Lower extremity venous thrombosis

Introduction to lower extremity venous thrombosis Phlebitis caused by venous thrombosis of the lower extremities is called thrombophlebitis, which is common in the superficial veins of the lower extremities. It can be injected intravenously by drugs, or by complications of large and small saphenous varices or with inflammatory disease or autoimmune diseases of vasculitis. Part of it exists. Due to prolonged illness in bed, trauma or fracture, larger surgery, pregnancy, childbirth, long-distance ride or plane sedentary, or long sitting and squatting can slow blood flow, stasis, and promote lower extremity venous thrombosis form. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: pulmonary embolism, cerebral embolism

Causes of lower extremity venous thrombosis

Venous wall damage (25%):

The vein wall is affected by any factor, usually mechanical damage, infective and chemical damage, the collagen in the basement membrane and connective tissue of the vein is exposed, the platelets then adhere to it, aggregation occurs, and many are released. Bioactive substances, such as catecholamines, serotonin, etc., and under the action of platelet thrombin, form a prostaglandin PGG2, PGH2 and other substances through arachidonic acid, which can aggravate the aggregation of platelets and facilitate the formation of thrombus.

Blood stasis status (35%):

Due to prolonged illness in bed, trauma or fracture, larger surgery, pregnancy, childbirth, long-distance ride or plane sedentary, or long sitting and squatting can slow blood flow, stasis, and promote lower extremity venous thrombosis form.

Hypercoagulable state of blood (30%):

Such as trauma, post-operative, large-area burns, pregnancy, postpartum, etc. can increase platelets, adhesion, and easy to form thrombosis.

Other factors (10%):

Such as age, obesity and anti-activated protein C.

Pathogenesis

Virchow's blood flow stagnation in the 20th century, vein wall damage and hypercoagulable state are still the three major factors of venous thrombosis, but since then all factors have been embodied or updated concepts, blood stasis promotion The adhesion, aggregation and release of platelets to the blood vessel wall contribute to the formation of thrombus. In the anatomy, the left iliac vein is behind the left iliac artery, causing the left iliac vein to be easily compressed, making the left lower extremity deep vein more susceptible to disease, vein Wall damage includes mechanical, chemical (intravenous), infectious and autoimmune diseases, as well as infection, tumor, oral contraceptives, antithrombin III activity, and C protein. And S protein abnormalities and high phospholipidemia.

Prevention of lower extremity venous thrombosis

Mechanical method

It is intended to promote the venous return of the lower extremities, stimulate the gastrocnemius muscle with an electric stimulator, and promote the limb circulation by a circulatory drive or a rhythmic positive pressure or negative pressure drive. The patient is encouraged to perform ankle and quadriceps activity early. Do more deep breathing and coughing action. It is also important to get out of bed as soon as possible. After wearing the medical elastic stockings with poor pressure, such as calf 4.0kPa (30mmHg), thigh 2.67kPa (20mmHg) pressure also plays a cyclical driving role. .

2. Drug prevention law

The first is low-dose subcutaneous heparin therapy. Comprehensive data show that subcutaneous heparin therapy reduces the incidence of post-operative deep vein thrombosis from 25% to 7%; the incidence of large-scale pulmonary embolism is reduced from 6% to 0.6%, low-dose heparin The reason why the preventive effect is not fully understood, the subcutaneous route slows down the absorption of the drug, and the body may maintain a certain heparin concentration. The main method is to use subcutaneous injection of 50 mg 2 hours before surgery. Once every 12 hours, 50mg each time, antiplatelet therapy mainly includes enteric-coated aspirin and dipyridamole. The role of low-molecular dextran is to reduce the viscosity of the blood. It can be intravenously instilled 500-1000ml per day.

Lower extremity venous thrombosis complications Complications, pulmonary embolism, cerebral embolism

There may be thromboembolism (pulmonary embolism, cerebral embolism, etc.), chronic ulcers of the lower extremities, etc. In severe cases, acute pulmonary embolism may occur and sudden death may occur.

Symptoms of venous thrombosis of lower extremities Common symptoms Acute pain varicose vein thrombosis Migration superficial vein thrombosis persistent pain venous return disorder venous blood flow stagnation sputum superficial vein has a redness...

1. Primary iliac-femoral vein thrombosis

Thrombosis is located in the iliac-femoral vein, and the incidence is lower than that of the calf muscle venous thrombosis. The left side is more common, which is 2 to 3 times of the right side. In a group of 1432 cases, the left side accounts for 69.3%. 26.6%, 4.1% on both sides.

The iliac-femoral vein is the main channel for venous return of the whole lower extremity. Once thrombosis occurs, it is rapidly onset. The main clinical manifestations of this disease are: 1 pain and tenderness of the affected limb; inflammatory reaction induced by thrombus can cause local persistent pain; Lateral venous return obstruction causes pain, and the symptoms are aggravated when standing. In the iliac-femoral vein, the cord and tenderness are often touched. 2 Swollen: caused by severe venous return disorder, so it is generally quite serious, 3 limbs The skin color is purple, and severe cases can cause plaque and even gangrene. In 4 severe cases, the arterial pulsation of the extremities is obviously weakened and disappears. 5 superficial varices are compensatory, and the acute phase is not obvious.

The outcome of primary iliac-femoral vein thrombosis is: 1 fibrinolysis and recanalization, 2 limitations and mechanization, 3 thrombus expansion: retrograde expansion may involve the entire lower extremity deep venous system; antegrade expansion may invade the inferior vena cava, such as Thrombosis can lead to fatal pulmonary embolism.

2. Secondary iliac-femoral vein thrombosis

The thrombus originates from the venous plexus of the calf muscle. When the antegrade expansion, it can affect the entire iliac-femoral vein system. This is a mixed type, which is the most common type in the clinic. It is characterized by: 1 the onset of the disease is mostly hidden; 2 at the beginning of the symptoms Slightly, many patients are not found until the sputum-femoral vein is involved, and the typical symptoms are found, so the actual stage is longer than the symptom period; 3 the vegetative changes in the boot area, including desquamation, pigmentation, eczema-like changes and ulcers, etc. Because the deep and shallow traffic veins of the lower leg have lesions, the evolution is much faster and more severe than the primary type.

3. Femoral bruises

In 1938, Gregoire described a severe diffuse iliac-femoral thrombosis involving the entire extremity vein, called phlegmasia cerulea, which is not uncommon clinically. This is the most severe type of deep venous thrombosis of the lower extremities. The entire venous system, including the potential collaterals, is almost completely blocked, with a sharp increase in venous pressure, severe pain in the limbs, marked swelling of the entire affected limb, shiny and cyanotic skin, decreased skin temperature, due to arterial spasm and/or gap syndrome It causes severe swelling of the affected limb, ischemia and even necrosis. This is venous or wet gangrene. It can cause shock due to a large amount of body fluid entering the affected limb and sudden limb pain in a short period of time.

Examination of lower extremity venous thrombosis

Radioactive fibrinogen test: 125I-labeled human fibrinogen can be absorbed by fresh thrombus, so after blocking the thyroid iodine absorption function, the agent is injected intravenously to scan both lower extremities, if a sudden increase or set of radioactivity is observed. This will help diagnose.

Radionuclide venography

Venous imaging was performed after injection of 99m (99mTc) human albumin microparticles from the dorsal vein of the bipedal vein to observe the calf, thigh, pelvic and abdominal vein imaging. The hot spot indicates the presence of fresh thrombus.

2. Doppler blood flow and plethysmograph examination

For non-invasive examination methods, it helps to determine the blood return and blood supply of the affected limb.

3. Venous angiography

It can directly develop the vein, can judge the presence or absence of thrombus, its scope, morphology and collateral circulation, not only help to determine the diagnosis, but also help to directly observe the treatment results. This method is the most reliable, but when the condition is too heavy It is not necessary to force the completion of this examination, and it must be considered that the angiography itself may aggravate the lesion. Generally, a small amount of heparin is injected from the angiographic portion after the contrast agent is injected, which helps to prevent the lesion from being aggravated.

4. Determination of venous pressure

It helps to understand the condition and observe the development. It can be measured alone or at the time of angiography.

Diagnosis and diagnosis of venous thrombosis of lower extremities

diagnosis

In the clinical work, detailed medical history, careful physical examination, and the necessary auxiliary examination, it is not difficult to diagnose the lower extremity venous thrombosis.

Differential diagnosis

Lower extremity venous thrombosis is easily confused with certain lower extremity venous reflux disorders, limb ischemic diseases, etc., and clinical attention is given to identification.

Primary deep venous insufficiency

Due to the free edge of the deep venous valve of the lower extremity, the free edge of the lower limb is sagging, the valve leaflets can not be tightly aligned, so that the venous blood completely flows back to the distal end of the limb, causing deep venous hypertension and congestion, and destroying the traffic venous valve, and swelling of the lower extremity occurs. Obvious superficial varicose veins, more common in people who have been engaged in standing for a long time, the incidence is concealed, relatively slow, these are not exactly the same as the venous thrombosis of the lower extremities, it is necessary to pay attention to identification.

2. Simple varicose veins of the lower extremities

More common young and middle-aged males, mainly the lower saphenous veins of the lower extremities, characterized by small saphenous veins, heavy lower limbs, fatigue, and little swelling. After a long standing or activity, the calves and the ankles are slightly swollen. Disappeared, and the lower extremity venous thrombosis, the lower extremity swollen, obvious pain or severe pain, and secondary superficial venous engorgement, varicose is also significant and extensive, if necessary, ultrasound Doppler examination and lower extremity venography Can confirm the diagnosis.

3. Lower extremity acute arterial embolism

More common in rheumatic heart disease, coronary heart disease, atrial fibrillation, etc., sudden severe limb pain, with fingertips, cold limbs, pale, loss of feeling, limb shrinkage, superficial vein collapse, arteries below the embolization plane The pulsation disappears, and a wide range of limb gangrene can occur, and attention should be paid to identification.

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