Delayed-onset heparin-induced thrombocytopenia. A potentially malignant syndrome

Delayed-onset thrombocytopenia developed in 12 patients while they were receiving either prophylactic or therapeutic heparin. Five of the patients had thrombocytopenia alone, and seven had thromboembolic complications which contributed to the death of one patient. These complications included deep venous thrombosis (four patients), pulmonary embolism (three patients), myocardial infarction (one patient), sagittal sinus thrombosis (one patient), and femoral artery occlusion (one patient). The diagnosis of heparin-induced thrombocytopenia was delayed for between one and 13 days after the initial complicating event. All patients had heparin-dependent platelet-aggregating factor in their plasma. The characteristics of the heparin-dependent platelet-aggregating reaction were the same in all patients, but the nadir of thrombocytopenia was lower in patients with delayed-onset heparin-induced thrombocytopenia and complicating thromboembolism. These findings highlight the necessity for early recognition of this syndrome and for the prompt withdrawal of heparin to prevent considerable patient morbidity.     

肝素诱导的血小板减少症的临床观察

目的 分析静脉血栓栓塞症肝素诱导的血小板减少症及其治疗.方法 对我院2006年5月至2008年5月临床确诊并以肝素抗凝治疗的静脉血栓栓塞症患者202例进行临床分析,定期监测血常规.结果 其中有6例患者发生肝素诱导的血小板减少症,在应用肝素第3～9天出现血小板数目下降,发生率为2.97%,其下降率为60.4%～82.2%.对需要继续抗凝的4例患者停用肝素后改为阿加曲班继续治疗,第3～7天血小板数目回升至入院时水平.结论 在使用肝素进行抗凝治疗期间,应常规监测血小板数目变化,如发现血小板数目进行性下降大于50%,应及时停用肝素,需继续抗凝的患者可改用阿加曲班治疗.     

A rare case of arterial thrombosis due to heparin-induced thrombocytopenia

A 78-year-old man presented with an eight-hour history of chest distress. Electrocardiograph and serum cardiac enzymes were suggestive of acute inferior myocardial infarction with right ventricular infarction. The patient, who underwent emergency percutaneous coronary intervention, suffered from thrombocytopenia presenting with cerebral infarction and myocadial reinfarction during haparin exposure. The laboratory test for heparin-induced thrombocytopenia (HIT) specific antibodies (heparin-platelet factor, PF4) was positive. The case was diagnosed as arteries thrombosis due to heparin-induced thrombocytopenia; the patient died after cessation of heparin.

     

低分子肝素诱导的血小板减少症 1 例临床用药分析

1例74岁的男性患者,因“双下肢动脉粥样硬化闭塞症”行“左髂动脉、左胭动脉支架成形术”后出现急性肾功能衰竭,行连续性肾脏替代治疗（CRRT）过程中血小板计数从93×10^9／L降至8×10^9／L,并伴有下肢发绀,临床药师果断判定患者的血小板减少伴血栓形成与CRRT过程中所用的抗凝剂低分子肝素高度相关,建议将低分子肝素更换为阿加曲班继续抗凝治疗。3d后患者血小板回升至正常,下肢发绀症状明显改善。此病例提醒医务工作者虽然低分子肝素较之肝素较少引起肝素诱导的血小板减少症,但在低分子肝素的临床使用中,尤其用于CRRT体外抗凝时,不要忽视其诱导血小板减少症的不良反应。     

4 例复杂先天性心脏病术后并发肝素诱导的血小板减少症患者的监测

2013年7月至2015年2月中南大学湘雅医院心脏大血管外科收治的复杂先心病接受心脏直视手术的患者中有 4例先后出现肝素诱导的血小板减少症(heparin-induced thrombocytopenia,HIT),通过严密动态监测血小板计数,观察 HIT所致的栓塞性皮肤损伤情况,监测阿加曲班用药效果等综合治疗,3例痊愈,1例死亡。HIT是接受肝素治疗出现 的罕见的严重并发症,栓塞发生率和病死率较高。早期识别、早期诊断高风险人群可以有效改善预后。     

Acute aortic occlusion in a patient with heparin-induced thrombocytopenia treated by thrombectomy

Introduction

Heparin-induced thrombocytopenia syndrome (HITS) is an infrequent complication of heparin anticoagulation.

Case report

We present the case of a 44-year-old male who was admitted with acute ischaemia of his right lower limb. He was initially treated with unfractionated heparin and thrombolysis, but subsequently developed acute aortic thrombosis 8 days following initiation of heparin therapy. This was treated with bilateral per-femoral thrombectomy with curative result.

Conclusion

This case report draws the attention of surgeons to the difficulties in diagnosing HITS and highlights the multidisciplinary management of a complicated case of acute ischaemia.     

Thrombolytic therapy in acute pulmonary embolism due to heparin-induced thrombocytopenia type II

Hospitalized patients are in danger of deep venous thrombosis either due to a genetic tendency, immobilization or the underlying medical condition. Paradoxically heparin, the substance used to prevent this complication, can lead to thrombo-embolic phenomena, which can be life threatening. We report a case of heparin-induced thrombocytopenia, which caused a massive pulmonary embolism, and its management by administering a thrombolytic agent in a situation where bleeding seems inevitable.     

缓痛经，冶过敏，助瘦身 让你大吃一惊的蜂蜜小用途

爱因斯坦说,如果蜜蜂从地球上消失,人类将最多再存活4年。蜜蜂周身都是宝,尤其是兼具滋润及养颜功效的蜂蜜,除了众所周知的润肠通便、美容护肤、解除疲劳、提高免疫力等,还有很多鲜为人知的健康妙用——     

酶联免疫吸附法检测抗肝素/血小板因子4复合物抗体的临床意义

目的：评价酶联免疫吸附法（ELISA）检测抗肝素/血小板因子4复合物抗体对临床诊断肝素诱导的血小板减少症（HIT）的敏感性及特异性。方法：选取应用肝素制剂患者197例（男120例、女77例）,ELISA法进行HIT抗体检测,并根据临床4Ts评分法分析其敏感性和特异性。结果：临床诊断HIT患者6例,ELISA法检测HIT抗体对诊断HIT的敏感性为83.3%,特异性为90.0%,阳性预测值为20.8%,阴性预测值为99.4%。结论：4Ts评分系统仍是目前临床诊断HIT的重要依据,HIT抗体的检测对HIT诊断的敏感性及特异性较好、可用于辅助诊断HIT。     

阿加曲班防治肝素致血小板减少症诱发的血栓综合征4例临床观察

目的 观察阿加曲班对4例肝素致血小板减少症的抗凝疗效。方法 对临床确诊并以肝素进行抗凝治疗的202例静脉血栓栓塞症患者进行临床分析,定期监测血常规及凝血指标,以确定是否发生血小板减少症的不良反应。对其中4例肝素致血小板减少症患者,停用肝素,给以阿加曲班治疗,20 mg/d,治疗3～7 d。结果 4例肝素致血小板减少症患者换用阿加曲班后,血小板水平恢复至入院时水平,没有发生血栓综合征,同时患者下肢肿痛症状缓解速度快、疗效好。结论 阿加曲班可替代肝素,有效预防肝素致血小板减少症继发的血栓综合征。     

Pathophysiology, epidemiology, diagnosis and treatment of heparin-induced thrombocytopenia (HIT)

Due to the widespread use of unfractionated (UFH) and low molecular weight heparins (LWH) for prophylaxis and treatment of thrombosis, heparin-induced thrombocytopenia is considered to be the most frequent (and potentially the most devastating) drug-induced thrombocytopenia. Induced by an immune response, excessive activation of platelets and endothelium cells causes massive thrombin generation and, as a result, life-threatening venous and arterial thrombotic vessel occlusion. The rate of mortality and amputation in HIT II is estimated to be 30% and 20%, respectively. The clinical course of HIT II depends highly on early therapeutic intervention consisting of immediate interruption of heparin application and, most important, of compatible thrombin inhibition. All measures implying a potentially procoagulant risk such as begin of oral anticoagulation or platelet substitution may result in disastrous side effects.     

The impact of the heparin-induced thrombocytopenia (HIT) computerized alert on provider behaviors and patient outcomes

Objective

The aim of this study was to measure the effect of an electronic heparin-induced thrombocytopenia (HIT) alert on provider ordering behaviors and on patient outcomes.

Materials and Methods

A pop-up alert was created for providers when an individual''s platelet values had decreased by 50% or to <100 000/mm³ in the setting of recent heparin exposure. The authors retrospectively compared inpatients admitted between January 24, 2008 and August 24, 2008 to a control group admitted 1 year prior to the HIT alert. The primary outcome was a change in HIT antibody testing. Secondary outcomes included an assessment of incidence of HIT antibody positivity, percentage of patients started on a direct thrombin inhibitor (DTI), length of stay and overall mortality.

Results

There were 1006 and 1081 patients in the control and intervention groups, respectively. There was a 33% relative increase in HIT antibody test orders (p=0.01), and 33% more of these tests were ordered the first day after the criteria were met when a pop-up alert was given (p=0.03). Heparin was discontinued in 25% more patients in the alerted group (p=0.01), and more direct thrombin inhibitors were ordered for them (p=0.03). The number who tested HIT antibody-positive did not differ, however, between the two groups (p=0.99). The length of stay and mortality were similar in both groups.

Conclusions

The HIT alert significantly impacted provider behaviors. However, the alert did not result in more cases of HIT being detected or an improvement in overall mortality. Our findings do not support implementation of a computerized HIT alert.     

Rifampicin-induced thrombocytopenia.

Rifampicin occasionally causes thrombocytopenia when given as part of an intermittent regimen. A case is reported of severe thrombocytopenia developing after one dose of rifampicin, following a 4-month gap in daily therapy. The literature on rifampicin-induced thrombocytopenia is reviewed.     

Chlorpropamide-induced thrombocytopenia.

Thrombocytopenia is a rare complication of chlorpropamide therapy. An immunological mechanism is generally held responsible, but has never previously been proved. In the present case the existence of such a mechanism has been established.     

Alternative diagnosis to heparin-induced thrombocytopenia in two critically ill patients despite a positive PF4/heparin-antibody test

Abstract

Thrombocytopenia can cause diagnostic challenges in patients who have received heparin. Heparin-induced thrombocytopenia (HIT) is often considered in the differential diagnosis, and a positive screening can be mistaken as confirmation of the disorder. We present two patients who both received low-molecular-weight heparin for several days. In the first patient, clinical judgment rejected the suspicion of HIT despite a positive screening assay, and treatment for the alternative diagnosis of post-transfusion purpura was correctly initiated. In the second patient, the inaccurate diagnosis HIT was pursued due to a positive screening assay, while the alternative diagnosis of drug-dependent thrombocytopenia caused by piperacillin/tazobactam was rejected. This resulted in re-exposure to piperacillin/tazobactam which caused a second episode of severe thrombocytopenia. A positive screening assay for platelet factor 4/heparin-antibody should be verified by a functional assay, especially in patients with low pretest probability for HIT.