***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Sequential ascending venographic studies were used to assess the healing of deep venous thrombosis in 50 patients r and omly assigned to streptokinase or heparin therapy .  Various degrees of thrombolysis and /or recanalization were demonstrated by venograms performed on the fourth and tenth days of treatment . Late follow-up studies ( mean , 7 months after treatment ) showed three basic patterns of resolution : ( 1 ) return to normal , ( 2 ) complete recanalization , and ( 3 ) incomplete recanalization and /or collateralization . Loss of valves or their function was associated with recanalization . The character , speed , and outcome of healing reflected the nature and extent of thrombosis , prior thrombotic disease in the extremity , and the type and timing of treatment . Streptokinase was highly effective and preferable to heparin in patients with deep vein thrombosis when therapy was begun within 4 days of onset of symptoms . In later stages of acute or recurrent deep vein thrombosis , the effectiveness of both drugs was significantly reduced Objectives . We compared the efficacy and safety of percutaneous endovenous intervention ( PEVI ) plus anticoagulation with anticoagulation alone in the reduction of venous thromboembolism ( VTE ) and post‐thrombotic syndrome ( PTS )  in acute proximal deep venous thrombosis ( DVT ) . Background . Recurrent VTE and PTS are common complications of DVT . There are no r and omized trials investigating the efficacy of PEVI in the reduction of the above complications . Methods . Patients with symptomatic proximal DVT were r and omized to receive PEVI plus anticoagulation or anticoagulation alone . Anticoagulation consisted of intravenous unfractionated heparin or subcutaneous low‐molecular weight heparin plus warfarin . PEVI consisted of one or more of a combination of thrombectomy , balloon venoplasty , stenting , or local low‐dose thrombolytic therapy . Results . At 6 months follow‐up , recurrent VTE developed in 2 of 88 patients of the PEVI plus anticoagulation group versus 12 of 81of the anticoagulation‐alone group ( 2.3 % vs. 14.8 % , P = 0.003 ) . PTS developed in 3 of 88 patients of the PEVI plus anticoagulation Group and 22 of 81 of the anticoagulation‐alone group ( 3.4 % vs. 27.2 % , P < 0.001 ) . Conclusions . In patients with symptomatic proximal DVT  , PEVI plus anticoagulation may be superior to anticoagulation — alone in the reduction of VTE and PTS at 6 months . © 2010 Wiley‐Liss , Heparin or streptokinase was administered in a prospect i ve r and omized fashion to 50 patients with phlebographically confirmed venous thrombosis of the extremities of 14 days or less duration . A total of 49 patients completed the investigative protocol with 26 receiving heparin  and 23 receiving streptokinase .  All patients were evaluated with sequential phlebograms . Complete thrombolysis with restoration of venous valve function occurred in one of 26 patients receiving heparin and in six of 23 patients receiving streptokinase . Fifty per cent of the patients treated with streptokinase with a total duration of symptoms of three days or less achieved complete lysis . The total incidence of therapeutic complications was similar in the two groups , but was more severe in the streptokinase treated patients Twenty-two patients who had an acute episode of thrombosis in the deep veins of the legs were studied by a new technique of ascending functional cinephlebography 6 to 12 months after the episode of thrombosis . If the condition was diagnosed within 36 hours and the thrombus was dissolved rapidly valve function was preserved . When diagnosis was delayed there was a very great risk of permanent damage to the valves Patients with symptoms of deep vein thrombosis for less than 10 days were treated with a st and ard dose of heparin . In the open label phase of the trial , 11 patients received 100 mg rt-PA on the first day and 50 mg on the subsequent day in an 8 hour infusion . In the double-blind phase , 8 patients were r and omized to the same rt-PA regimen , 6 patients to an infusion of 50 mg rt-PA over 8 hours on days 1 and 2 , and 7 patients to placebo infusions . The mean change in venographic score in all patients treated with rt-PA plus heparin is -3.8 units compared to -0.6 units in patients treated with heparin alone ( p = 0.06 ) . Bleeding complications classified as major were noted in 8/25 patients receiving the combined treatment The management of acute deep vein thrombosis ( DVT ) by medical therapy with anticoagulation has long been supported by evidence -based clinical practice guidelines outlined in the American College of Chest Physicians supplement . Early thrombus removal in patients with iliofemoral DVT has been reported to lead to improved venous valve function , improved quality of life , and decreased incidence of postthrombotic syndrome over anticoagulation alone . The ATTRACT trial will r and omize patients to medical management with st and ard anticoagulation versus catheter-directed thrombolysis in addition to st and ard anticoagulation after stratification to iliofemoral versus femoropopliteal DVT in order to determine the primary outcome of postthrombotic syndrome over a 24-month follow-up Treatment with streptokinase ( ' Kabikinase ' ) was given to 26 patients with venographically confirmed deep vein thrombosis extending into the popliteal vein or above . Treatment was continued for 4 days and the patients were allocated r and omly to oral anticoagulant therapy or a course of treatment with ancrod ( ' Arvin ' ) for 6 days followed by oral anticoagulant therapy . The degree of thrombolysis as judged by further venographic examination at 10 days was not significantly different between the 2 groups . The majority of patients showed clinical improvement but there was no appreciable difference between the groups at 3 and 6 months . Haemorrhagic complications were a more serious problem during the period of treatment with ancrod than during the equivalent period in the control group 
    Output:
    
Thrombolysis increases the patency of veins and reduces the incidence of PTS following proximal DVT by a third .
In those who are treated there is a small increased risk of bleeding .
In recent years CDT is the most studied route of administration , and results appear to be similar to systemic administration