Category: Heart anatomy

Echocardiography is a method for studying the structure and function of the heart, based on recording the reflected pulse signals of ultrasound generated by a sensor with a frequency of about 2.5 – 5.0 MHz. Wave reflection occurs at the interface between two media with different acoustic densities if the object is larger than the ultrasonic wavelength (1–1.5 mm). The higher the oscillation frequency of ultrasound (i.e., the shorter the wavelength), the higher the resolution the instrument has, but the depth of signal penetration in the tissue decreases. Therefore, in the study of the heart in adults use sensors with a frequency of 2.5 – 3.5 MHz, and children – 5.0 MHz. A slightly different principle is used in Doppler echocardiography (DehoKG). The Doppler effect is that the ultrasonic beam directed at any moving object is reflected from it and is sent back to the sensor, but with a different frequency. Knowing the frequency of the reflected ultrasound, you can determine the speed of movement of particles (blood cells). It should be remembered that ultrasound practically does not pass through the gas environment and does not penetrate into the organs containing gas (lungs, intestines)

In the study of the heart and blood vessels, usually three modes of operation of the device are used: one-dimensional (M – modal), two-dimensional (sectoral, B- or 2D-mode) and Doppler (EchoKG) modes.

M-mode (Motion-movement) allows you to get an idea of ​​the movement of various structures of the heart, which crosses the ultrasonic beam. In this mode, the vertical axis is the distance from one or another structure of the heart to the sensor, and the horizontal axis is time. It is usually used to measure the chambers of the heart, the lumen of large vessels, calculate the wall thickness, some hemodynamic parameters. Although one-dimensionality is its disadvantage, however, the image quality and measurement accuracy of intracardiac structures are higher than when using other modes.

In or 2D mode (Two dimensional) allows you to get on the screen a planar two-dimensional image of the heart, which clearly shows the mutual arrangement of individual structures and their movement in real time. To some extent, the two-dimensional EchoCG is simpler for perception than one-dimensional, because it is more realistic reflects the anatomy and structure of the heart in a particular sectional plane (a kind of tomogram of the heart).

DehoKG – Doppler mode is used for qualitative (laminar or turbulent flow) and quantitative (speed) characteristics of intracardiac blood flows. The Doppler signal is depicted on the screen as a graph (time is plotted on the horizontal axis, and flow velocity on the vertical axis). The isoline divides the screen into two parts – blood particles moving to the sensor form a curve above the isoline, and from the sensor – below the isoline. Such curves are obtained using a constantly wave (LDPE) or pulsed (IVD) doppler. The difference between them is that in the pulse-wave mode we can estimate the blood flow at an arbitrarily chosen depth, i.e. at the level of a “control” or “gated” volume, and with a constant-wave one we obtain the character of the flow throughout the entire ultrasonic beam, which makes it possible to measure flows at high speeds and at a greater depth.

One of the varieties of DehoKG is color Doppler research (CDS). The principle of the method is based on the fact that different directions of the blood flow and its nature (turbulent or laminar) are coded in different colors, the intensity of which varies depending on the flow velocity. CDI greatly facilitates the study (especially for heart defects) and reduces the possibility of errors, since the color identification of the blood flow is very clear.

It is not possible to answer the question which of the three EchoCG techniques is the most important, since any one may be the most important in the diagnosis of various forms of pathological conditions of the heart . 
 In this section, I would like to highlight some of the erroneous ideas that exist about the method of echocardiography among general practitioners.

Healing doctors tend to overestimate the value of echocardiography (as well as other modern diagnostic methods – the effect of novelty). It should be determined immediately – the doctor of ultrasound diagnosis does not make a diagnosis. The EchoCG specialist gives a conclusion on the basis of which, like on the basis of other data, a clinical diagnosis is established by a doctor.

It must be emphasized that EchoCG is a rather subjective technique, and the interpretation of the same data by different specialists is often different. 
 You should not pay much attention to the images attached to the protocol – the image directly depends on the device and printer settings, on the section angle and other factors, so even experienced specialists try not to advise on them. Moreover, using acoustic phenomena and artifacts, one can sometimes get a picture of what the patient does not have.

In some clinics (usually where EchoCG refers to the functional diagnostics department) in conclusion, one can read about whether the patient has “focal myocardial changes” or “myocardial fibrosis”, although an echocardiographer can only assume the nature of the histological changes.

Consequently, the accuracy and reliability of echoCG research depends not only on the experience and knowledge of the doctor, but also on the following factors:

the quality of the ultrasonic device, the set of sensors and programs, the size of the monitor screen (for example, some devices have measurement resolutions of up to 0.2–0.3 mm, and others only 1.0 mm; with a low resolution of the sensor, the back may not be visible) left ventricular wall, which significantly increases the size of its cavity; a small screen does not allow viewing small structures, for example – small vegetations on the valve);

constitutional features of the patient, the presence of concomitant pathology of the lungs (more than 20% of the studied cannot obtain a high-quality image due to the lack of an echo window due to the pathology of the lungs, displacement of the mediastinal organs, etc.);

the specialist’s awareness of this patient (the attention of the researcher is unevenly distributed, and the identification of small changes is sometimes determined by random factors, and often interpreted differently. Therefore, in the direction of the study, it is necessary to put specific questions to the doctor EchoCG diagnosis);

the quality of the protocol (in the protocol it is necessary to indicate not only absolute numbers, but at least an approximate degree of their changes). However, it should be taken into account that many regulatory indicators have not yet been developed, and those that have already been published often differ from different authors. There are changes that cannot yet be accurately quantified, for example, the volume of effusion in the pericardium;

It is desirable that the ultrasound control when evaluating the dynamics of the process is carried out by the same doctor, since the evaluation is carried out on the basis of not only dimensions, but also subjective perception.

EchoCG is performed from the following standard sensor positions: 1. Parasternal access – region 3 – 4 intercostal spaces to the left of the sternum

2. Apical (apical) – apical impulse zone

3. Subkostal – from the xiphoid process

4. Suprasternal – jugular fossa

In some standard positions of the sensor, ultrasound examination of the heart is carried out in several directions: along the long and short axis of the organ (as a rule, it is parasternal and subkostal). Since B mode gives the most complete picture of the structural and geometric features of the organ under study, the study usually begins with it. Below are the schematic images of the heart and its structures in B – mode in the study of the main approaches.

Systole (valves open), diastole (valves closed).

Parasternal access on the short axis at the level of the aortic valves.

Research in the M -mode is often carried out from the left parasternal access along the long axis of the heart. The angle of inclination of the sensor is chosen so that the ultrasound beam “cuts through” the heart at the level of the aorta, the cusps of the mitral valve, and also the LV cavity at the level of the tendon filaments. In these positions, a quantitative and qualitative assessment of the studied structures is carried out. At the level of the aortic section: aortic diameter, aortic valve opening degree, size of the left atrium. At the level of the mitral valve: an assessment of its structure and nature of movement. Normally, diastole is determined by a two-phase M-shaped movement of the anterior and W-shaped movement of the posterior cusps (Fig.1.10). On the curve of movement of the front flap there are several sections with the letter designation:

The CD interval corresponds to the LV systole and complete closing of the valves. 
 The DE interval reflects the divergence of the valves in the fast filling phase. 
 Interval EF incomplete valve cover in the slow filling phase. 
 Wave A is caused by repeated divergence of the valves into the atrial systole phase.

At the level of tendon filaments, a measurement is made of the systolic-diastolic size of the LV cavity, the thickness of the IVS and CS in the diastole, their excursion, as well as the size of the RV cavity and the thickness of its wall.

The absolute values ​​of the parameters under study, and their indices (IKDRlzh – index of the end-diastolic size of the LV, IKSRlzh-index of the end-systolic size of the LV, ITMZhP – index of the thickness of the interventricular septum, etc.). Dubois tables are used to calculate indexed indicators. This is essential in the diagnosis of myocarditis, small hypertrophies, etc.

The study of blood flow at the level of the mitral, aortic and tricuspid valves is usually carried out with the upper apices, and the flow at the pulmonary trunk is carried out along the short axis at the level of the aorta. It is important that the beam was directed strictly parallel to the blood flow.

Normally, the diastolic transmission stream has a two-phase character and is located above the basal line of the spectrogram (since the flow is directed to the sensor). The first phase (peak E) characterizes the movement of blood in the fast filling phase, the second (peak A) – in the atrial systole. The flow through the tricuspid valve has the same shape.

The systolic blood flow through the aortic valve normally has a triangular shape and is represented by one peak, directed below the spectrogram baseline (the flow is directed from the sensor) (Figure 1.13). Flow on the pulmonary valve of the same nature.

Using the scale on the screen, we estimate the velocity of these flows, the pressure gradient on the valve (the pressure difference between the cavities) and some other characteristics. Using special formulas (they are included in the program of the device), it is possible to calculate the orifice area of ​​the corresponding valves. Normally, the flow rate at the valve level usually does not exceed 1.5 meters per second, which roughly corresponds to a pressure gradient of no more than 8–10 mm Hg. All streams are laminar in nature with a clearly defined narrow band spectrum and the presence of a “window” between the points with maximum and minimum intensity.

In the case of color Doppler examination (CDS), blood flows to the sensor are colored red, and from the sensor – blue. The intensity of coloring depends on the flow rate, and in the presence of turbulent flows, additional colors (yellow, green, etc.) are added to the primary colors.

The systolic function of the LV is estimated by several indicators, the central place among which is occupied by stroke volume (PP), minute volume (MO), ejection fraction (EF) and the rate of circular shortening of myocardial fibers (V cf). 
 TEICHOLZ method. Until recently, the calculation of PP, FV and other hemodynamic parameters was carried out on the basis of measurements in the M-mode when registering the image of the LV in the left parasternal approach. For the calculation, the degree of anteroposterior LV shortening is taken into account, i.e. the ratio of KDR and DAC.The calculation is carried out according to the formula L. Teicholz:

V = 7.0 * D3 / (2, 4 + D), 
 where V is the LV volume (KSO or KDO) and D is the anteroposterior size of the LV in systole or diastole. EO is defined as the difference between BWW and CSR, and EF is defined as the ratio of EO to BWW.

Calculation of the main hemodynamic parameters using the Teicholz method (EDV-end diastolic volume, ESV – end-systolic volume, SV – stroke volume, CO – minute volume, EF-left ventricular ejection fraction).

Currently, most researchers have abandoned this method of determining hemodynamic parameters, since the calculation of LV and CSR LV, according to this method, is based on measuring the CRD and CSR of only a small part of the LV at its base and does not take into account the entire complexity of the ventricular cavity geometry (which is important for patients with violation of local contractility, for example in patients with coronary artery disease). This requires the practitioner to be very careful about the results of measurements and calculations using the Teicholz method. In addition, in some patients, the endocardium of the posterior wall is difficult to locate, and pericardial movements are mistaken for its movements , which leads to an overestimation of the dimensions of the cavities and a decrease in EF values.

Disk method (SIMPSON method). Significantly more accurate results of calculating global LV contractility can be obtained by quantifying two-dimensional echocardiograms. The Simpson method (disc method) is most suitable for this purpose, based on planimetric determination and summation of the areas of 20 discs, which are peculiar LV cross sections at different levels. To calculate the volumes of the LV, two LV images are taken from the apical position (to systole and diastole), then the cursor traces its cavity and determines the long axis in each of the phases of the cardiac cycle (Figure 1.15).

Calculation of hemodynamic parameters of the LV according to the Simpson method and area-length.

Normally, the average values ​​of PV are within 55 – 65%. With a decrease in EF below 55%, talk about a decrease in LV contractility, and EF above 70% indicates a hyperkinetic type of hemodynamics. 
 At present, the rate of circular shortening of myocardial fibers is used less frequently than EF.It is calculated as follows:

Vcf = (KDR * KSR) / PI * KDR, 
 where PI is the period of exile. Normally, this indicator exceeds 0.9 s.

In a number of patients with EF 60% or more, signs of heart failure are clinically detected. As a rule, such a condition is caused by LV diastolic dysfunction (impaired relaxation processes due to ischemia, cardiosclerosis, hypertrophy of the walls, pericardial effusion, etc.). According to a number of researchers, patients with signs of heart failure caused only by diastolic dysfunction constitute 15–25% of all patients with HF.

Diastolic dysfunction of the LV is estimated according to the results of a study of transmitral diastolic blood flow in a pulsed mode. Determine: 1. the maximum speed of the early peak of the diastolic filling M1, 2. the maximum speed in the atrial systole M2, 3. the integral of speed (area under the curve) of the early diastolic filling (VTI E), 4. the integral of the speed of atrial systole (VTI A), 5 LV isovolumetric relaxation time (IVRT), 6. time to slow the early diastolic filling (DT).

In the early stages of LV diastolic dysfunction with a slight increase in the end-diastolic pressure in the LV cavity, a decrease in the time of isovolumetric relaxation is observed and blood flow increases during the atrial systole (M1 and VTI E values ​​decrease, while M2 and VTI A increase), which is a rigid type of filling. This indicates that most of the diastolic filling of the LV occurs in the atrial systole. Further deterioration of diastolic compliance of the left ventricle leads to a significant increase in end-diastolic pressure in it (respectively in the left atrium) and “pseudonormalization” of transmitral blood flow – a restrictive type of filling.

Evaluation of impaired regional contractility 1

To assess the regional contractility of the LV, the B-mode cardiac imaging along the long and short axes with LV division into segments reflecting the preferential blood supply from the corresponding branches of the coronary arteries is used.

The division of the LV into segments and their correspondence to the branches of the coronary arteries (according to Edwards)

In each of these segments, the nature and amplitude of myocardial movement is assessed. There are 3 types of local disorders of the contractile function of the left ventricle, united by the concept of “asinergy”: hypokinesia – pronounced local reduction in the degree of contraction, akinesia – the absence of contractions of the myocardium, dyskinesia – paradoxical movement (bulging) of the myocardial segment in the systole.

The violation of local LV contractility in patients with coronary artery disease is usually described on a five-point scale: 1 point – normal contractility; 2 points – moderate hypokinesia; 3 points – severe hypokinesia; 4 points – akinesia; 5 points – dyskinesia. After assessing the nature of regional contractility, an index of local contractility is calculated, which is the sum of the scoring of the contractility of each segment divided by the total number of segments studied -n (usually 16):

HUD =  S / n

Normally, the ILS values ​​are 1 (one). High values ​​of this indicator in patients with MI or postinfarction cardiosclerosis are often associated with an increased risk of death and the development of HF. It should be remembered that with EchoCG it is not always possible to achieve a sufficiently good visualization of all 16 segments. In these cases, only those areas of the myocardium of the LV that are well identified in a two-dimensional study are taken into account.

The main causes of local impairment of LV contractility can be: acute myocardial infarction (AMI), post-infarction cardiosclerosis, transient myocardial ischemia (including induced stress tests – stress echocardiography), permanent myocardial ischemia with the development of a “beating myocardial heart attack.” intraventricular conduction (blockade of the bundle branch block, WPW syndrome, etc.)

An echocardiographic study for heart defects reveals: 1. the nature of valve lesions (presence of fibrosis, calcification, vegetations on the valve), 2. to determine the severity of the defect (degree of stenosis and valve insufficiency, the size of defects in congenital defects), 3. to assess the degree of hemodynamic disturbances (cavity size, ejection fraction, pressure gradient at the discharge site for congenital malformations, etc.).

The most informative use of all three modes of echocardiographic research. Two-dimensional echocardiography provides a holistic view of the structural lesions of the heart. The M-mode makes it possible to measure the degree of opening of the valves and describe the characteristic of movements (for example, the diastolic tremor of the mitral valve in aortic insufficiency). Finally, the Doppler echocardiogram makes it possible to estimate the magnitude and direction of blood flow through the valve, determine the pressure gradient before and after the place of narrowing, etc.

It should be noted that the degree of severity of the defect according to ultrasound does not always correspond to its clinical stage (which takes into account the degree of circulatory failure). For example, a patient with aortic valve insufficiency of grade 3 may have stage 11 according to the results of a clinical examination.

The reasons:

Congenital anomaly. Calcinosis (idiopathic) of the left atrioventricular orifice. Rheumatism. Lyutembash syndrome

Mode B: 1. dome-shaped diastolic bulging of the fibro-modified or calcined anterior cusp of the mitral valve into the LV cavity (“sailing” of the leaf); 2. the increase or dilatation of the cavity of the LP, the appearance of blood clots in it; 3. The image of the mitral orifice in the shape of a “fish mouth” in a section along the short axis.

M-mode: 1. the movement of the anterior cusp into the diastole acquires a “P” shaped form (atrial wave A disappears); 2. unidirectional movement of the rear sash relative to the front; 3. a decrease in the EF velocity of the anterior cusp (speed of the early diastolic cover) and the degree of divergence of the cusps in the diastole (less than 20 mm).

Doppler: 1. an increase in the diastolic pressure gradient between LP and LV (from 12 to 40 mm Hg); 2. slowing down the rate of diastolic filling (flattening of the spectrogram); 3. pronounced flow turbulence. By the speed of tilt of the anterior leaf in diastole EF (M-mode), the half-time of the flow curve (Doppler mode), and also planimetrically along the short axis (B-mode), you can determine the area of ​​the mitral orifice (Smo) and estimate the degree of mitral stenosis. The following degrees of stenosis are distinguished: critical stenosis (Smо less than 1.1 cm 2 ); pronounced stenosis (Smo = 1.2 – 1.7 cm 2 ); moderate stenosis (Sm = 1.8 – 2.2 cm 2 ) and minimal stenosis (S m exceeds 2.3 – 2.4 cm 2
 ). It must be emphasized that these authors may differ among themselves by different authors.

From apical position On long axis from parasternal access

The nature of the movement of the valves MK Calculation of pressure gradient and hole area

Measurement of the MO area along the short axis of echoCG in mitral stenosis (explained in the text).

The reasons:

Rheumatism. Congenital mitral valve anomaly. Large mitral valve prolapse with regurgitation. a) golistystolichesky, b) late systolic. The syndrome of free-hanging mitral valve: a) at the separation of the chords leading to the anterior mitral valve, b) at the separation of the chords leading to the posterior mitral valve. Mitral regurgitation secondary to left ventricular dilatation and / or dysfunction, the so-called double-diamond mitral valve. Hypertrophic subaortic stenosis. Idiopathic calcification of the left atrioventricular orifice. Hereditary diseases of the connective tissue.

Structural changes of the heart during this defect are due to the syndrome of volume overload of the left heart.

With “pure” mitral insufficiency in the M – and B – modes, only indirect signs of this defect are revealed, which most often indicate volume overload of the left heart sections: 1. separation (nonlocking) of fibrosis modified MK cusps in systole (with rheumatic insufficiency) , 2. an increase in the cavities of the left ventricle and the left ventricle with an increase in the stroke volume of the left ventricle (the left ventricular cavity is more than 5.5 cm, LV CDR) is more than 6.5 cm, 3. hyperkinesis of the MZhP and LVSL and their hypertrophy. The most reliable method for detecting mitral regurgitation is Doppler research, in particular, color Doppler scanning. The latter method is the most informative and illustrative and allows you to determine the severity of mitral regurgitation. With a minimal degree of regurgitation, the jet is narrow and not more than 2 cm into the LP cavity,with the second – from 2 to 3.5 cm, with the third degree – by 3.5 – 5 cm, with the fourth (heavy) – jet of regurgitation reaches the roof of the LP. Some authors propose to measure the area of ​​the jet of regurgitation according to the color spectrum, while others – to calculate the volume of regurgitation. However, only the totality of all the above methods can be generally judged on the degree of mitral insufficiency.

Doppler examination of transmitral Color Doppler scanning of blood flow during regurgitation in LP 2-3 degree