sentence: Heparin infusion , followed by oral warfarin , is indicated for symptomatic thromboembolic disease as well as for asymptomatic patients with substantial proximal deep venous thrombosis or large pulmonary emboli .
paragraph: Therapy for postoperative thromboembolic disease:  indications and treatment. Postarthroplasty patients develop venous thromboembolic disease because of venous stasis, hypercoaguability, and vessel wall injury.  However, most venous thrombi are nonocclusive or small and elicit few symptoms; pulmonary emboli also tend to be asymptomatic.  Noninvasive techniques to detect deep vein thrombosis do not appear to be reliable in this population, so venography may be required.  Postoperative perfusion lung scans, with comparison to preoperative perfusion scans, are the best screen for asymptomatic pulmonary emboli. Heparin infusion , followed by oral warfarin , is indicated for symptomatic thromboembolic disease as well as for asymptomatic patients with substantial proximal deep venous thrombosis or large pulmonary emboli .