Iliac vein compression syndrome

Introduction to iliac vein compression syndrome The iliacvenous compression syndrome (iliacvenous compression syndrome) is a disease of the lower extremity and pelvic venous stenosis caused by iliac vein compression and/or the presence of abnormal adhesion structures in the lumen. In 1965, Cockett and LeaThomas had sputum by venography and surgery. A study of patients with a history of femoral vein thrombosis and severe thrombotic sequelae found that in the site of the right common iliac artery crossing the left common iliac vein, thrombosis is easily formed in the venous lumen, and the formed thrombus is difficult to recanalize, causing veins in the lower extremities and pelvis. The reflux disorder creates a series of clinical signs and symptoms, so this syndrome is called Cockett syndrome. The iliac vein compression not only causes venous return dysfunction and lower extremity venous hypertension, but also becomes one of the causes of venous valve insufficiency and superficial varices of the lower extremity. It can also cause sacral-femoral vein thrombosis, which is a potential factor for venous thrombosis in the left lower limb. . basic knowledge Sickness ratio: 0.0001%-0.0005% Susceptible people: no specific population Mode of infection: non-infectious Complications: thrombosis

Causes of iliac vein compression syndrome

(1) Causes of the disease

Anatomical factors (20%):

The anatomical relationship between the radial artery and the iliac vein is the basis of the iliac vein compression syndrome. The bilateral common iliac vein is on the right side of the middle and lower plane of the fifth lumbar vertebral body, which merges into the inferior vena cava and goes up the spine. The right common iliac vein is almost The line is continuous with the inferior vena cava, while the left common iliac vein is traversed to the right from the left side of the pelvis. It is almost at right angles to the inferior vena cava before the lumbosacral vertebrae, and the abdominal aorta is descended from the left side of the spine. The lower limb plane of the lumbar spine is divided into the left and right common iliac artery. Therefore, the right common iliac artery spans the front of the left common iliac vein and then extends to the lower right of the pelvis. Studies have found that in the proximal 3/4 human body, the right common iliac artery At the bilateral common venous junctions, the level of the left common iliac vein is horizontal; 1/5 of the people are at this level of mild upper, a few are below this point, so that the left iliac vein is more or less waisted. The physiological lordosis of the atlas is pushed forward, and at the same time, the right common iliac artery across the front is pressed backwards, so that it is in the anatomical position after the front pressure, when the human body is upright and the lumbosacral height is tilted forward, Physiological lordosis increases the pressure more obvious; when the human body When in a sitting position, the pressure is relieved or disappears. Occasionally, the compression of the left common iliac vein originates from the low bifurcation of the abdominal aorta, the distorted left common iliac artery, the bladder, the tumor, and the ectopic kidney.

Intracavitary abnormalities (30%):

McMurrich, Erich, and Krumbharr et al. performed anatomic observations on a large number of corpses without significant left venous venous disease. The incidences of left iliac vein compression and intraluminal adhesion were 32.3%, 23.8%, and 14%, respectively. In the year, May and Thurner proposed that 22% of the autopsy had a similar sacral structure in the left common iliac vein. This scorpion-like structure contains fibroblasts, collagen and a large number of capillaries. To this structure, they thought that this was due to an acquired response of the left common iliac vein to the right common iliac artery and the fifth lumbar vertebrae. Pinsolle et al. observed the venous-iliac vein connection points of 130 corpses in detail. There is an abnormal structure in the left iliac vein of the corpse, and he divides it into five categories:

(1) : The sagittal triangle at the junction of the sacral venous junction protrudes perpendicularly into the small structure in the cavity.

(2) Flap: The structure of the bird's nest similar to the lateral edge of the common iliac vein.

(3) Adhesion: a fusion of a certain length and width of the anterior and posterior walls of the vein.

(4) Bridge: The long strip structure divides the lumen into 2 to 3 sections of different caliber and spatial directions.

(5) Band: The diaphragm-like structure causes the lumen to form a sieve-like porous change, and the source and significance of the abnormal structure of the common iliac vein remains controversial.

At present, it is more inclined to explain that the right common iliac artery, the close contact between the lumbosacral vertebrae and the left common iliac vein, and the arterial pulsation cause the vein wall to be repeatedly stimulated, causing chronic damage and tissue reaction of the vein. :

1 This anatomical position is fairly constant, always at the level of the right common iliac artery and the left common iliac vein;

2 there is dense fibrous tissue between the arteries and veins;

The normal endometrium in the 3 cavity, the middle membrane tissue is replaced by a neat connective tissue, the surface is covered with a layer of normal endothelial cells, this structure is significantly different from the mechanized thrombus, another view involves congenital factors, think The abnormal structure of the cavity is significantly different from the similar adhesion structure of the new tissue or the inflammatory tissue. Secondly, from the embryonic development, the right common iliac vein is completely derived from the right iliac vein; the left common iliac vein is derived from The fusion of the main veins of bilateral iliac crests often forms two or more conduits. The abnormal structure of the veins is derived from the incomplete degradation of these pipelines during development. According to reports in the literature, the existence of this tissue structure has a family history tendency.

Secondary thrombosis (28%):

On the basis of the presence of iliac vein compression and abnormal structure in the lumen, once the trauma, surgery, childbirth, malignant tumor or long-term bed rest, the venous return or blood coagulation is increased, the sputum-femoral vein thrombosis can be secondary. Formation, Johnson et al believe that contraceptives help explain the iliac vein compression syndrome in young women.

Once the thrombus is formed, the iliac vein compression and adhesion segment further inflammation and fibrosis, which makes the iliac vein develop from partial obstruction to complete obstruction. Due to the existence of compression and abnormal structure in the lumen, it is difficult to recanalize after the iliac vein thrombosis. The left common iliac vein is occluded for a long time and is difficult to cure.

(two) pathogenesis

The venous hemodynamic changes of the lower extremities caused by stenosis or obstruction caused by internal and external factors of the iliac vein are the basis of the pathophysiology and evolution of the iliac vein compression syndrome.

1. The collateral vessels form a rich collateral vein in the pelvic cavity, which plays an important role in slowing the hemodynamic changes of the common iliac vein compression syndrome. For example, the left common iliac vein can pass through the internal iliac vein. Anterior tibial venous plexus and contralateral iliac vein of female organ venous plexus, lumbar ascending vein - middle sacral, anterior and external vein - abdominal thoracic cavity and azygous vein; pelvic vein - vertebral venous system, branch vein of proximal deep and shallow vein of lower limb, also It will play a certain side branch circulation, and the compensatory ability of the collateral circulation is relatively strong. For example, the total diameter of the left iliac vein, the lumbar ascending vein and the middle iliac vein can be expanded by an average of 3 mm, and the total venous pressure syndrome vein. Hemodynamic changes, in the case of collateral circulation can be compensated or under load, the lower limbs will not appear or only mild clinical manifestations.

2. The degree of hemodynamic changes in the evolution process depends on the degree of iliac vein occlusion and the venous return disorder caused by the pelvic and lower extremity venous pressure - venous dilatation - secondary relative valvular insufficiency, shallow Vein and varicocele, women with severe pelvic veins, will form the so-called "parasexual tissue varicose veins."

When the internal and external iliac veins are severe, there are obvious stenosis or obstruction. This is the anatomical factor of common venous thrombosis in the common iliac vein compression syndrome. Zhang Yuanliang et al reported that the intraluminal adhesion structure can reduce the iliac vein by 4.3%-88.6. %, an average of 33.9%, when Fu Jiayu reported 1 and 2 adhesion structures, the veins were reduced by 20% and 43%, respectively, and Zhao et al. 35 limbs were caused by deep venous thrombosis of the lower extremities caused by iliac vein compression syndrome. The stenosis of 41.7% and 100% were 31.4% and 45.7%, respectively. This shows the role of severe stenosis and complete occlusion in venous thrombosis, and it is believed that the venous stenosis is nearly 50%, and its formation rate will be greatly increased.

Prevention of iliac vein compression syndrome

There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Complications of iliac vein compression syndrome Complications thrombosis

Calf ulcers, vasospasm secondary thrombosis is the most common complication of this disease.

Symptoms of iliac vein compression syndrome Common symptoms varicocele varicocele pulmonary embolism collateral circulation establish venous return disorder lower extremity edema venous thrombosis female lumbosacral physiology...

Some scholars have divided the clinical manifestations of sacral venous compression syndrome into asymptomatic, edematous, iliofemoral venous thrombosis and varicocele, asymptomatic without clinical significance, iliofemoral venous thrombosis and sputum The relationship between total venous compression syndrome is close, but it is not the inevitable result of sacral venous compression syndrome. There is no thrombosis in 14 cases including Baowen. The varicocele does not appear alone, and it will be compared with other body surface. The presence of venous veins at the same time, I am afraid that more sacral venous compression syndrome appears as the "face" of deep venous insufficiency, the incidence rate is as high as 71.4%, which shows that the above classification is not comprehensive, the common iliac vein The clinical manifestations of compression syndrome are mainly determined by the degree of venous return disorder in the lower extremities.

According to the severity of hemodynamic changes, the clinical manifestations were divided into three phases.

Initial stage: lower extremity swelling and fatigue are the most common early symptoms. The affected limb has only mild edema, especially when standing and sedentary for a long time. The physiological anterior protrusion of the female lumbosacral is obvious, and the left lower extremity will appear as a periodical lymphoid. In edema, Ferri had 3 patients with long-standing left lower extremity edema. The angiography was confirmed by compression of the left iliac vein. In 1993, Sloame et al studied 215 elderly people and found 88 cases of lower extremity 3mm deep edema. 34.5% on the left side and 6.9% on the right side. It is believed that the left lower extremity edema in the middle-aged and elderly people is probably caused by the right common iliac artery pressing the left common iliac vein and the accompanying lymphatic vessels. Therefore, it should be thought that there is no other reason for lower extremity edema. There may be this possibility, female patients may have menstrual period prolonged and increased menstrual flow, as well as menstrual pelvic visceral congestion, increased venous pressure and swelling of the lower extremities and other symptoms.

Mid-term: As the venous return disorder increases and the venous pressure continues to rise, it will lead to deep venous insufficiency. Once it reaches the calf and the venous valve, similar symptoms to the primary deep venous insufficiency will occur. It is characterized by varicose veins of the lower extremities, edema of the lower extremities, pigmentation, and varicocele.

Late stage: symptoms of severe deep venous insufficiency, such as calf ulcers, or thrombosis of the iliac vein. The majority of cases reported at home and abroad are found in the treatment of thrombosis, for non-thrombotic Patients with venous obstruction and symptomatic venous obstruction should pay special attention to the clinical manifestations of similar but different venous thrombosis due to the strict stenosis of the iliac vein and the limitation of obstructive lesions, and the collateral veins. The original stenosis, thrombosis of the deep veins of the lower extremities is not prone to shedding and pulmonary embolism occurs.

Examination of iliac vein compression syndrome

1. Air plethysmography and post-activity venous pressure measurement: It is the best screening index for iliac vein compression syndrome. The maximum flow rate of lower extremity vein in this patient is normal at rest, and it is lower than normal after activity, and the time of venous refilling is shortened; After the activity, the venous pressure is higher than that of normal people. There is a high false positive rate in this method. The diagnosis depends on the imaging examination.

2. Lower extremity antegrade and (or) femoral vein catheterization: It is the only specific diagnostic method currently known as the gold standard for the diagnosis of iliac vein compression syndrome. The image shows the widening of the transverse diameter of the compressed vein. Upper and lower fine trumpet shape; limited filling and defect, fiber cord and adhesion structure shadow; different degrees of stenosis, such as external iliac vein compression, there are shadows of compression, venous occlusion or pressure shifting; The degree of pelvic collateral vein; visible collateral vein drainage delay phenomenon, suggesting that the iliac veins are not smooth, the iliac vein adhesion structure is one of the main causes of iliac vein compression syndrome, its shape is different, There is still a lack of imaging reports on this.

3. Dynamic venous manometry: suggesting that the stenosis of the stenosis and the distal venous pressure measurement in the femoral vein catheterization, such as the pressure difference of 0.20kPa has diagnostic significance, but lack of specificity, such as calm phase difference is not obvious, The calf gastrocnemius can be squeezed to increase blood flow for a clear indication.

4. Color ultrasound examination:

(1) Two-dimensional ultrasound: Ultrasound findings of primary iliac vein compression syndrome:

1 The left common iliac vein is compressed by the right common iliac artery, and the posterior is pushed forward by the spine to make the local blood vessels thinner. The characteristic is that the anteroposterior diameter becomes flat, and the left and right diameters are widened up to about 4 cm.

2 The left anterior and posterior diameter of the left iliac vein was gradually widened to form a "bell" shape, and the transverse diameter became narrower <2 cm.

3 The syndrome is often accompanied by thrombosis of the left iliac vein. After embolization, the inner diameter of the deep vein of the lower extremity is widened. The longer course of the disease will form the ipsilateral deep venous thrombosis of the lower extremity, and a large number of collateral circulation will be formed.

Ultrasound manifestations of secondary iliac vein compression syndrome:

1 venous localized pressure is narrowed, often with varying degrees of displacement, the compressed vein has a longer segment of stenosis, and a substantial mass echo is seen around it.

2 The degree of iliac stenosis is related to the degree of tumor compression. In severe cases, the occlusion can be completely occluded, and the deep veins and superficial veins of the ipsilateral lower extremities have signs of dilatation.

3 Sometimes it is also possible to detect metastatic lymph nodes in the groin.

(2) Color Doppler: Color Doppler manifestation of primary iliac vein compression syndrome: the stenosis area under compression is a multicolored mosaic continuous high-speed blood flow, and the color flow is interrupted when the pressure is completely occluded. The color flow interruption is exactly the same as the compression of the right common iliac artery. It is helpful to use color Doppler to check the disease. It is easy to identify the relationship between the common iliac artery and the common iliac vein. It is more convenient than two-dimensional ultrasound. The collateral circulation is most common in the left common iliac vein. Most of them are gradually expanded through the rich anastomosis in the pelvic cavity, and they have a compensatory effect. There are many circular and banded liquid dark areas in the pelvis, which can display high-speed blood. Flow, due to the accelerated circulation of the collateral circulation, the color of the blood flow is bright, and the collateral vein of the external iliac vein is rarely formed.

Color Doppler manifestations of secondary iliac vein compression syndrome:

1 In the compression, the iliac vein has a limited color blood flow, the color is bright, and the edges are not neat.

2 Complete occlusion of the achromatic blood flow shows that under normal circumstances, the radial artery is not easy to flatten, and its color blood flow can pass through a substantial mass.

3 The lower extremity vein has signs of blood reflux obstruction.

(3) Pulse Doppler: Pulse Doppler manifestation of primary iliac vein compression syndrome: variability at high pressure and high-speed continuous blood flow spectrum, local occlusion without blood flow signal, distal vein The blood flow velocity slowed down, and the venous blood flow velocity did not change significantly during the Valsalva test.

Pulse Doppler manifestations of secondary iliac vein compression syndrome: stenosis of the iliac vein at the compression site and high-speed continuous blood flow spectrum, complete occlusion can not measure blood flow signals.

4. Magnetic resonance and CT venography: At the same time as the diseased blood vessels are displayed, the extraluminal structures (arteries, collateral vessels, lumbosacral vertebrae, etc.) can also be displayed, which is helpful for the diagnosis of the disease.

Diagnosis and differentiation of iliac vein compression syndrome

1. Primary deep venous insufficiency: only through satisfactory iliac vein angiography to exclude axillary stenosis.

2. Primary deep vein thrombosis: often sudden onset, unlike the generalized venous compression syndrome has a long history of lower extremity venous reflux disorder, late deep venous thrombosis occurs, due to the latter limitation of iliac vein stenosis and obstruction And the collateral vein is better, so there is a clinical manifestation similar to and different from venous thrombosis. In addition, due to the original stenosis of the common iliac vein, the thrombus of the deep vein of the lower extremity is not prone to shedding and pulmonary embolism occurs. It is quite difficult to identify the two clinically. Only a satisfactory iliac vein angiography can determine the presence or absence of axillary stenosis or obstruction.

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