RU2093077C1 - Method for diagnosing atherosclerosis case - Google Patents

Abstract

FIELD: medicine; diagnostics. SUBSTANCE: patient's femoral artery is examined in area, in which superficial and deep femoral veins merge with affected zone in arterial wall and in adjoining to it paravasal fatty tissue, followed by determining number of most frequently occurring pixels in affected zone (L) in relation to projection of point L. Next base of grey colored scale is divided into two intervals expressed in units of that same scale. Ratio is determined of section extending from beginning of scale up to projection of point L, to length of section extending from point L up to end of curve. If ratio thus-established is greater than normal value, disease case is diagnosed. EFFECT: greater accuracy of diagnosis; course of atherosclerotic process can be followed. 2 dwg

Description

 The invention relates to medicine, namely to clinical research methods using ultrasound, and can be used to diagnose atherosclerosis.

 Diagnosis and treatment of obliterating atherosclerosis is a central problem of angiology. Its relevance is determined by the steady increase in the number of patients and the unsatisfactory results of treatment in general. Surgical restoration of patency of arteries, which was still relevant a decade ago, gave priority to tasks related to the progression of atherosclerosis. The complexity of this direction is determined by insufficiently developed methods for controlling the dynamics of the atherosclerotic process in the artery wall.

 The main method for diagnosing the nature and localization of atherosclerotic lesions of arteries at present is radiopaque arteriography (Waters DD Lesperance J. // Regression of coronary atherosclerosis. Angiographic perspective. // Drugs (EC2). 1988, v. 36. suppl. 3. p. 37-42). With all its advantages, the known method is invasive, associated with the appearance in some patients of allergic reactions to a contrast medium, and may be complicated by thrombosis and bleeding. In addition, radiopaque arteriography evaluates the regression or progression of atherosclerosis only by the degree of stenosis of the lumen of the arteries, the formation of new stenoses and does not allow us to judge the atherosclerotic process in areas that have not yet formed atherosclerotic plaques.

 It is known that the regression of the atherosclerotic process depends on the severity of the course of atherosclerosis. Allocate a mild degree of atherosclerosis fat strip on the intima of the artery; moderate severity of the formation of fat droplets on the endothelial membranes; severe atherosclerosis crystallization of cholesterol and the formation of atheromatous plaques (Small DM // George Lyman Dyff memorial lecture. Progression and regression of atherosclerotic lesions. Insights from lipid physical biochemistry.//Arteriosclerosis (89S). 1988, Mar.-Apr. v. 8 ( 2), p. 103-129. To date, the following pathomorphological criteria for the regression of atherosclerosis studied in animal experiments have been proposed: plaque shrinkage due to lipid resorption and cell desquamation; thrombus lysis and retraction; thrombus incorporation into the arterial wall; resolution of arterial spasm and her dilation; ulceration and retraction plaque, decreasing its size and increasing density by increasing the collagen content in the fibrous capsule of the plaque (Malinow MR // Atherosclerosis: progression, regression and resolution.//Amer. Heart J, 1984, v. 108 (6), p. 1523- 1537).

 Meanwhile, Blankenhorn D.H. (1991) shows that angiography fails to record progress, stabilization, and regression of atherosclerosis (Blankenhorn DH // Regression of atherosclerosis: what does it mean? // Am. Med. 1991, Feb. 21, v. 90 (2A), p. 429-478). In recent years, there have been reports of the inappropriateness of using angiography as a method for verifying the regression of atherosclerosis, due to the large number of artifacts (Bellon EM Reid JD // Arteriography and histopathology in experimentally produced atherosclerosis in rhesus and fascicularis monkeys.//Acta Radiol. Suppl. - (Stockh .). 1986, v. 368, p. 1-48).

 In the last decade, ultrasound (US) research methods are widely used in the clinic. Ultrasound criteria have been developed for the severity of atherosclerosis according to the degree of development of atherosclerotic plaques. So, given their density, soft, medium, dense and mixed were distinguished, while their surface and the degree of stenosis of the affected artery were assessed (Poli A. Tremoli E. Colombo A. et al. // Ultrasonographic measurement of the common carotid artery wall thickness in hypercholesterolemic patients. A new model for the quantitation and follow-up of living human subjects.//Atherosclerosis (95X). 1988, Apr. v. 70 (3), p. 253-261). Ultrasound scanning can reliably distinguish between calcium and fibrous structures of the arterial wall from thrombotic masses and intimal hemorrhages, since the latter is characterized by lower reflection of the ultrasonic wave (Spagnoli LG Mauriello A. Bonanno E. et al. // Echodensitometry: a methodologie approach to the non-invasive diagnosis of carotid atherosclerotic plaques.//Int. Angiol. 1989, Oct.-Dec. v. 8 (4), p. 216-223). Based on this, the authors proposed the division of atherosclerotic changes in the artery wall according to the type of pixel distribution curves. The curves were a graphical representation of the distribution of the ultrasonic wave in objects with different acoustic densities.

 The latter method is accepted by us as a prototype. In the prototype method, a classification of the histostructure of the atherosclerotic plaque according to the types of echocentiometric curve A, B or C is proposed (Fig. 1). However, as our experience with the use of this method in clinical practice has shown, the prototype method is not without drawbacks.

 The main one is that the actual registration of the severity of atherosclerosis by the type of curve does not provide information on its dynamics during treatment and does not suggest how this curve should be modified, devoid of objective criteria for its assessment, since the same curve can vary in its width, platforms, etc. remaining within the same option (type), for example A. Possible changes in diagnostic parameters have not been developed depending on the severity of atherosclerosis, which does not allow diagnostics to evaluate progress, stabilization and regression of the atherosclerotic process.

 The above circumstances limit the use of the prototype method in the diagnosis of atherosclerosis and do not allow to evaluate the dynamics of the atherosclerotic process in the artery wall.

 The aim of the invention is to improve the accuracy of diagnosis in assessing the course of the atherosclerotic process.

 This goal is achieved by the fact that the patient performs echodsitometry of the femoral artery wall above the confluence of the superficial and deep femoral veins, calculates and evaluates the objective parameters of the histogram and, depending on this, determines the possibility of transformation of the curve during treatment, which allows recording the stages of the course of atherosclerosis.

 New in the invention is that all repeated dynamic studies are carried out at a standard (control) point, which makes it possible to objectify the information received, and the developed parameters for evaluating the echocentiometric curve make it possible to objectively record the severity of the atherosclerotic process. Based on the objective indicators we proposed, criteria for the progress, stabilization, and regression of atherosclerosis have been developed.

 The proposed method is as follows.

 A sensor with a frequency of 5 MHz was used to measure the density of the artery and paravasal tissue. The femoral artery was visualized in the area of confluence of the superficial and deep femoral veins. A zone of interest was chosen in the artery wall and adjacent paravasal tissue (PVC). A pixel distribution curve was constructed on a gray scale from 0 to 64.

 The information obtained during the study contains three main parameters: T is the total number of pixels in the zone of interest; L is the value of the most common pixels in the area of interest; M is the number of the most common pixels in the area of interest. The peak of the curve corresponds to L. The gray scale under the curve was divided into two intervals, expressed in units of the gray scale: “a” from the beginning of the curve to the value of L on the scale: “b” from L to the end of the curve. The exponent G (a + b) is an inversely proportional characteristic of tissue uniformity.

As shown above, in the prototype method, three types of curves A, B, and C are distinguished. Our studies have shown that each of the types can have numerous options that need to be evaluated. We propose determining the type of curve in relation to a / b (Fig. 2): a / b <1 type A;
a / b> 1 type B;
a / b 1 type C.

 In the analysis of the echodysitometric curve of the artery and paravasal tissue, we studied all the parameters we proposed both in the control group of healthy young 20-year-olds and in the group of patients with arteriosclerosis obliterans of the lower limbs.

 Option A was typical for arteries in both groups, but in the absence of a difference in the width of the G curve (11.55 ± 0.36 and 11.83 ± 0.46, respectively), the a / b ratio was significantly different in these studies: 0.260 ± 0.022 in the control group and 0.68 ± 0.09 for atherosclerosis. Significantly increased the value of the most common pixels L for atherosclerosis (23.46 ± 1.25) compared with the control group (16.75 ± 0.97).

 Similar changes were established in the analysis of echocentiometric curves taken from paravasal tissue.

 An analysis of the correlation dependence of the parameters of the characteristics we proposed showed the following.

 The interval "a" was in a high direct correlation dependence on the value of L (h = + 0.875) and before treatment the patient did not depend on the concentration of cholesterol (cholesterol) and triglycerides (TG) in blood plasma, which, apparently, is a reflection of a whole complex of pathomorphological changes in the wall of the artery and paravasal tissue for atherosclerosis. However, with dynamic echodsitometry, the interval “a” during treatment reveals high inverse correlation relationships with the concentration of plasma lipids, especially with cholesterol and high density lipoproteins (h = -0.784 and h = -0.872, respectively), i.e. the more plasma lipids were reduced during treatment, the smaller the interval "a"; interval "b" positively correlated with cholesterol and low-density lipoproteins (+0.764 and +0.696, respectively).

 Thus, the proposed parameters for evaluating the echodysitometric curve allow reliable recording of the course of the atherosclerotic process in the arterial wall.

 The invention is illustrated by the following examples.

 Example 1

 Patient A., 46 years old, case history No. 3276, was in the clinic for a malignant flowing dyslipoproteinemia of the 2B phenotype, complicated by obliterating atherosclerosis, occlusion of the right common iliac artery, stenosis of the left common iliac and common femoral artery, and grade 2B chronic arterial insufficiency.

Biochemical blood test before treatment:
HS 286 mg / dl
TG 243 mg / dl
HDL 42 mg / dl
LDL 19564 mg / dl
Ka 5.8
Ultrasound angioscanning was performed with echodsitometry of the left femoral artery at the proposed standard point with the following results:
T 11664
L 10 units

 interval "a" 2 srvc units

 interval "b" 6 srvc units

 G 8 srvc units

 a / b 0.33 (curve type A).

The patient was treated with the drug with an inhibitor of HMG-CoA reductase for six months, however, the dose of the drug was insufficient and the lipid spectrum of blood plasma remained practically unchanged:
HS 262 mg / dl
TG 236 mg / dl
HDL 36 mg / dl
LDL 178.8 mg / dl
Ka 6.2
This therapy did not allow stabilization of the course of atherosclerosis. This is confirmed by the following echodensitometric indices taken during ultrasound angioscanning at a standard point on the left femoral artery:
T 11664
L 18 units

"a" 4 srvc. units
"b" 8 srvc units
G 12 srvc units
a / b 0.5 (curve type A).

 An increase in the value of the most common pixels L from 10 to 18 units was noted. an increase in the interval "a" and "b" indicates a decrease in tissue uniformity, although the ratio a / b remains less than unity, i.e. the type of curve has not changed.

 This example shows that only the type of curve (in this case, type A) does not allow you to control the dynamics of atherosclerosis.

 Example 2

 Patient P. 39 years old, medical history N 1239, was in the clinic for type 2B hyperlipidemia, obliterating atherosclerosis, grade 2A chronic arterial insufficiency, stenosis of both iliac and common femoral arteries.

Biochemical parameters of the lipid spectrum of blood plasma:
CS 298 mg / dl
TG 312 mg / dl
HDL 47 mg / dl
LDL 188.8 mg / dl
Ka 5.3
When conducting ultrasonic angioscanning of the left femoral artery at a standard point, the following indices of echocensitometry were obtained:
T 11664
L 21 units
"a" 3.5 srvc units

 "b" 8.5 srvc units

 G 12 srvc units

 0.41 (curve type A).

During treatment with Mevacor (an HMG-CoA reductase inhibitor), the level of plasma lipids decreased significantly and after 6 months amounted to:
CS 251 mg / dl
TG 239 mg / dl
HDL 48 mg / dl
LDL 155.2 mg / dl
Ka 462
Echo densitometric indices taken from the standard point of the femoral artery after 6 months remained almost unchanged, which indicated the stabilization of the atherosclerotic process:
T 11664
L 18 units
"a" 3 conv. units

 "b" 9 srvc units

 G 12 srvc units

 a / b 0.33 (curve type A).

 This example reflects the possibility of reliable registration of the absence of negative dynamics of the course of atherosclerosis under the influence of adequate lipid-lowering therapy.

 Example 3

A 35-year-old patient M., N, case history 1710, was in the clinic for type 2B hyperlipidemia, obliterating atherosclerosis, occlusion of the right superficial femoral artery, stenosis of both common iliac and left common femoral arteries. During the examination, the following indicators of the lipid spectrum of blood plasma and the echocentiometric curve recorded at a standard point developed by us were recorded:
HS 478 mg / dl
TG 419 mg / dl
HDL 37 mg / dl
LDL 357.2 mg / dl
Ka 11.9
T 11664
L 20 units
"a" 4 conv. units

 "b" 9 srvc units

 G 13 srvc units

 a / b 0.44 (curve type A).

Given the high severity of hyperlipidemia, the patient underwent a radical correction of lipid metabolism and performed partial ileo-bypass surgery. During the control study 6 months after the operation, the following results were obtained:
HS 244 mg / dl
TG 213 mg / dl
HDL 58 mg / dl
LDL 143.4 mg / dl
Ka 3.2
L 13 units
"a" 1,5 srvc units

 "b" 4,5 srvc units

 G 6 srvc units

 a / b 0.33 (curve type A).

 As can be seen from this example, the type of curve has not changed, but such a significant change in the echocentiometric curve against the background of a pronounced long-term decrease in plasma lipid levels indicates the beginning of a regression of atherosclerotic changes. This is expressed by a decrease in "a", "b" and G.

 To verify the correct selection of the criteria for the echodsitometric curve and evaluate them, we conducted a dynamic study of these parameters in 24 patients with a positive biochemical effect of the treatment of hyperlipidemia, which is expressed in a significant decrease in plasma lipids and atherogenic lipoproteins and an improvement in the clinical manifestations of the disease. The data presented show that before treatment and 6 months after the start of treatment, the type of echodysitometric curve did not change (the a / b ratio indicates one type of curve A). Therefore, the use of only the type of curves proposed in the prototype method is ineffective in assessing the dynamics of the atherosclerotic process. Evaluation of the proposed criteria for the dynamics of the curve, namely, a reliable increase in the interval "a" from 2.40 ± 0.21 to 3.17 ± 0.11 (p <0.05), a decrease in the interval "b" from 9.17 ± 0 , 28 to 7.42 ± 0.56 (p <0.05), a significant increase in the a / b ratio indicates the dynamics of the ehodensitometric curve to type C, which is a reflection of the regression of the atherosclerotic process.

 Thus, the proposed method for evaluating the parameters of the echodysitometric curve allows us to identify significant differences in changes in the structure of the arterial wall, which makes it possible to evaluate the dynamics of the atherosclerotic process.

Claims (1)

 A method for diagnosing atherosclerosis by echo densitometry, characterized in that, in order to increase the accuracy of diagnosis in assessing the course of the atherosclerotic process, the femoral artery is examined in the area of fusion of the superficial and deep femoral veins with the zone of interest in the artery wall and adjacent paravasal tissue, the value is most often determined pixels in the study area (L) relative to the projection of this point, divide the base of the gray scale into two intervals, expressed in units of the scale, defined divide the ratio of the magnitude of the segment from the beginning of the scale to the projection of point L to the magnitude of the segment from this point to the end of the curve, and with an increase in this indicator compared with the norm, a disease is diagnosed.

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