To observe the clinical efficacy of fibrinolytic enzyme combined with low molecular heparin in the treatment of lower extremity deep vein thrombosis. Methods 63 patients with lower limb deep vein thrombosis were randomly divided into treatment group and control group, of which 32 cases were in the treatment group and 31 cases were in the control group; in the treatment group, fibrinolytic enzyme 100u was injected intravenously once a day for 10 days, and low molecular heparin calcium 5000u was injected subcutaneously 2 times a day for 10 days, and the rest of them were the same as that in the control group. In the control group, low molecular heparin calcium 5000u was injected subcutaneously twice a day for 10 days, and low molecular dextrose anhydride injection with danshen drip was applied. The clinical effect of fibrinolytic enzyme combined with low molecular heparin in the treatment of lower extremity deep vein thrombosis was evaluated by comparing the two groups. Results The effective rate of the treatment group was 93.75%, and the effective rate of the control group was 74.19%, and there was a significant difference between the two groups (p<0.05). Conclusion Fibrinolytic enzyme combined with low molecular heparin in the treatment of lower extremity deep vein thrombosis in the clinical symptoms, signs and symptoms significantly improved or disappeared at the same time, no serious complications. It has better clinical efficacy. Lower extremity deep venous thrombosis (deep venous thrombosis DVT) is one of the more common peripheral vascular obstructive diseases, easy to cause post-thrombotic syndrome and long-term impact on the quality of life, and can even lead to pulmonary infarction, which threatens the patient's life. Preventing pulmonary embolism, removing thrombus, restoring smooth blood flow in the deep veins of the lower limbs, preserving the function of venous valves, and preventing recurrence of thrombus are the ideal goals of treating acute deep vein thrombosis of the lower limbs, which can reduce the mortality rate of pulmonary embolism from 36% to about 8%. Thrombolysis is an important method in the current treatment of DVT. We have many years of experience in applying fibrinolytic enzymes plus low molecular heparin to treat DVT and have achieved good results. 1, Materials and methods 1.1 General information Case selection The selected cases were all hospitalized DVT patients, all patients met the diagnostic criteria of lower extremity deep vein thrombosis, and all patients had ultrasound diagnosis confirmed as lower extremity deep vein thrombosis, all for the first time, the duration of the disease is from 1 day to 2 months. 63 cases were randomly divided into the treatment group and the control group, the treatment group of 32 cases, 12 men, 20 women, age 21 to 66 years old, average 48 cases. The treatment group consisted of 32 cases, 12 males and 20 females, aged 21-66 years, with a mean of 48±6.8 years; the control group consisted of 31 cases, 10 males and 21 females, aged 20-68 years, with a mean of 47±6.9 years. There was no significant difference in age, gender, onset time and condition before treatment between the two groups. 1.2 Treatment Methods In the treatment group, 100U of fibrinolytic enzyme was dissolved in 250 ml of saline and injected intravenously once a day, with 10 days as a course of treatment. Low molecular heparin calcium 5000u, subcutaneous injection, twice a day, 10 days for a course of treatment. In a few patients, the second course of treatment was carried out at intervals of 3-5 days. The rest of the treatment was the same as the control group. The control group was treated with low molecular heparin, dextrose, and compound danshen. Prothrombin time and fibrinogen were measured during the treatment. Both groups were given warfarin orally for 3-6 months after stopping the above drugs. 1.3 Therapeutic efficacy standards Cured: no pain in the affected limbs, swelling completely disappeared, color Doppler showed that the deep vein trunks were completely clear; obvious effect: the swelling of the affected limbs was obviously reduced, but there was still swelling and pain in the lower limbs after standing for a long time, and the deep vein trunks were partially clear on color Doppler; effective: the symptoms were reduced to a certain extent, but there were serious sequelae, and there was no flow signal in the deep veins on color Doppler; ineffective: the symptoms were obvious, no reduction, and there was even the tendency of aggravation [1]. 1.4 Statistical processing Apply spss11.0 software for statistical processing, measurement data with t-test, count data with x2 test, p<0.05 there is a significant difference. 2, results 2.1 Clinical efficacy The clinical efficacy of the two groups of patients is shown in Table 1. the total effective rate of the treatment group is 93.75%, while 2.2 the total effective rate of the control group is 74.19%, 2.3 According to statistical processing, 2.4 is statistically significant (p<0.05), 2.5 indicates that the therapeutic efficacy of the treatment group is significantly better than that of the control group. 2.2 Comparison of blood rheology indexes between the two groups before and after treatment See Table 2 The results show that all the indexes of the treatment group improved significantly, and the degree of improvement was better than that of the control group (p<0.05). 2.3 Complications There were two cases of subcutaneous hemorrhagic spots in the treatment group and one case of subcutaneous hemorrhagic spots in the control group. Comparing the two groups, p>0.05, no statistical significance. Group Number of cases n Cured n(%) Apparent effect n(%) Effective n(%) Ineffective n(%) Total effective rate % Treatment group 32 22(68.75) 6(18.75) 2(6.25) 2(6.25) 93.75 Control group 31 13(41.94) 8(25.81) 2(6.45) 8(25.81) 74.19 Table 1 Comparison of the clinical outcomes of the patients in the two groups P <0.05 Table 2 Changes of blood rheological indexes before and after treatment (x ±s) Group Whole blood high cut viscosity (mpa.s) Whole blood low cut viscosity (mpa.s) Plasma viscosity (mpa.s) Fibrinogen (g/l) Treatment group Before treatment 5.39±0.73 12.51±1.94 1.7±0.15 3.14±0.67 After treatment 4.75±0.60* 11.22±1.52* 11.22±1.52* 11.22±1.52* 11.22±1.52* 11.25±1.52* 11.25±1.52* 11.25±1.52* 11.25±1.52 11.22±1.52*△ 1.3±0.13*△ 2.49±0.45*△ Control group Pre-treatment 5.40±0.91 12.50±2.21 1.78±0.15 3.13±0.56 Post-treatment 5. 06±0.89 12.15±2.24 1.72±0.15 2.87±0.47 Comparison with the pre-treatment in this group, * P< 0.05; compared with the control group after treatment, △P<0.05 3. Discussion Deep vein thrombosis of the lower limbs can cause chronic venous insufficiency or post phlebitis syndrome on the one hand, and even make the patients physically disabled. On the other hand, 44.7% of patients may suffer from pulmonary embolism, which may jeopardize their lives. Modern medicine believes that slow blood flow, damage to the vein wall and hypercoagulability of the blood are the three major factors in the formation of DVT. When there is an imbalance between coagulation and fibrinolysis or when the activated coagulation state exceeds the anticoagulant capacity, it will lead to a pre-thrombotic state, which in turn will cause thrombosis. One factor alone does not necessarily cause clinical consequences; it takes the combined involvement of several risk factors to cause thrombosis, with hypercoagulability and stagnation of blood flow being the key factors. The ideal goal in the treatment of DVT is the rapid restoration of venous blood flow, the prevention of thrombus extension, the maintenance of venous valve function, and the elimination of the risk of thrombus dislodgement, which will minimize the long-term complications of elevated venous pressure and post-thrombotic syndrome. The treatment is a combination of therapeutic processes, which has been recognized by scholars. The type of treatment that should be used as the mainstay of the program is a matter of individual emphasis. In general, simple thrombolysis and anticoagulants, phlebotomy, and percutaneous endoluminal intervention are the mainstays of treatment. Thrombolysis or anticoagulation alone is still our main treatment for DVT. However, thrombolysis combined with anticoagulation is currently debated. Thrombolytic therapy has the advantages of dissolving the thrombus, restoring blood circulation, and reducing or preventing damage to the vein wall. Exploring efficient and safe thrombolytic agents remains a current concern. An ideal thrombolytic drug should be easy to administer and exert thrombolytic effects rapidly, and be able to maintain effective concentrations in the body for a long enough period of time to prevent the occurrence of reinfarction early after treatment. The third-generation thrombolytic agent fibrinolysis belongs to single-chain zinc metalloproteinase, different from blood fibrinolysis, fibrinolysis does not exist in the form of inactive zymogen, it is an active protein hydrolase, which can directly degrade fibrinogen and fibrin, but its dissolution activity is different, it has a specific affinity for fibrin in the thrombus, and it can directly act on the formation of thrombus fibrin, and dissolve the fibrin into X ', Y', D', E' 4 soluble fragments, and dissolve them. In addition to the degradation of fibrinogen and fibrin, fibrinolytic enzyme has no activating effect on fibrinogen, and does not hydrolyze other coagulation factors and platelet membranes, and it has good substrate specificity, which makes fibrinolytic enzyme have better safety. After thrombolysis by fibrinolytic enzyme, the residual thrombus fragments have strong procoagulant effect, and the plasma inhibitor of fibrinogen activator will be elevated, resulting in hypercoagulable state after thrombolysis, so it is necessary to give anticoagulant and antiplatelet drugs to avoid re-occlusion of recanalized blood vessels. Low molecular heparin is a small molecular weight fragment isolated from the standard, mainly to inhibit the factors that promote the conversion of plasminogen to thrombin and inhibit platelet aggregation, so that blood coagulation is impeded, to prevent platelet adhesion, aggregation, and to reduce blood viscosity. But no thrombolytic effect. The application of low molecular heparin calcium will strengthen and consolidate the thrombolytic effect and prevent further expansion of thrombus and reocclusion of recanalized blood vessels. This has been reported to support this view. The combination of fibrinolytic enzyme and low molecular heparin calcium has both thrombolytic and anticoagulant effects, which is ideal. The results of this study showed that the effective rate of 93.75% in the treatment group was higher than that of 74.19% in the control group, p<0.05, which is a significant difference between the two groups, and the therapeutic efficacy of the treatment group was better than that of the control group, and there was no difference between the two in terms of the adverse reactions. It shows that the combination of fibrinolytic enzyme and low molecular heparin has positive significance in the treatment of DVT. In conclusion, the combination of fibrinolytic enzyme and low molecular heparin calcium should treat DVT with good clinical effect and mild adverse reaction, which is an effective and safe treatment method.