variations in the titers of inflammatory markers, patients who tested ELISA-positive for HPF4 antibodies showed markedly elevated levels of both soluble CD40L and C-reactive protein. Most strikingly, the C-serotonin release assay-positive patients showed up to a 10-fold increase in the level of CD40L. It is concluded that approximately 15% Asian-Indian patients receiving UFH during cardiovascular surgery develop functional HPF4 antibodies, which are associated with the increased levels of inflammatory markers/mediators in this catastrophic HIT syndrome.
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Affiliation(s)
- Meganathan Kannan
- All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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25
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Hoh BL, Aghi M, Pryor JC, Ogilvy CS. Heparin-induced Thrombocytopenia Type II in Subarachnoid Hemorrhage Patients: Incidence and Complications. Neurosurgery 2005; 57:243-8; discussion 243-8. [PMID: 16094152 DOI: 10.1227/01.neu.0000166539.02280.e5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
ABSTRACTOBJECTIVE:Heparin-induced thrombocytopenia Type II (HIT II) is the autoimmune-mediated severe form of the disease characterized by a significant reduction in platelets, and it carries a high risk of “paradoxical” serious thrombotic complications. Although HIT II has been studied in several different patient populations, the incidence of HIT II and the rate of thrombotic complications have never been reported in a neurosurgical patient population. Subarachnoid hemorrhage (SAH) patients, among neurosurgical patient populations, have a high exposure to heparin because they are in critical care units and have indwelling vascular catheters. In addition, the increase in neuroendovascular procedures with the associated use of heparinization will increase the exposure of SAH patients to heparin.METHODS:During a 3.5-year period (January 2000–June 2003), 389 consecutive SAH patients were treated at our center. We retrospectively reviewed their laboratory data and medical records and used accepted clinical criteria for the diagnosis of HIT II to determine the incidence of HIT II, thrombotic complications, management, and outcome.RESULTS:Fifty-nine patients (15%) met the clinical diagnostic criteria for HIT II. The average platelet count nadir in the HIT II patients was 68,600 ± 25,300/μl (mean ± standard deviation). Female patients and patients with Fisher Grade 3 were more likely to develop HIT II (P < 0.01). Thirty-six patients (61%) underwent a neuroendovascular procedure. The rate of systemic thrombotic complications in the HIT II patients was 37 versus 7% in SAH patients without HIT II (P < 0.001), and the rate of new hypodensities on head computed tomographic scans was 66% in the HIT II patients versus 40% in the SAH patients without HIT II (P < 0.001). Clinical outcomes were worse in the HIT II patients. The outcome was favorable for 38% in the HIT II patients versus 52% in all SAH patients (P < 0.05), and deaths were more common (29%) in the HIT II patients than in all SAH patients (12%, P < 0.001).CONCLUSION:The incidence of HIT II in SAH patients at a single center was 15%. The SAH patients with HIT II had significantly higher rates of thrombotic complications, new hypodensities on head computed tomographic scans, more deaths, and significantly less favorable outcomes. This is the first report of the incidence of HIT II in a neurosurgical patient population.
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Affiliation(s)
- Brian L Hoh
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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Valenstein PN, Walsh MK, Meier F. Heparin Monitoring and Patient Safety: A College of American Pathologists Q-Probes Study of 3431 Patients at 140 Institutions. Arch Pathol Lab Med 2004; 128:397-402. [PMID: 15043451 DOI: 10.5858/2004-128-397-hmapsa] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Context.—Appropriate laboratory monitoring of unfractionated heparin therapy promotes effective anticoagulation while minimizing hemorrhagic complications.
Objectives.—To measure heparin therapy monitoring in a “real-world” setting and to assess the degree of anticoagulation achieved.
Design.—One hundred forty institutions abstracted laboratory and pharmacy data from up to 30 inpatients receiving standard-dose unfractionated heparin therapy for 72 hours. Institutions also reported their therapeutic ranges and described heparin prescribing and monitoring policies.
Results.—Activated partial thromboplastin times or anti–factor Xa levels were measured at least once within the first 12 hours of administration for 95% of 3431 heparinized inpatients. Eighty-seven percent of patients had a platelet count performed within 72 hours of heparin administration. Seventy-eight percent of heparinized inpatients achieved therapeutic anticoagulation within 24 hours, but more than one third of patients entered the supratherapeutic range on at least 2 occasions during the first 72 hours. We found moderate variation in performance among the 140 institutions participating in the study, with more consistency in monitoring patients but less consistency in achieving therapeutic levels of anticoagulation. In one fourth of hospitals, more than half of the heparinized patients entered the supratherapeutic range on 2 or more occasions during the first 72 hours of therapy. None of 20 institutional practices we examined were meaningfully associated with more thorough monitoring of patients or with a higher percentage of patients achieving therapeutic anticoagulation. There was moderately wide variation in therapeutic ranges among the 140 sites.
Conclusions.—The prevention of heparin over-anticoagulation represents an important opportunity for improving patient safety in a significant number of institutions.
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Affiliation(s)
- Paul N Valenstein
- Department of Pathology, St Joseph Mercy Hospital, Ann Arbor, Mich 48106-0995, USA.
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Trask AS, Gosselin RC, Diaz JA, Dager WE. Warfarin Initiation and Monitoring with Clotting Factors II, VII, and X. Ann Pharmacother 2004; 38:251-6. [PMID: 14742761 DOI: 10.1345/aph.1d266] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To report a case of a patient with antiphospholipid antibody syndrome and multiple thromboses who developed heparin-induced thrombocytopenia (HIT) and subsequent international normalized ratio (INR) prolongation possibly due to antiphospholipid antibodies. CASE SUMMARY A 56-year-old white woman with a history of antiphospholipid antibody syndrome and thrombosis taking chronic warfarin was admitted for gastrointestinal concerns and found to have an INR >14. Warfarin was discontinued, vitamin K was administered, and a heparin infusion was initiated. Over the next 2 days, thrombocytopenia, hypotension, tachycardia, hyponatremia, and progressive abdominal pain developed. Upon transfer to a tertiary care center, HIT was diagnosed, and a lepirudin infusion was initiated. Subsequently, a sudden elevation of the INR occurred (>14) with low prothrombin (factor II) activity. After INR values declined to 2–3, warfarin was reinitiated with dosing adjusted using factor X and II activity levels. Clotting factors II and X activities were measured to monitor long-term warfarin therapy, with no evidence of complications after 7 months. DISCUSSION Typically, the INR is used to assess the intensity of anticoagulation. The INR value represents the reduction of clotting factors II, VII, and X. In rare circumstances, an independent inhibitor or interfering substance can interfere with the process of measuring the INR. In such situations, an alternative approach can be direct measurement of clotting factor concentrations. CONCLUSIONS Factor II and/or factor X activity levels provided an alternative means for measuring the anticoagulant effects of warfarin in the presence of a significant inhibitor (antiphospholipid antibodies) that biased the INR measurements.
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Affiliation(s)
- Ashley S Trask
- Department of Pharmacy, University of California Davis Medical Center, Sacramento, CA, USA
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Gobbi G, Mirandola P, Tazzari PL, Talarico E, Caimi L, Martini G, Papa S, Conte R, Manzoli FA, Vitale M. New laboratory test in flow cytometry for the combined analysis of serologic and cellular parameters in the diagnosis of heparin-induced thrombocytopenia. ACTA ACUST UNITED AC 2004; 58:32-8. [PMID: 14994373 DOI: 10.1002/cyto.b.10062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is a major complication of heparin therapy. A quick and reliable laboratory assay for the combined determination of pathogenic anti-heparin and platelet factor 4 (H:PF4) antibodies in the serum and platelet activation is not currently available. METHODS We developed a new single-tube assay in flow cytometry that combines the detection of antibodies in the serum and their activatory properties on platelets. The assay was tested on 13 serum samples from patients with suspected HIT and six samples from normal donors. The presence of anti-H:PF4 antibody complexes was detected by H:PF4-coated beads, and donor platelet activation induced by HIT sera was determined by Annexin V binding. All data were compared with the patients' clinical setting, laboratory tests, and standard enzyme-linked immunosorbent assay detection of anti-H:PF4 antibodies. RESULTS This flow cytometry assay allowed unequivocal, simultaneous detection of anti-H:PF4 antibodies in sera and their activatory properties on platelets. All cases for which the diagnosis of HIT was confirmed were detected by the flow assay. CONCLUSIONS This assay, combining for the first time functional and nonfunctional testing on anti-H:PF4 antibodies, is likely to influence the clinical decision for the management of HIT patients.
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Affiliation(s)
- Giuliana Gobbi
- Department of Anatomy, Human Anatomy Section, University of Parma, Parma, Italy
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29
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Coagulation Abnormalities in Stroke. Stroke 2004. [DOI: 10.1016/b0-44-306600-0/50040-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Ahmad S, Bacher HP, Lassen MR, Hoppensteadt DA, Leitz H, Misselwitz F, Walenga JM, Fareed J. Investigations of the immunoglobulin subtype transformation of anti-heparin-platelet factor 4 antibodies during treatment with a low-molecular-weight heparin (clivarin) in orthopedic patients. Arch Pathol Lab Med 2003; 127:584-8. [PMID: 12708902 DOI: 10.5858/2003-127-0584-iotist] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT It is now widely accepted that the pathophysiology of heparin-induced thrombocytopenia (HIT) syndrome is mediated by the generation of a wide array of functional and molecularly heterogeneous anti-heparin-platelet factor 4 (AHPF4) antibodies that may mediate platelet and/or endothelial cell activation/destruction. OBJECTIVE We investigated the differential prevalence and functionality of AHPF4 immunoglobulin subtypes (IgA, IgG, and IgM) in plasmas obtained from orthopedic patients immobilized with Plaster-Cast and treated with clivarin (a low-molecular-weight heparin) in comparison to a placebo for the prophylaxis of deep-vein thrombosis. DESIGN AND METHODS Clivarin was administered subcutaneously at a fixed daily dosage of 1750 U without any adjustment or loading dosage. Citrated plasmas were obtained at baseline, at 10 to 14 days, and at postbrace procedure (5-12 weeks). An enzyme-linked immunosorbent assay (ELISA) was used to quantitate the AHPF4 antibody titers. The functionality of the ELISA-positive samples was determined by a 14C-serotonin release assay (SRA). RESULTS In the ELISA test, 16 of 1073 samples (1.5%; 6 in clivarin and 10 in placebo groups) were positive for AHPF4 antibodies (mean optical density [OD] = 0.46 +/- 0.02). None of the ELISA-positive samples for AHPF4 antibodies could mediate platelet activation responses as determined by the SRA (0%-3% serotonin release, P >.10, n = 16). Through differential immunoglobulin subtype analysis of the samples positive for (cumulative) AHPF4 antibodies, we determined that their relative prevalence in plasma were as follows: IgM (mean OD = 0.71 +/- 0.13) > IgG (0.31 +/- 0.08) > IgA (0.14 +/- 0.02). Although there was no significant difference in the total antibody titers between clivarin and placebo groups, the antibody subtyping data showed conversion trends (ie, IgA [clivarin to placebo], IgG [placebo to clivarin], and IgM [clivarin to placebo]). CONCLUSION These observations indicate that even at reduced dosages, clivarin can shift the immunogenic up-regulation toward the IgG subpopulation; however, the IgG subtype is of a nonfunctional type of AHPF4 antibody and thus may not cause any HIT-related pathogenic responses.
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Affiliation(s)
- Sarfraz Ahmad
- Loyola University of Chicago, Stritch School of Medicine, Maywood, Ill, USA
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Abstract
OBJECTIVE To audit the frequency of heparinoid (standard heparin and low molecular weight heparin) use in a tertiary paediatric hospital, and to determine the occurrence of heparin-induced thrombocytopenia (HIT). METHODS A 1-week cross-sectional audit of all heparinoids given to inpatients at a tertiary paediatric hospital was undertaken and a retrospective medical record review of all suspected HIT cases at the tertiary paediatric centre over a 2-year period was carried out. RESULTS One hundred and sixteen patients received heparinoid medications over a 7-day period. An average of 29 children received heparin daily. The retrospective medical record review identified four patients with suspected HIT over a 2-year period. Two patients developed thrombotic complications, which were fatal in one patient. CONCLUSION Heparin is used frequently in paediatric tertiary hospitals, yet the occurrence of HIT in children is much lower than that reported in adults. Improved laboratory techniques could facilitate improved screening and diagnosis of this serious adverse drug reaction.
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Affiliation(s)
- F Newall
- Department of Haematology, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052, Australia
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Kieta DR, McCammon AT, Holman WL, Nielsen VG. Hemostatic analysis of a patient undergoing off-pump coronary artery bypass surgery with argatroban anticoagulation. Anesth Analg 2003; 96:956-958. [PMID: 12651640 DOI: 10.1213/01.ane.0000052381.47101.a2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPLICATIONS This case describes the impact of argatroban and off-pump coronary revascularization on hemostasis as assessed by conventional hemostatic measures and Thrombelastography in a patient with heparin-induced thrombocytopenia.
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Affiliation(s)
- Derek R Kieta
- Departments of *Anesthesiology and †Surgery, The University of Alabama at Birmingham
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Nguyen TN, Gal P, Ransom JL, Carlos R. Lepirudin use in a neonate with heparin-induced thrombocytopenia. Ann Pharmacother 2003; 37:229-33. [PMID: 12549954 DOI: 10.1177/106002800303700214] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE To describe a case of heparin-induced thrombocytopenia (HIT) in a premature infant and the doses of danaparoid and lepirudin needed to achieve appropriate therapeutic endpoints. CASE SUMMARY A 30-week gestational age infant was diagnosed with HIT with heparin antibodies. Danaparoid 2.0-2.4 units/kg/h achieved anti-Xa levels of 0.2-0.4 U/mL, but thrombocytopenia failed to resolve. Lepirudin was started in place of danaparoid. Lepirudin doses of 0.03-0.05 mg/kg/h achieved target activated partial thromboplastin time values of 1.5-2.0 times baseline. DISCUSSION Dosing information for danaparoid in neonates is limited, and information for lepirudin appears only in German literature at this time. HIT is well documented in newborns, and lepirudin use in these situations is likely to increase. This report provides some guidance for optimal dosing. It also provides some guidance for HIT evaluation in preterm infants, in whom blood volume for laboratory tests is a major issue. CONCLUSIONS HIT is an important and potentially fatal problem in neonates. Lepirudin may be the drug of choice, especially since danaparoid is now unavailable. Initial lepirudin dosing should not exceed 0.05 mg/kg/h.
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Affiliation(s)
- Thuy N Nguyen
- Neonatal Intensive Care, The Women's Hospital of Greensboro, Moses Cone Health System, Greensboro, NC 27401-1020, USA
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Abstract
Heparin-induced thrombocytopenia (HIT) is an important side effect of heparin therapy associated with significant morbidity and mortality if unrecognized. The platelet count typically falls below 150,000/ micro l 5-14 days after heparin is started. Thrombosis is the major clinical complication. The diagnosis is confirmed with a variety of functional and antigenic assays. Heparin binds to PF4, resulting in a conformational change in the molecule that exposes neo-epitopes that act as immunogens. Antibodies form against the heparin-PF4 complex, the major target antigen. The IgG-heparin-PF4 immune complex binds either via its Fab domain to the platelet surface or via its Fc domain to the FcgammaIIA receptor on the surface of the platelet, resulting in further platelet activation. Continued release of PF4 from activated platelets leads to increasing PF4-heparin complex formation, and a self-propagating cycle of platelet consumption and generation of procoagulant platelet-derived microparticles. Other procoagulant effects of the HIT antibody include endothelial cell damage, stimulation of platelet-leukocyte aggregates, and release of tissue factor from monocytes.
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Affiliation(s)
- Robert F Reilly
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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35
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Ahmad S, Haas S, Hoppensteadt DA, Lietz H, Reid U, Bender N, Messmore HL, Misselwitz F, Bacher P, Gaikwad BS, Jeske WP, Walenga JM, Fareed J. Differential effects of clivarin and heparin in patients undergoing hip and knee surgery for the generation of anti-heparin-platelet factor 4 antibodies. Thromb Res 2002; 108:49-55. [PMID: 12586132 DOI: 10.1016/s0049-3848(02)00397-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The pathophysiology of heparin-induced thrombocytopenia (HIT) syndrome is mediated via a heterogeneous group of heparin(s)-platelet factor 4 (H-PF4) complexes bound to their antibodies. These anti-H-PF4 (AHPF4) antibodies that are capable of binding to the FcgammaRIIA receptor [cluster of differentiation (CD) 32] on platelets, resulting in platelet activation, widely vary in their specific activities as platelet activation (functionality). Predisposing factors related to specific pathologic conditions may also contribute to the generation of these antibodies and their relative functionality during HIT syndrome. To understand this phenomenon, a sub-study was carried out in patients undergoing elective total hip and knee replacement surgery (ECHOS Study) and who were treated with unfractionated heparin (UFH) and a low-molecular-weight heparin (LMWH; Clivarin). Approximately 600 patients per arm [UFH=7,500 anti-Xa U twice a day (b.i.d.) subcutaneous (s.c.) and clivarin=4200 U once daily (o.d.) s.c.], age >40 years, received prophylactic treatment for a minimum of 11-14 days. Plasma samples were collected at pre-dose, days 2-4, days 11-14 and at follow-up 6-8 weeks after discharge and were analyzed for AHPF4 antibody titers. Functionality of the enzyme-linked immunosorbant assay (ELISA)-positive AHPF4 antibodies to cause platelet activation was tested by 14C-serotonin release assay (SRA). Both UFH and clivarin treatments in orthopedic surgical patients resulted in a progressive generation of AHPF4 antibodies. The relative prevalence/functionality of AHPF4 antibodies in clivarin arm was markedly lower (two- to threefold, p<0.001) as compared to UFH at each time point. Most of the samples in clivarin group were found to be SRA negative, suggesting the presence of AHPF4 antibodies that did not activate platelets (nonfunctional). Within the UFH arm, the relative prevalence/functionality of AHPF4 antibodies was much higher (p<0.002) in knee group compared to the corresponding hip group. This study, for the first time, reports on the elevated levels of AHPF4 antibodies generated by heparin associated with the pathogenesis of knee surgery. Clinical significance of the differential generation of HIT-associated antibodies remains unexplored at this time.
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Affiliation(s)
- Sarfraz Ahmad
- Cardiovascular Institute, Loyola University Chicago, Maywood, IL, USA
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Liautard C, Nunes AMC, Vial T, Chatillon F, Guy C, Ollagnier M, Descotes J. Low-molecular-weight heparins and thrombocytosis. Ann Pharmacother 2002; 36:1351-4. [PMID: 12196050 DOI: 10.1345/aph.1a461] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND A possible association between low-molecular-weight heparins (LMWHs) and thrombocytosis was suspected from spontaneous reports to the French Pharmacovigilance System. This association is not mentioned in LMWH's summary of product characteristics. METHODS All case records in the French Pharmacovigilance database were reanalyzed for relevance and causality, and the case/noncase approach was used including reports of thrombocytosis as cases and all other reports as noncases. RESULTS Fifty-one patients treated with LMWHs had platelet counts >500 x 10(3)/mm(3). All patients were asymptomatic, and 1 had a positive rechallenge. There were 143 cases of thrombocytosis among the 174 213 reports in the database, with 61 of 4644 involving LMWHs. The calculated relative reporting ratio is 27.5 (p < 0.0001; 95% CI 19.5 to 38.9). CONCLUSIONS There is a highly significant association of thrombocytosis reported with LMWH treatment.
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Affiliation(s)
- Christine Liautard
- Centre Antipoison, Centre de Pharmacovigilance, Hôpital Edouard Herriot, Lyon, France.
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37
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Abstract
Heparin-induced thrombocytopenia/thrombosis (HIT/T) is the most frequent cause of drug-induced antibody-mediated thrombocytopenia, a common cause of life-and limb-threatening platelet activation and thrombosis. Although antibodies to heparin-platelet factor 4 (PF4) complexes are found in essentially all patients with HIT/T, it is unclear how antibody formation is initiated, why only a small subset of these antibodies cause disease, or the mechanism by which they initiate thrombosis. The recent development of a transgenic mouse model of HIT/T showed, for the first time in vivo, that heparin, PF4, antibodies to the heparin-PF4 complex, and Fc gamma RIIA are necessary and sufficient to recapitulate the severe thrombocytopenia and thrombosis seen in patients. This model can be expanded to systematically study individual factors important to HIT/T development in vivo, to determine their contribution to the spectrum of human disease. Several recent papers have examined the role of other contributors, such as monocyte tissue factor, endothelial cell activation, and leukocyte-platelet aggregates in the pathogenesis of the disease. Mouse models will provide a means to test new diagnostic and therapeutic approaches.
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Affiliation(s)
- Michael P Reilly
- Cardeza Foundation for Hematologic Research and Division of Hematology, Department of Medicine, Thomas Jefferson University, 1015 Walnut Street - Room 705, Philadelphia, Pennsylvania 19107, USA.
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38
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Fabris F, Luzzatto G, Soini B, Ramon R, Scandellari R, Randi ML, Girolami A. Risk factors for thrombosis in patients with immune mediated heparin-induced thrombocytopenia. J Intern Med 2002; 252:149-54. [PMID: 12190890 DOI: 10.1046/j.1365-2796.2002.01021.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND As reported by major clinical series in the literature, about 2% of patients receiving unfractionated heparin (UFH) develop immune-mediated (type II) heparin-induced thrombocytopenia (HIT) that may be complicated in 30-75% of cases by a paradoxical thrombotic syndrome (HITTS), either arterial or venous. HITTS carries relevant rates of mortality and morbidity, amongst which cerebral and/or myocardial infarction and limb amputations. It is unclear as yet why some patients suffer from isolated thrombocytopenia (HIT), whilst others have HITTS. The aim of the present study was to look for clinical and laboratory features related to the occurrence of HITTS. PATIENTS AND METHODS We retrospectively analysed the clinical records of 56 patients with proven HIT, as diagnosed on clinical grounds and by in vitro demonstration of immunoglobulin (IgG)/IgM against the PF4/heparin complex. Thirty-four patients (61%) had HITTS (19 venous thrombosis, seven arterial thrombosis, five arterial and venous thrombosis, two skin necrosis, one diffuse intravascular coagulation), whereas 22 had uncomplicated HIT. Amongst HITTS patients, two had limb amputation, five had recurrent thrombosis and seven died. Amongst HIT patients three died from causes unrelated to HIT. RESULTS No significant difference in sex, age, previous exposure to heparin, UFH route of administration or dose, duration of therapy, time of onset of thrombocytopenia and platelet count recovery, nor antiheparin/PF4 antibodies subtype (IgG or IgM) was detected when comparing HIT and HITTS. In contrast, in the HITTS group a higher prevalence of orthopaedic surgery (15 of 34 vs. 2/22; P=0.01), a significantly lower platelet count nadir (43 +/- 32 vs. 75 +/- 63 x 109/L; P=0.01) and a significantly higher titre of antiheparin/PF4 antibodies, expressed as optical density of enzyme-linked immunosorbent assay (ELISA); (1989 +/- 1024 vs. 1277 +/- 858; P=0.009), were observed in comparison with the HIT group. Amongst HITTS patients, the prevalence of venous thrombosis was significantly higher in orthopaedic patients and in those being treated for venous thromboembolism (18/24 vs. 1/9 patients, chi2 8.4, P=0.004), whilst arterial thrombosis (ART) occurred more often in heparin treatment for arterial disease (3/4 vs. 4/29 patients, chi2 4.6, P=0.03). CONCLUSIONS Orthopaedic surgery, the severity of thrombocytopenia and high antiheparin/PF4 antibodies titre are adverse prognostic or concurrent factors in the development of HITTS.
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Affiliation(s)
- F Fabris
- Clinica Medica II, Department of Medical and Surgical Sciences, University of Padua Medical School, Padova, Italy.
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39
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Abstract
Heparin-induced thrombocytopenia (HIT) occurs in 1-5% of patients treated with heparin. The pathogenesis involves the formation of antibodies to heparin-platelet factor 4 complexes, and the major clinical sequelae are thrombotic. Diagnosis is based on a combination of clinical and laboratory data. Treatment consists of stopping heparin, but, insofar as the risk of thrombosis remains high, treatment by alternative antithrombotic agents is indicated. Most clinical experience has been with danaparoid sodium and hirudin. The use of low-molecular-weight heparins (LMWH) in subsequent HIT episodes has been described, but is not recommended, especially with the introduction of new agents, such as oral thrombin inhibitors and pentasaccharides, which are hoped to reduce the use of heparins and the occurrence of HIT.
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Affiliation(s)
- Yoav Goor
- Department of Internal Medicine 6, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, 6 Weizman Street, Tel-Aviv, 64239 Israel.
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40
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Iqbal O, Ahmad S, Lewis BE, Walenga JM, Rangel Y, Fareed J. Monitoring of argatroban in ARG310 study: potential recommendations for its use in interventional cardiology. Clin Appl Thromb Hemost 2002; 8:217-24. [PMID: 12361198 DOI: 10.1177/107602960200800304] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Argatroban is a peptidomimimetic synthetic direct thrombin inhibitor with reversible and specific properties resulting in predictable anticoagulant effects. Usually, argatroban therapy is monitored by the activated dotting time (ACT) or activated partial thromboplastin time (aPTT). While other global dotting tests for the monitoring of anticoagulants are useful, their applicability to antithrombin agents (particularly of argatroban at higher dosages) is rather questionable. In this study, we sought to compare the argatroban anticoagulant levels in patients undergoing percutaneous transluminal angioplasty (PTCA) and stenting procedures, utilizing both functional and absolute quantitation methods. Argatroban produced a comparable increase of ACT and HMT, 5 to 10 minutes after administration. The level of anticoagulation achieved (400-450 seconds with ACT and HMT) following a slow bolus of argatroban (350 microg/kg) was maintained throughout the procedure using 25 microg/kg/min infusion. Following discontinuation of argatroban at the end of the procedure, the ACTs and HMTs showed a comparable progressive reduction in the anticoagulant response, which reflected the elimination of argatroban 2 to 3 hours after the procedure. No significant differences between the three methods (Hemotec, Hemochron, and HMT) were noted at any given sampling time. Argatroban dosage at 350 microg/kg intravenous slow bolus followed by 25 microg/kg/min infusion was adequate to perform PTCA and stenting procedures. There was no incidence of bleeding complications. Absolute quantitation of argatroban levels in patient plasmas by a newly developed HPLC method was found to be quite comparable with the ecarin dotting time (ECT) results. The ECT system was found to be less sensitive when compared to other tests, and therefore, could be used as a point-of-care test during the PTCA/stenting procedures to monitor argatroban.
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Affiliation(s)
- Omer Iqbal
- Department of Pathology, Loyola University of Chicago, Maywood, Illinois, USA.
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41
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Abstract
Acute coronary syndromes encompass a spectrum of conditions, including myocardial infarction and unstable angina. These syndromes are related to the formation and disruption of atherosclerotic plaque. Rupture of plaque leads to thrombin generation, fibrin deposition, and platelet aggregation, ultimately resulting in restriction of blood flow and ischemia of cardiac tissue. Percutaneous coronary intervention (PCI), including angioplasty and coronary stent placement, has been developed to open occluded arteries. The frequency with which these procedures are performed speaks to their largely successful outcomes. However, the mechanical manipulations of PCI result in additional plaque rupture and damage to the vessel wall, exposing subendothelial components to blood and resulting in the initiation of the clotting cascade and in platelet activation. Left unchecked, these intertwined processes lead to formation of arterial thrombi at the site of endothelial damage, and potentially to abrupt vessel closure or embolization of thrombi into the distal microcirculation. Thrombin plays a central role in thrombus formation and platelet activation, and its inhibition significantly reduces thrombus-related sequelae. Current antithrombotic strategies during PCI are based on the traditional indirect thrombin inhibitor heparin. Heparin has several limitations in efficacy and safety, due in part to its indirect mechanism of action. Bivalirudin, a direct thrombin inhibitor, offers significant improvement over heparin in the clinical outcomes and risks associated with PCI.
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Affiliation(s)
- Ann K Wittkowsky
- Department of Pharmacy, University of Washington Medical Center, Seattle 98195, USA.
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42
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Untch B, Ahmad S, Messmore HL, Schultz CL, Ma Q, Hoppensteadt DA, Walenga JM, Fareed J. Development of a non-human primate sub-clinical model of heparin-induced thrombocytopenia: platelet responses to human anti-heparin-platelet factor 4 antibodies. Thromb Res 2002; 106:149-56. [PMID: 12182915 DOI: 10.1016/s0049-3848(02)00081-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to characterize the responses of human and non-human primate (Macaca mulatta) platelets to anti-heparin-platelet factor 4 (AHPF4) antibodies. Due to the variations observed in the functionality and immunoglobulin isotypes in patients with heparin-induced thrombocytopenia (HIT), we used highly characterized human AHPF4 antibodies to study platelet activation responses. Using ELISA and 14C-serotonin release assay (SRA) systems, three patients' plasmapheresis fluid with similar responses to these assays were pooled. This pool was then used to study the platelet activation responses of human and primate platelets in the HIT platelet aggregation assay, a flow cytometry assay, and a variation of the aggregation assay in which glycoprotein IIb/IIIa inhibitors were supplemented. In the plasmapheresis fluid from three patients, the most significant AHPF4 immunoglobulin isotype present (based on optical density readings) was IgG, with less IgM (p < 0.001) and IgA (p < 0.001). The SRA yielded equivalent platelet activation results in all three patients. Using this pool in the platelet aggregation assay, without any heparin present, there was less percent aggregation (p < 0.001) with human platelets (11.8 +/- 2.35, n = 5) compared to the primate platelets (54.3 +/- 10.2, n = 9). In presence of 0.4 U/ml heparin, both platelet types had similar percent aggregations (p > 0.05). Three glycoprotein IIb/IIIa receptor inhibitors were used to evaluate the similarities in platelet activation. Eptifibatide was found to be a strong inhibitor of both species' platelet types at concentrations greater than 0.01 microg/ml. This was not the case with tirofiban which inhibited both human and monkey platelets at concentrations greater than 0.025 microg/ml. Abciximab inhibited aggregation at concentrations greater than 6.25 microg/ml. These data indicate that phylogenetic similarities in platelets of humans and primates may be used to further characterize the pathophysiology of HIT syndrome.
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MESH Headings
- Abciximab
- Animals
- Antibodies, Monoclonal/pharmacology
- Antibody Specificity
- Autoantibodies/immunology
- Autoantibodies/pharmacology
- Blood Platelets/drug effects
- Blood Platelets/metabolism
- Eptifibatide
- Heparin/immunology
- Heparin/metabolism
- Heparin/toxicity
- Humans
- Immunoglobulin Fab Fragments/pharmacology
- Macaca mulatta
- Models, Animal
- Peptides/pharmacology
- Phylogeny
- Plasmapheresis
- Platelet Activation/drug effects
- Platelet Aggregation Inhibitors/pharmacology
- Platelet Factor 4/immunology
- Platelet Factor 4/metabolism
- Platelet Glycoprotein GPIIb-IIIa Complex/antagonists & inhibitors
- Purpura, Thrombocytopenic, Idiopathic/blood
- Purpura, Thrombocytopenic, Idiopathic/chemically induced
- Purpura, Thrombocytopenic, Idiopathic/immunology
- Purpura, Thrombocytopenic, Idiopathic/therapy
- Serotonin/metabolism
- Species Specificity
- Tirofiban
- Tyrosine/analogs & derivatives
- Tyrosine/pharmacology
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Affiliation(s)
- Brian Untch
- Department of Pathology, Stritch School of Medicine, Loyola University of Chicago, Maywood, IL 60153, USA
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43
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Abstract
Automated systems are currently in widespread use for the assessment of patients' complete blood counts. The evaluation of the peripheral blood smear, however, still constitutes a pivotal tool in the evaluation of patients with hematologic disorders. This article focuses on disorders affecting the number or morphology of platelets as assessed by evaluation of a peripheral blood smear and also outlines some of their important clinical findings.
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Affiliation(s)
- Alvaro Moreno
- Division of Hematology Oncology and Internal Medicine, Mayo Medical School, Jacksonville, Florida, USA.
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44
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Abstract
Heparin-induced thrombocytopenia (HIT) is the most important immunological drug reaction that patients face today. HIT typically develops in patients 5 days after starting heparin therapy, but can occur sooner with recent heparin exposure or rarely have a delayed onset. The platelet count typically drops below 150 x 10(9)/L (average 60 x 10(9)/L), and patients may experience a thrombotic episode simultaneously or shortly after the onset of thrombocytopenia. The thrombocytopenia and the associated thrombotic episodes are now considered to be overlapping outcomes of the same syndrome. The pathophysiology of HIT has been characterized: immune complexes of IgG and heparin in association with a small platelet peptide, platelet factor 4 (PF4), activate platelets by binding to the Fc receptors (FcR) and releasing procoagulant-active, platelet-derived microparticles. The recognition that HIT is characterized by intense thrombin generation dictates the use of antithrombin agents in HIT therapy. Therapeutic approaches that are currently prevalent in the management of HIT will be discussed.
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Affiliation(s)
- J G Kelton
- Department of Medicine, McMaster University Medical Center, Hamilton, Ontario, Canada.
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45
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Chern I, Sharma A, Dennis D. Concurrent use of reteplase and lepirudin in the treatment of acute anterior wall myocardial infarction. J Thromb Thrombolysis 2001; 12:185-91. [PMID: 11729371 DOI: 10.1023/a:1012931707016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A 61-year-old male with a history of severe heparin-induced thrombocytopenia (HIT) type II after aorto-femoral bypass surgery presented to the emergency department within 8 hours of development of substernal chest pain radiating to the left arm. Electrocardiogram (ECG) on arrival and at 3 hours showed no acute changes; cardiac enzymes revealed minimal MB elevation. Echocardiogram showed normal left ventricular systolic function with mild mitral and tricuspid regurgitation and trace aortic insufficiency. Five hours after arrival, the patient reported a recurrence of severe chest pain. ECG showed marked ST elevations consistent with acute myocardial infarction. Reteplase was administered with concomitant lepirudin. Follow-up ECG showed improvement in ST-segment elevation and eventual resolution to pre-event tracing; cardiac enzymes showed slight elevations. Catheterization revealed 90% midstenosis of the left anterior descending artery, which was successfully treated with percutaneous transluminal coronary angioplasty (PTCA) and stent placement. Repeat PTCA was performed 10 days postdischarge due to intraluminal stent occlusion. The patient was doing well at 6 months follow-up.
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Affiliation(s)
- I Chern
- Department of Emergency Medicine, Plantation General Hospital, 401 N.W. 42nd Avenue, Plantation, Florida 33317, USA
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46
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Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2001; 10:173-88. [PMID: 11499857 DOI: 10.1002/pds.547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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