How should deep vein thrombosis of the lower extremities be treated?
A small number of deep vein thrombosis of the lower extremities can lead to fatal pulmonary embolism. Therefore, treatment should include the venous thrombosis of the lower extremities itself and how to prevent the occurrence of pulmonary embolism. The acute treatment methods mainly include surgical treatment and non-surgical treatment, each of which has two methods. Characteristics and which method is better are still debated. Treatment methods in the chronic phase include drug therapy, surgery and compression therapy.
1. Acute treatment
(1) General treatment: Once the deep vein thrombosis is formed, the patient should stay in bed to reduce the chance of pulmonary embolism caused by the thrombus falling off due to walking. Do not massage the swollen lower limbs. Elevating the affected limb over the plane of the heart facilitates the return of blood and promotes the swelling to subside. The bed rest time is generally about 2 weeks. After 2 weeks, wearing step pressure difference elastic stockings or bandaging the affected limbs can speed up tissue swelling and reduce symptoms.
(2) Anticoagulation therapy: Anticoagulation therapy is the earliest and most widely used method in the treatment of lower extremity venous thrombosis. Anticoagulation itself cannot dissolve the formed thrombus, but it can inhibit the spread of thrombus and cooperate with the body's own fibrinolysis The system dissolves thrombus, so as to achieve the purpose of treatment. At the same time, it can effectively reduce the occurrence of pulmonary embolism and plays a pivotal role in the prevention and treatment of pulmonary embolism. Other surgical or non-surgical treatment methods should generally be accompanied by anticoagulant therapy as adjuvant therapy. The duration of anticoagulation treatment can run through the entire course of the disease, usually 1 to 2 months, and some patients can last as long as half a year to 1 year, and some even require lifelong anticoagulation. However, anticoagulant therapy is prohibited in the following situations: patients with digestive tract ulcers, patients with severe liver and kidney dysfunction, patients with recent cerebral hemorrhage, post-abortion, patients with congenital coagulation factor deficiency, etc.
①Heparin: The most commonly used anticoagulant drug. Its anticoagulant effect is mainly to inhibit thrombus formation by increasing the activity of antithrombin Ⅲ (AT Ⅲ). Heparin takes effect quickly, has a short half-life, and has a stable effect in the body. The heparin water solvent is mainly 12,500 U/piece, which is equivalent to 100 mg. The dosage of heparin varies greatly among individuals, so it is necessary to adjust the dosage of heparin at any time according to laboratory monitoring. At present, the most commonly used heparin monitoring index is partial thromboplastin time (aPTT). During the medication, aPTT is controlled at 1.5 times of the normal control or the upper limit of the normal value. APTT was first tested after intravenous injection of heparin 6250U, and then every 4-6 hours. After it is stable, it can be tested every 12 hours.
② Low-molecular-weight heparin: As mentioned earlier, low-molecular-weight heparin has many advantages over heparin. Because it is mainly aimed at factor Xa, it is anticoagulant and the risk of bleeding is greatly reduced. With its good tissue absorbability and long half-life, the method of medication becomes simple, and the frequency of medication is also reduced compared with heparin. There are several types of low-molecular-weight heparin on the market, and the ingredients and usage of each product are different, so generalizations cannot be made. The common point is subcutaneous injection. When deep vein thrombosis of lower extremity forms, injection is once every 12 hours.
The use of low-molecular-weight heparin generally does not require laboratory monitoring, but like heparin, low-molecular-weight heparin can also cause thrombocytopenia. Although its incidence is lower than that of heparin, the detection of platelet count can help early detection of this complication.
Since the use of low molecular weight heparin is safer than heparin, it is currently used more and more clinically, and there is a tendency to gradually replace heparin.
③Warfarin: As an oral anticoagulant, warfarin has been used clinically for a long time. As an oral preparation, warfarin has become the first choice for outpatient anticoagulation therapy. Warfarin takes effect slowly in the body, generally starting to take effect 2 to 3 days after taking the medicine. Therefore, it is often used clinically together with heparin or low molecular weight heparin. When warfarin reaches the therapeutic effect, stop heparin or low molecular weight heparin. Molecular weight heparin.
Usage: 7.5 mg orally once on the first day, 5 mg orally once on the second day, 2.5 mg/d orally on the third day, this dose is adjusted according to the prothrombin time (PT). Generally, the PT is tested twice a week, and the INR value is controlled at 2 to 3, then changed to once a week, and gradually transitioned to once a month. The treatment time of warfarin for patients with deep vein thrombosis of the lower limbs is generally at least 2 months. If there is a history of pulmonary embolism, the treatment time of warfarin can be extended to 1 year.
(3) Thrombolytic therapy: Thrombolytic therapy is the use of thrombolytic drugs to activate plasminogen in the body, turning it into active plasmin, and promoting the dissolution of thrombus to achieve the purpose of removing fresh thrombus.
There are two main types of thrombolytic therapy, namely systemic therapy and local therapy. Systemic treatment is to inject thrombolytic drugs into a vein and then flow through the body with the blood to dissolve the clot. The local treatment is to inject thrombolytic drugs into the blood vessel through a cannula to dissolve the thrombosis in a certain area. Since collateral circulation is easy to establish after venous thrombosis of the lower extremities, thrombolytic drugs are not easy to concentrate locally, so infusion of thrombolytic drugs at the distal end of venous obstruction is not as effective as intubation into the thrombus. The vein is blocked by a valve, and it is sometimes difficult to reach the thrombus from the contralateral side. Generally, the popliteal vein from the affected side is punctured and the thrombus is continuously infused with thrombolytic drugs. At present, most clinical treatments are systemic treatment.
Thrombolytic therapy is mainly for fresh blood clots, and the sooner after the onset, the better the effect. For patients with a disease course of more than 3 days, the thrombolytic effect will be reduced. It has been observed clinically that some patients with a disease course of more than 3 days, after receiving urokinase treatment, the swelling of the limbs also disappeared rapidly. The possible mechanism is that urokinase dissolves the fresh thrombus secondary to the proximal and distal ends, thereby promoting the production of collateral circulation. The swelling of the limbs subsided, but the primary thrombus often cannot be completely dissolved. Even for patients within 3 days, due to the large range of thrombosis, and most of the thrombosis has been more than 24 hours before treatment, the application of thrombolytic therapy can only dissolve the secondary fresh thrombus, and it is generally difficult to dissolve all the original Thrombosis. In only a few very early cases, the thrombus may all dissolve.
The most common side effect of thrombolytic therapy is bleeding, with an incidence of 12% to 45%. The bleeding is related to the dosage, method and time of medication. The greater the dose and the longer the medication time, the greater the risk of bleeding. Systemic medication is more dangerous than topical medication. Superficial skin hemorrhage is easier to control, but deep body hemorrhage, especially intracranial hemorrhage, is very dangerous. Therefore, thrombolytic therapy should be stopped when hemorrhage occurs, and fresh plasma should be infused if necessary to supplement clotting factors. The chance of pulmonary embolism in thrombolytic therapy has increased, and placing a vena cava filter may be a better prevention method.
During thrombolytic therapy, avoid any operation that damages blood vessels. Thrombolytic therapy should be disabled for patients with the following conditions: ① those with active bleeding in the body; ② those with stroke or intracranial lesions within 2 months; ③2 Those who have had major surgery, organ biopsy or major trauma within the first week; ④ perinatal women; ⑤ Those who have digestive tract ulcers or history of gastrointestinal bleeding (excluding hemorrhoids); ⑥ Those who have severe liver and kidney insufficiency; ⑦ Uncontrolled hypertension patients; ⑧ patients with mural thrombus in the left heart; ⑨ patients with subacute endocarditis, etc. Pregnancy women, patients with atrial fibrillation, patients with recent cardiopulmonary resuscitation, patients with diabetic retinopathy, patients with recent minor operations, and patients with mild liver and kidney dysfunction should be treated with thrombolysis with caution.
During thrombolytic therapy, attention should be paid to laboratory tests. Common tests include hematocrit, platelet count, thrombin time (TT), partial thromboplastin time (APTT), fibrinogen, and determination of fibrin degradation products. When preparing for thrombolytic therapy, stop anticoagulant therapy, and measure the above-mentioned laboratory indicators, and repeat the test every 3 to 4 hours after the start of thrombolytic therapy. TT or APTT is controlled at about 2 times of the normal control, and the fibrinogen concentration should not be less than 1g/L (100mg/dl). If the hematocrit is decreased, occult gastrointestinal bleeding should be considered. In addition, attention should be paid to observe the patient's mental changes to detect intracranial hemorrhage as soon as possible. Anticoagulant therapy should not be carried out immediately after the thrombolytic therapy is over. Generally, it should be carried out after 2 to 3 hours. If heparin is used, the first shock dose is not required.
Commonly used thrombolytic drugs are as follows.
①Streptokinase (SK): The method of using streptokinase is as follows: first, 250,000 U of streptokinase is slowly injected intravenously over 30 minutes, and then maintained at a rate of 100,000 U/h. In addition to an allergy test before using streptokinase, intravenous infusion of 100 mg hydrocortisone can help prevent or reduce allergic reactions. Patients who have recently had hemolytic streptococcal infection or have used streptokinase within six months should not use streptokinase.
②Urokinase (UK): Urokinase can be extracted from urine or from cultured human embryonic kidney cells. Unlike streptokinase, urokinase does not need to form a complex, it can directly activate plasminogen and dissolve thrombus. It is equally effective for circulating plasminogen and plasminogen bound to fibrin, so it is not selective. Urokinase has no antigenicity and no allergy test is required. Its half-life is 14min.
In recent years, the use of urokinase is to inject 4400U per kilogram of urokinase intravenously for 10 minutes, and then maintain it at a rate of 4400U/(kg·h). If intubation is involved in thrombolysis, puncture the affected popliteal vein under ultrasound positioning, insert a straight-end multilateral perfusion catheter into the thrombus anteriorly, and infuse urokinase at a rate of 150,000 to 200,000 U/h, and perform X every 12 hours Light contrast, understand the thrombus dissolution, and adjust the position of the perfusion catheter until the thrombus dissolves. If the thrombus is checked for no signs of dissolution after 12 hours of medication, the medication should be discontinued. Authors from various regions reported that the practical dose of urokinase varies greatly.
③Tissue-type plasminogen activator (t-PA): Many tissues of the human body can produce t-PA. In the absence of fibrin, the enzyme activity of t-PA is very low; but when there is fibrin, Its activity is significantly enhanced, decomposing plasminogen to turn it into plasmin, so t-PA can selectively act on plasminogen in thrombus, and its bleeding risk is less than the above two thrombolytic drugs. Because of this selectivity, when the plasminogen bound to fibrin is rapidly reduced, the thrombolytic effect of t-PA is significantly weakened. Therefore, compared with non-selective thrombolytic drugs, its thrombolytic ability is relatively higher. low. At present, t-PA is mainly extracted from melanoma cells by genetic engineering, called recombinant t-PA (rt-PA), and has a half-life of 4 to 7 minutes in the human body. The method of using t-PA is intravenous injection of 40-50 mg every 2 hours until the symptoms are relieved.
④Others: The above 3 thrombolytic drugs are mainly used clinically, and some drugs are still in experiment. Such as acylated streptokinase-plasminogen complex, B-chain plasmin-streptokinase complex, prourokinase, etc., these drugs have improved half-life and selectivity.
(4) Surgical treatment: intravenous thrombectomy was popular in the 1950s and 1960s, but since the 1970s, there have been more and more reports of thrombus recurrence after thrombus removal, which has re-understood the value of thrombectomy. , And the safety of thrombolytic therapy is gradually increasing, which also limits the thrombectomy operation. However, some scholars still believe that thrombectomy is fast, safe and simple. As long as the indications are mastered, the method is improved, and anticoagulation is used, the success rate is still quite high. Other scholars believe that the effects of thrombectomy and drug therapy are similar.
①Indications: A. The onset time should not exceed 5 days, preferably within 72 hours; B. Lower limb iliac and femoral vein thrombosis.
Color Doppler ultrasound or lower extremity venography should be performed before surgery to determine the location of the thrombus. It should be noted whether the thrombus is derived from the inferior vena cava.
②Surgery method: (omitted) After the operation, the swelling of the affected limb disappears quickly. Start anticoagulation treatment on the day after the operation, and use warfarin and heparin or low molecular weight heparin at the same time. When the prothrombin time INR value reaches 2 to 3 , Stop heparin or low molecular weight heparin, continue to use warfarin anticoagulant therapy for about half a year.
. According to statistics from Shanghai Renji Hospital, there were 118 patients with acute DVT in the lower extremities, of which 59 limbs were surgically removed, and only 6 cases were confirmed by anterograde venography after surgery. The reasons for such a high rethrombus rate may include: thrombosis is extensive and cannot be removed, especially intravenous thrombosis; thrombus is too old and adheres to the venous intima, resulting in intimal damage when the thrombus is removed, collagen tissue exposure, and platelet adhesion, causing recurrence. thrombus. Venous thrombosis caused by compression of the left iliac vein is more common. Forgarty catheters are more difficult to remove intravenous thrombosis, and thrombectomy cannot remove the cause of thrombosis. Although the incidence of venous rethrombosis is very high, it can remove a large number of thrombus at one time, quickly reduce the intravenous pressure, thereby quickly alleviate the swelling of the limbs, promote the establishment of venous collaterals, and actively cooperate with appropriate drug treatments to improve The efficacy of thrombectomy.
(5) Intracavitary interventional inferior vena cava filter placement: the purpose is to place a filter in the inferior vena cava so that the venous thrombosis of the lower limbs will fall off without causing pulmonary embolism. This operation is derived from the inferior vena cava ligation, but the biggest difference between the filter and the traditional operation is that the filter does not affect the return of the inferior vena cava, and the filter is placed through the peripheral vein through a unique release catheter, so the trauma is more than traditional surgery The case fatality rate is significantly reduced. ①Indications: A. Patients with deep vein thrombosis of the lower extremities who are contraindicated in anticoagulation therapy; B. Patients with deep vein thrombosis of the lower extremities who have severe hemorrhage during anticoagulation treatment; C. Lower extremities who still have pulmonary embolism during regular anticoagulation treatment Patients with venous thrombosis; D. Patients with repeated pulmonary embolism; E. Patients with venous thrombosis of the lower extremities who need to undergo pulmonary artery incision and thrombus removal; F. Patients with large floating thrombus masses at the proximal end of the thrombus found on examination.
A. Thrombosis: thrombosis can occur at the venipuncture site. Due to different devices, the incidence is 5% to 27%. The thicker the release catheter, the greater the chance of venous thrombosis at the puncture site. In addition, the filter itself can also form thrombus, causing the inferior vena cava obstruction. In contrast, the Greenfield filter has the lowest incidence of about 4%, while the Simon filter and Vena Tech filter have a higher probability of causing inferior vena cava obstruction. Reach 16% to 30%. Some patients with inferior vena cava obstruction do not have any clinical manifestations, and a few patients may develop thigh bruises.
B. Blood vessel puncture: The filter hook punctures the blood vessel and damages the surrounding tissues. In order to prevent the filter from shifting, most of the filters have barbs fixed on the wall of the inferior vena cava. If the fixed hook penetrates the wall of the blood vessel and damages adjacent organs, corresponding symptoms can occur, with an incidence of about 9%. Organs that may be damaged include the duodenum, small intestine, abdominal aorta, pancreas, etc., and can cause retroperitoneal hematoma.
C. Filter displacement: The filter is generally placed under the renal vein. If the filter is not well fixed, it can be displaced with the blood flow. Most of the displacement distance is less than 7cm, and very few can be displaced to The right atrium, right ventricle, and even move to the pulmonary artery. Moving the filter into the heart can cause cardiac arrest. If the filter is moved below the renal vein, it will generally not affect renal function. In theory, thrombosis in the renal vein may lead to renal failure, but there is no clinical report. The positioning error of the filter may also be caused by technical errors.
D. It is rare in clinical practice that the guide wire is stuck and the filter is broken.
③Surgery method: (omitted)
2. Treatment of chronic lower extremity venous thrombosis. Chronic lower extremity venous thrombosis is formed if the venous lumen is not recanalized or incompletely recanalized. If the collateral veins are insufficiently compensated, the swelling of the affected limb will not easily disappear, which will give the patient's life and Work has a big impact. The treatment of chronic venous obstruction of the lower extremities should be based on the patient's condition to choose non-surgical or surgical treatment.
(1) Mechanical physical therapy: As the venous blood return of the lower extremities is blocked, resulting in venous stasis and tissue swelling, the use of elastic bandages or elastic stockings can significantly improve the patient’s symptoms, reduce the swelling and pain of the affected limb, accelerate the swelling and subsidence, and can effectively Prevent late complications of deep vein thrombosis. Elastic stockings should be medical elastic stockings with a stepped pressure difference. The upward pressure from the ankle is gradually reduced. It should be worn during the day and removed before going to bed. This method is simple and easy to accept, but it should be disabled in the acute phase of lower extremity venous thrombosis to prevent thrombosis from falling off and causing pulmonary embolism.
(2) Drug treatment: Patients with chronic venous obstruction of the lower extremities should still be given anticoagulation therapy, because patients with a history of thrombosis have a high chance of thrombosis again, and anticoagulation therapy can effectively prevent thrombosis from forming again. Oral anticoagulation therapy is generally used, such as warfarin, and anti-platelet aggregation drugs such as aspirin and ticlopidine (Ticlide) are also used. Traditional Chinese medicine for blood circulation, such as Salvia miltiorrhiza, helps to establish collateral circulation.
(3) Intracavitary interventional therapy: mainly for large blood vessels, such as iliac vein and inferior vena cava. When venous thrombosis is formed and recanalization is not complete, local stenosis is likely to form. After venography is used to identify the stenosis, the contralateral femoral vein is intubated to the stenosis, and balloon catheter is used to expand, and stents are placed to restore the inner diameter of the lumen. The intracavitary intervention method is simple, but it is only suitable for short-segment stenosis of large veins, and the stent is placed in the venous lumen, which itself is also a factor inducing thrombosis, and the long-term effect is not certain.
(4) Surgical treatment: Surgery is generally not required for chronic venous obstruction of the lower extremities. Surgical treatment is mainly to rebuild venous bypass. Due to the particularity of venous blood flow, the long-term patency rate of bypass vessels is not as good as arterial vessels. Therefore, surgical treatment should be strictly controlled. Indications. Preoperative color Doppler ultrasound, magnetic resonance venography or conventional venography can help to determine the location and scope of venous disease. Pelvic CT examination can rule out the possibility of tumor compression.
① Surgical indications: patients with obvious symptoms of lower limb vein obstruction after conservative treatment.
②Factors affecting long-term patency of venous bypass vessels:
A. Bypass vascular materials: same as arterial bypass surgery, autologous veins are the first choice for bypass vessels, which have a better long-term patency rate than artificial blood vessels. The most commonly used is the great saphenous vein. If it is cut longitudinally and then arranged in a spiral, it can be made into a blood vessel with a larger diameter for bypass surgery of the iliac vein or even the inferior vena cava. The contralateral superficial femoral vein is sometimes used as a bypass vessel, but this may cause swelling of the contralateral leg or other complications. Upper limb veins and jugular veins are occasionally used. Cryopreserved human allogeneic veins have also begun to be used in clinical practice, but their long-term effects have yet to be confirmed. Among the artificial blood vessel materials, expanded polytetrafluoroethylene (ePTFE) is used the most, because ePTFE artificial blood vessels can be made into any diameter and length, and do not need to be pre-coagulated during use. The artificial blood vessel with support ring is not easy to collapse and become At the same time, ePTFE artificial blood vessel has better anti-thrombotic properties than other materials.
B. Temporary arteriovenous fistula: Kunlin first proposed to build an arteriovenous fistula at the distal end of the bypass vessel in 1953, which can accelerate the blood flow in the bypass vessel and reduce the chance of thrombosis. Practice has shown that temporary arteriovenous fistula can indeed improve the long-term patency rate of bypass vessels. But for patients with cardiac insufficiency, the increase in the amount of return heart blood will increase the burden on the heart. Menawat believes that the ratio of the diameter of the fistula to the diameter of the bypass vessel should not be greater than 0.3. A non-absorbable 2-0 thread can be wound around the arteriovenous fistula and knotted loosely. The end of the thread is buried under the skin so that it is easy to identify the ligation and close the fistula in the future. The closure of the fistula can also be intubated and embolized by interventional methods. The fistula closure time is generally 6 months after surgery.
C. Thrombosis prevention measures: As mentioned above, anticoagulant drugs and intermittent leg inflation compression can effectively prevent thrombosis. During the operation, find a branch in the vein at the far end of the bypass vessel, insert a thin catheter, and draw the other end out of the body. After the operation, the heparin diluent is continuously instilled, and the partial thromboplastin time (APTT) is measured to make it less than 2 times the normal control. After 48 hours, the catheter was removed, and heparin anticoagulation therapy was continued through the body surface vein, and the oral anticoagulation therapy was gradually switched to oral anticoagulation therapy.
D. Close observation of bypass vessels: After the bypass vessels are established during the operation, color Doppler ultrasound or venography can be used to determine the patency of the anastomosis. If problems are found, they can be corrected in time. Measure the distal venous pressure, compare the changes of the venous pressure before and after the bypass vessel is blocked, and understand the influence of the bypass vessel on hemodynamics. One day after surgery, angiography is performed through the indwelling catheter of the venous branch, which can timely understand the patency of the bypass vessel. Regular color Doppler follow-up after discharge from the hospital, once problems are found, they should be corrected as soon as possible.
A. Great saphenous vein-popliteal vein bypass (May-Husni operation): It was first designed by Warren and Thayer in 1954, but it was not promoted. It was introduced and promoted by May and Husni again in the 1970s. This procedure is suitable for cases of simple superficial femoral vein or proximal popliteal vein occlusion. The large saphenous vein on the same side was reserved for the operation, and the distal popliteal vein was exposed. After the large saphenous vein was cut off, it was performed with the distal end of the popliteal vein and anastomosed end to side. During the anastomosis, strive to perform fine operations, as far as possible not to damage the vascular intima, and use 6-0 or 7-0 non-absorbable non-invasive sutures for continuous suture. Temporary arteriovenous fistula can be selected in the ankle, one of the posterior tibial vein or the great saphenous vein and the posterior tibial artery end-to-side anastomosis. Because there are fewer patients with simple superficial femoral vein thrombosis, and the long-term patency rate of bypass vessels after surgery is not high, this surgery is currently rarely performed.
B. Suprapubic Vein Bypass (Palma-Dale): It was first reported by Uruguayan physician Palma in 1960 and promoted by Dale. This operation is suitable for cases where one iliac vein is blocked, the contralateral iliac-femoral vein is normal, and there is no thrombosis in the vein under the affected inguinal ligament, and there is no venous valve insufficiency of the lower limbs. In addition, only cases with a circumference difference of more than 4 cm between the two lower limbs were selected for surgery. The great saphenous vein on the contralateral side is used as a bypass vessel for the operation. The great saphenous vein requires a circumference of 4 mm or more, and varicose veins should not be used. Free a section of the great saphenous vein on the contralateral side, cut and ligate its branch, leave 25～30cm, cut off at its distal end, lead the great saphenous vein from the subpubic epithelial tunnel to the affected femoral vein, use heparin and poppy After dilating the great saphenous vein with alkali diluent, it is anastomosed end-to-side with the femoral vein with 5-0 or 6-0 non-injury and non-absorbable sutures. One branch of the great saphenous vein or femoral vein on the affected side was selected to establish a temporary arteriovenous fistula with the femoral artery, and another branch was selected to be inserted into a thin catheter as a channel for continuous heparin perfusion and postoperative angiography (Figure 10). If the autologous vein conditions are not ideal, an 8mm caliber ePTFE artificial blood vessel can also be selected as the bypass vessel. Because the long-term patency rate of this operation is relatively satisfactory, it is still being carried out in many medical centers.
C. Femoral-vena cava, iliac-vena cava, and vena cava artificial blood vessel bypass surgery: suitable for cases of unilateral or bilateral iliac vein thrombosis and inferior vena cava thrombosis that cannot be performed by Palma-Dale. Femoral-vena cava bypass surgery selects 10-12mm PTFE artificial blood vessels, and a temporary arteriovenous fistula should be established (Figure 11). Iliac-vena cava bypass surgery uses 14mm PTFE artificial blood vessel, inferior-inferior vena cava bypass or cavity-atrial bypass surgery uses 16-20mm artificial blood vessel, generally does not need to build a temporary arteriovenous fistula, all artificial blood vessels should be worn Outer support ring. Due to the large size of the operation and the unsatisfactory long-term patency rate, the indications should be strictly controlled, and cases with severe symptoms and ineffective treatment by other methods should be selected.
General Surgery Department of First Vascular Surgery, Changyi City People's Hospital, Weifang, Shandong