A small amount of deep venous thrombosis of lower limbs can lead to fatal pulmonary embolism, so the treatment should include venous thrombosis of lower limbs itself and how to prevent pulmonary embolism. There are two main treatment methods for acute phase: surgical treatment and non-surgical treatment, each with its own characteristics, and which method is better is still controversial. The treatment methods of chronic stage include drug therapy, surgical therapy and compression therapy.
1. Acute treatment
(1) General treatment: Once deep venous thrombosis of lower limbs occurs, patients should stay in bed to reduce the chance of pulmonary embolism caused by thrombus falling off due to walking, and do not massage swollen lower limbs. Raising the affected limb above the heart level is beneficial to blood return and promotes the swelling to subside. Bed rest time is generally about 2 weeks. After 2 weeks, wearing elastic socks with step pressure difference or wrapping the affected limb with elastic bandage can accelerate tissue swelling and relieve symptoms.
(2) Anticoagulation therapy: Anticoagulation therapy is the earliest and most widely used method to treat venous thrombosis of lower limbs. Anticoagulation itself cannot dissolve the formed thrombus, but it can inhibit the diffusion of thrombus and cooperate with the body's own fibrinolytic system to dissolve thrombus, thus achieving the purpose of treatment. At the same time, it can effectively reduce the occurrence of pulmonary embolism and play a decisive role in the prevention and treatment of pulmonary embolism. Other surgical or non-surgical treatment methods should generally use anticoagulant therapy as adjuvant therapy. The duration of anticoagulation therapy can run through the whole course of disease, which usually takes 1 ~ 2 months, some patients can last for half a year ~ 1 year, and some even need lifelong anticoagulation. However, anticoagulant therapy is prohibited in the following cases: patients with digestive tract ulcer, patients with severe liver and renal insufficiency, patients with recent cerebral hemorrhage, patients with abortion, patients with congenital coagulation factor deficiency, etc.
① Heparin: the most commonly used anticoagulant, whose anticoagulant effect is mainly to inhibit thrombosis by increasing the activity of antithrombin ⅲ (AT ⅲ). Heparin takes effect quickly, has a short half-life and is stable in the body. The aqueous solvent of heparin is mainly 12500U/ branch, which is equivalent to 100mg. There are two ways of administration: intravenous injection and subcutaneous deep fat injection. Intramuscular injection is easy to cause hematoma at the injection site and should not be used. Subcutaneous injection of deep fat layer is simple, but the concentration of heparin in the body is not easy to control accurately, and the injection site is generally selected under the abdominal wall. Intravenous injection method uses micropump for continuous intravenous administration. This heparin administration method has the advantages of quick onset, easy dosage control, stable heparin concentration in vivo and easy adjustment, and is an ideal administration method. The specific method is to inject heparin 50mg (6250U) intravenously at one time, so that the concentration of heparin in the body quickly reaches the peak, and then drip heparin diluent intravenously at 30ml/h (heparin 200mg (25000U) dissolved in 500ml 5% glucose saline). However, the dosage of heparin should be reduced to 20 ml/h in the following cases: those who have had surgery within 2 weeks; Stroke within 2 weeks; platelet count
The dose of heparin varies greatly among individuals, so it is necessary to adjust the dose of heparin at any time according to laboratory monitoring. At present, the most commonly used monitoring index of heparin is partial thromboplastin time (aPTT), and aPTT is controlled at 65438 0.5 times of the normal control or the upper limit of the normal value during medication. APTT was detected for the first time after intravenous injection of heparin 6250U, and then every 4 ~ 6 hours 1 time, and every 12 hours/time after stabilization.
Common side effects of heparin include: a. bleeding. Pay attention to subcutaneous ecchymosis and ecchymosis during medication. If hematuria and gastrointestinal bleeding occur, medication should be reduced or stopped. When the amount of bleeding is large, protamine can be injected intravenously at the ratio of 1: 1 to resist the anticoagulant effect of heparin. Thrombocytopenia may be related to autoimmune reaction induced by heparin in vivo. The incidence was 1% ~ 2%, which showed a decrease in platelet count. In severe cases, extensive thrombosis of arteries and veins occurs, which leads to the death or residual limb of the patient, so we should attach great importance to it in clinic. During the use of heparin, we should pay attention to the detection of platelet count. If thrombus diffusion or new thrombus appears during medication, this complication should be considered, and the drug should be stopped immediately and hirudin or argatroban, a selective antithrombin, should be used instead. C. Osteoporosis. Long-term use of heparin may cause osteoporosis and even lead to vertebral body or long bone fracture.
② Low molecular weight heparin: As mentioned above, low molecular weight heparin has many advantages over heparin. Because it is mainly aimed at factor ⅹ A, the risk of bleeding is greatly reduced while anticoagulating. It has good tissue absorbability, long half-life, simple administration method and less times than heparin. There are several kinds of low molecular weight heparin sold in the market, and the composition and usage of each product are different, so it is impossible to generalize. Its similarity is mainly subcutaneous injection. In the case of deep venous thrombosis of lower limbs, injection 12 hours/time.
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 heparin, detecting platelet count is helpful to find this complication early.
Because the use of low molecular weight heparin is safer than heparin, it is widely used in clinic at present, and there is a trend of gradually replacing heparin.
③ Warfarin: Warfarin has been used as an oral anticoagulant for a long time in clinic. As an oral preparation, warfarin has become the first choice for anticoagulant therapy in outpatient department. Warfarin takes effect slowly in the body, usually after 2 ~ 3 days, so it is often used with heparin or low molecular weight heparin in clinic. When warfarin achieves therapeutic effect, stop using heparin or low molecular weight heparin.
Usage: Take 7.5mg 1 time on the first day, change it to 5mg 1 time on the second day, and take 2.5mg/d on the third day. The dosage was adjusted according to prothrombin time (PT). Generally, the PT is measured twice a week, and the INR value is controlled at 2 ~ 3, then it is changed to once a week 1 time, and then it is gradually changed to once a month 1 time. Warfarin is usually used for at least 2 months in patients with deep venous thrombosis of lower limbs. If there is a history of pulmonary embolism, the medication time of warfarin can be extended to 1 year.
(3) Thrombolytic therapy: Thrombolytic therapy is to use thrombolytic drugs to activate plasminogen in vivo, make it become active plasmin, promote thrombolysis, and achieve the purpose of clearing fresh thrombus.
There are two main types of thrombolytic therapy, namely systemic therapy and local therapy. Systemic therapy is to inject thrombolytic drugs into veins, and then flow all over the body with blood to dissolve thrombus. Local treatment is thrombolysis in a certain area after injecting thrombolytic drugs into blood vessels through intubation. Because the collateral circulation of venous thrombosis in lower limbs is easy to establish and thrombolytic drugs are not easy to concentrate locally, the thrombolytic effect of distal injection of thrombolytic drugs in venous obstruction is not as good as that of intubation into thrombosis. There is a valve obstruction in the vein, and it is sometimes difficult to reach the thrombus by intubation from the healthy side. Usually, thrombolytic drugs are continuously infused into the thrombus from the affected bile vein puncture. At present, systemic therapy is widely used in clinic.
Thrombolytic therapy is mainly aimed at fresh thrombus, and the sooner it is used after onset, the better the effect. For patients with a course of more than 3 days, the thrombolytic effect will be reduced. Clinically, it has been observed that some patients with a course of more than 3 days, after receiving urokinase treatment, the swelling of limbs also quickly subsided. The possible mechanism is that urokinase dissolves fresh thrombus secondary to proximal and distal ends, thus promoting collateral circulation and reducing limb swelling, but the primary thrombus is often not completely dissolved. Even for patients within 3 days, thrombolytic therapy can only dissolve the secondary fresh thrombus, and it is generally difficult to completely dissolve the primary thrombus because of the large range of thrombus, and most of them have been in hospital for more than 24 hours. Only in very few early cases can the thrombus be completely dissolved.
The most common side effect of thrombolytic therapy is bleeding, the incidence rate is 12% ~ 45%, and bleeding is related to dosage, mode and time. The greater the dose, the longer the medication time and the greater the risk of bleeding. Systemic medication is more dangerous than local medication. Superficial skin bleeding is easy to control, but deep body bleeding, especially intracranial bleeding, is very dangerous. Therefore, thrombolytic therapy should be stopped when bleeding, and fresh plasma should be infused to supplement coagulation factors when necessary. The incidence of pulmonary embolism increases in thrombolytic therapy, and placing vena cava filter may be a better preventive method.
During thrombolytic therapy, any operation that damages blood vessels should be avoided, and thrombolytic therapy is prohibited in the following cases: ① active bleeding in the body; ② Stroke or intracranial lesions occurred within 2 months; ③ Patients with major surgery, organ biopsy or major trauma within 2 weeks; ④ Perinatal women; ⑤ Patients with a history of digestive tract ulcer or gastrointestinal bleeding (excluding hemorrhoids); ⑥ Severe hepatic and renal insufficiency; ⑦ Uncontrolled hypertensive patients; ⑧ Patients with left ventricular mural thrombosis; Pet-name ruby patients with subacute endocarditis. Pregnant women, patients with atrial fibrillation, patients who have recently received cardiopulmonary resuscitation, patients with diabetic retinopathy, patients who have recently undergone minor surgery and patients with mild hepatic and renal insufficiency should be treated with thrombolysis with caution.
During thrombolytic therapy, attention should be paid to laboratory tests, including hematocrit, platelet count, thrombin time (TT), partial thromboplastin time (APTT), fibrinogen and fibrin degradation products. When preparing for thrombolytic therapy, stop anticoagulation therapy and determine the above laboratory indexes, and repeat the detection every 3 ~ 4 hours after thrombolytic therapy begins. TT or APTT should be controlled at about 2 times of the normal control, and the fibrinogen concentration should not be
Commonly used thrombolytic drugs are as follows.
① Streptokinase (SK): Streptokinase is produced by β -hemolytic streptococcus and was first discovered by Tillett and Garner in 1933. In vivo, it first forms a streptokinase-plasminogen complex with plasminogen according to the stoichiometric ratio of 1: 1, and then activates plasminogen to become a fibrinolytic enzyme with thrombolytic activity, and the streptokinase-plasminogen complex is gradually transformed into a streptokinase-plasminogen complex, which also has the function of activating plasminogen. Because streptokinase is not selective to thrombus and plasminogen in circulating blood, a considerable part of it forms a complex with circulating plasminogen after being input into the body, thus increasing the risk of bleeding.
Streptokinase has antigenicity and is easily neutralized by streptokinase antibody after entering the body. People who have been infected by hemolytic streptococcus recently and those who have used streptokinase within six months have high levels of streptokinase antibodies in their blood. Because of the antigenicity of streptokinase, some patients may have allergic reactions, and the incidence rate is 1.7% ~ 18%. Therefore, before using streptokinase, an allergy test should be carried out. After streptokinase enters the body, it is first neutralized by streptokinase antibody, and the rest combines with circulating plasminogen to form an active complex, which activates plasminogen to become plasmin. Fibrinolytic enzyme and excess free streptokinase form a complex, part of which is neutralized by circulating antifibrinolytic enzyme, and the rest is combined with fibrin in thrombus and decomposed, which really plays a role in thrombolysis. The half-lives of streptokinase-plasminogen complex and streptokinase-plasminogen complex are 65438 06 minutes and 83 minutes respectively.
The usage of streptokinase is: firstly, slowly inject 250,000 U streptokinase intravenously for 30min, and then maintain the speed of 654.38+100000 U/h. Before using streptokinase, intravenous drip of 100mg hydrocortisone is helpful to prevent or alleviate allergic reactions. Streptokinase should not be used in patients who have recently been infected with hemolytic streptococcus or have used streptokinase within six months.
② Urokinase (UK): Urokinase can be extracted from urine or cultured human embryonic kidney cells. Different from streptokinase, urokinase can directly activate plasminogen, dissolve thrombus and form no complex. It has the same effect on circulating plasminogen and plasminogen combined with fibrin, so it has no selectivity. Urokinase has no antigenicity, so there is no need to do an allergy test. Its half-life is 14 minutes.
In recent years, the method of using urokinase is to inject 4400U urokinase per kilogram of body weight intravenously at 10min, and then maintain the speed of 4400 U/(kg h). If the catheter is involved in thrombolysis, the popliteal vein of the affected side will be punctured under ultrasonic positioning, and the straight-ended porous perfusion catheter will be inserted into the thrombus in an anterograde way, and urokinase will be infused at the rate of 1.5 million ~ 0.2 million U/h, and X-rays will be taken every 1.2 hours to understand the thrombolysis situation, and the position of the perfusion catheter will be adjusted until the thrombus dissolves. If there is no sign of thrombolysis after taking 1.2 h, the drug should be stopped. Authors in different places report that the actual dose of urokinase varies greatly.
③ Tissue plasminogen activator (t-PA): Many tissues in human body can produce t-PA, and its enzyme activity is very low without fibrin; However, when fibrin exists, its activity is obviously enhanced, and plasminogen is decomposed into plasmin, so t-PA can selectively act on plasminogen in thrombus, and its bleeding risk is less than that of the above two thrombolytic drugs. Because of this selectivity, when the plasminogen bound to fibrin decreases rapidly, the thrombolytic effect of t-PA is obviously weakened, so its thrombolytic ability is relatively low compared with non-selective thrombolytic drugs. At present, t-PA is mainly extracted from melanoma cells by genetic engineering, which is called recombinant t-PA(rt-PA), and its half-life in human body is 4 ~ 7min. T-PA is injected intravenously for 40 ~ 50mg every 2 hours until the symptoms are relieved.
④ Others: At present, the above three thrombolytic drugs are mainly used in clinic, and some other drugs are still being tested. Such as acylated streptokinase-plasminogen complex, B- chain plasmin-streptokinase complex, prourokinase, etc. These drugs improve the half-life and selectivity.
(4) Surgical treatment: Thrombolysis by intravenous operation was once popular in 1950s and 1960s, but since 1970s, there have been more and more reports of thrombus recurrence, which made people realize the value of thrombectomy again, and the safety of thrombolytic therapy gradually improved, which also limited thrombectomy. However, some scholars still think that embolectomy is fast, safe and simple. As long as the indications are mastered, the methods are improved and anticoagulation is combined, the success rate is still quite high. Another scholar thinks that the effect of embolectomy is close to drug treatment.
Indications: A. The onset time should not exceed 5 days, preferably within 72 hours; B. thrombosis of iliac vein and femoral vein of lower extremity.
Color Doppler ultrasound or venography of lower limbs should be done before operation to determine the location of thrombus, and pay attention to whether the thrombus comes from inferior vena cava.
② Operation method: The operation should be performed by X-ray fluoroscopy in the operating room. If the thrombus is confined to one iliac vein and femoral vein, make an incision along the femoral vein in the affected groin to expose the great saphenous vein first, and find the junction between the great saphenous vein and femoral vein along the great saphenous vein to expose the femoral vein. Carefully separate the common femoral vein, superficial femoral vein and deep femoral vein, and operate gently as much as possible to avoid artificially squeezing out thrombus. Make an incision on the common femoral vein along the long axis of the vein, insert the Fogarty catheter into the proximal femoral vein, expand the balloon after reaching the inferior vena cava, and pull out the thrombus, and repeat it several times until there is no thrombus. Under the direct vision of X-ray fluoroscopy or angioscope, the suction catheter was selectively inserted into the internal iliac vein to suck up the thrombus in the internal iliac vein. Venography confirmed that there was no residual thrombus in the internal iliac vein. If angiography finds local stenosis of the left iliac vein, the balloon can be expanded at the stenosis under X-ray fluoroscopy, and a stent can be placed at the stenosis if necessary. Squeeze the calf and thigh with a blood drive belt or hand to squeeze out the distal venous thrombosis. If the thrombus in the femoral vein is difficult to remove, the superficial femoral vein can be ligated to prevent the distal venous thrombus from deriving to the proximal end. Catheterization of deep femoral vein to restore venous blood flow after embolectomy. A branch of the great saphenous vein was selected, and after it was cut off, the proximal end was anastomosed with the superficial femoral artery end to side. The purpose of establishing arteriovenous fistula is to speed up the blood flow of iliac vein and reduce the risk of thrombosis. Arteriovenous fistula can be closed by interventional embolization after 6 weeks, or the fistula can be ligated surgically.
The thrombus has spread to the inferior vena cava. If the femoral vein is directly cut to remove the thrombus, the risk of pulmonary embolism may increase during the operation. Take out the inferior vena cava thrombus under direct vision, and then take out the thrombus in the lower extremity vein. The specific method is to make an arc incision in the middle and lower abdomen of the affected side and expose the inferior vena cava and bilateral renal veins through retroperitoneal approach. Cut the inferior vena cava vertically, remove the thrombus in the inferior vena cava, and then suture the vein incision. Then thrombectomy of iliac vein and femoral vein and temporary arteriovenous fistula were performed according to the above methods.
Generally speaking, the swelling of the affected limb disappears quickly after the operation. Anticoagulation therapy was started on the second day after operation, and warfarin and heparin or low molecular weight heparin were used at the same time. When the INR value of prothrombin time reaches 2 ~ 3, heparin or low molecular weight heparin is stopped and warfarin anticoagulation treatment is continued for about half a year.
According to the statistics of Shanghai Renji Hospital, there were 8 patients with acute lower extremity deep venous thrombosis 1 18, of which 59 cases were surgically removed, and only 6 cases were diagnosed by anterograde venography after operation. The reasons for the high incidence of re-thrombosis may be as follows: (1) Thrombosis is extensive and cannot be removed, especially in venules; Thrombosis is too old and attached to the intima of vein, which leads to intima damage, collagen tissue exposure and platelet adhesion when thrombus is taken out. Venous thrombosis caused by left iliac vein compression is common, and it is difficult for Forgarty catheter to remove all venous thrombosis, and embolectomy can not remove the causes of thrombosis. Although the incidence of postoperative venous thrombosis is high, it can remove a large number of thrombus at one time, quickly reduce the pressure in the vein, thus quickly relieving limb swelling, promoting the establishment of venous collateral, and actively cooperating with appropriate drug treatment, which is expected to improve the curative effect of embolectomy.
(5) Inserting filter screen into inferior vena cava: The purpose is to prevent pulmonary embolism after venous thrombosis of lower limbs falls off by placing filter screen in inferior vena cava. The operation originated from ligation of inferior vena cava. Since the middle of19th century, in order to prevent pulmonary embolism, various methods of blocking inferior vena cava have been used clinically. However, surgical ligation or occlusion of inferior vena cava has certain risks, and its mortality rate can reach 17% ~ 30%. 1969 Mobbin-Uddin first reported that the umbrella filter was placed in the inferior vena cava to effectively reduce the incidence of pulmonary embolism. 1973, Jin Rui-Greenfield invented the Greenfield filter, which pushed the filter technology to maturity and quickly popularized it in clinic. The biggest difference between the filter and the traditional operation is that the filter does not affect the reflux of the inferior vena cava. By placing the filter through the peripheral vein through a special release catheter, the trauma is less than that of the traditional operation, and the mortality rate is obviously reduced. The material of the filter screen is mostly stainless steel or titanium alloy, which has no rejection reaction in the body, and the titanium alloy material does not affect the magnetic vibration inspection. At present, the commonly used filters in clinic include Greenland stainless steel filter, Greenland titanium alloy filter, nest filter, Simon nickel-titanium alloy filter, VenaTech filter and so on. Greenfield filter is widely used in clinic. With the continuous improvement of technology and materials, Greenfield filter can be released through 14F or even 12F sheath, which is suitable for the diameter of inferior vena cava.
Indications: A. Patients with deep venous thrombosis of lower limbs who are contraindicated by anticoagulant therapy; B. Patients with deep venous thrombosis of lower limbs who suffered from severe bleeding during anticoagulant therapy; C patients with venous thrombosis of lower limbs who still have pulmonary embolism during routine anticoagulant therapy; D. Patients with multiple pulmonary embolism; E patients with venous thrombosis of lower limbs who need pulmonary artery incision and embolectomy; F. Patients with large floating thrombus found near the thrombus heart.
② Complications:
A. Thrombosis: Venous puncture site can cause secondary thrombosis. Due to different instruments, its incidence rate is 5% ~ 27%. The thicker the release catheter, the greater the probability of venous thrombosis at the puncture site. In addition, the filter itself will also form thrombus, leading to inferior vena cava obstruction. In contrast, the incidence of Greenfield filter is the lowest, about 4%, while the probability of inferior vena cava obstruction caused by Simon filter and VenaTech filter is higher, reaching 16% ~ 30%. Some patients with inferior vena cava obstruction have no clinical manifestations, and a few patients may have femoral contusion.
B. Blood vessel puncture: the filter screen fixing hook pierces the blood vessel and damages the surrounding tissues. In order to prevent the screen from shifting, most screens are fixed on the wall of inferior vena cava with barbs. If the fixing hook pierces the blood vessel wall and further damages the adjacent organs, the corresponding symptoms can appear, and the incidence rate is about 9%. Organs that may be damaged include duodenum, small intestine, abdominal aorta, pancreas, etc. , and can cause retroperitoneal hematoma.
C. filter screen displacement: the filter screen is generally placed under the renal vein. If the filter is not fixed properly, it can shift with the blood flow. Most of the displacement distance is below 7cm, and a few of them can be displaced to the right atrium, right ventricle and even 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 the renal function. Theoretically, renal vein thrombosis may lead to renal failure, but there is no corresponding report in clinic. The positioning error of the filter screen may also be caused by technical operation errors.
D the guide wire is stuck and the filter screen is broken, which is rare in clinic.
③ Surgical methods:
A. The right femoral vein is generally selected as the puncture point, and the right jugular vein or the left femoral vein can also be selected. However, the jugular vein approach is in danger of air embolism, and the anatomical particularity of the left iliac vein makes the left femoral vein approach more difficult than the right femoral vein approach.
B. After successful puncture, send a guide wire with a diameter of 0.035in (in) into the inferior vena cava, pull out the puncture needle, put on an expanding sheath, send the expanding sheath directly into the inferior vena cava, and then pull out the expanding tube.
C, insert the screen releaser into the guide sheath, and place the top end of the releaser at the level of the second lumbar vertebra under X-ray perspective positioning.
D. Pull out the catheter and sheath in the releaser and release the filter screen. Once the filter is released, you can't try to move it. E. Pull out the guide sheath together with the releaser, and press the puncture point to stop bleeding.
2. Treatment of chronic venous obstruction Lower extremity venous thrombosis, such as venous lumen failure or incomplete recanalization, forms chronic venous obstruction of lower extremity. If the collateral vein is not compensated enough, the swelling of the affected limb is not easy to subside, which has a great impact on the life and work of patients. The treatment of chronic venous obstruction of lower limbs should choose non-surgical treatment or surgical treatment according to the patient's situation.
(1) Mechanical physical therapy: venous congestion and tissue swelling caused by blocked venous blood return of lower limbs. The use of elastic bandage or elastic socks can obviously improve the symptoms of patients, relieve the pain of affected limbs, accelerate the regression of swelling, and effectively prevent the late complications of deep vein thrombosis. Elastic socks should be medical elastic socks with step pressure difference, and the pressure gradually decreases from the ankle. They should be worn during the day and taken off before going to bed. This method is simple and easy to accept, but it should be banned in the acute stage of venous thrombosis of lower limbs to prevent pulmonary embolism caused by thrombus shedding.
(2) Drug therapy: Patients with chronic venous obstruction of lower limbs should still be given anticoagulant therapy, because patients with a history of thrombosis have a great chance of thrombosis again, and anticoagulant therapy can effectively prevent thrombosis from forming again. Oral anticoagulation therapy, such as warfarin, can also be used as anti-platelet aggregation drugs, such as aspirin and ticlopidine. Traditional Chinese medicine, such as salvia miltiorrhiza, is helpful to the establishment of collateral circulation.
(3) Endovascular interventional therapy: mainly for large blood vessels, such as iliac vein and inferior vena cava. When venous thrombosis is not completely recanalized, it is easy to form local stenosis. After the stenosis was confirmed by venography, the contralateral femoral vein was intubated to the stenosis, dilated with balloon catheter, and placed with stent to restore the lumen diameter. Endovascular interventional therapy is simple, but it is only suitable for short-segment stenosis of great vein. Stent placement in static vascular lumen is also a factor inducing thrombosis, and the long-term effect is uncertain.
(4) Surgical treatment: Chronic venous obstruction of lower limbs generally does not require surgical treatment, and the surgical treatment is mainly to reconstruct venous bypass. Because of the particularity of venous blood flow, the long-term patency rate of bypass blood vessels is not as good as that of arterial blood vessels, and the indications should be strictly controlled in surgical treatment. Preoperative color Doppler ultrasound, magnetic resonance imaging or routine venography are helpful to determine the location and scope of venous lesions, and pelvic CT examination can rule out the possibility of tumor compression.
① Indications for operation: patients with obvious symptoms and ineffective after conservative treatment.
② Factors affecting the long-term patency of venous bypass vessels:
A. materials of bypass blood vessels: like arterial bypass surgery, autologous vein is the first choice for bypass blood vessels, which has a better long-term patency rate than artificial blood vessels. Great saphenous vein is the most commonly used vein. If it is cut vertically and then sutured spirally, it can be made into larger diameter blood vessels, which can be used for iliac vein or even inferior vena cava bypass surgery. The contralateral superficial femoral vein is sometimes used as a bypass vessel, but it may cause swelling of the contralateral lower limb or other complications. Occasionally use upper limb veins and jugular veins. Cryopreserved human allogenic vein has also been used in clinic, but its long-term effect remains to be confirmed. Among the artificial blood vessel materials, polytetrafluoroethylene (ePTFE) is used most, because it can be made into any caliber and length, and does not need to be pre-solidified. The artificial blood vessel with support ring is not easy to collapse into an angle after compression, and it has better antithrombotic characteristics than other materials.
B. Temporary arteriovenous fistula: 1953, Lin Kun first proposed to construct an arteriovenous fistula at the distal end of the bypass vessel, which can accelerate the blood flow in the bypass vessel and reduce the chance of thrombosis. Practice shows that temporary arteriovenous fistula can really improve the long-term patency rate of bypass vessels. But for patients with cardiac insufficiency, the increase of blood volume will increase the burden on the heart. Menawat thinks that the ratio of fistula diameter to bypass vessel diameter should not be >: 0.3. An unabsorbable 2-0 thread can be wound around the arteriovenous fistula and tied loosely, and the end of the thread is buried under the skin, which is convenient for identifying the ligation and closure of the fistula in the future. Fistula can also be closed by interventional intubation and embolization. The time of fistula closure is generally 6 months after operation.
C. Thrombosis prevention measures: As mentioned above, anticoagulants and intermittent leg air compression can effectively prevent thrombosis. During the operation, 1 branch was found in the distal vein of the bypass vessel, and a thin catheter was inserted and the other end was taken out of the body. After operation, heparin diluent was continuously dripped, and the partial thromboplastin time (APTT) was not more than twice that of the normal control group. After 48 hours, the catheter was removed, heparin anticoagulation therapy was continued through superficial vein, and oral anticoagulation therapy was gradually changed.
D. Close observation of bypass vessels: After the establishment of bypass vessels during operation, color Doppler ultrasound or venography is helpful to judge the patency of anastomosis and correct the problems in time. To measure the distal venous pressure, compare the changes of venous pressure before and after blocking bypass vessels, and understand the influence of bypass vessels on hemodynamics. After operation 1 day, the patency of bypass vessels can be known in time through intravenous branch indwelling catheter angiography. Follow-up with color Doppler ultrasound regularly after discharge, and correct the problems as soon as possible.
③ Surgical methods:
A. great saphenous vein-popliteal vein bypass (May-Husni operation): 1954 was first designed by Warren and Thayer, but it was not popularized. It was not until 1970s that May and Husni were introduced and popularized again. This operation is suitable for cases with simple superficial femoral vein or proximal popliteal vein occlusion. The ipsilateral great saphenous vein was reserved and the distal popliteal vein was exposed. After the great saphenous vein was cut off, it was anastomosed with the distal end of popliteal vein. When anastomosing, try to be careful, try not to damage the intima of blood vessels, and use 6-0 or 7-0 non-absorbent non-invasive suture to suture continuously. Temporary arteriovenous fistula can be selected in ankle, and a branch of posterior tibial vein or great saphenous vein is anastomosed with posterior tibial artery end to end. Because there are few patients with simple superficial femoral vein thrombosis and the long-term patency rate of bypass vessels after operation is not high, this operation is rarely performed at present.
B. Superior pubic vein bypass (Palma-Dell operation): 1960 was first reported by Uruguayan doctor Palma and popularized by Dell. This operation is suitable for cases where one iliac vein is occluded, the other iliofemoral vein is normal, there is no thrombosis in the vein below the inguinal ligament of the affected side, and there is no venous valve insufficiency of the lower limbs. In addition, only cases with a circumference difference of more than 4cm between the two lower limbs were selected for surgery. The contralateral great saphenous vein was selected as the bypass vessel during the operation. The circumference of great saphenous vein should be above 4mm, and varicose veins should not be chosen. A section of the contralateral great saphenous vein is free, and its branches are cut off and ligated, leaving 25 ~ 30cm, and then cut off at its distal end. The great saphenous vein leads from the suprapubic subcutaneous tunnel to the affected femoral vein. After the saphenous vein was dilated with heparin and papaverine diluent, it was anastomosed with femoral vein end-to-end with 5-0 or 6-0 non-invasive suture. The 1 branch of the great saphenous vein or femoral vein was selected to establish a temporary arteriovenous fistula with the femoral artery, and the other 1 branch was selected to insert a fine catheter as a channel for continuous heparin perfusion and postoperative angiography (Figure 10). If the autologous vein condition is not ideal, an expanded PTFE artificial blood vessel with a diameter of 8mm can also be selected as a bypass blood vessel. Because the long-term patency rate is satisfactory, this kind of operation is still going on in many medical centers.
C femoral-vena cava, iliac-vena cava, vena cava-atrial vein artificial vascular bypass: it is suitable for cases of unilateral or bilateral iliac vein thrombosis and inferior vena cava thrombosis that cannot be operated by Palma-Dell. Using 10 ~ 12 mm PTFE artificial blood vessel for femoral-vena cava bypass, a temporary arteriovenous fistula should be established (Figure 1 1). 14mmPTFE artificial blood vessel was used for iliac-vena cava bypass, and 16 ~ 20 mm artificial blood vessel was used for inferior vena cava bypass or cavo-atrial bypass. Generally, temporary arteriovenous fistula is not needed, and the artificial blood vessel used should have an external support ring. Because of the large amount of operation, the long-term patency rate is not ideal, we should strictly grasp the indications and choose cases with serious symptoms that are ineffective by other methods.
(2) Prognosis
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