Pregnant patients with visual symptoms, headaches, abdominal pain, or influenzalike. Hit does not induce bleeding paradoxical prothrombotic state 1 in 5000 patients 1 to 3% risk after cardiac surgery. A positive hit antibody was not required to enter this study, but samples obtained at presentation proved posi tive for heparin dependent platelet antibody by plate. Heparin induced thrombocytopenia hit is a serious complication of heparin therapy that has a high rate of morbidity thrombosis and amputation and mortality. Hit occurs in up to 5% of patients receiving unfractionated heparin ufh for. The adoption of low molecular weight heparins is one reason for the reduced incidence of. Heparin induced thrombocytopenia hit, even rare, is a lifethreatening, immunemediated complication of heparin exposure. The onset of clinical symptoms and laboratory changes is usually delayed 12 weeks after exposure to heparin. Hit predisposes to thrombosis the abnormal formation of blood clots inside a blood vessel because platelets release microparticles that activate thrombin, thereby.
American and british guidelines recommend therapeutic dose. Apr 24, 2020 the clinicopathological syndrome of heparin induced thrombocytopenia hit can present as isolated thrombocytopenia or in association with a thrombotic event. Data are presented relative to the day that argatroban was started day 0. Thrombocytopenia differential diagnosis falsely low platelet count in vitro platelet clumping caused by edtadependent agglutinins giant platelets common causes of thrombocytopenia pregnancy gestational thrombocytopenia, preeclampsia drug induced thrombocytopenia i.
An iv or central line that is flushed with heparin or coated with heparin. Heparin induced thrombocytopenia summary heparin induced thrombocytopenia hit is a known complication of heparin exposure. Aug 01, 2000 heparin induced thrombocytopenia hit is a wellknown complication of heparin therapy. Target population adult patients with suspicion or diagnosis of heparin induced thrombocytopenia key practice recommendations screening for. It is considered the most severe nonbleeding adverse reaction of heparin treatment and one of the most important adverse drug reactions. Administration of low molecular weight heparin lmwh is recommended for prophylaxis of venous thromboembolism in patients undergoing hip surgery. Heparin induced thrombocytopenia syndrome is an acquired potentially lifethreatening prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 bound to heparin or. Thrombocytopenia is a serious condition in which patients have a low platelet count. During the treatment with heparin and while being transitioned to warfarin, she developed arterial thrombosis. Treatment of heparininduced thrombocytopenia involves discontinuing heparin and starting a non heparin anticoagulant. Pdf heparin is widely used for the prevention and treatment of thrombotic and particularly cardiovascular disorders.
Pf4 antibodies and thus has a very low likelihood of causing, or exacerbating, hit. Heparin induced thrombocytopenia hit is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 pf4 and heparin. Heparin induced thrombocytopenia hit is a clinicopathological syndrome that occurs when heparin dependent, igg antibodies bind to heparin platelet factor 4 pf4 complexes to activate platelets and produce a hypercoagulable state. Hit is a clinicopathologic diagnosis where laboratory testing plays an essential role. Heparin induced thrombocytopenia and thrombosis is a severe immunemediated adverse drug effect caused by the igg antibodies to platelet factor4 heparin complexes. This complication of heparin is often confusing because in hit, heparin does the opposite of what it is supposed to do. General guidelines for prevention of heparin induced heparin thrombocytopenia. Heparininduced thrombocytopenia hit is the most important and most frequent drug induced, immunemediated type of thrombocytopenia. Hit predisposes to thrombosis because platelets release microparticles that activate thrombin, thereby leading to thrombosis. Physicians evidencebased clinical practice guidelines. Heparininduced thrombocytopenia hit is a serious complication of heparin therapy that has a high rate of morbidity thrombosis and amputation and.
Heparininduced thrombocytopenia with thromboembolic. Key clinical pointsheparin induced thrombocytopenia heparin induced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count valu. Thrombocytopenia following heparin administration can be associated with an immune reaction, now referred to as heparininduced thrombocytopenia. Heparin induced thrombocytopenia hit is an antibodymediated adverse drug reaction that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic limb necrosis necessitating limb amputation, acute myocardial infarction, and stroke. A 63yearold man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. However, not all thrombocytopenia is due to such system alterations. Immunemediated hit causes much lower platelet counts. Heparininduced thrombocytopenia and thrombosis syndrome hitts is an immunemediated response to the administration of heparin that results in lifethreatening thrombosis. Heparininduced thrombocytopenia type ii hit is a more serious autoimmune disease causing a low platelet count and paradoxical blood clotting. Overtreatment of heparin induced thrombocytopenia in the surgical icu continues even with recent increased caution encouraging a higher antiplatelet factor 4 heparin enzymelinked immunosorbent assay optical density threshold before initiating treatment. Hit is a transient, immunemediated adverse drug reaction in patients recently exposed to heparin that generally produces thrombocytopenia and often results in venous andor arterial thrombosis. In patients who have recent within 100 days exposure to heparin. The role of apixaban in the treatment of heparininduced. Its central feature is thrombocytopenia caused by antibody.
This article concludes with a concise table of clinical management questions and guidance recommendations to provide a quick reference for the practical management of. Treatment and prevention of heparin induced thrombocytopenia. Therefore, understanding and identifying the symptoms of hit are essential to ensure the best outcome for patients. The american college of chest physicians accp guidelines recommend. Heparininduced thrombocytopenia circulation aha journals. Been receiving low molecular weight heparin 40k daily since admission. Heparin induced thrombocytopenia adult inpatient clinical.
However, there have been three reported isolated cases of fondaparinux. Guidance for the practical management of the heparin. Heparin induced thrombocytopenia diagnosis and management theodore e. Diagnosis is essentially clinical and negative results of laboratory assays do not exclude the diagnosis. Overtreatment of heparininduced thrombocytopenia in the. Heparin induced thrombocytopenia thrombosis hitt is associated with a high morbidity and mortality. Hit is a severe prothrombotic condition, occurring with fractionated and. Heparin induced thrombocytopenia hit treatment page 1 of 7. The pathophysiological basis of hit results from the formation of an immunocomplex consisting of an autoantibody against platelet. Hit is usually an immune response which typically occurs 410 days after exposure to heparin. Heparininduced thrombocytopenia hit is an adverse drug reaction characterized by thrombocytopenia and a high risk for venous or arterial thrombosis. Scores of 4 to 5 indicate possible hit with potentially other causes. American society of hematology guidelines suggest that some agents may be preferred in certain circumstances, as follows.
In the past, a number of different anticoagulants have been used to treat hit in an attempt to prevent these complications. Heparininduced thrombocytopenia hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. Treatment options for heparininduced thrombocytopenia. It is associated with significant morbidity and mortality if unrecognized. Heparin induced thrombocytopenia hit is the development of thrombocytopenia a low platelet count, due to the administration of various forms of heparin, an anticoagulant. Failure of early heparin cessation as treatment for. The condition is caused by antibodies, usually of the igg class against a heparin platelet factor iv complex on the surface of platelets. We present a case of a patient who developed hit when she was treated for deep venous thrombosis dvt and pulmonary embolism with heparin. The risk of hit is greatest in those on treatment doses, but risk at. Pathogenic antibodies to pf4 heparin bind and activate cellular fc. Heparininduced thrombocytopenia symptoms, diagnosis and. For prophylaxis or treatment of thrombosis in adult patients with heparin.
Platelet factor 4 heparin antibody testing has a high negative, but low positive, predictive value. Heparin induced thrombocytopenia is a prothrombotic iatrogenic disorder induced by plateletactivating antibodies that target multimolecular complexes of platelet factor 4 and heparin. Heparininduced thrombocytopenia and thrombosis syndrome. This results in thrombocytopenia or thrombosis in temporal relation to a preceding heparin exposure. Dosing and administration, dosing in pediatric patients with heparin induced thrombocytopenia heparin induced thrombocytopenia and thrombosis syndrome 2. Heparininduced thrombocytopenia genetic and rare diseases. Essentials heparin induced thrombocytopenia hit is a thrombogenic condition that is dif. Heparin induced thrombocytopenia hit is a complication of heparin therapy and is characterized by two types.
Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight heparin. Heparininduced thrombocytopenia hit is a complication of. More stringent criteria should be used to determine when to order serologic. This cardiology patient page focuses on heparin induced thrombocytopenia hit, a complication of heparin therapy. Heparininduced thrombocytopenia hit is a wellknown complication of heparin therapy. In this context, heparin induced thrombocytopenia hit type ii is a complication of rare incidence but sometimes fatal outcome.
Heparin induced thrombocytopenia hit is a lifethreatening complication of exposure to heparin eg, unfractionated heparin, low molecular weight lmw heparin that occurs in a small percentage of patients exposed, regardless of the dose, schedule, or route of administration. Heparin induced thrombocytopenia hit is an antibodymediated adverse drug reac tion that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic limb necrosis necessitating limb amputation, acute myocardial infarction, and stroke. May 03, 2012 heparin induced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. Guidelines from the american college of chest physicians accp. Heparin induced thrombocytopenia or hit is defined as the clinical condition where an individual under heparin treatment suffers from thrombocytopenia. When thrombosis is identified the condition is called heparininduced thrombocytopenia and thrombosis. This results in thrombocytopenia andor thrombosis in temporal.
Fortunately, this is a rare complication of hit if it is detected promptly and managed with an alternative blood thinner. How we manage patients with heparin induced thrombocytopenia. Because the platelet count normalizes even with continued heparin therapy, it is not associated with increased thrombotic risk. Target population adult patients with suspicion or diagnosis of heparin induced thrombocytopenia key practice recommendations screening for hit 1. Heparin induced thrombocytopenia hit can present as arterial and venous thrombosis in adults who are treated with heparin. It is important as a healthcare worker to recognize the signs of heparin induced thrombocytopenia hit as treatment should begin before the laboratory confirms the diagnosis. Diagnosis of hit heparin induced thrombocytopenia should be suspected if the platelet count decreases by 50%. This algorithm has been developed for md anderson using a multidisciplinary approach considering circumstances particular to md andersons specific patient population, services and structure, and clinical information. Heparin induced thrombocytopenia kettering health network. Heparininduced thrombocytopenia heparininduced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count value after the start of heparin, an onset 5 to 10 days after the start of heparin, hypercoagulability, and the presence of heparindependent, plateletactivating igg.
Heparin induced thrombocytopenia and thrombosis syndrome hitts is an immunemediated response to the administration of heparin that results in lifethreatening thrombosis. Heparin induced thrombocytopenia is an intensely procoagulant disorder and carries significant morbidity and mortality. Heparininduced thrombocytopenia hit is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 pf4 and heparin. Heparin induced thrombocytopenia hit is defined as a decrease in platelet count shortly after starting heparin, which resolves after stopping heparin and has no other apparent cause. Hit usually occurs after you are treated with heparin.
We can better understand the disease by knowing what are heparin and thrombocytopenia. The most commonly used intravenous anticoagulant is heparin. Heparininduced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. The pathophysiology of hitts remains controversial. Duration of anticoagulation therapy for hit is based on concurrence of thrombosis. Riia on platelets and monocytes to propagate a hypercoagulable state culminating in lifethreatening thrombosis. Free igg antibodies bind specific receptors on platelets called the fc. Heparin induced thrombocytopenia hit treatment page 1 of 7 disclaimer. Feb 03, 2020 heparin induced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood. Heparininduced thrombocytopenia hit has three characteristic features that can distinguish it from other causes of thrombocytopenia. Mild thrombocytopenia occurring within four days of starting heparin is the result of a direct effect of heparin. However, the elevations in serum aminotransferases are characteristically. In the past, a number of different anticoagulants have been used to treat hit in an.
The most common form of hit occurs 510 days after treatment with heparin was started. Heparininduced thrombocytopenia rn continued education. Demographic, clinical, and laboratory findings were compared in patients by whether heparin treatment was stopped early 48 hours after the onset of thrombocytopenia, as well as between patients with and without thrombosis. Heparininduced thrombocytopenia type ii occurs in 15% of patients started on heparin. Treatment and prevention of heparininduced thrombocytopenia. Heparin induced thrombocytopenia hit is a clinicopathological syndrome that occurs when heparin dependent igg antibodies bind to heparin platelet factor 4 complexes to activate platelets and produce a hypercoagulable state.
The 4ts scoring system is a screening tool that accurately rules out hit. American college of chest physicians evidencebased clinical practice guidelines. Heparininduced thrombocytopenia hit is a serious complication of heparin therapy that has a high rate of morbidity thrombosis and amputation and mortality. Hit can be viewed as an acquired hypercoagulability disorder, with increased thrombin generation in vivo, and increased risk for arterial and, especially. Hit is caused by the formation of abnormal antibodies that activate platelets. Heparininduced thrombocytopenia treatment algorithm. Heparin is widely used for thromboprophylaxis or treatment in many clinical situations, including cardiovascular and orthopaedic surgery and invasive procedures, acute coronary syndromes, venous thromboembolism, atrial fibrillation, peripheral occlusive disease, dialysis, and during extracorporeal circulation. Warkentin, md h eparin induced thrombocytopenia hit is an adverse drug reaction characterized by thrombocytopenia and a high risk for venous or arterial thrombosis. The following guideline is intended to guide the management of heparin induced thrombocytopenia and includes recommendations for diagnosis and treatment agents. First is the timing of the onset of thrombocytopenia. This is the case with heparin induced thrombocytopenia, or hit. Heparin induced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up to 5 percent of patients exposed, regardless of the dose, schedule, or route of administration.
Heparininduced thrombocytopenia is the development of thrombocytopenia, due to the administration of various forms of heparin, an anticoagulant. Pdf heparininduced thrombocytopenia hit is the most important and most frequent. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compared with 225,000 per cubic millimeter at the time of discharge nine days earlier. Activated platelets, vascular endothelium, and monocytes generate the lifethreatening thrombocytopenia and thrombosis. This can occur due to certain disease processes such as alterations in the immune system or with leukemia. Hit is characterized by a plateletcount fall of more than 50% at 5 to 10 days after the start of heparin and hypercoagulability. Treatment involves stopping all heparin immediately and giving an alternative thrombin inhibitor. Heparininduced thrombocytopenia hit is a clinicopathological syndrome that occurs when heparindependent, igg antibodies bind to heparin platelet factor 4 pf4 complexes to activate platelets and produce a hypercoagulable state. Heparininduced thrombocytopenia what you need to know. Heparininduced thrombocytopenia hit natalie s evans. Sample sizes varied from 18 to 119 patients across the days. Heparininduced thrombocytopenia in a nonheparinnaive.
Pathogenic antibodies to pf4heparin bind and activate cellular fc. This patient had a severe form of heparin induced thrombocytopenia hit and developed gangrene of the toes and foot related to blood clots. Treatment involves therapeuticdose anticoagulation. Hit is essentially a prothrombotic disorder mediated by an igg antiplatelet factor 4 heparin antibody, which induces platelet, endothelial cell, monocyte, and other cellular activation, leading to thrombin generation and thrombotic complications. Heparininduced thrombocytopenia type i is harmless, causing a mild and transient reduction in platelet count. Heparin induced thrombocytopenia hit is a syndrome of platelet activation, thrombocytopenia, and thrombosis that occurs in 15% of patients who receive heparin. Heparininduced thrombocytopenia blood american society of. Heparin induced thrombocytopenia hit is an autoimmune reaction to heparin which results in thrombocytopenia. Triggered by the immune system in response to heparin, hit causes a low. Heparin induced thrombocytopenia thrombosis hitt syndrome.
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