Doppler analysis of lower limb arteries

In healthy individuals, the location of the UPA, OBA, and SCA was performed in all examined individuals. In case of vascular damage, blood flow signals were not obtained in the UPA in 1.7% of examined individuals, in the OBA - in 2.6%, in the SCA - in 3.7%, which in 96% of examined individuals was a consequence of vessel occlusion in the studied area, confirmed by angiography data. Signals from one of the arteries: PBA or PBA (ATS) - were not obtained in 1.8% of healthy individuals, and in patients, the frequency of location of the lower leg arteries sharply decreased depending on the prevalence of the lesion.

Normally, the arterial signal is short and three-component. The initial sound is loud and high-frequency, and the two subsequent ones have lower volume and lower tonality. Changes in the sound characteristics of blood flow signals above the stenosis zone are associated with an increase in the blood flow velocity through the narrowed zone and with the accompanying turbulence. As stenosis increases, the characteristics of the Doppler signal change: the frequency decreases, the duration increases, and the three-component structure disappears. In case of occlusion, the changes are the same as in case of severe stenosis, but they are more pronounced, the signals have an even lower tonality and continue throughout the cardiac cycle.

Auscultatory analysis of Doppler blood flow signals is the initial stage of ultrasound examination and, with some experience, provides a good opportunity to locate vessels and differentiate normal and pathological blood flow signals. The method is of particular importance when using ultrasound stethoscopes that do not have recording devices.

Evaluation of Doppler curves of blood flow velocity in the arteries of the lower extremities

Registration of Doppler blood flow signals in the form of analog velocity curves (Dopplerogram) makes it possible to conduct a qualitative and quantitative analysis of the blood flow velocity in the vessels under study.

[ 1 ], [ 2 ]

Qualitative analysis of Doppler blood flow velocity curves

The normal peripheral arterial blood flow curve, like the auscultatory signal, consists of three components:

1. the greatest deviation in systole due to direct blood flow;
2. reverse blood flow in early diastole associated with arterial reflux due to high peripheral resistance;
3. deviation in late diastole caused by forward blood flow due to the elasticity of the arterial walls.

As the stenotic disease progresses, the pulse wave shape changes, transforming from the main type to the collateral type. The main criteria for wave shape disturbance are the disappearance of the reverse blood flow component, blunting of the velocity peak, and prolongation of the rise and fall time of the pulse wave velocity.

Normally, all curves are characterized by a steep rise and fall, a sharp peak of the first component and a pronounced wave of reverse blood flow. In case of SFA occlusion, the deformation of Dopplerograms is detected from the level of the SCA, and in case of OPA occlusion, the collateral type of the curve is recorded at all locations.

Quantitative and semi-quantitative analysis of Doppler curves of blood flow velocity in the arteries of the lower extremities

Quantitative evaluation of Dopplerograms can be performed based on the analysis of both analog blood flow velocity curves and spectrogram data of Doppler blood flow signals in real time. In quantitative evaluation, the amplitude and time parameters of the Dopplerogram are analyzed, and in semi-quantitative evaluation, its calculated indices are analyzed. However, due to the presence of factors changing the shape of the Doppler velocity curve, there are problems associated with the interpretation and quantitative evaluation of Dopplerograms. Thus, the amplitude of the curve depends on the position of the sensor and its angle of inclination relative to the blood flow axis, the depth of ultrasound penetration into the tissue, the distance of the sensor from the main narrowing area, the gain setting, background interference, superposition of venous noises, etc. If the ultrasound beam intersects the vessel partially (not along the entire axis) and, especially if it is directed to the vessel axis at an angle approaching 90 ^e, erroneous results are obtained. In this regard, a number of researchers have proposed (as a more preferable) a semi-quantitative method of Dopplerogram evaluation - calculation of ratios characterizing the waveform and representing relative indices (for example, pulsation index, dumping factor), the value of which is not affected by the above-mentioned factors. However, a number of authors criticize this method, giving preference to quantitative evaluation of blood flow signals based on spectral analysis data; other researchers associate the reliability of non-invasive evaluation of vascular damage only with duplex scanning, in which the determination and analysis of blood flow signals is carried out in the visualized section of the vascular system.

At the same time, there are a number of situations when the only possible and diagnostically significant non-invasive method for assessing vascular damage is the analysis of the shape and quantitative assessment of the Dopplerogram: when the possibilities for measuring the SVD are limited when it is impossible to apply the cuff in a position proximal to the sensor, when the cuff application site coincides with the surgical wound, when assessing the condition of the iliac arteries, and also when a falsely high SVD is determined in vessels that are incompressible as a result of calcification or sclerosis of the arterial wall, despite the presence of arterial disease. According to the apt expression of J. Yao et al., recording the pulse wave of peripheral arteries allows for the recognition of limb ischemia, similar to how ECG is used to diagnose myocardial ischemia.

Spectral analysis of Doppler blood flow signals

Spectral analysis of Doppler blood flow signals has become widespread in work with continuous-wave Doppler systems for assessing occlusive lesions of the extracranial parts of the carotid basin, when the study area is in close proximity to the location of the sensor and it is possible to examine the vessels along their length.

The availability of peripheral arteries for blood flow location only at certain points where they are closest to the body surface and the varying degrees of distance of the main lesion sites from the examination point reduce the value of spectral analysis for assessing peripheral lesions. Thus, according to the data, recording Doppler spectrum signals more than 1 cm distal to the main lesion site is diagnostically insignificant and is virtually indistinguishable from Doppler signals recorded proximal to the stenosis site. Doppler signal spectra of blood flow in common femoral arteries with 50% monofocal stenosis of iliac arteries of various locations - there is no correlation between spectral analysis data and the degree of stenosis: spectral broadening (SB) - the main stenosis indicator characterizing the turbulent flow profile - varies widely - from 19 to 69%. The reason for such a wide range of SB values with the same degree of narrowing becomes clear if we recall the flow turbulence occurrence scheme. In a vessel, the blood flow is laminar. A decrease in the cross-section during stenosis leads to an increase in the flow velocity. When, after narrowing, the vessel expands sharply, a "flow separation" is observed, the movement at the walls slows down, reverse flows occur, and turbulence is formed. Then the flow again acquires a laminar character. Therefore, the spectrum obtained immediately after narrowing of the vessel and having a spectral expansion of 69% is the only diagnostically significant one in this case.

The maximum Doppler frequency shift in systole, which determines the blood flow velocity, increases with stenosis and decreases with occlusion. The vascular resistance index decreased with the transition from stenosis to occlusion, and the spectral broadening increased. The greatest changes were observed for the pulsation index with the transition from normal to occlusion.

Comparative evaluation of spectral analysis data of Doppler blood flow signals and analog velocity curves showed that the most sensitive signs of occlusive disease development were: decrease or disappearance of the reverse blood flow wave, increase in the A/D ratio (mainly due to prolongation of the deceleration phase), decrease in IP _GK and appearance of DF<1. Thus, reverse blood flow in the OBA was absent in all patients with iliac artery occlusion and stenosis>75%. However, with SFA occlusion, we observed reverse blood flow in the lower leg arteries in 14% of patients and in the popliteal artery in 4.3% of patients. Similar observations were described by M. Hirai, W. Schoop. The most indicative and therefore most widely used index of occlusive disease is the Goessling-King pulsation index - IP _GK. Changes in IP _GK in the norm and in single-segment proximal lesions were expressed in an increase in the value of IP _in the distal direction; the value of IP _ecoBA in the norm was the highest, averaging 8.45 ± 3.71, and individual variations were within 5.6-17.2. IP _GK significantly decreased with occlusion and dropped sharply with stenosis. We noted a decrease in IP _ecoBA compared to the norm with SFA occlusion, and a more distally located lesion of the arteries of the leg did not affect this indicator. The data obtained are consistent with the results of other authors who showed the dependence of IP _GK on both proximal and distal lesions:

In isolated lesions of the SFA or arteries of the leg, the drop in IP _GK at the corresponding levels also turned out to be highly reliable. In multilevel lesions, the dynamics of IP _GK was important for the diagnosis of primarily distal lesions.

Segmental systolic blood pressure in the lower extremities

For blood flow to occur between two points in the vascular system, a pressure difference (pressure gradient) must exist. At the same time, as the arterial pulse wave moves toward the periphery of the lower extremities, systolic pressure increases. This increase is a consequence of wave reflection from an area of relatively high peripheral resistance and differences in the compliance of the walls of the central and peripheral arteries. Thus, systolic pressure measured at the ankle will normally be higher than at the arm. In this situation, to maintain blood flow in the distal direction, diastolic and mean pressures must gradually decrease. At the same time, physiological studies have shown that in occlusive diseases, a significant drop in diastolic pressure in the lower extremities occurs only in the presence of severe proximal stenosis, while maximum systolic pressure decreases at lower degrees of the disease. Therefore, determining maximum systolic blood pressure is a more sensitive non-invasive method for diagnosing arterial stenosis.

The first to measure segmental systolic pressure in occlusive diseases of the lower extremities was proposed by T. Winsor in 1950, and noninvasive measurement of segmental systolic pressure using the Doppler method was first described in 1967 by R. Ware and C. Laenger. The method involves the use of a pneumatic cuff, which is tightly applied around the examined segment of the limb, and can be used where it is possible to apply a cuff. The cuff pressure at which blood flow is restored (which is recorded by Dopplerography) in the distal part of the limb with respect to the cuff during decompression is the systolic blood pressure at the level of the cuff, or segmental systolic pressure. The necessary conditions for obtaining accurate results are a sufficient rate of cuff decompression, repeated (up to three times) measurements and the appropriate length and width of the cuff.

Foreign researchers pay special attention to the size of cuffs for measuring segmental systolic pressure. After a long and broad discussion on this issue, the American Heart Association developed recommendations according to which the width of the pneumatic cuff should be 40% of the circumference in the examined segment or exceed the diameter of the examined limb area by 20%, and the length of the cuff should be twice its width.

To perform multilevel manometry, it is necessary to have 10 cuffs: 6 arm cuffs and 4 thigh cuffs. The arm cuffs are applied to both arms to determine the pressure in the brachial arteries and to both shins below the knee joint and above the ankle, and the thigh cuffs are applied to the thigh in the upper and lower thirds. The SBP is measured at all four levels of the lower limb based on signals from the distal sections of the vascular system: ZBBA - at the ankle or ATS - in the first interdigital space. Air is pumped into the cuff located around the limb to a level exceeding the systolic blood pressure by 15-20 mm Hg. The Doppler sensor is placed above the artery distal to the cuff. Then, air is slowly released from the cuff until the Doppler blood flow signals are restored. The pressure at which blood flow is restored at the registration point distal to the cuff is the systolic pressure at its level. First, the pressure in the upper limbs is determined at the shoulder level using signals from the brachial artery. Quite often, in the norm - in the absence of lesions of the arteries supplying blood to the upper limbs - a moderate asymmetry of BP equal to 10-15 mm Hg is detected. In this regard, the higher BP is considered to be the systemic pressure. Then, segmental systolic pressure is measured at all four levels of the lower limb, starting from the lower cuff using signals from the distal sections of the vascular system (as already mentioned, the ZBBA - at the ankle or the ATS - in the first interdigital space). In the absence of signals from the ATS, which may be associated with anatomical variants of its development, for example, with the scattered type, the SBA can be located above the ankle joint. If there are blood flow signals from both arteries, the pressure is measured by the one that has a higher segmental systolic pressure value at all four levels, and the segmental systolic pressure is measured by the second artery at two levels of the shin - to exclude possible arterial damage. It is advisable to follow the sequence of measurements from the distal cuff to the proximal one, since otherwise the pressure measurement in the distal cuffs will take place under conditions of post-occlusive reactive hyperemia.

In order to exclude the influence of individual differences on the profile of segmental systolic pressure, the pressure index (PI) proposed by T. Winsor in 1950 is calculated for each cuff level based on the value of systemic pressure. The pressure index is the ratio of the pressure obtained at a specific level to the systemic pressure measured on the shoulder (in Russian literature, the pressure index is also called the ankle pressure index (API), although, to be precise, the latter reflects only the ratio of the pressure on the ankle (IV cuff) to the systemic pressure. Usually, a complete profile of segmental systolic pressure is formed for each limb based on the absolute values of segmental systolic pressure and the pressure index at all levels of the limb.

Normally, segmental systolic pressure measured in the upper third of the thigh may exceed brachial pressure by 30-40 mm Hg, which is due to the need to supply excess pressure to the cuff to compress the muscle mass of the thigh.

A pressure index exceeding 1.2 indicates the absence of hemodynamically significant damage to the APS. If PI ₁ is within 0.8-1.2, then the presence of a stenotic process in the APS is very likely. If PI ₁ is less than 0.8, there is an occlusion of the APS.

A difference in segmental systolic pressure between the limbs in the upper third of the thigh equal to or greater than 20 mm Hg suggests the presence of occlusive disease above the inguinal fold on the side with lower pressure. At the same time, such a decrease in pressure in the upper third of the thigh may occur with combined lesions of the SFA and GBA. In these situations, the method of compression measurement of segmental systolic pressure in the OBA along with the analysis of Dopplerograms of blood flow in the OBA is useful for detecting the spread of the disease to the APS.

Normally, the gradient of segmental systolic pressure between two adjacent cuffs with a four-cuff measurement technique should not exceed 20-30 mm Hg. A gradient exceeding 30 mm Hg suggests the presence of a pronounced stenotic process, and in case of occlusion it is equal to or exceeds 40 mm Hg.

Finger pressure of the lower extremities is usually determined when occlusion of the digital arteries or plantar arch is suspected. Normally, systolic pressure in the fingers is about 80-90% of the brachial pressure. A finger/brachial pressure index below 0.6 is considered pathological, and a value below 0.15 (or an absolute pressure value of less than 20 mm Hg) usually occurs in patients with pain at rest. The principle of measuring finger pressure is the same as at other levels of the lower extremities, and special finger cuffs should be 2.5 x 10 cm in size or exceed the diameter of the finger being examined by 1.2 times.

Measurement of finger pressure in clinical practice using ultrasound Doppler is rarely used due to difficulties in locating the digital arteries of the feet, especially distal to the place of application of the finger cuff. The problem of locating digital arteries also exists in healthy individuals, but in patients with decompensated arterial circulation due to reduced blood flow, obliteration of distal vessels, hyperkeratosis and other causes, locating distal vessels using ultrasound Doppler becomes difficult. Therefore, photoplethysmography is usually used to measure finger pressure.

Despite the advances in noninvasive diagnostics in establishing the presence of arterial occlusive disease, difficulties remain in accurately determining the level of damage.

The most difficult problem is the precise localization and quantitative assessment of APS lesions, especially in combination with SFA lesions. As studies in foreign clinics have shown, successful diagnostics of such combined lesions using the Doppler method is achieved only in 71-78% of patients. B. Brener et al. showed that in 55% of patients with angiographically proven lesion of the aortoiliac segment, the SDS in the upper third of the thigh (1st cuff) was normal, and in 31% of patients with SFA occlusion without iliac artery lesions, the SDS on the 1st cuff was higher than the systemic one.

Compression measurement of arterial pressure in the common femoral artery

In the practice of vascular surgery, when deciding on the choice of the required level of reconstruction, it is necessary to assess the condition of the common femoral and iliac arteries, primarily based on such an important hemodynamic parameter as blood pressure. However, even the most proximally applied cuff on the thigh reflects the pressure in the distal sections of the common femoral artery and the proximal sections of its main branches. In this regard, we used the technique for measuring compression arterial pressure (CAD) in the common femoral artery, which is shown in the diagram. The pneumatic chamber of the pediatric cuff measuring 5.0 x 9.0 cm is applied to the site of the femoral artery projection under the inguinal ligament after preliminary palpation of the pulse of the common femoral artery or location of blood flow signals in the common femoral artery. A pressure of 10 mm Hg is created in the chamber, the graduates are blocked so that a closed circuit is created between the cuff and the measuring system. During the study, continuous location of blood flow signals is performed using the ZBBA or ATS. The femoral cuff is gradually pressed with the palm of the researcher's hand until the blood flow signals disappear (when palm compression was ineffective, a plate made of dense plastic corresponding in size to the cuff was used, which was placed on the pneumatic chamber, which ensured its uniform compression). The pressure at which blood flow signals arise (after decompression) is equal to the pressure in the OBA.

The method of compression measurement of the CAD in the OBA was first described by J. Colt; the method was further developed in the works. It was tested on a group of healthy individuals: 15 people aged 26 to 54 years (mean age 38.6 years) without signs of cardiovascular pathology were examined. The value of the CAD in the OBA was compared with the systemic arterial (brachial) pressure, while the CAD index was 1.14 ± 0.18 (fluctuations 1.0-1.24).

[ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ]

Ultrasound Dopplerography in Assessing the Degree of Lower Limb Ischemia

The severity of ischemic syndrome of the lower extremities in occlusive diseases of the abdominal aorta and its branches is due to insufficiency of peripheral circulation and depends on the localization of occlusion or stenosis, the presence of multi-stage lesions, the patency of the distal vascular bed and the degree of development of collateral circulation.

A clinical description of the severity of vascular disease of the extremities was first proposed by R. Fontaine, who identified 3 stages: intermittent claudication (I), pain at rest (II), and gangrene or ulcers of the extremities (III). Later, this gradation was expanded by dividing patients with intermittent claudication depending on the walking distance. This principle underlies the classification developed by A.V. Pokrovsky in 1979, which is still used today. According to this classification, stage I of the disease - pain in the lower extremities - occurs after walking more than 1000 m; IIA - distance 200-1000 m; IIB - distance 25-200 m; III - distance less than 25 m or pain at rest; IV - the presence of gangrene or ulcers of the extremities.

The degree of ischemic manifestations in the lower extremities is determined by the summation of the hemodynamic effect of the severity and stage of damage to the vascular system of the lower extremities at the peripheral level, and therefore changes in regional hemodynamics in the distal sections can be criteria in assessing the degree of ischemia of the lower extremities.

A study of regional hemodynamics conducted separately for patients with single- and multi-level occlusions at the same degree of ischemia showed that there is no reliable difference in the parameters of regional hemodynamics between these groups of patients. Undoubtedly, the architectonics of thrombo-obliterating lesions affects the course and duration of chronic arterial insufficiency. However, the stage of the disease is determined by the functional state of regional circulation.

In clinical practice, the most common method of assessing the degree of lower limb ischemia is based on the magnitude of the main parameters of ultrasound dopplerography (ASD and ID at the ankle level, LSC) in comparison with the Dopplerogram shape. At the same time, it is useful to compare the parameters of arterial and venous pressure based on the determination of post-occlusive venous pressure at the ankle level (POVD) and the calculated arteriovenous index (AVI), calculated using the formula: AVI = POVD / ASD x 100%.

The method for determining the POVD is the same as for the SSD: when the compression pressure in the IV cuff on the ankle decreases, the first pulse beats correspond to the SSD, and with a further decrease in pressure, a low-frequency venous noise is recorded, the moment of appearance of which reflects the value of the POVD.

Comparison of ultrasound data with the study of leg skin microcirculation based on the results of laser Doppler and transcutaneous monitoring of partial pressure of O ₂ and CO ₂ showed that in some patients classified as stage IV, regional hemodynamic indices correspond to stage II, and trophic ulcers occurred as a result of traumatic damage to the integrity of the skin under conditions of impaired blood circulation and were not true ischemic ulcers. Thus, assessing the degree of lower limb ischemia in the presence of ulcerative-necrotic changes is the most complex task requiring an integrated approach based on the study of the state of macro- and microhemodynamics.

An increase in the POVD and AVI against the background of a decrease in segmental systolic pressure is reliably noted in stage II of ischemia, which is due to the result of the discharge of arterial blood from arterioles directly into venules, bypassing the capillary bed. The expediency of arteriovenous shunt blood flow is that it promotes an increase in the blood flow velocity in the main arteries below the level of occlusion and thereby prevents their blockage.

The arterial inflow, which decreases with increasing ischemia, leads to a decrease in the values of the PODV. However, the value of the AVI, which reflects the state of the shunting blood flow, practically does not change, and the increasing tissue hypoxia is the result of a decrease in the blood circulation of the soft tissues of the foot against the background of increasing exhaustion of the second compensation mechanism - dilation of the microcirculation system with inhibition of vasoconstrictor reactions.

Measuring the POVD and AVI allows us to understand the processes of development of chronic ischemia of the lower extremities and the formation of mechanisms of circulatory compensation, which include arteriovenous shunt blood flow and vasodilation in the microcirculation system.

When assessing the degree of ischemia based on noninvasive diagnostic data, it is necessary to take into account the etiology of the disease. Thus, in diabetes mellitus (as well as in obliterating endarteritis, thromboangiitis), hemodynamic parameters may differ significantly from those in atherosclerosis, especially in the initial period of diabetes mellitus, which is associated with the predominant lesion of the arteries of the foot with the continued patency of the arteries of the lower leg to the ankle level for a long time. In diabetes mellitus, the DI parameters at the ankle will correspond to the norm or exceed it, and the changes in Dopplerograms at the ankle and at the level of the dorsum of the foot will be insignificant and not corresponding to the severity of ischemic lesions in the toes. In these conditions, methods of studying microcirculation, such as laser Doppler flowmetry and transcutaneous monitoring of the partial pressure of O ₂ and CO ₂, acquire diagnostic significance.

Algorithm for examining patients with lower extremity arterial lesions

Prehospital screening allows differentiating obstructive peripheral arterial disease from neuroorthopedic disorders. The established fact of arterial disease determines the need for a full range of noninvasive examination of peripheral arteries, which allows identifying the localization and extent of the lesion, the degree of hemodynamic disorders, and the type of lesion. If surgical treatment is necessary, an aortoarteriographic study is indicated to determine the possibility of performing and the required volume of surgical reconstruction.

[ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ]

Errors and shortcomings of ultrasound non-invasive diagnostic methods for diseases of the arteries of the lower extremities

Ultrasound Doppler examination of peripheral arteries, like any other instrumental diagnostic method, contains potential for diagnostic errors, both objective and subjective. The latter include the qualification and experience of the researcher, the accuracy of calculations, and pedantry in observing all the conditions of the method. Objective reasons are quite diverse and require special consideration.

• The impossibility of examining the vessels along their length - this is possible only at fixed points, which excludes accurate topical diagnostics of the lesion. Duplex scanning solves the problem only partially, since individual sections of the vascular system of the lower extremities, such as the middle third of the SFA, the trifurcation area of the popliteal artery and the proximal sections of the arteries of the leg, remain inaccessible for visualization in most subjects due to the deep location of the vessels and powerful muscle mass in these areas.
• Errors in measuring blood pressure in the lower extremities.
  • In obese patients, due to excess subcutaneous fat and muscle mass of the thigh, the measured segmental systolic pressure is falsely high due to the need to inflate the femoral cuff under high pressure to fully compress the arteries; in this case, the differences in brachial and femoral pressure can reach 50-60%, while direct puncture measurement of pressure at the same levels does not reveal significant differences. Therefore, in this category of patients, it is recommended to measure pressure on the shins.
  • In patients with diabetes or chronic renal failure, the vascular wall may be so saturated with calcium salts that it becomes incompressible, and therefore measuring segmental systolic pressure in this category of patients loses its meaning.
  • Often, there may be increased pressure in the upper third of the lower leg, significantly exceeding the pressure in the lower third of the thigh and associated with the peculiarities of the development of bone formations in this area and with the need to create increased pressure in the compression cuff.
• There are difficulties in measuring digital pressure on the feet using ultrasound Dopplerography, since the location of digital arteries distal to the applied digital cuff is rarely feasible. Photoplethysmography is usually used for these purposes.
• Recently, a nonlinear dependence of the ankle segmental systolic pressure on the brachial (systemic) pressure has been shown: with a systemic pressure below 100 and above 200 mm Hg, the ankle segmental systolic pressure was below normal (up to 25%), and in the range of 100-200 mm Hg it was equal to or higher than the brachial pressure. Thus, with hypo- and hypertension, the pressure index can be less than one.

• 5. When interpreting the Doppler waveform, in order to avoid errors, it should be remembered that, under normal conditions, the component of reverse blood flow may be absent in the popliteal arteries in 10-11% of cases, in the posterior tibial artery - in 4%, and in the dorsalis pedis artery - in 8%. The third component of the Dopplerogram is preserved in the iliac and common femoral arteries in all healthy individuals, while it may be absent in the popliteal, posterior tibial, and dorsalis pedis arteries in 22, 4, and 10%, respectively. Under normal conditions, in 2-3% of cases, the location of one of the lower leg arteries may also be absent due to the anatomical features of their development (scattered type of structure).
• 6. The peculiarities of the development of compensatory collateral circulation, which corrects arterial insufficiency, can be the cause of both false-positive and false-negative diagnostic errors.
  • A. Well-developed collateral vessels with high BFV in the iliofemoral zone with iliac artery occlusion may be the cause of misdiagnosis.
  • Analysis of such errors showed that they are based on well-developed collateral circulation of the iliofemoral zone. The use of synchronous ECG recording may be useful in complex cases of diagnosing iliac artery lesions.
  • B. Well-developed collateral circulation in the basin of the arteries of the leg is a common cause of false-positive assessment of the state of the arteries of the leg and erroneous indications for reconstructive operations in the aortoiliac and femoropopliteal zones. This is important, since the effectiveness of surgical treatment depends on the state of the outflow tract, the function of which is performed by the arteries of the leg. Erroneous preoperative diagnostics of the distal vascular bed of the extremities limits the operation to only revision of the vessels with intraoperative angiography.
  • B. Decompensation of collateral circulation, especially in multilevel lesions, complicates the diagnosis of lesions of the underlying segments of the lower limb arteries. Difficulties in assessing the condition of the leg arteries in occlusion of the abdominal aorta and iliac arteries, accompanied by severe insufficiency of collateral circulation, have been noted by various researchers in 15-17% of patients. The significance of this problem increases in patients who require repeated operations. The number of these patients, due to the widespread development of reconstructive vascular surgery, increases every year, and repeated operations often lead to damage to the pathways of compensatory collateral circulation.
• 7. The lack of information on the volumetric blood flow, summing up the main and collateral channels, when using ultrasound Doppler makes it difficult to diagnose SFA lesions in APS occlusions. Quantitative analysis of Dopplerograms using the pulsation index and the dumping factor is sensitive in such a situation only in 73% of patients. The inclusion of plethysmographic techniques in the complex of non-invasive diagnostics, such as volumetric segmental sphygmography (sometimes called "volume segmental plethysmography"), included in the mandatory list of methods of angiological laboratories of leading foreign clinics, but undeservedly ignored by specialists in our country, increases the sensitivity of diagnostics of lesions in this localization to 97%.
• 8. The capabilities of ultrasound Dopplerography in determining only hemodynamically significant (>75%) lesions are no longer sufficient in modern conditions, when, in connection with the advent of gentle and vessel-preserving angioplastic treatment of stenotic lesions, conditions have been created for preventive treatment, which is more effective in the early stages of disease development.

Therefore, the need to introduce the duplex scanning method into the clinic will increase significantly, allowing the disease to be detected at early stages, the type and nature of vascular damage to be determined, and the indications for choosing one or another treatment method in most patients without preliminary angiography.

• The capabilities of ultrasound Dopplerography in determining GBA damage, even hemodynamically significant, are limited, and in most patients the diagnosis of GBA damage is made only presumptively or is an incidental angiographic finding. Therefore, successful noninvasive diagnostics of GBA damage and the degree of its hemodynamic insufficiency is possible only with the help of duplex scanning.

In conclusion, it should be noted that the introduction of the ultrasound Doppler method into the clinical diagnostics of lower limb ischemia was of invaluable and revolutionary significance in its essence, although one should not forget about the limitations and shortcomings of the method. Further increase in the diagnostic significance of ultrasound diagnostics is associated with both the use of the entire arsenal of ultrasound methods and their integration with other non-invasive methods of vascular disease diagnostics, taking into account the clinical picture and etiology of the disease in each individual patient, the widespread use of a new generation of ultrasound equipment implementing the latest technologies of three-dimensional vascular scanning.

However, the assessment of the diagnostic capabilities of lower extremity vascular lesions may not be complete enough, since arterial lesions are often combined with lower extremity venous disease. Therefore, ultrasound diagnostics of leg lesions cannot be complete without assessing the anatomical and functional state of their extensive venous system.

[ 13 ], [ 14 ], [ 15 ]