Ultrasound signs of acute venous thrombosis. Ultrasound diagnosis of acute venous thrombosis Ultrasound diagnosis of acute venous thrombosis
Book "Ultrasound diagnosis of acute venous thrombosis"
ISBN: 978-5-900094-51-9
The guide reflects issues of variable anatomy of the superior and inferior vena cava systems, presents the basic principles and features of ultrasound examination in patients with suspected acute venous pathology, and highlights issues of differential diagnosis. Particular attention is paid to the role of ultrasound diagnostics in determining the potential embologenicity of phlebothrombosis as the basis for developing individual angiosurgical tactics. Separately, the issues of ultrasound diagnosis of venous thrombosis with an atypical source of formation are considered as the reason for the diagnosis of “PE from an unknown source”. The principles of dynamic ultrasound examination, including for surgical prevention of pulmonary embolism, are described in detail. The chapter devoted to special cases of venous thrombosis examines the issues of diagnosing this pathology of interventional origin. The manual comes with a CD with video clips of the research. The publication contains clinical examples, as well as illustrated and commentary protocols for ultrasound examinations for various types of venous thrombosis. A separate appendix is devoted to comments on video clips that complement the visual content of the publication. Intended for ultrasound diagnostic doctors, cadets of primary retraining cycles in the specialty “ultrasound diagnostics”, senior students of medical universities, phlebologists and doctors of other clinical disciplines, in whose practice acute venous pathology occurs.
Methodology of ultrasound examination in the diagnosis of acute venous thrombosis
Research methodology
Ultrasound techniques for determining the presence of acute venous thrombosis
Ultrasound characteristics of acute venous thrombosis
Combined thrombosis of deep and superficial veins
Ultrasound criteria and algorithm for determining the potential embologenicity of floating phlebothrombosis
Ultrasound criteria for assessing the embologenicity of floating phlebothrombosis
Location and hemodynamics in the area of the floating thrombus head
Source of thrombosis
Neck width and flotation length, their ratio
Flotation with quiet breathing
Spring effect during Valsalva maneuver
Structure of a floating thrombus head
Dynamics of increase in the level and/or length of thrombus flotation
Algorithm for determining the degree of potential embologenicity of floating phlebothrombosis
Features of ultrasound examination before performing surgical prevention of pulmonary embolism
Differential diagnosis of acute venous thrombosis
Special cases of acute venous thrombosis
Phlebothrombosis in cancer patients
Phlebothrombosis in pregnant women
Interventional phlebothrombosis
Dynamic ultrasound examination in the treatment of acute venous thrombosis
With conservative treatment
With conservative treatment when signs of recanalization appear
For surgical prophylaxis of pulmonary embolism
After vena cava filter implantation
In extreme cases of negative dynamics of acute venous thrombosis
Ultrasound diagnosis of atypical venous thrombosis as
one of the methods for differential diagnosis of pulmonary embolism from an unknown source
Features of ultrasound examination
acute venous thrombosis of the superior vena cava system
Examples of ultrasound protocols
List of abbreviations
Appendix 1
Test questions
Ultrasound diagnosis of acute venous thrombosis
Acute venous thrombosis of the inferior vena cava system is divided into embologenic (floating or non-occlusive) and occlusive. Non-occlusive thrombosis is the source of pulmonary embolism. The superior vena cava system accounts for only 0.4% of pulmonary embolism, the right side of the heart - 10.4%, while the inferior vena cava is the main source of this formidable complication (84.5%).
A lifetime diagnosis of acute venous thrombosis can be established only in 19.2% of patients who died from pulmonary embolism. Data from other authors indicate that the frequency of correct diagnosis of venous thrombosis before the development of fatal pulmonary embolism is low and ranges from 12.2 to 25%.
Postoperative venous thrombosis is a very serious problem. According to the B.C. Savelyev, postoperative venous thrombosis develops after general surgical interventions on average in 29% of patients, in 19% of cases after gynecological interventions and in 38% after transvesical adenomectomies. In traumatology and orthopedics this percentage is even higher and reaches 53-59%. A special role is given to early postoperative diagnosis of acute venous thrombosis. Therefore, all patients at risk for postoperative venous thrombosis should undergo a complete examination of the inferior vena cava system at least twice: before and after surgery.
It is considered fundamentally important to identify violations of the patency of the main veins in patients with arterial insufficiency of the lower extremities. This is especially necessary for a patient in whom surgical intervention is proposed to restore arterial circulation in the limb; the effectiveness of such surgical intervention is reduced in the presence of various forms of obstruction of the main veins. Therefore, all patients with limb ischemia should have both arterial and venous vessels examined.
Despite the significant advances achieved in recent years in the diagnosis and treatment of acute venous thrombosis of the inferior vena cava and peripheral veins of the lower extremities, interest in this problem has not only not diminished in recent years, but is constantly increasing. A special role is still assigned to the early diagnosis of acute venous thrombosis.
Acute venous thrombosis, according to its localization, is divided into thrombosis of the ilicaval segment, femoral-popliteal segment and thrombosis of the veins of the leg. In addition, the great and small saphenous veins may be susceptible to thrombotic damage.
The proximal border of acute venous thrombosis can be in the infrarenal section of the inferior vena cava, suprarenal, reaching the right atrium and located in its cavity (echocardiography is shown). Therefore, examination of the inferior vena cava is recommended to begin with the area of the right atrium and then gradually go down to its infrarenal section and the place where the iliac veins flow into the inferior vena cava. It should be noted that the closest attention must be paid not only to examining the trunk of the inferior vena cava, but also the veins flowing into it. First of all, these include the renal veins. Typically, thrombotic lesions of the renal veins are caused by a mass formation in the kidney. It should not be forgotten that the cause of thrombosis of the inferior vena cava can be the ovarian veins or testicular veins. Theoretically, it is believed that these veins, due to their small diameter, cannot lead to pulmonary embolism, especially since the distribution of the thrombus to the left renal vein and the inferior vena cava along the left ovarian or testicular vein due to the tortuosity of the latter looks casuistic. However, it is always necessary to strive to examine these veins, at least their mouths. In the presence of thrombotic occlusion, these veins increase slightly in size, the lumen becomes heterogeneous, and they are well located in their anatomical areas.
With ultrasonic triplex scanning, venous thrombosis is divided in relation to the lumen of the vessel into parietal, occlusive and floating thrombi.
Ultrasound signs of parietal thrombosis include visualization of a thrombus with the presence of free blood flow in this area of the altered lumen of the vein, the absence of complete collapse of the walls when the vein is compressed by a sensor, the presence of a filling defect during color circulation, and the presence of spontaneous blood flow during spectral Dopplerography.
Thrombosis is considered occlusive, the signs of which are the absence of collapse of the walls when the vein is compressed by a sensor, as well as the visualization of inclusions of varying echogenicity in the lumen of the vein, the absence of blood flow and staining of the vein in the spectral Doppler and Color Doppler modes. Ultrasound criteria for floating thrombi are: visualization of the thrombus as an echogenic structure located in the lumen of the vein with the presence of free space, oscillatory movements of the apex of the thrombus, absence of contact of the vein walls during compression with the sensor, presence of free space when performing respiratory tests, envelope type of blood flow with color coding of the flow , the presence of spontaneous blood flow during spectral Doppler sonography.
The capabilities of ultrasound technologies in diagnosing the age of thrombotic masses are of constant interest. Identification of signs of floating thrombi in all stages of thrombosis organization allows increasing the efficiency of diagnosis. Particularly valuable is the earliest diagnosis of fresh thrombosis, which allows early measures to be taken to prevent pulmonary embolism.
After comparing the ultrasound data of floating thrombi with the results of morphological studies, we came to the following conclusions.
Ultrasound signs of a red thrombus are a hypoechoic indistinct contour, anechoic thrombus in the apex and hypoechoic distal section with individual echogenic inclusions. Signs of a mixed thrombus are a heterogeneous structure of the thrombus with a hyperechoic clear outline. The structure of the thrombus in the distal sections is dominated by heteroechoic inclusions, in the proximal sections - predominantly hypoechoic inclusions. Signs of a white thrombus are a floating thrombus with clear contours, a mixed structure with a predominance of hyperechoic inclusions, and with CDK, fragmentary flows through thrombotic masses are recorded.
21 GBUZ of the Republic of Mordovia “Republican Clinical Hospital No. 4”
2 Federal State Budgetary Educational Institution of Higher Education “Saratov State Medical University named after. V.I. Razumovsky Ministry of Health of Russia"
The article discusses the results of sonographic diagnosis of phlebothrombosis of the lower extremities in 334 patients. The main factors for the development of thrombosis in men were polytrauma, combined surgical interventions and cardiovascular diseases; in women - cardiovascular diseases and tumors of the uterus and ovaries. Color duplex scanning of veins makes it possible to identify the presence and level of phlebothrombosis, flotation of thrombotic masses, and assess the effectiveness of anticoagulant therapy and surgical prevention of pulmonary embolism. Tactical issues in case of floating thrombosis of the inferior vena cava system should be resolved individually, taking into account both the localization and extent of the proximal part of the thrombus, as well as the age of the patient and the presence of phlebothrombosis factors. In the presence of embolic thrombosis against the background of severe concomitant pathology and contraindications to open surgery, installation of a vena cava filter is a measure to prevent pulmonary embolism. In young patients, open or endovascular installation of temporary vena cava filters is advisable. In 32.0?% of patients with a vena cava filter after its implantation, massive thrombosis was detected, and in 17.0?%, flotation of thrombi was detected below the level of plication, which confirms the importance and effectiveness of urgent surgical prevention of PE.
sonography
dopplerography
vein thrombosis
vena cava filter
veins of the lower extremities
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DIAGNOSIS AND TREATMENT OF FLOATING THROMBOSIS IN THE SYSTEM OF THE VENA CAVA INFERIOR
Ipatenko T.V. 1 Davydkin V.I. 2 Shchapov V.V. 1 Savrasov T.V. 1, 2 Makhrov V.V. 1 Shirokov I.I. 21 State budgetary institution of health of the Republic of Mordovia “Republican clinical hospital No. 4”
2 Saratov State Medical University. V. I. Razumovsky
Abstract:
The article contains the results of ultrasonic diagnosis of acute venous thrombosis of lower extremities in 334 patients. The main risk factors of venous thrombosis in men include injury, combined surgery and severe cardiovascular diseases; in women – cardiovascular diseases and tumors of female genitals. Color duplex scanning of the veins allows to establish the presence and level of the thrombotic process, flotation of a blood clot, to evaluate the effectiveness of treatment and surgical prevention of pulmonary embolism. Tactical issues with floating thrombus in the inferior Vena cava should be decided individually, taking into account both the localization of the proximal part of the thrombus and its extent and age of the patient and factors of the phlebothrombosis. In the presence of this conclusion was thrombosis on the background of severe comorbidity, and contraindications for open surgery to install a Vena cava filter is a measure for the prevention of pulmonary embolism. In patients of young age it is appropriate to install a removable Vena cava filters, or perform open surgery with a temporary Vena cava filter. From 32.0?% patients showed thrombosis of the Vena cava filter after implantation, 17.0?% of patients found to have a floating thrombus below the level of plication, which confirms the importance and effectiveness of urgent surgical prevention of pulmonary embolism.
Keywords:
venous thrombosis
veins of the lower extremities
Phlebothrombosis of the lower extremities is one of the leading problems in practical phlebology in terms of clinical and scientific significance. They are widespread among the adult population, and drug treatment is not effective enough. At the same time, a high level of incapacity and disability remains. Phlebothrombosis is distinguished by the blurring of the clinical picture in the first hours and days of the disease, and the first symptom is pulmonary thromboembolism (PE), which is the leading cause of both general and surgical mortality. In this regard, timely and accurate diagnosis of embolic venous thrombosis using informative, accessible and non-invasive methods is extremely important. Doppler ultrasound scanning (USDS) has become the main method for diagnosing these phlebothrombosis, which is a potential source of the development of pulmonary thromboembolism.
There are few publications in the literature that detail the ultrasound characteristics of embologenicity of venous thrombus. The leading criteria for the embologenicity of a thrombus are the degree of its mobility and the length and echogenicity of the floating part, the characteristics of the external contour of the thrombus (smooth, uneven, fuzzy), the presence of a circular blood flow around the thrombus in color duplex mapping mode both in longitudinal and transverse scanning.
Prevention of pulmonary embolism is an integral component of the treatment of patients with acute venous thrombosis. Unfortunately, the use of indirect anticoagulants does not help prevent the separation and migration of formed blood clots into the pulmonary arteries. Therefore, when extensive floating and embolic thrombosis is detected, surgical intervention aimed at preventing thromboembolic migration (thrombectomy, plication or endovascular implantation of a vena cava filter) is indicated.
The issue of surgical tactics for floating deep vein thrombosis of the extremities should be decided individually, taking into account the localization of the proximal part of the thrombus, its extent, flotation, and the presence of comorbid and intercurrent pathology.
In the presence of severe intercurrent pathology and contraindications to open surgery in patients with embolic-dangerous thrombosis of the main veins, installation of a vena cava filter is indicated according to absolute indications (contraindications to anticoagulant therapy, embolic-dangerous thrombosis when it is impossible to perform surgical thrombectomy, recurrent pulmonary embolism). In this case, it is important to take into account the fact of fixation of floating blood clots (the length of the blood clot is no more than 2 cm) and the possibility of conservative treatment tactics.
The unpredictability of the course of venous thrombosis in the inferior vena cava system is proven by the diagnosis of floating thrombosis in patients without any clinical signs of venous pathology, the detection of embolic thrombosis in patients with chronic venous diseases, the facts of pulmonary embolism in occlusive forms of deep vein thrombosis.
Purpose of the study: improvement of sonographic diagnosis and results of urgent interventions in patients with acute phlebothrombosis.
Materials and research methods
We analyzed the results of physical and sonographic diagnostics of phlebothrombosis of the lower extremities in 334 patients who were hospitalized in the state budgetary healthcare institution of the Republic of Mordovia “Republican Clinical Hospital No. 4”. The age of the patients was 20-81 years; 52.4% were women, 47.6% were men; 57.0% of them were of working age, and 19.4% were young (Table 1).
Table 1
Gender and age of examined patients
Table 2
Distribution of floating thrombi in the deep vein system of the lower extremities
The largest group was of patients aged 61 years and older (143 people); among men, people aged 46 to 60 years predominated - 66 (52.3%) people, among women aged 61 years and older - 89 (62%) respectively. .3%) people.
Phlebothrombosis in men under 45 years of age was more common in individuals who abused intravenous substances. At the age of 60 years or more, the number of female patients begins to predominate over male patients, which is explained by the predominance of other risk factors in women: gynecological diseases (large uterine fibroids, ovarian tumors), coronary heart disease, obesity, trauma, varicose veins and others. The decrease in incidence in the general population in men aged 60 years or more is explained by a decrease in their proportion in the corresponding age groups, high mortality from pulmonary embolism, the development of chronic venous insufficiency and postthrombophlebitis syndrome.
Ultrasonographic diagnostics and echoscopic monitoring were carried out on ultrasonic devices Vivid 7 (General Electric, USA), Toshiba Aplio, Toshiba Xario (Japan), operating in real time using convex sensors 2-5, 4-6 MHz and linear sensors with a frequency of 5 -12 MHz. The study began with a projection of the femoral artery (in the groin area) with an assessment of blood flow in the transverse and longitudinal sections in relation to the longitudinal axis of the vein. At the same time, the blood flow of the femoral artery was assessed. During scanning, the diameter of the vein, its compressibility (by compressing the vein with a sensor until the blood flow stops while maintaining blood flow in the artery), the state of the lumen, the safety of the valve apparatus, the presence of changes in the walls, and the condition of the paravasal tissues were assessed. The hemodynamic state of the veins was assessed using functional tests: respiratory and cough tests or straining tests. At the same time, the condition of the veins of the thigh, popliteal vein, veins of the leg, as well as the great and small saphenous veins was assessed. The hemodynamics of the inferior vena cava, as well as the iliac, great saphenous, femoral and distal calf veins were assessed with the patient in the supine position. The study of the popliteal veins, veins of the upper third of the leg and the small saphenous vein was carried out with the patient lying on his stomach with a cushion placed under the ankle joints. To study the main veins and in case of difficulties in the study, convex sensors were used, otherwise linear sensors were used.
Cross-sectional scanning was performed to identify the mobility of the thrombus head, as evidenced by complete contact of the venous walls with slight compression by the sensor. During the examination, the nature of phlebothrombosis was determined: parietal, occlusive or floating.
The list of laboratory diagnostic methods included determination of D-dimer level, coagulogram, and study of thrombophilia markers. If a history of pulmonary embolism is suspected, the examination also included computed tomography in angiopulmonography mode and examination of the abdominal cavity and pelvis.
For the purpose of surgical prevention of pulmonary embolism in acute phlebothrombosis, 3 surgical methods were used: implantation of a vena cava filter, plication of a vein segment, and crossectomy and/or phlebectomy. In the postoperative period, ultrasound diagnostics aimed to assess the state of venous hemodynamics, the degree of recanalization or intensification of the thrombotic process in the venous system, the presence or absence of thrombus fragmentation, the presence of flotation, thrombosis of the veins of the contralateral limb, thrombosis of the plication zone or vena cava filter, and the linear and volumetric blood flow rates were determined and collateral blood flow.
Statistical analysis was performed using the Statistica program. Differences in results between groups were assessed using Pearson's (Pearson's) and Student's tests (t). Differences with a significance level of more than 95% were considered statistically significant (p< 0,05).
Research results and discussion
The leading sign of phlebothrombosis was the presence of echo-positive thrombotic masses in the lumen of the vessel, the density of which increased as the age of the thrombus increased. In this case, the valve leaflets ceased to differentiate, the transmitting pulsation from the artery was not determined, the diameter of the thrombosed vein increased by 2-2.5 times compared to the contralateral vessel, and when compressed by the sensor, it is not compressed. At the beginning of the disease, when blood clots are visually indistinguishable from the normal lumen of the vein, we consider it especially important to perform compression ultrasonography. On the 3-4th day of the disease, compaction and thickening of the venous wall due to phlebitis was noted, and the perivasal tissues became “blurred.”
Parietal thrombosis was diagnosed in the presence of a thrombus, free blood flow in the absence of complete contact of the walls during a compression test, the presence of a filling defect in duplex scanning and spontaneous blood flow in spectral Dopplerography.
The criteria for floating thrombosis were visualization of a thrombus in the lumen of the vein with the presence of free space and blood flow around the head, movement of the head of the thrombus in rhythm with cardiac activity, when testing by straining or compression with a vein sensor, absence of contact of the venous walls during a compression test, an enveloping type of blood flow, the presence of spontaneous blood flow with spectral Dopplerography. To finally determine the nature of the thrombus, the Valsalva maneuver was used, which, however, poses a danger due to additional flotation of the thrombus.
Thus, according to color duplex scanning data, floating thrombi were detected in 118 (35.3%) cases. Most often they were detected in the system of deep veins of the pelvis and thigh (in 45.3% - in the deep veins of the thigh, in 66.2% - in the iliac veins), less often in the system of deep veins of the leg and the great saphenous vein of the thigh. There were no differences in the incidence of thrombus flotation between men and women.
The frequency of floating phlebothrombosis has increased in recent years, which is associated with color duplex scanning in all patients before surgery who are in long-term immobilization, as well as mandatory in patients with limb injuries and after operations on the osteoarticular system. We believe that, despite the obvious clinical picture of the presence of superficial varicothrombophlebitis, there is always a need to perform CDS to exclude subclinical floating thrombosis in both superficial and deep veins.
As is known, coagulation processes are accompanied by activation of the fibrinolytic system, and these processes occur in parallel. For clinical practice, the fact of establishing both the flotation of a blood clot, the nature of the spread of a blood clot in a vein, and the likelihood of its fragmentation during the process of recanalization is very important.
In case of CDS of the lower extremities, it is important: non-floating thrombi were identified in 216 (64.7%) patients, of which occlusive thrombosis was found in 181 (83.8%) patients, non-occlusive mural thrombosis - in 35 (16.2%).
Parietal thrombi were detected as masses fixed to the walls of the veins over a significant extent. At the same time, the lumen of the vein was maintained between the thrombotic masses and the wall itself. During anticoagulant therapy, parietal thrombi can fragment, causing an embolic state and recurrent embolism of small branches of the pulmonary artery. With mobile and floating thrombi, fused to the venous wall only in its distal section, a real and high risk of thrombus rupture and pulmonary embolism is created.
Among the non-occlusive forms of thrombosis, one can distinguish a dome-shaped thrombus, the sonographic signs of which are a wide base equal to the diameter of the vein, the absence of oscillatory movements in the blood flow and the length of the thrombus up to 4 cm. The risk of pulmonary embolism with this type of thrombosis is low.
Repeated color duplex scans were performed in all patients until the floating tail of the thrombus was fixed to the vein wall, then from 4 to 7 days of treatment and always before the patient was discharged.
In patients with floating thrombi, ultrasound angioscanning of the veins of the lower extremities was mandatory on the day of surgery, as well as 48 hours after implantation of a vena cava filter or vein plication (Figure). Normally, during longitudinal scanning of the inferior vena cava, the vena cava filter is visualized as a hyperechoic structure, the shape of which depends on the filter model. The typical position of the vena cava filter in the vein was considered to be at the level or slightly distal to the orifices of the renal veins or at the level of 1-2 lumbar vertebrae. With CDS, at the site of the filter, there is usually an expansion of the lumen of the vein.
According to color duplex scanning data after implantation of vena cava filters, fixation of massive blood clots was detected on the filter in 8 (32.0%) of 25 patients. The vein segment in the area of plication was passable in 29 (82.9%) of 35 patients, in 4 (11.4%) continued thrombosis was detected below the plication site, in 2 (5.7%) blood flow in the area of plication was not possible at all determine, and blood flow was carried out only through collateral pathways.
Inferior vena cava with installed sensor. A colored blood flow is visible (blue - flowing to the sensor, red - flowing from the sensor). At the border between them there is a normally functioning vena cava filter.
It has been established that implantation of a vena cava filter promotes the progression of the thrombotic process and increases the frequency of recurrent thrombosis, which can be explained, among other things, not only by the progression of the process, but also by the presence of a foreign body in the lumen of the vein and a slowdown in the main blood flow in this segment. The incidence of thrombosis progression in patients who underwent plication and were treated only with medication is almost the same, but it is significantly lower compared to the same indicator after endovascular interventions.
Conclusions
1. The main risk factors for phlebothrombosis in men include concomitant trauma, combined surgical interventions and the presence of severe cardiovascular diseases; in women - severe diseases of the cardiovascular system and genitals.
2. The advantages of color duplex scanning include the ability to objectively monitor the presence and level of the thrombotic process, flotation of blood clots, evaluate the effectiveness of drug therapy, and monitor the course of phlebothrombosis after surgical prevention of pulmonary embolism. Ultrasonography allows you to solve tactical issues with floating thrombi individually, taking into account both the localization of the proximal part of the thrombus, its extent, the nature of the thrombotic process and phlebothrombosis factors.
3. In the presence of embolic thrombosis against the background of severe concomitant pathology and contraindications to open surgery, installation of a vena cava filter is a measure to prevent pulmonary embolism. In young patients, it is advisable to install removable vena cava filters or perform open operations with the installation of a temporary vena cava filter.
4. In 32.0% of patients, massive thrombi were detected on the vena cava filter after its endovascular implantation; in 17.0% of cases, floating thrombi were found below the site of vein plication. These data indicate the effectiveness of PE prevention through surgical treatment of floating embologenic thrombosis in the inferior vena cava system.
Bibliographic link
Ipatenko V.T., Davydkin V.I., Shchapov V.V., Savrasova T.V., Makhrov V.V., Shirokov I.I. DIAGNOSTICS AND TREATMENT OF FLOATING THROMBOSIS IN THE INNER VENA CAV SYSTEM // Scientific review. Medical Sciences. – 2017. – No. 6. – P. 34-39;URL: https://science-medicine.ru/ru/article/view?id=1045 (access date: 01/27/2020). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"
E.A. MARUSHCHAK, Ph.D., A.R. ZUBAREV, Doctor of Medical Sciences, Professor, A.K. DEMIDOVA
Russian Research Medical University named after. N.I. Pirogov, Moscow
Methodology of ultrasound examination of venous thrombosis
The article presents four years of experience in performing ultrasound studies of venous blood flow (12,394 outpatient and inpatient patients with acute venous pathology of the Central Clinical Hospital of the Russian Academy of Sciences). Based on a large clinical material, the methodology for performing primary and dynamic ultrasound examinations in patients during the conservative treatment of venous thrombosis and when performing various methods of surgical prevention of pulmonary embolism is outlined. Particular attention is paid to the interpretation of ultrasound results in terms of the likelihood of pulmonary embolism. The results of application of the proposed ultrasound research methodology in the practice of a multidisciplinary emergency hospital and diagnostic and treatment center are analyzed.
Key words: ultrasound angioscanning, vein, acute venous thrombosis, deep vein thrombosis, pulmonary embolism, surgical prevention of pulmonary embolism
About Introduction
The epidemiology of acute venous thrombosis (AVT) is characterized by disappointing data: the incidence of this pathology in the world reaches 160 people per 100 thousand population annually, and in the Russian Federation - no less than 250 thousand people. According to M.T. Severinsen (2010) and L.M. Lapie1 (2012), the incidence of phlebothrombosis (PT) in Europe annually is 1:1000 and reaches 5:1000 in patients with skeletal trauma. A large-scale analysis of the incidence of deep vein thrombosis (DVT) conducted in the United States in 2012 showed that 300-600 thousand Americans are diagnosed with this pathology annually, and 60-100 thousand of them die from pulmonary embolism (PE). These indicators are due to the fact that OVT occurs in patients with a wide variety of pathologies and are often secondary, complicating any diseases or surgical interventions.
For example, the frequency of venous thromboembolic complications (VTEC) in inpatient (including surgical) patients reaches 10-40%. V.E. Barinov et al. cite data on the incidence of pulmonary embolism in air travelers, equal to 0.5-4.8 cases per 1 million passengers, with fatal pulmonary embolism causing 18% of deaths on airplanes and airports. PE is the cause of death in 5-10% of hospital patients, and this figure is steadily increasing. Massive and, as a consequence, lethal pulmonary embolism in some patients is the only, first and last manifestation of OVT. In a study by L.A. Laberko et al., devoted to the study of pulmonary embolism in surgical patients, provide data on mortality from VTEC in Europe: their number exceeds the total mortality from breast cancer, acquired immunodeficiency syndrome and car accidents and is more than 25 times higher than the mortality from infections caused by Staphylococcus aureus .
An interesting fact is that from 27 to 68% of all deaths from pulmonary embolism are potentially preventable. The high value of the ultrasound method in diagnosing OVT is due to its non-invasiveness and sensitivity and specificity approaching 100%. Physical methods of examining patients with suspected OVT make it possible to make a correct diagnosis only in typical cases of the disease, and the frequency of diagnostic errors reaches 50%. Thus, an ultrasound diagnostician has a 50/50 chance of verifying or excluding OVT.
Instrumental diagnosis of OVT is one of the urgent tasks in terms of visual assessment of the substrate of the disease, since the determination of angiosurgical tactics depends on the data obtained, and, if surgical prevention of pulmonary embolism is necessary, the choice of its method depends. Execution of dynamic
Ultrasound is necessary both during conservative treatment of OVT in order to assess emerging changes in the affected venous bed, and in the postoperative period.
Sonographers are at the forefront of visual assessment of OVT. Ultrasound is the method of choice in this category of patients, which dictates the need not only to detect OVT, but also to correctly describe and interpret all possible characteristics of this pathological condition. The purpose of this work was to standardize the methodology for performing ultrasound examination during OVT, aimed at minimizing possible diagnostic errors and maximizing adaptation to the needs of clinicians who determine treatment tactics.
About Materials
In the period from October 2011 to October 2015, 12,068 primary ultrasound scans of the blood flow of the inferior vena cava system and 326 of the superior vena cava system (12,394 ultrasound scans in total) were performed at the Central Clinical Hospital of the Russian Academy of Sciences (CDB RAS, Moscow). It is important to emphasize that the Central Clinical Hospital of the Russian Academy of Sciences does not purposefully accept acute venous pathology through the “ambulance” channel. Of the 12,394 studies, 3,181 were performed on outpatient patients of a diagnostic and treatment center, 9,213 on inpatient patients for suspected acute venous pathology or for prophylactic purposes in patients at risk for venous thromboembolic complications, as well as for indications as preoperative preparation. OVT were diagnosed in 652 inpatients (7%) and 86 outpatients (2.7%)
(total 738 people, or 6%). Of these, the localization of OVT in the bed of the inferior vena cava was detected in 706 (95%), in the bed of the superior vena cava - in 32 patients (5%). Vascular ultrasound was performed on the following devices: Voluson E8 Expert (GE HC, USA) using multi-frequency convex (2.0-5.5 MHz) and linear (5-13 MHz) sensors in the following modes: B-mode, color Doppler mapping, power Doppler mapping, pulsed wave mode and mode of sub-ppler blood flow imaging (B-flow); Logiq E9 Expert (GE HC, USA) with a similar set of sensors and programs plus a high-quality ultrasound elastography mode.
About Methodology
The first task when performing ultrasound is to detect the substrate of the disease - venous thrombosis itself. OVT are characterized by individual and often mosaic anatomical localization in the bed of the vena cava. That is why it is necessary to examine in detail and multipositionally not only the superficial and deep beds of both lower (or upper) extremities, but also the iliocaval segment, including the renal veins. Before performing an ultrasound, it is necessary to familiarize yourself with the available data from the patient’s medical history, which in some cases will help to refine the search and suggest atypical sources of OVT formation. You should always remember the existing likelihood of a bilateral and/or multifocal thrombotic process along the venous bed. The informativeness and value of ultrasound for angiosurgeons is associated not so much with the fact of verification of OVT, but with the interpretation of the results obtained and their decomposition.
Talization. Thus, based on the ultrasound conclusion, presented as “non-occlusive thrombosis of the common femoral vein,” the angiosurgeon, in addition to confirming the fact of OVT, does not receive any other information and, accordingly, cannot determine further tactics in detail. Therefore, in the ultrasound protocol, the identified OVT must necessarily be accompanied by all its characteristics (border, nature, source, extent, flotation length, relation to anatomical landmarks, etc.). At the conclusion of the ultrasound, there should be an interpretation of the results aimed at further determining the tactics by the clinician. The terms “iliocaval” and “iliofemoral” are also clinical, not ultrasound.
About Primary ultrasound
The main technique for verifying OVT during ultrasound is compression of the zone of interest (a fragment of the visualized vessel) by the sensor. It should be noted that the compression force must be sufficient, especially when examining a deep bed, in order to avoid obtaining false-positive information about the presence of thrombotic masses where there are none. A clean vessel that does not have pathological intravenous inclusions, containing only liquid blood, undergoes complete compression when compressed, its lumen “disappears”. If there are thrombotic masses in the lumen (the latter can be of different structure and density), it will not be possible to completely compress the lumen, which can be confirmed by compression of the unchanged contralateral vein at a similar level. The thrombosed vessel has a larger diameter compared to the free contralateral one, and its staining in color mode
commercial Doppler mapping (DCM) will be at least uneven or completely absent.
The study of the iliocaval segment is carried out with a low-frequency convex sensor, however, in some cases, in patients with low body weight, it is possible to use high-frequency linear sensors. In obese patients with severe flatulence, as well as in the presence of adhesive disease after surgical interventions, visualization of the iliocaval segment will be greatly difficult. The use of drugs that suppress and reduce the manifestations of gas formation, as well as cleansing enemas, improves visualization conditions only slightly, and in addition, requires additional time or may be completely contraindicated in patients with suspected OVT of a non-occlusive nature. The use of auxiliary modes, such as color flow, in these cases does not reduce the risk of diagnostic errors. For example, with non-occlusive local thrombosis of the external iliac vein in an obese patient, the lumen of the vessel in the CD mode can be completely stained, and it is not possible to compress the vein. To study the veins of the pelvis and some fragments of the iliac veins in case of poor visualization from a transabdominal approach, it is possible to use intracavitary sensors (transvaginal or transrectal ultrasound). When studying the deep venous bed of the lower extremities in obese patients, as well as in the presence of lymphostasis, when the depth of penetration of the ultrasound beam from a linear high-frequency sensor is insufficient, it is necessary to use a low-frequency convex one. In this case it is possible to determine
border of thrombosis, but the quality of visualization of the actual thrombus apex in B-mode will be unimportant. If there is poor visualization of the upper border and the nature of the thrombosis or the venous segment as such, there is no need to give these characteristics in conclusion, remembering the main rule of the ultrasound doctor: do not describe what you did not see or saw poorly. In this case, it is worth making a note that obtaining this information using ultrasound at the time of examination is not possible for technical reasons. It should be understood that ultrasound as a technique has its limitations and the lack of clear visualization of the upper limit and the nature of thrombosis is a reason to use other research methods.
In some cases, visualization of the upper limit and the nature of thrombosis is helped by the Valsalvi test (straining the patient in order to create retrograde blood flow in the vessel under study, in which the diameter of the vein will increase and, possibly, flotation of the thrombus will be visible) and the distal compression test (squeezing the lumen of the vein above the level of thrombosis, at which the diameter of the vessel will also increase, which will improve the visual assessment). Figure 1 demonstrates the moment of occurrence of retrograde blood flow in the cerebral vein during the Valsalvi maneuver, as a result of which the floating thrombus, being washed on all sides by the blood flow, took a central position relative to the axis of the vessel. The Valsalvi maneuver, as well as the distal compression test, must be used with caution, since in case of embolic thrombosis, they can provoke PE. In relation to OVT, it is the B-mode that has the greatest diagnostic value. With good visualization, one se-
scale mode for a detailed description of all characteristics of the OHT. The remaining modes (CDC, energy mapping (EC), B-A^, elastography) are auxiliary. In addition, additional modes are to some extent inherent in artifacts that can mislead the doctor. Such artifacts include the phenomenon of “flooding” of the lumen in the CD mode with non-occlusive thrombosis or, conversely, the complete absence of staining of the lumen of a patently patent vessel. There is little chance of diagnosing thrombosis that is not recognized in the B-mode using only auxiliary ones. Also, when drawing up an ultrasound report, you should not completely rely on data obtained only by additional modes.
It was mentioned above that for the competent construction of an ultrasound conclusion, the mere fact of detection of thrombotic masses in the lumen of the vein is not enough. The conclusion should contain information about the nature of thrombosis, its source, the border in relation to ultrasound and anatomical landmarks and - in the case of floating thrombosis - an individual characteristic of its potential embologenicity. A detailed assessment of the listed parameters allows us to determine the indications for conservative treatment or surgical prevention of pulmonary embolism, including the choice of its type.
Occlusive OVT and non-occlusive OVT of a parietal nature, being fixed to the walls of the vessel completely or on one side, respectively, have a low degree of embologenicity and, as a rule, are treated conservatively. A floating thrombus is a thrombus that has a single point of fixation and is surrounded by blood flow from all sides. This
FIGURE 1. Use of the Valsalvi maneuver to improve visualization of the floating thrombus head in B-mode (common femoral vein in the projection of the saphenofemoral junction)
1 - retrograde blood flow in the common femoral vein during straining with the effect of “spontaneous contrast”; 2 - lumen of the common femoral vein; 3 - floating thrombus; 4 - sapheno-femoral anastomosis
FIGURE 2. Floating thrombi with varying degrees of embologenicity (top - thrombus with low risk of PE, bottom - thrombus with high risk of PE)
classic definition of FT. However, in different patients with floating thrombosis, even with the same length of flotation, the degree of embologenicity will be different, and therefore must be determined individually in real time. Thus, in a floating thrombus with a short body length and localization in the superficial femoral vein, the embologenicity will be quite low. A long floating thrombus, which has the appearance of a “worm” and is located in the lumen of the common femoral vein and above, has a greater risk of embolism (Fig. 2). Below we will consider in more detail the characteristics of the floating head of a thrombus from the standpoint of determining its embolic danger.
The need to measure the flotation length, as a rule, is beyond doubt, as is the fact that the larger the value obtained, the worse the prognosis in terms of possible thrombus fragmentation. The thickness of the neck of the thrombus and its ratio to the length of the floating head, as well as the amplitude and type of oscillatory (floating) movements of the head in the lumen of the vein characterize the elastic deformation forces acting on the thrombus, leading to separation. Echo-
The geneity and structure of the thrombus also provide information about the likelihood of fragmentation: the lower the echogenicity and the less homogeneous the structure of the thrombus, the higher the likelihood of its fragmentation. In addition to the characteristics of the apex of a floating thrombus, the upper limit of the thrombus (the zone where the vessel begins to be completely compressed and no longer contains thrombotic masses) and its source are important to determine the degree of potential embologenicity. The higher the threshold of thrombosis, the higher the blood flow speed there. The more venous segments there are anastomoses, the more “washing away” turbulent flows there are. The closer the location of the thrombus head is to the natural bends of the limb (groin, knee), the higher the likelihood of permanent compression of the lumen containing the thrombus. When characterizing the source of thrombosis, it should be remembered that a typical OVT “originates” in small muscular branches giving rise to the medial group of sural veins, and progresses from bottom to top, spreading to the popliteal (PF), then to the superficial femoral (SFE), common femoral vein (CFV). ) and higher. Typical
thrombophlebitis forms in the dilated great saphenous (GSV) and small saphenous (SSV) veins.
Defining and describing a typical OVT using ultrasound does not pose any difficulties. A thrombus with an atypical source in some cases remains undiagnosed, and it is atypical thromboses that are the most embolic. Sources of atypical DVT can be: deep femoral veins (DFE), pelvic veins, injection sites of narcotic drugs (so-called cutaneous vascular fistula), the site of the venous catheter and the catheter itself, renal veins, tumor invasion, gonadal veins, hepatic veins , as well as the transition of thrombosis to the deep veins through the anastomosis and communicants of the affected saphenous veins (Fig. 3). Most often, atypical thromboses are of a floating nature with weak fixation in the neck and are located in the femoral and iliocaval segments. Interventional OVT (post-injection and post-catheter) are formed at the point of damage (alteration) of the vessel, which is also the only point of fixation of the blood clot. Interventional thrombosis is often local
nal, or segmental, i.e., they are determined only in one venous segment (usually the venous segment), while the deep veins above and below the thrombus are passable. Another group of atypical OVTs are combined deep and superficial vein thrombosis. Among them, according to the ultrasound picture, 3 options can be distinguished: 1. Ascending thrombophlebitis in the GSV basin and thrombosis of the medial group (most often) of the sural veins (occurs through the passage of a thrombus from the superficial veins through thrombosed perforating veins).
2 Ascending thrombophlebitis in the basin of the GSV and/or SVC with transition to the deep vein system at the site of the anastomosis of the trunks (saphen-femoral, sapheno-popliteal phlebothrombosis).
3 Various combinations of the above options, up to thrombosis of the OBV with several floating heads. For example, ascending thrombophlebitis in the GSV basin with transition to the SVV at the site of the saphenofemoral junction (SFJ) plus SVV thrombosis with the progression of thrombosis from the deep veins of the leg through the passage of a thrombus from the superficial veins through thrombosed perforators (Fig. 4). The likelihood of developing a combination
The presence of thrombosis of the superficial and deep vein systems and bilateral FT once again confirms the need to perform a complete ultrasound of the venous blood flow of the inferior vena cava system throughout both primary and dynamic studies.
Atypical thrombosis also includes OVT, complicating the course of oncological diseases (thrombosis of the renal veins with a transition to the inferior vena cava is not uncommon). Another atypical source is the deep femoral veins, which are most often affected during operations on the hip joint, as well as the pelvic veins, in which thrombosis occurs in a number of diseases of the organs of this region. The most insidious variant of atypical thrombosis is in situ thrombosis. This is a variant of local segmental thrombosis without an obvious source. As a rule, the place of thrombus formation in these cases is the valvular sinuses with low blood flow velocity in this area. Often, thrombi in situ occur in the iliac veins or venous veins and in most cases are diagnosed after the fact of pulmonary embolism, using second-order imaging methods (computed tomography).
physical phlebography, angiography) or are not diagnosed at all, thereby being a source of “PE without a source”, completely detaching from the vessel wall, leaving no substrate in the lumen of the vein.
The description of mosaic or bilateral OVT should contain detailed information on both lower extremities and on all segments of the lesion separately. The assessment of the potential embolic hazard of a floating thrombus is carried out through a cumulative analysis of its characteristics. To facilitate this process, each of the criteria for a floating thrombus head is assigned 1 or 0 conditional points according to the scheme described below (Table 1). The resulting total score provides a more accurate indication of potential PE. Working according to this scheme allows you to avoid omissions in the assessment of one or a number of criteria and, thus, not only standardize the ultrasound technique, but also improve its effectiveness. When diagnosing a patient with OVT with a high risk of PE, it is necessary to understand that he will probably be indicated for one or another type of surgical prevention of this complication. The main operation for OVT on
FIGURE 3. Various sources of atypical thrombosis (projection of the saphenofemoral junction of the common femoral vein)
1 - source - femoral catheter; 2 - source - cutaneous vascular fistula (drug addicts); 3 - source - great saphenous vein; 4 - source - deep femoral vein; 5 - source - superficial femoral vein
TABLE 1. Determination of the potential degree of embologenicity of floating phlebothrombosis
US criteria Interpretation of US criteria Points
Phlebohemodynamics in the localization zone of the floating head Active 1
Thrombus “outcome” zone Atypical thrombosis 1
Typical thrombosis 0
Ratio of neck width to flotation length (in mm, coefficient) Less than 1.0 1
Greater than or equal to 1.0 0
Flotation with quiet breathing Yes 1
Spring effect during Valsalva maneuver Yes 1
Flotation length More than 30 mm 1
Less than 30 mm 0
Structure of the floating head Heterogeneous, low echogenicity, with contour defects or torn apex 1
Homogeneous, increased echogenicity 0
Dynamics of thrombosis increase Negative 1
Absent or minimal 0
Note. Evaluation of the obtained data. 0-1 point - low degree of potential embologenicity. 2 points - average degree of potential embologenicity. 3-4 points - high degree of potential embologenicity. More than 4 points - an extremely high degree of potential embologenicity.
at the level of the lower extremities itself is the ligation of the PBB. A necessary condition for performing this intervention is to establish the fact of patency of the deep vein vein, as well as the upper limit of thrombosis. Thus, if the floating head moves from the SPV into the SBV, then thrombectomy from the SBV will be necessary. In this case, information about the length of the flotation and the anatomical landmark of the location of the apex of the thrombus (for example, relative to the inguinal fold, SPS, anastomosis of the SMV with the distal GV) will be very important. In case of transition of thrombosis significantly above the level of the inguinal fold, ligation of the external iliac vein (Eiliac vein) is likely to be performed, for which it is also necessary to obtain information about the anatomical landmark of the upper border
thrombosis (for example, its relation to the anastomosis with the internal iliac vein (SIV) or its distance from the inguinal fold) and the patency of the SVC. All this information should be contained in the descriptive part of the ultrasound protocol.
When an embolic-dangerous VVT is localized in the iliocaval segment, implantation of a vena cava filter or plication of the inferior vena cava (IVC) is most often performed. The vena cava filter or plication zone should be located under the orifices of the renal
FIGURE 5. Upper limit of ascending thrombophlebitis of the great saphenous vein
1 - lumen of the common femoral
2 - thrombus in the lumen of the great saphenous vein; arrow - distance to the safeno-femoral anastomosis
veins to exclude disturbances in venous outflow through the renal veins in case of closure of the IVC lumen distal to this area. In addition, it is necessary to assess the patency of the renal veins themselves, as well as the deep bed of the contralateral side and the veins of the superior vena cava system, since through these veins, if patency, access for intervention will be provided. It is also necessary to indicate the distance from the apex of the thrombus to the renal vein closest to it, since vena cava filters come in different types and differ from one another at least in their size. For the same purposes, it is necessary to indicate the diameter of the IVC during inhalation and exhalation. When the floating head of a thrombus is localized above the mouth of the renal veins, it is necessary to indicate where exactly in relation to the mouths of the renal veins the thrombosis changes its character from occlusive or parietal to actually floating, and measure the length of flotation. If flotation begins below the orifices of the renal veins, it is possible to perform endovascular thrombectomy from the IVC. In case of ascending thrombophlebitis, it is necessary to indicate the upper limit of thrombosis in relation to anatomical landmarks (for example, the distance to the SPS, Fig. 5), as well as the presence and diameter of the upper tributaries of the GSV (in some cases, with pronounced varicose transformation of the upper tributaries, their diameter is greater than the diameter of the trunk GSV, which can lead to ligation of the wrong vessel). It is also important to state the fact that the lumen of the deep vessels (BV, GV, PBB) is intact, excluding the option of combined thrombosis. As a rule, indications for surgical intervention are given when thrombosis moves to the thigh. It should be remembered that with ascending thrombophlebitis, the true limit of thrombosis is practically
technically always above the clinical zone of hyperemia! In case of thrombophlebitis of the GSV with the transition of a thrombus into the lumen of the SVV (combined sapheno-femoral phlebothrombosis), one should remember the need to perform venotomy and thrombectomy from the SVV, which will require information about the length of the floating head of the thrombus in the lumen of the SVV and the anatomical landmark of the localization of its apex in the deep bed . In some cases, in the presence of concomitant thrombosis, it will be necessary to perform simultaneous ligation of the SSV and ligation of the GSV, possibly in combination with thrombectomy. In these cases, information must be given in detail on the deep and superficial beds separately: on thrombophlebitis (thrombosis of the superficial veins with or without transition to the deep bed and in relation to anatomical landmarks) and on phlebothrombosis (deep vein thrombosis, also in relation to anatomical landmarks) according to the algorithms described above.
About Repeated ultrasounds
Ultrasound dynamics of OVT during conservative treatment are interpreted as positive when the flotation length and/or level of thrombosis decreases, as well as when signs of recanalization appear. Another positive aspect is the increased echogenicity and homogeneity of thrombotic masses and the absence of floating movements. Negative dynamics is the registration of reverse processes. Ultrasound dynamics of OVT in the postoperative period are interpreted as positive in the absence of thrombotic masses above the level of deep vein ligation and in the presence of signs of recanalization of thrombotic masses below the ligation site; with preserved blood
flow through the veins above the level of the ligation. Ultrasound dynamics are interpreted as negative in the presence of thrombotic masses above the site of ligation of the deep vein, in case of damage to the deep vein or the appearance of bilateral phlebothrombosis.
Based on dynamic ultrasound data, including the degree of recanalization of thrombotic masses in the postoperative period (as well as during conservative treatment), the effectiveness of anticoagulant therapy is assessed, and drug doses are adjusted. When performing ultrasound after surgery, one should remember the possibility of progression of thrombosis. The greatest risk of this complication occurs in a situation where, in addition to ligation of the SPV, a thrombectomy from the SPV was performed. As thrombosis progresses, “fresh” thrombotic masses are located above the site of vein ligation. The source may be GBV, the site of ligation itself, or the site of thrombectomy. The reason for the progression of thrombosis may be inadequate anticoagulant therapy and/or technical errors in surgical intervention (for example, when ligating a vein above the anastomosis with an GBV - this situation is interpreted not as ligation of the SBV, but as ligation of the SBV).
In case of ascending thrombophlebitis of the GSV, ligation of the GSV at the anastomosis with the GSV or ostial resection of the GSV can be performed. A possible finding in the event of technical errors in performing the operation may be a residual stump of the GSV, often with upper tributaries opening into it or the presence of stump thrombosis. If there is a residual stump, the so-called stump is located. “Mickey Mouse’s second ear”, i.e. during transverse scanning, 3 gaps are determined in the groin projection
TABLE 2. Decrease in mortality from pulmonary embolism
2009 2010 2011 2012 2013 2014 2015
Treated 13,153 1,4229 14,728 15,932 14,949 14,749 10,626
Died 119 132 110 128 143 105 61
Died from pulmonary embolism b 12 11 0 4 3 3
vessel: common femoral artery, GSV and the GSV stump opening into it. The stump of the GSV, especially if the upper tributaries flowing into it are preserved, can serve as a source of progression of thrombosis with transition to the SV. Another finding may be a statement of the actual failure to perform the operation. This is possible in the case of ligation or resection not of the GSV trunk itself, but of one of its large varicose transformed tributaries. This ultrasound picture should be differentiated from a separate upper tributary flowing into the GSV or from a doubling of the GSV trunk. When simultaneously performing ostial resection of the GSV and ligation of the SSV (with or without thrombectomy from the SSV) for combined thrombosis, during postoperative ultrasound, blood flow along the SSV is located, emanating only from the GSV. The presence of additional flows in this case may indicate technical errors in the operation.
The vena cava filter is located in the form of clear hyperechoic signals, different in shape, depending on the type of filter: umbrella or spiral. The presence of a clear blood flow in the projection of the vena cava filter, which occupies the entire lumen of the vein during color circulation, indicates its complete patency. In B-mode, the complete patency of the filter is characterized by the absence of thrombotic masses in it, which have the appearance of echo-positive fragments.
There are 3 types of thrombotic lesions of the vena cava filter. 1. Filter embolism due to detachment of the floating head of the thrombus (depending on the size of the occluding head, it can be complete or incomplete, with complete closure of the lumen or with the presence of parietal blood flow).
2. Filter ingrowth due to progression of iliofemoral thrombosis. In this case, it is also necessary to evaluate the safety or absence of blood flow in the inferior vena cava.
3. Filter thrombosis as a new source of thrombus formation (the vena cava filter is a foreign body and can itself serve as an intravenous matrix for thrombus formation).
Extremely rare, isolated observations are cases of migration of the vena cava filter above the established position and progression of thrombosis above the level of the renal veins through the filter (the latter is impeded by blood flow from the renal veins). In the latter case, it is necessary to establish the anatomical landmarks of the upper limit of thrombosis already above the filter level, establish its nature, the presence or absence of flotation and measure its length, i.e., describe all those characteristics that are described during the initial study.
In patients with an implanted vena cava filter or IVC plication, attention should be paid to the presence or absence of a retroperitoneal hematoma, as well as free fluid in the abdominal cavity.
If the patient was implanted with a vena cava filter of a removable design, then a necessary condition for its removal will be a combination of two factors determined by ultrasound: the absence of fragments of thrombotic masses in the filter and the absence of embolic-dangerous thrombi in the inferior vena cava bed. May have me-
one hundred variants of the course of floating PT, when embolism does not occur in the filter: the head does not come off, but continues to remain at its level for several days, maintaining the threat of separation; Moreover, over time, under the influence of anticoagulant therapy, its lysis “in situ” occurs. This is the same case when the vena cava filter is removed without fulfilling its intended purpose.
0 Ultrasound for OVT of the superior vena cava system
In most cases, OVT of the upper extremities are occlusive in nature and are not embolic. The authors did not encounter a floating nature of FT of the superior vena cava bed in any patient. The bed of the superior vena cava is well accessible for ultrasound; difficulties may arise only when visualizing some fragments of the subclavian veins. Here, as in the study of the iliocaval segment, it is possible to use a convex low-frequency sensor, as well as the use of auxiliary modes. The main information that is required from an ultrasound diagnostic physician is to verify the OVT of the superficial or deep bed, or their combined lesion, as well as to describe the occlusive or parietal nature of the thrombosis, since thrombosis of the superficial and deep bed has different conservative treatment. Ultrasound becomes especially important
if there is a suspicion of OVT of the superior vena cava bed in patients with the presence of intravenous catheters (cubital, subclavian). In case of occlusive thrombosis of the venous segment carrying the catheter, its removal is indicated, and in case of atypical non-occlusive catheter thrombosis, when thrombotic masses, localized on the catheter, float in the lumen, it is likely to perform a venotomy with thrombectomy and removal of the catheter. The very fact of diagnosing catheter thrombosis as a probable source of angiosepsis can provide additional information in relation to
bearing on the severity of the patient’s condition and further tactics for its management.
About Conclusion
Ultrasound of venous blood flow is a mandatory study both for the purpose of primary diagnosis of OVT and throughout the entire hospital stage of patient treatment. Wider implementation of ultrasound for preventive purposes, taking into account the risks of venous thrombo-embolic complications in relevant categories of patients, minimizes the onset of both
my pulmonary embolism, and, accordingly, death from it. The methodology for performing ultrasound of venous blood flow presented in the article, combined with the high frequency of the examination itself, as well as the active implementation of endovascular methods of surgical prevention of PE (used in the Central Clinical Hospital of the Russian Academy of Sciences since 2012), led to a significant decrease in mortality from PE, which is reflected in Table 2 (2015 - data at the time the article was submitted to the editor as of the beginning of October).
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