Antithrombotic therapy in deep vein thrombosis and pulmonary embolism

After 50 years of clinical use anticoagulants are still the mainstay of treatment for venous thromboembolism. Several studies have demonstrated that failure to attain or to maintain an adequate anticoagulant effect with heparin after venous thromboembolism is associated with an increased risk of recurrence. The safety and effectiveness of heparin administered by continuous intravenous infusion has been compared with administration by intermittent intravenous injection; three studies reported less bleeding with the former. The relative efficacy and safety of continuous intravenous and intermittent subcutaneous heparin appear to be comparable. The readily available and relatively inexpensive activated partial thromboplastin time test is used most commonly to monitor heparin therapy. Recent audits indicate that current practices in the administration of heparin are often suboptimal because of an inadequate starting dose, a delay in obtaining or responding to activated partial thromboplastin time test results, or inappropriate adjustments of heparin doses. Attempts have recently been made to improve practices in the administration of heparin by developing a standardization protocol. Recommendations for patient management are discussed.