Disorders of Hemostasis

BACKGROUND: Patients with heparin-platelet factor 4 (PF4) antibodies, particularly platelet-activating ones, are at risk for heparin-induced thrombocytopenia if administered heparin. We determined the heparin-PF4 antibody prevalence in emergency department (ED) patients presenting with chest pain or symptoms of thrombosis. METHODS: Admission samples from 324 ED patients with chest pain or symptoms of thrombosis were tested for heparin-PF4 antibodies and, if positive, platelet-activating antibodies...

INTRODUCTION: Up to 5% of patients who receive heparin develop heparin allergy (HA), manifested by the presence of heparin antibodies (HAb) and/or the clinical syndrome of heparin-induced thrombocytopenia. As many as 10% of patients with HA develop serious thrombotic complications when reexposed to heparin. Heparin is often given empirically to emergency department (ED) patients, some of whom have been recently hospitalized and are at risk for HA/heparin-induced thrombocytopenia. Emergency department physicians should have a rapid means of determining which patients are at risk for heparin sensitivity...

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse drug reaction caused by heparin. As thrombocytopenia is common in hospitalized patients receiving heparin, it would be useful to have a clinical scoring system that could differentiate patients with HIT from those with other reasons for thrombocytopenia. AIM: To compare prospectively the diagnostic utility of a clinical score for HIT in two different clinical settings. METHODS: The pretest clinical scoring system, the '4 T's', was used to classify 100 consecutive patients referred for possible HIT in one hospital (Hamilton General Hospital, HGH) into high, intermediate, and low probability groups...

In contrast with extensive documentation in patients treated with unfractionated heparin (UFH), the incidence of heparin-induced thrombocytopenia (HIT) in medical patients receiving low-molecular-weight heparin (LMWH) is less well defined. In a prospective cohort study, the platelet count was monitored in 1754 consecutive patients referred to 17 medical centers and treated with LMWH for prophylaxis or treatment of thromboembolic disorders. The diagnosis of HIT was accepted in case of a platelet drop of at least 50%, the absence of obvious explanations for thrombocytopenia, and the demonstration of heparin-dependent IgG antibodies...

Heparin-induced thrombocytopenia (HIT) is an uncommon but potentially devastating complication of anticoagulation with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). Our objective was to determine and compare the incidences of HIT in surgical and medical patients receiving thromboprophylaxis with either UFH or LMWH. All relevant studies identified in the MEDLINE database (1984-2004), not limited by language, and from reference lists of key articles were evaluated. Randomized and nonrandomized controlled trials comparing prophylaxis with UFH and LMWH and measuring HIT or thrombocytopenia as outcomes were included...

Delayed-onset heparin-induced thrombocytopenia is a syndrome in which thrombocytopenia and thrombosis begin several days after heparin discontinuation. Delayed-onset heparin-induced thrombocytopenia is caused by immunoglobulin G antibodies that are reactive against the heparin-platelet factor 4 complex in the absence of circulating heparin. We describe 2 patients with delayed-onset heparin-induced thrombocytopenia who presented to the emergency department. An 88-year-old man and a 62-year-old man experienced thrombocytopenia and thrombosis 9 or more days after heparin cessation and demonstrated a further decrease in platelet count on reexposure to heparin...

Easy bruising and bleeding are not only characteristic manifestations of clotting and platelet disorders, they are also prominent features in some heritable collagen disorders, such as the Ehlers-Danlos syndromes (EDS). The EDS comprise a heterogeneous group of connective tissue diseases sharing clinical manifestations in skin, ligaments and joints, blood vessels and internal organs. Most EDS subtypes are caused by mutations in genes encoding the fibrillar collagens type I, III and V, or in genes coding for enzymes involved in the post-translational modification of these collagens...

We describe 3 patients who presented to the emergency department (ED) with stroke, deep venous thrombosis, or pulmonary embolism and renal failure after undergoing cardiac surgery 7 to 17 days earlier. Their onset of thrombosis after previous heparin exposure was temporally plausible for complications of heparin-induced thrombocytopenia, an immune-mediated thrombotic disorder triggered by heparin. The patients had normal platelet counts at presentation, yet each had circulating heparin-induced thrombocytopenia antibodies that were ultimately confirmed...

Whereas bleeding is the most frequent adverse event encountered in patients receiving glycoprotein (GP) IIb/IIIa inhibitors, there are currently no recommendations for how to treat such patients. The present study tested the hypothesis that infusion of desmopressin (DDAVP) reverses the in vitro platelet dysfunction induced by GPIIb/IIIa inhibitors (+l-aspirin). Study group 1 (10 healthy volunteers) received a DDAVP infusion to establish dose-response curves for the in vitro inhibition of platelet function by eptifibatide, abciximab, and tirofiban together with l-aspirin before and after DDAVP...

BACKGROUND: Platelet-mediated arterial occlusion is a well-recognized cause of limb loss in patients with heparin-induced thrombocytopenia. However, the syndrome of distal ischemic necrosis complicating the deep venous thrombosis (venous limb gangrene) sometimes associated with heparin-induced thrombocytopenia has not been well characterized. OBJECTIVE: To study the pathogenesis of venous limb gangrene associated with heparin-induced thrombocytopenia. DESIGN: Characterization (based on descriptive and case-control studies) of a novel syndrome of limb loss and hypothesis testing by analysis of plasma samples...

PURPOSE: To determine the sites of thromboses (venous versus arterial circulation) that complicate the clinical course of immunemediated heparin-induced thrombocytopenia, and to determine the 30-day risk for thrombosis in patients who are initially recognized with isolated heparin-induced thrombocytopenia. PATIENTS AND METHODS: We analyzed objectively documented thrombotic events that complicated the clinical course of 127 patients with serologically confirmed heparin-induced thrombocytopenia identified in one medical community over a 14-year period...

Excessive bleeding caused by aspirin therapy in patients undergoing coronary artery bypass surgery is an increasing problem. This case report of six patients illustrates the benefits of using desmopressin to control aspirin-induced coagulopathy. A brief review of the mechanism of coagulation disturbances associated with aspirin and its correction by desmopressin is presented.

In a randomized double-blind cross-over trial we gave either 1-deamino-8-D-arginine vasopressin or placebo to 12 patients with uremia, hemorrhagic tendencies, and prolonged bleeding times. After vasopressin infusion, all patients had shortened bleeding times, with the effect lasting for at least four hours in most cases. Platelet count, platelet cyclic AMP levels, platelet retention on glass beads, plasma fibronectin, serum thromboxane B2 and residual prothrombin, hematocrit, and plasma osmolarity were unchanged after vasopressin...