Deep vein thrombosis in the lower extremity is an abnormal clotting of blood in the lumen of the skeletal vein and beyond, blocking the venous lumen and resulting in impaired venous return in the lower extremity. Due to the anatomical relationship, the left lower extremity is the most affected.
The disease is a common peripheral vascular disease with high incidence and is characterized clinically by swelling and pain in the lower extremities. Most of them have a history of long-term bed rest, postpartum, abdominal surgery, etc. If not treated in time, it will lead to chronic lower limb venous insufficiency, which will seriously affect life and work.
I. Etiology and pathology
1.Western medical etiology and pathology
In 1846, Virchon proposed three major factors of venous thrombosis, namely: venous damage, slow blood flow and blood hypercoagulation.
(1) vascular injury: surgery, trauma, fracture, chemical drugs and some other factors can directly lead to vascular wall damage, when the venous injury subendothelial layer and collagen exposed, so that the venous wall charge change, easy to platelet adhesion; trauma endothelial cell function damage, can release bioactive substances, start the endogenous coagulation system, easy to form thrombus; so platelets due to the venous wall charge change cause or due to The platelets adhere and aggregate to form thrombus due to the change in charge of the vein wall or due to the initiation of coagulation system when endothelial cells are damaged.
(2) Slow blood flow: prolonged bed rest, physiological reaction during surgery, postoperative limb braking, sedentary state or vascular compression stenosis can cause slow blood flow to the limb. The slow blood flow causes it to form vortices in the valve sinus; local hypoxia in the valve causes expression of leukocyte adhesion factors, and leukocyte adhesion contributes to thrombus formation. In addition, the normal axial flow of blood is disrupted, causing platelets and leukocytes to flow toward the side of the vessel wall, increasing the opportunity for platelets and leukocytes to aggregate and adhere and form thrombi.
(3) Blood hypercoagulation: pregnancy, postpartum, long-term use of contraceptives, tumor tissue lysis products, large burns and other factors can make the blood in a hypercoagulable state. At this time, the platelet count increases, the content of coagulation factors increases and the activity of anti-coagulation factors decreases and thrombus is formed.
(4) Thrombus morphology: Typical thrombus includes three parts: head, neck and tail. The head is white thrombus (including fibrin, layered platelets and leukocytes, and very few red blood cells); the neck is mixed thrombus (a mixture of white and red thrombus); and the tail is red thrombus (platelets and leukocytes scattered in a reticular mass of red blood cells and fibrin).
(5) Thrombus regression: thrombus can grow and spread distally and proximally. Subsequently, the thrombus can be dissolved and dissipated under the action of fibrinogenolytic enzymes, and sometimes the small cleaved emboli can enter the lung with the blood and cause pulmonary embolism. When the thrombus is not completely dissolved and dissipated, a fissure can be formed in the vein called incomplete recanalization. At the same time, the venous valve can be damaged, triggering reflux disease and secondary deep vein valve insufficiency of the lower limbs.
2, Chinese medicine etiology pathogenesis: Chinese medicine theory that prolonged lying, prolonged sitting, postpartum injury, surgery trauma, etc. can cause the poor running of qi and blood, “qi is the handsome of blood” qi is not smooth then the blood travels slowly, so that blood stasis blocked in the veins, the veins and ligaments are blocked, the return flow of blood is blocked, water and fluid overflow, the flow of the lower limbs and the onset of disease.
If the stasis is blocked and does not pass through, the pain will occur; if the water and fluid overflow, the swelling of the femur will appear; the stasis will turn into heat for a long time and lead to heat in the skin of the affected limb; the Qi deficiency cannot control the veins and ligaments, so the superficial veins and ligaments can be seen to be angered.
Clinical manifestations
The thrombosis is divided into the following three types according to the site of occurrence.
1. Central type: thrombosis occurs in a vein of the iliac strand.
(1) Symptoms: heavy, swollen or sore limbs, and pain in the femoral triangle may be present. It is often not noticed at the early stage because the condition is mild and the symptoms are not obvious, so it is often ignored or found late.
(2) Signs: rapid onset, swelling of the entire lower limb, pain and pressure in the femoral triangle of the iliac fossa on the affected side; there may be indentation marks in front of the tibia, superficial veins on the affected side, fever, and increased skin temperature of the limb. The left side is more than the right side.
2.Peripheral type: thrombosis in femoral-s vein and deep vein at the end of calf.
(1)Symptoms: swelling and pain in the thigh or calf, heaviness, soreness and swelling occur in the deep vein of calf, pain is obvious, can not step flat walking.
(2) Signs: swelling of the thigh mainly in the femoral vein, but the degree is not very heavy, the skin temperature is usually not significantly increased, and the skin color is normal or slightly red. If it is confined to the deep calf vein, the calf is in severe pain and cannot walk, and the pain is aggravated by walking, often with claudication, gastrocnemius muscle pressure pain is obvious, and Homans’ sign is positive (i.e., when lying on the back, both lower limbs are straightened, and excessive dorsiflexion of the ankle joint will trigger gastrocnemius muscle tension pain).
3.Mixed type: Total lower limb deep vein thrombosis
(1)Symptoms: heaviness, soreness, pain, pain in the femoral triangle and s fossa and calf muscles of the whole lower limbs.
(2)Signs: swelling of lower limb, pressure pain at femoral triangle, s fossa and gastrocnemius muscle is obvious. If the elevated body temperature and accelerated pulse rate are not obvious and the skin color change is not significant, it is called white swelling of the femur. If the disease is severe and the swelling of the limb is obvious, which affects the arterial blood supply, the pulsation of the dorsal foot and posterior tibial artery is weakened or disappears; the skin of the limb is bruised and the skin temperature is elevated, which is called femoral cyanosis. Gangrene of the limb may occur in the latter case.
4.Complications and sequelae
(1) Complications: Deep vein thrombosis of the lower limb may spread to its distal and proximal ends, further aggravating the reflux obstruction. If the thrombus spreads to the inferior vena cava, it may cause bilateral lower limb reflux obstruction. If the thrombus is dislodged and flows back to the pulmonary artery, it can cause pulmonary embolism, which can be fatal.
(2) sequelae: after the formation of venous thrombosis in lower limbs, it can destroy the venous valves and leave the syndrome of deep venous valve insufficiency. The lumen is occluded in the early stage of the disease; while partial recanalization can occur in the middle stage; all of them can be recanalized in the later stage; and thrombosis can be formed again.