Seminars in vascular medicine
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The requirement for a safe diagnostic strategy should be based on an overall posttest incidence of venous thromboembolism (VTE) of less than 1% during 3-month follow-up. The negative predictive value (NPV) during 3 months of follow-up is 98.1 to 99% after a normal venogram, 97 to 98% after a normal compression ultrasonography (CUS), and > 99% after serial CUS testing. Serial CUS testing is safe but 100 CUS must be repeated to find one or two CUS positive for deep vein thrombosis (DVT), which is not cost-effective and indicates the need to improve the diagnostic workup of DVT by the use of clinical score assessment and D-dimer testing. ⋯ A normal perfusion lung scan and a normal rapid ELISA VIDAS D-dimer test safely excludes PE. Helical spiral computed tomography (CT) detects all clinically relevant PE and a large number of alternative diagnoses in symptomatic patients with suspected PE and can replace both the ventilation perfusion scan and pulmonary angiography to safely rule in PE and to rule out PE with an NPV of > 99%. The combination of clinical assessment, a rapid ELISA VIDAS D-dimer, followed by CUS will reduce the need for helical spiral CT by 40 to 50%.
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Recent advances in the management of patients with suspected venous thromboembolism have both improved diagnostic accuracy as well as made management algorithms safer and more accessible. It is now clear that determination of clinical probability prior to diagnostic testing will improve patient management. ⋯ Imaging test interpretation benefits from consideration of pretest probability also as this helps clinicians determine when a test may be falsely negative or falsely positive. Diagnostic strategies should include pretest clinical probability, D-dimer assays, and noninvasive imaging tests.
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Review Case Reports
Ximelagatran in the clinic: practical management of patients.
Several case studies are briefly introduced, followed by a description of the clinical problem from an epidemiological point of view. The evidence for established management strategies is reviewed and, finally, practical handling of the case is considered.
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Patients undergoing major lower-extremity orthopedic surgery such as total hip replacement (THR) and total knee replacement (TKR) are at an increased risk of venous thromboembolism (VTE). Routine prophylaxis is necessary to reduce the risk of deep vein thrombosis (DVT), which may progress to potentially fatal pulmonary embolism and secondary complications such as postthrombotic syndrome, recurrent DVT, and chronic pulmonary hypertension. Prophylaxis in patients undergoing TKR, THR, and hip fracture surgery is now standard practice and generally involves anticoagulant treatment with either low-molecular-weight heparin (LMWH) or warfarin for a period of 7 to 10 days, with extended prophylaxis in those with ongoing risk factors such as obesity, cancer, or previous VTE. ⋯ Early administration of the first postoperative melagatran dose (4 to 8 hours) was also associated with better prophylactic efficacy relative to a later postoperative start (8 to 12 hours). The results of the comprehensive international clinical trial program and in particular the optimal balance of efficacy/safety data provided by the METHRO III study have led to approval of melagatran/ximelagatran in 2004 in the European Union for the prevention of VTE in patients undergoing elective hip or knee replacement surgery. Ximelagatran has the potential to maximize the use of anticoagulation in patients discharged following major lower-extremity orthopedic surgery.
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Nonvalvular atrial fibrillation (AF) is an independent risk factor for stroke that becomes increasingly prevalent as populations age. More than half a dozen clinical trials have demonstrated that anticoagulation with the vitamin K antagonist warfarin is the most effective therapy for stroke prophylaxis in AF. The narrow therapeutic index of warfarin requires that the intensity of anticoagulation be maintained within the international normalized ratio (INR) range of 2.0 to 3.0 to optimize efficacy while minimizing bleeding risk. ⋯ Elevated serum transaminase enzymes were observed in approximately 6% of patients given ximelagatran in these trials. These typically occurred 1 to 6 months after initiating treatment and usually abated without clinical sequelae whether or not treatment was continued. Given the consistency of response, the favorable overall benefit-risk ratio and the convenience of fixed oral dosing, ximelagatran may increase the number of patients with AF eligible for anticoagulation and amplify the potential for prophylaxis against stroke.