肝素诱导性血小板减少症亚心诊疗要点

肝素诱导性血小板减少症是由IgG抗体介导的促血栓形成性免疫性疾病。临床表现为肝素治疗后数天至数月发生血小板减少计数（与肝素治疗前相比）减低与伴或不伴新发血栓,呈现高凝与血栓矛盾状态。发病隐蔽,死亡率高。这为临床诊疗带来极大挑战。本文根据武汉亚洲心脏病医院185例疑似HIT患者的诊疗数据结合最新欧美HIT管理指南汇集成以下疑似HIT诊疗思路,降低HIT患者不良事件发生率。     

肝素诱导性血小板减少症诊疗策略

<正>肝素诱导性血小板减少症(heparin-induced thrombocytopenia,HIT)是指临床使用肝素类药物治疗后出现血小板计数降低,且机体处于易栓状态,不伴或伴有新发血栓的一类患者。如未经治疗,高于50%患者将在数天或数周内发生血栓,及时治疗将明显降低血栓并发症[1,2]。因此,临床早期诊断极为重要。本文主要介绍HIT的临床表现及早期诊断策略的新进展。发病机制与流行病学HIT是肝素治疗的严重并发症之一。肝素在体内与血小板4因子结合形成血小板4因子-肝素     

心脏手术围术期肝素诱导的血小板减少症

肝素诱导的血小板减少症(HIT)是肝素治疗引起的严重并发症之一,是一种免疫介导的血栓形成前疾病,它与血栓形成密切相关,在围术期能及时的诊断和治疗非常有意义.发病机制主要与肝素-血小板因子4抗体介导的免疫反应有关,实验室抗体检测结合临床有助于早期诊断.而替代性药物抗凝治疗是治疗HIT的有效措施.     

肝素诱导的血小板减少症

接受抗凝剂治疗或预防栓塞的病人,最常使用肝素,而肝素诱导的血小板减少症(heparin-inducedthrombocytopenia,HIT)是肝素治疗的并发症,此并发症与肝素预期的治疗效果相反。1什么是HIT?通常,肝素预防血栓栓塞,不影响血小板,由于肝素触发免疫系统,HIT导致血小板数降低(血小板减少症)。HIT可出现2种明显的类型:非免疫和免疫介导。非免役介导HIT:最常出现,血小板数轻微减少,对身体无害。免疫介导HIT:较少出现,但很危险。免疫介导HIT引起血小板数明显降低,但尽管血小板数很低,HIT病人仍有栓塞的危险。病人使用肝素后,在肝素和特殊的血…     

急性冠脉综合征伴发肝素诱导的血小板减少症4例

肝素是临床上常用的抗凝剂,广泛应用于心血管介入、血管外科和血液透析等方面,并发症也被大家所熟知,包括出血、骨质疏松、过敏反应和血小板减少。但肝素诱导的血小板减少症（HIT）还未引起人们的重视。HIT是由肝素类物质诱导的免疫反应,临床表现为自相矛盾的血小板减少和血栓栓塞并发症,是一种后果严重的药物不良反应。我院2010年～2012年心血管内科收治了急性冠脉综合征伴发HIT患者4例。     

肝素诱导血小板减少导致下肢、脑、肝、脾、肾多器官栓塞

肝素诱导血小板减少症(heparin induced thrombocytopenia, HIT)是一种由肝素引起的并发症。HIT 可以导致血栓形成,出现动脉和/或静脉栓塞。我们报道一例少见的HIT伴血栓栓塞病例。患者,男性,48岁,因急性心肌梗死接受肝素治疗后并发肝素诱导的血小板减少,随后并发下肢、脑、肝、脾、肾等多个部位和器官血栓栓塞。经过及时调整治疗方案,停用肝素,改为阿加曲班和华法林抗凝治疗,逆转了病情,避免了病情进一步的恶化。     

肝素诱导的血小板减少症研究进展

肝素诱导的血小板减少（HIT）是一种由肝素诱导、免疫介导的以血小板减少和血栓形成为主要特征的药物不良反应,具有一定的致残和致死风险,死亡发生率约为5％～10％.临床研究发现,约1％～5％接受肝素治疗的患者会在应用肝素5～10天后出现HIT[1].目前临床上尚未得到充分重视,极易漏诊、误诊.我们对近年来HIT的发生机制、临床表现、诊断和治疗进展作一综述.     

二尖瓣置换术后肝素诱导性血小板减少症的诊治体会

<正>肝素诱导性血小板减少症(heparin induced thrombocytopenia,HIT)是临床使用肝素治疗的不良反应之一,由抗血小板4因子-肝素复合物(PF4-H)抗体所介导的高血栓风险性疾病[1,2]。约占所有接受肝素患者的0.5%~5.0%,HIT相关性病死率高达5%~10%[2]。对于HIT患者,一方面血小板计数较低,出血风险较高;另一方面处于高凝高血栓风险状态,需要积极抗凝,预防血栓形成[3],这给临床医生带来极大诊疗困惑。现将我院诊治HIT1例报道如下。     

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肝素诱导的血小板减少症(HIT)的常见表现包括轻中度血小板减少和静脉或动脉的血栓栓塞,后者是HIT的主要死亡原因。及时诊断和正确治疗HIT可明显降低不良预后的危险。目前我们亟待提高对HIT的认识,改善HIT的诊断方法。     

急性冠状动脉综合征患者PCI围术期肝素或替罗非班诱导血小板减少症的临床观察及干预分析

目的:探讨急性冠状动脉综合征患者在经皮冠状动脉介入治疗(PCI)围术期发生肝素或替罗非班诱导血小板减少后的临床变化、干预效果及预后。方法:连续入选郑州大学第一附属医院2016年1月1日—2019年12月30日收治的118例急性冠状动脉综合征PCI围术期发生血小板减少的患者,根据纳入与排除,纳入78例患者,分为替罗非班诱导的血小板减少(TIT)组(48例)和肝素诱导的血小板减少(HIT)组(30例),比较最低血小板计数、血小板降低幅度、院内出血事件和随访期主要心脑血管不良事件(MACCE);根据TIT组和HIT组患者发生血小板减少后是否使用激素和(或)免疫球蛋白再分为治疗组和非治疗组两个亚组,比较亚组间血小板恢复时间和MACCE发生率。结果:TIT组最低血小板计数显著低于HIT组[18(4,60)×10~9/L∶57(32,84)×10~9/L,P=0.004],TIT组血小板降低幅度显著高于HIT组[90.74(74.18,98.30)%∶71.78(53.34,81.76)%,P=0.001];院内两组患者均未发生大出血事件;随访6个月内缺血事件HIT组明显高于TIT组(P=0.048);中位随访16个月,Kaplan-Meier生存分析显示两组远期MACCE发生率差异无统计学意义(Log-rank P=0.097);HIT组内治疗组和非治疗组血小板恢复时间、随访6个月内缺血事件和中位随访16个月MACCE发生率差异无统计学意义(P0.05);TIT组内治疗组较非治疗组血小板恢复时间更长[5(1,6) d∶4(2,7) d,P=0.014],随访6个月内缺血事件和中位随访16个月MACCE发生率两个亚组比较差异无统计学意义(P0.05)。结论:肝素和替罗非班均能导致严重血小板减少,替罗非班的血小板减少程度更重;与替罗非班相比,肝素明显增加患者近期缺血风险,二者对患者远期预后影响无明显差异;激素和(或)免疫球蛋白治疗对血小板恢复无改善作用,也不能改善患者的预后。     

Heparin-induced thrombocytopenia: a review

Immune heparin-induced thrombocytopenia (HIT) is a relevant adverse drug reaction consisting in a hypercoagulable state caused by an anticoagulant agent. The incidence is approximately 6.5% in patients receiving unfractionated heparin after orthopedic surgery, and is equal to or lower than 1% in other settings. HIT occurrence is a function of heparin type, duration of heparin administration, patient population, and gender. The pathogenesis is due to an antibody response to the complex heparin/platelet factor 4 in most cases, with secondary activation of platelets and coagulation, and finally increased thrombin generation. Thrombocytopenia, venous or arterial thrombosis, heparin-induced skin necrosis, adrenal hemorrhage, and transient amnesia can characterize the clinical course of HIT. Platelet monitoring in patients receiving heparin is indicated to early detect HIT. A thrombotic event can be the first manifestation of HIT. Laboratory demonstration of heparin-dependent platelet activation confirms the clinical diagnosis; antigenic or functional assays are available. Once HIT is highly likely or confirmed serologically, immediate heparin cessation is mandatory and an alternative therapeutic anticoagulant is needed due to the high risk (or the presence) of thrombotic events. The available nonheparin anticoagulants aim to reduce thrombin generation. Lepirudin, argatroban, and bivalirudin (direct thrombin inhibitors) and danaparoid and fondaparinux (factor Xa inhibitors) represent the current treatment options for HIT. Vitamin K antagonists can be used safely only after a stable platelet count has been obtained.     

The use of direct thrombin inhibitors in cardiovascular surgery in patients with heparin-induced thrombocytopenia

One of the most important adverse drug reactions that physicians encounter is the life- and limb-threatening prothrombotic syndrome known as heparin-induced thrombocytopenia (HIT). Unfractionated heparin (UFH), administered during cardiopulmonary bypass (CPB), is highly immunogenic. Heparin-dependent antibodies can develop in 25 to 50% of UFH-treated cardiac surgery patients within 5 to 10 days. These antibodies can activate platelets and are considered the causative agents of HIT. HIT is a relatively common complication, occurring in 1 to 3% of cardiovascular surgery patients when UFH administration is continued postoperatively. It is strongly associated with new thromboembolic events leading to limb amputation and death. In acute or recent (< 100 days) HIT, alternative anticoagulatory regimens are needed during CPB surgery for prevention of HIT-related thrombosis. Treatment options for such patients now generally include the use of alternative anticoagulants such as lepirudin, bivalirudin, or danaparoid, as well as a combined treatment with platelet-function inhibitors and heparin. In patients with a history of HIT and no detectable antibodies, heparin is currently the safest approach for high-dose anticoagulation during CPB. Before and after surgery, however, alternative anticoagulants should be used. The risk of clinical HIT after heart surgery could potentially be reduced by using low-molecular-weight heparins for postsurgery anticoagulation.     

Gouty tophi in the bone marrow

Heparin induced thrombocytopenia (HIT) remains a rare, but significant, condition related to mortality and morbidity. The incidence has decreased with reduced use of unfractionated heparin, with the exception of cardiac surgery. Due to the high risk of thrombosis, a switch to a non‐heparin anticoagulant is required, until platelet counts normalize. Within the acute setting, argatroban, fondaparinux and direct acting oral anticoagulants (DOACS) are therapeutic options. In patients with HIT‐associated thrombosis or who require long‐term anticoagulation, warfarin remains the preference, but DOACs are attractive alternatives.     

Heparin-induced thrombocytopenia in intensive care patients

Heparin-induced thrombocytopenia (HIT) is a serious, prothrombotic, immune-mediated complication of heparin therapy that can cause limb- and life-threatening thromboembolic events. Prompt diagnosis and therapeutic dose anticoagulation by an alternative anticoagulant are crucial to improve clinical outcome. In critically ill patients, the diagnosis of HIT is difficult due to the high incidence of thrombocytopenia, often caused by reasons other than HIT, and the high incidence of clinically irrelevant, non-platelet-activating anti-PF4-heparin antibodies. Also, treatment of HIT is problematic in these patients. No antidote is available for any of the alternative anticoagulants, and their half-lives are often prolonged in the presence of renal or hepatic insufficiency. This increases the risk of bleeding complications and mandates careful balancing of both risks, thrombosis and bleeding. Therefore, accurate diagnosis of HIT and individual choice of alternative anticoagulant are important for the adequate management of critically ill HIT patients.     

Heparin-induced thrombocytopenia

Opinion statement Treatment with heparin is associated with two types of thrombocytopenia. The most worrisome of these is the immune-mediated heparin-induced thrombocytopenia (HIT type II). Suspicion of HIT type II mandates immediate cessation of heparin adminis-tration and consideration of an alternative anticoagulation therapy. Hirudin and argatroban are approved alternative anticoagulants with no cross-reactivity with the HIT antibody. HIT type II is a clinicopathologic syndrome, and therefore diagnosis requires clinical and laboratory confirmation. The laboratory evaluation for HIT type II should also determine whether or not there is HIT-antibody cross-reactivity with danaparoid and low molecular weight heparin. Patients with HIT type II who require coronary artery bypass graft surgery present a particularly difficult situation, as there is no ideal alternative to heparin anticoagulation.     

Heparin induced thrombocytopenia

This article describes the pathogenesis, diagnostics, treatment and prevention of heparin induced thrombocytopenia (HIT). Although HIT is considered to be a hematological diagnosis, every physician who treats patients with heparin can encounter it in daily practice. It is even more probable that surgeons of any specialisation will meet with HIT patients. A section of them elude diagnostic detection. There are two forms of HIT - HIT I and HIT II. HIT I is caused by a direct pro-aggregation effect of heparin. It has no clinic significance. HIT II is an antidote mediated adverse reaction to heparin. Antidotes will generate only after the exposure to heparin. They are targeted against the platelet factor 4 and they act only at the presence of heparin. They may lead to the aggregation of thrombocytes in the vascular system (there is a decrease in thrombocyte count). This event can be accompanied by a development of venous or arterial thrombosis that can have a rapid and even fatal course. This fact clarifies the importance of HIT II diagnostics. Diagnosis of HIT II is based on recognizing of the typical decrease in thrombocyte count usually 1 day after heparin administration is initiated. Clinical manifestations are more likely in patients with already damaged endothelium. If thrombocyte count decrease is not connected with clinical manifestations, it is the so called isolated HIT II and in patients who display the signs of thrombosis, it is HIT II associated with thrombosis. The goal of this article is apart from implementing the recommendations of the 7th conference of the American Respiratory Society in real life also the exploration of the diagnostic and therapeutic limits (availability) in the Czech Republic.     

Heparin-induced thrombocytopenia: an update

Heparin-induced thrombocytopenia (HIT) is an immune response to heparin that can progress to severe thrombosis, amputation, and in some cases death. The diagnosis and treatment of HIT is complex, but needs to be considered in the clinical management of patients exposed to heparin due to its serious outcomes. Early diagnosis based on a comprehensive interpretation of clinical and laboratory information improves clinical outcomes. This begins with careful monitoring for thrombocytopenia and thrombosis during and for at least 5 to 10 days after heparin treatment of any dose and duration. Appropriate use and knowledgeable interpretation of laboratory tests for HIT are important, as these vary in sensitivity and specificity, with each type providing unique information. Clinical management of patients with HIT is with a non-heparin anticoagulant such as a direct thrombin inhibitor or danaparoid followed by a vitamin K antagonist for long-term treatment. Important drug-specific limitations, dosing, and monitoring guidelines must be respected for patient safety. There continues to be new developments in the field of HIT: laboratory testing, clinical scoring systems, and available new anticoagulants. Research and clinical studies will continue to address the unresolved issues and unmet clinical needs associated with HIT. This review summarizes the clinical management of HIT.     

Antithrombotic therapy in heparin-induced thrombocytopenia: guidelines translated for the clinician

Heparin-induced thrombocytopenia (HIT) is a clinicopathologic syndrome initiated by heparin exposure and characterized by thrombocytopenia and paradoxical thrombophilia. HIT is mediated by the formation of antibodies against the platelet factor 4/heparin complex, which leads to platelet activation, thrombin generation, and potentially fatal thrombotic sequelae. The clinical presentation of HIT is variable and can be easily overlooked. Although a number of functional and antigen-based immunoassays have been developed to detect the presence of HIT antibodies, initial diagnosis is often based on recognition of thrombocytopenia in the appropriate clinical context and later confirmed with immunologic testing. Given the serious clinical consequences of HIT, immediate cessation of heparin products and administration of non-heparin anticoagulants are crucial components of treatment. We provide a review of the clinical syndrome and practical summary of treatment recommendations from the most recent 2012 American College of Chest Physicians evidence-based guidelines for the treatment and prevention of HIT.     

Current agents for the treatment of patients with heparin-induced thrombocytopenia

Several counterintuitive treatment paradoxes complicate the management of immune heparin-induced thrombocytopenia (HIT). For example, simple discontinuation of heparin often fails to prevent subsequent HIT-associated thrombosis. Thus, current treatment guidelines recommend substituting heparin with a rapidly acting alternative anticoagulant (eg, danaparoid, lepirudin, or argatroban) even when HIT is suspected on the basis of thrombocytopenia alone ("isolated HIT"). Another paradox-coumarin (warfarin) anticoagulation-can lead to venous limb gangrene in a patient with HIT-associated deep-vein thrombosis. Thus, warfarin is not recommended during acute thrombocytopenia secondary to HIT. However, warfarin can be given as overlapping therapy with an alternative anticoagulant, provided that (1) initiation of warfarin is delayed until substantial platelet count recovery has occurred (to at least above 100 x 10(9)/L); (2) low initial doses of warfarin are used; (3) at least 5 days of overlapping therapy are given; and (4) the alternative agent is maintained until the platelet count has normalized. It has recently been recognized that HIT antibodies are transient and usually do not recur upon subsequent re-exposure to heparin. This leads to a further paradox-patients with previous HIT can be considered for a brief re-exposure to heparin under exceptional circumstances; for example, heart surgery requiring cardiopulmonary bypass, if HIT antibodies are no longer detectable using sensitive assays. For patients with acute or recent HIT who require urgent heart surgery, other approaches include use of alternative anticoagulants (eg, lepirudin or danaparoid) for cardiopulmonary bypass or antiplatelet agents (eg, tirofiban or epoprostenol) to permit intraoperative use of heparin.     

Vascular surgery using argatroban in a patient with a history of heparin-induced thrombocytopenia.

For patients with a history of heparin-induced thrombocytopenia (HIT) who undergo cardiac or vascular surgery, the optimal anticoagulation substitute for heparin has yet to be established. Recombinant hirudin has been recommended; however, this agent is unsuitable for patients with renal dysfunction. Argatroban was used in the present patient who had a history of HIT and renal dysfunction and required peripheral vascular surgery. Argatroban was easy to monitor and control, regardless of renal function, and has advantages over other anticoagulants for such patients.