Hypercoagulation and thrombosis

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

Effect of aspirin-dipyridamole and heparin and their combination on venous thrombosis in hypercoagulable or thrombotic animals

Epsilon-amino-caproic acid (EACA) induces a clinically-useful anti-haemorrhagic, mildly thrombotic state while ellagic acid (EA) induces a severe hypercoagulable one. Reversal of these states may on occasion be necessary. The effectiveness of the antiplatelet drugs, aspirin and dipyridamole (ASA/D), in reducing thrombus weight was studied in normocoagulable animals and animals made hypercoagulable with EACA (333mg/kg) or EA (1.2mg/kg). Heparin (114iu/kg) was tested in the EACA group, both alone and in combination with ASA/D. Thrombogenicity was measured by weight formed on intravenous platinum wire in one hour. In normocoagulable animals, ASA/D reduced thrombus by 32%. Ellagic acid trebled mean thrombus weight and ASA/D reduced this by 49%, but did not restore normality. EACA increased mean thrombosis by one sixth. Treatment with heparin reduced this by 48% to a level well below that of untreated animals. Addition of a single dose of aspirin/dipyridamole to the heparin regime, reduced thrombosis by a further 31%, reaching to 21% of control thrombus. The results were statistically significant. Kaolin-activated blood clotting time was shortened by EA, but EACA had little effect on it, while ASA/D slightly and heparin markedly lengthened it.

Abnormal coagulation profile in brain tumor patients during surgery

Neurosurgical patients are at high risk for the development of thrombosis and thromboembolism. We compared the perioperative clotting factor and coagulation parameters of 20 patients undergoing elective craniotomy for brain tumors to those of 20 patients undergoing elective abdominal surgery. We also measured the levels of plasma arginine vasopressin to determine if changes in this hormone might be associated with changes in clotting factors, activated partial thromboplastin times, or bleeding times. The results demonstrated a significant reduction in partial thromboplastin times and bleeding times in the neurosurgery group, which began at the initiation of surgery and lasted to the end of the study (12 h postoperatively). Elevations in factor assays and plasma arginine vasopressin occurred in both groups during surgery, but there were no differences between the neurosurgical and abdominal surgical patients, except with Factor IX levels, which were elevated only in the neurosurgical patients. Serum osmolality and hemoglobin levels were significantly higher in the neurosurgical cohort. These results suggest that there are hemostatic differences between neurosurgical patients with brain tumors and abdominal surgery patients that cannot be explained solely by elevations in plasma arginine vasopressin or the clotting factors measured; these differences may be the consequence of perioperative variables such as dehydration and hyperosmolality.

Postoperative venous thromboembolism and brain tumors: Part III. Biochemical profile

The plasminogen activator activity of 31 human brain tumor samples was assessed and the results correlated with clinical parameters and the postoperative occurrence of venous thrombosis. A significant negative correlation was found between plasminogen activator activity and venous thrombosis (P = 0.02), while positive correlations were observed between plasminogen activator activity and peritumoral brain edema (P = 0.03) and alpha 2 antiplasmin measured in the systemic circulation (P = 0.01). Tissue plasminogen activator was found in higher concentrations in meningioma tissue but did not correlate significantly with the occurrence of venous thrombosis. The results of this study suggest a local enzymatic degradation effect of plasminogen activator on thrombogenic substances present in the brain tumor and/or its environment.

Superficial thrombophlebitis. I. Primary hypercoagulable states

This review concentrates on those disorders in which superficial thrombophlebitis can be a significant or presenting clinical sign. Primary hypercoagulable states are those conditions associated with an increased risk of thrombosis caused by a specific measurable defect in the proteins of coagulation and/or fibrinolytic systems. These disorders are frequently inherited and include deficiencies of antithrombin III, heparin cofactor 2, protein C, protein S, abnormal fibrinolytic activity, dysfibrinogenemia, and Hageman trait. Patients with a lupus anticoagulant and anticardiolipin antibody syndrome with thrombotic episodes are also considered to have a primary hypercoagulable state. The physiology, pathophysiology, clinical characteristics, and treatment of primary hypercoagulable states are reviewed.

Drugs used for disorders of coagulation

Bleeding and thrombosis are altered states of hemostasis. Inhibition of normal hemostatic mechanisms results in spontaneous hemorrhage, whereas excessive hemostasis results in thrombus formation. The drugs used to prevent and treat thrombosis and those used to arrest bleeding are the subjects of this article.

Detection of hypercoagulability by the measurement of the dynamic loss modulus of clotting blood

The dynamic loss modulus of clotting whole blood was measured in thrombotic patients to characterize the physical properties of coagulation in the hypercoagulable state. The dynamic loss modulus was measured by a Sonoclot. Thrombotic patients consisted of 30 with deep vein thrombosis and 25 with arterial thrombosis. An accelerated increment rate of the dynamic loss modulus at the beginning of gelling was the characteristic of hypercoagulability. This characteristic occurred more frequently than other abnormalities in other tests for hypercoagulability (beta-thromboglobulin, antithrombin III and TEG). Only in deep vein thrombosis, a moderately positive correlation was noted between the increment rate of the dynamic loss modulus and the plasma fibrinogen level.

Survival in a heat stroke victim with a core temperature in excess of 46.5 C

Presented is a case report of a 52-year-old male heat stroke victim. The patient presented in deep coma with a temperature above 42 C. Following rapid assessment, the patient was intubated, rehydration was begun, and he was externally cooled with ice bags and internally cooled with ice water gastric lavage. After 25 minutes the patient's core temperature was measured at 46.5 C (115.7 F). Multiple organ system failure developed over the ensuing days. With aggressive care, the patient improved dramatically and was discharged at prior baseline status on the 24th day of hospitalization. This case now represents the highest human body temperature elevation reported without permanent residua.

Antithrombin III deficiency in a Chinese family

Familial antithrombin III deficiency, which is inherited by autosomal dominant transmission, is now well recognized as a cause of recurrent venous thromboembolism. Many such families have now been described, but few came from Asia. This report details a Chinese kindred with three members living in Sydney, two of whom are affected.