Ultrasound signs of varicose veins

Ultrasound diagnostics of chronic venous insufficiency and varicose veins

The most common form of chronic venous insufficiency is varicose veins. The cause of the disease is the failure of the valve apparatus of the superficial and deep veins of the lower extremities with the occurrence of pathological venous reflux. A mandatory sign of varicose veins are specific changes in the subcutaneous veins of the lower extremities: expansion, bulging through the skin and tortuosity, visible in a vertical position and disappearing in a horizontal position. Other clinical symptoms may include edema, increased volume, cyanosis of the skin of the distal parts of the leg, trophic disorders of the skin, mainly the lower third of the medial surface of the shin.

Meanwhile, it should be emphasized that all the listed signs are also inherent in another chronic pathology of the venous system of the lower extremities - post-thrombotic disease. The differences concern the localization of varicose veins and the timing of the appearance of clinical signs. Almost all patients with varicose disease first develop changes in the subcutaneous veins and only after three or more years other symptoms of the disease. As experience shows, in the case of a developed clinical picture, diagnosing varicose disease is not difficult. A more difficult task is to diagnose the initial forms of the disease and its atypical manifestations. In such a situation, special research methods are needed, they are also indicated in cases where the surgeon finds it difficult to answer questions regarding pathogenetic factors, among which the most important are: valvular insufficiency of the deep veins; retrograde blood flow through the trunks of the great and small saphenous veins; venovenous discharge through the perforating veins of the leg.

The examination is performed with the patient lying down and standing, without increased support on one or the other lower limb. All patients undergo an assessment of the state of blood flow in the large and small saphenous veins, perforating veins, and deep veins of the lower limbs. For this purpose, B-mode, color and energy mapping modes, spectral Dopplerography are used, using sensors with a frequency of 5-13 MHz.

In varicose veins, the vein wall is not thickened and is the same throughout. The vein is easily compressed by the sensor, the internal diameter changes when the subject strains. As a rule, varicose subcutaneous veins are visualized.

There are no structures inside the vein except for the valves. The latter are usually represented by two semicircular shadows that change position in the lumen of the vein depending on respiratory movements. At the height of the Valsalva maneuver, the valve cusps do not close and even prolapse during ectasia of the vein.

Clarification of the valve localization speeds up its search during surgical interventions. In addition, the surgeon must be given information not only about the presence of reflux, but also its nature and extent.

We will further describe the superficial veins of the lower extremities using the example of the great saphenous vein, since the changes in blood flow detected in it completely coincide with the blood flow data obtained during the study of the small saphenous vein.

Normally, blood flow in the trunk of the great saphenous vein can be easily located along the entire length of the vein from the ostial valve to the medial malleolus using color and power mapping.

With the use of these modes of visualization of blood flow in the lumen of the vein, it is not a problem to detect any reflux through the ostial valve, refluxes along the entire trunk of the great saphenous vein, refluxes from tributaries and perforating veins.

The use of the B-flow mode significantly changed the echographic picture of the previously known variants of blood flow in the system of the great and small saphenous veins. It turned out that normally the great saphenous vein works synchronously with its tributaries only in 68% of cases. In these patients, the blood flow simultaneously moves both in the trunk of the great saphenous vein and enters it from its tributaries.

In 32% of observations, the blood flow moves along the trunk of the great saphenous vein, but does not enter it from the tributaries. In this situation, there is no blood flow in the tributaries of the great saphenous vein. Their lumen is simply empty. Blood flow is determined only in the trunk of the great saphenous vein. After the entire volume of blood flow from the trunk of the great saphenous vein enters the common femoral vein, the trunk of the great saphenous vein becomes completely empty. Only the walls of the vessel and its anechoic lumen are visible. After the trunk of the great saphenous vein is freed from blood flow, blood synchronously enters the empty trunk of the vein from all visible tributaries, which gradually fills the lumen of the trunk of the great saphenous vein from the medial malleolus to the ostial valve. At the same time, the great saphenous vein begins to fill from the veins of the foot. Moreover, first of all, the part of the great saphenous vein located on the shin is filled, and then the more proximal parts of the trunk of the great saphenous vein.

If there is a tributary or tributaries of the great saphenous vein in the femoral part, the blood can fill only a certain section of the trunk of the great saphenous vein directly at the place where the tributary or tributaries enter the main trunk of the vein. Proximally and distally from the entry of the tributary or tributaries, the trunk of the great saphenous vein is not filled with flow. This tributary or tributaries, located in the thigh area, work synchronously with the tributaries of the great saphenous vein in the calf area, but not with the trunk of the vein. Gradually, the blood flow from the trunk of the great saphenous vein in the calf area reaches the part of the trunk of the great saphenous vein that is filled with blood flow from the tributary in the thigh area, then it spreads further to the ostial valve, and its entire volume simultaneously enters the common femoral vein. At the moment when the entire volume of blood begins to flow into the common femoral vein, the tributaries are completely emptied, and their lumen becomes anechoic. Then everything happens again.

The tributaries are simultaneously filled with blood (first phase), from which it enters the trunk of the great saphenous vein (second phase), the trunk is completely filled (third phase), and the entire volume of blood from the trunk of the great saphenous vein simultaneously enters the common femoral vein (fourth phase).

The role of tributaries of the great saphenous vein in the development of varicose veins is very significant. The nature of the blood flow in the trunk of the great saphenous vein depends on the angle of entry of the tributary into the trunk of the great saphenous vein. The smaller the angle (in relation to the antegrade direction of blood flow in the trunk of the great saphenous vein), formed when the tributary enters the trunk of the great saphenous vein, the more the direction of the two blood flows coincides with each other and turbulent flows do not arise at the confluence of the tributary and the trunk of the vein. This was noted in cases where the angle of entry of the tributary into the trunk of the vein does not exceed 70°. If the angle between the inflowing tributary and the trunk of the great saphenous vein is large enough and exceeds 70°, then turbulent blood flow appears in the trunk of the great saphenous vein, which cannot break through upward in the proximal direction. The blood flow in the trunk of the great saphenous vein bifurcates, and turbulent blood flow is clearly visible in front of the bifurcated part.

The development of varicose disease can be predicted in the preclinical stage of the disease. The main factor here is not primary valve insufficiency, but the direction of blood flow in the tributaries of the systems of the great and small saphenous veins when merging with the main blood flow in the trunks of the great and small saphenous veins.

The role of perforating veins in the occurrence of horizontal reflux has been fully proven. Ultrasound examinations allow visualization of perforating veins with a diameter of 1.5-2.3 mm. With such dimensions, the perforating vein is easy to detect by supplementing the B-mode examination with a color Doppler or EDC mode.

It is advisable to perform ultrasound examination of perforating veins of the lower extremities in patients with varicose veins together with a vascular surgeon. This is usually done the day before the operation. The presence of a vascular surgeon in the ultrasound diagnostics room has an important purpose - joint search and masking of perforating vein failure. In addition to identifying perforating veins, the vascular surgeon is given complete information about the state of the entire system of superficial and deep veins of the lower extremities with the localization of veno-venous discharges and patency of veins in all parts of the lower extremities, iliac and inferior vena cava.

Insufficiency of perforators with a diameter of 1.5-2 mm and more is easy to detect using color mapping supplemented by spectral Doppler. As for perforators with a diameter of 1 mm and less, here certain difficulties arise for these ultrasound methods in terms of detecting insufficiency of perforating veins. In a perforating vein with a diameter of 0.5 mm, it is already difficult to determine the direction of blood flow and, most importantly, to establish the insufficiency of a venous vessel of this diameter. In a perforating vein with a diameter of 0.2-0.4 mm, this is even more difficult to do. Using the B-flow mode, in a perforating vein, it is quite clearly visible how or in what way the blood flow moves through the vessel.

It is necessary to remember that the angle of confluence of the directions of blood flow from the perforating vein and the blood flow in the deep vein of the lower limb plays an important role in the development of perforating vein insufficiency. Most often, incompetent perforators are located in cases where the angle between the confluence of the antegrade directions of blood flows from the perforating vein and in the deep vein was greater than 70°. Probably, the angle of confluence of blood flows from the perforating and deep veins greater than 70° is one of the determining factors in the subsequent development of perforating vein insufficiency.

The coincidence of the directions of blood flows does not lead to the formation of turbulent parts of the blood flow in the deep vein at the point where the perforating vein enters it. Thus, in these cases, such a perforator, in the absence of other predisposing factors, does not lose its consistency.

The superficial veins may fill the bloodstream asynchronously with the deep veins. The trunks of the superficial veins are the first to fill. There comes a short-term moment when the pressure in the superficial veins exceeds the pressure in the deep veins of the lower extremities. Due to the increase in pressure in the superficial veins, the perforating veins are filled. At this time, the deep veins have empty trunks, without signs of their blood filling (the diastolic phase of the "muscle-venous pump"). The blood flow from the perforating veins enters the empty deep veins. Simultaneously with the beginning of the emptying of the perforating veins, the trunks of the deep veins begin to fill from other sources. Then the following happens: the deep veins are completely filled with blood flow and after that, instantly, the entire volume of blood flow from the deep veins of the lower extremities enters in the proximal direction.

Postthrombophlebitic disease develops as a result of acute deep vein thrombosis. The outcome of the thrombotic process depends on the degree of blood clot retraction and spontaneous thrombus lysis. In some cases, complete recanalization occurs, in others - complete obliteration, in others - vessel patency is partially restored. Most often, after thrombosis of the main veins, partial recanalization of the vessel lumen with phlebosclerosis and valvular insufficiency occurs. As a result, gross hemodynamic disorders develop in the limb: venous hypertension, pathological blood flow into the subcutaneous veins and their varicose veins, pronounced changes in the microcirculation system. Based on these premises, an ultrasound examination of the patient should answer the following questions:

1. Are the deep veins passable?
2. To what extent is the deep vein valve apparatus damaged?
3. What is the condition of the superficial vein valves?
4. where are the insufficient communicating veins localized?

Post-thrombotic damage to the main veins has a number of fundamental ultrasound features. Organic avalvulation of the affected venous segment does not allow visualization of the functioning cusps of the valve apparatus in it. The latter are completely destroyed or adhered to the vein walls. Aseptic inflammation leads to a perivascular reaction, as a result of which the vessel wall thickens several times compared to the intact one. Ultrasound examination reveals heterogeneity of the vein lumen due to the presence of thrombotic masses of varying degrees of organization. The affected venous segment becomes rigid and stops responding to compression.

The study in the CDC and EDC modes allows us to identify several types of venous segment recanalization. The most common is the cable type, characterized by the fact that several channels of independent blood flow are determined in the lumen of the vein. Less often, recanalization occurs according to the single-channel type. In this case, a channel with blood flow usually appears along the anterior and posterior walls, occupying from one third to half of the vessel lumen. The rest of the lumen is filled with organized thrombotic masses. It is significant that a large number of compensatory collaterals are visualized in the zone of the occluded vein.

In conclusion, it should be emphasized that the use of modern ultrasound technologies in the diagnosis of venous diseases of the lower extremities significantly expands the current understanding of doctors about the pathophysiology and hemodynamics of the veins of the legs, and facilitates the transition to an adequate choice of surgical treatment and physiologically sound methods for correcting venous insufficiency of the lower extremities.

It should be noted that the ultrasound assessment of the venous and arterial system of the lower extremities may seem incomplete if the issues of functional study of arterial insufficiency of the lower extremities by Doppler ultrasound and directly related prosthetic and rehabilitation care were left without attention, which will be covered in the last chapter.