Instrumental methods of heart examination

Heart phonocardiography allows you to record on paper heart sounds, tones and noises. The results of this study are similar to auscultation of the heart, but it should be borne in mind that the frequency of sounds recorded on a phonocardiogram and perceived during auscultation does not fully correspond to each other. Some noise, for example high-frequency diastolic noise at the V point with aortic insufficiency, is better perceived in auscultation. Simultaneous registration of the PCG, the sphygmogram of the artery and the ECG makes it possible to measure the duration of systole and diastole to evaluate the contractile function of the myocardium. The duration of intervals Q- I tone and II tone - the click of the opening of the mitral valve allows to assess the severity of mitral stenosis. Recording of ECG, PCG and the curve of pulsation of the jugular vein allows you to calculate the pressure in the pulmonary artery.

Radiographic examination of the heart

In chest X-ray examination, the shadow of the heart surrounded by airborne lungs can be carefully examined. Usually 3 projections of the heart are used: antero-posterior or straight, and 2 oblique when the patient rises to the screen at an angle of 45 °, first with the right shoulder forward (I oblique projection), then with the left (II oblique projection). In a direct projection, the shadow of the heart on the right is formed by the aorta, the superior hollow vein and the right atrium. The left contour is formed by the aorta, the pulmonary artery and the left atrial cone and, finally, the left ventricle.

In the I oblique position, the anterior contour forms the ascending part of the aorta, the cone of the pulmonary artery, the right and left ventricles. The posterior contour of the heart's shadow is formed by the aorta, the left and right atrium. In the second oblique position, the right contour of the shadow is formed by the upper vena cava, the ascending part of the aorta, the right atrium and the right ventricle, the posterior contour by the descending part of the aorta, the left atrium and the left ventricle.

In the usual examination of the heart, the size of the heart chambers is estimated. If the transverse size of the heart is more than half the transverse dimension of the chest, then this indicates the presence of cardiomegaly. The expansion of the right atrium causes the right border of the heart to shift, while the left atrial widening shifts the left contour between the left ventricle and the pulmonary artery. The expansion of the left atrium posteriorly is detected when barium passes through the esophagus, which reveals a displacement of the posterior contour of the heart. An increase in the right ventricle is better seen in the lateral projection by narrowing the space between the heart and the breastbone. An increase in the left ventricle causes the lower left part of the left contour of the heart to move outward. Extension of the pulmonary artery and aorta can also be recognized. However, it is often difficult to determine the enlarged part of the heart, since it is possible to rotate the heart around its vertical axis. On the roentgenogram, the expansion of the heart chambers is well reflected, however, when the walls are thickened, a change in the configuration and displacement of the boundaries may be absent.

Calculation of heart structures can be an important sign in diagnosis. Calcified coronary arteries usually indicate their severe atherosclerotic lesion. Calcification of the aortic valve takes place in almost 90% of patients with aortic stenosis. However, in the anteroposterior view, the projection of the aortic valve is superimposed on the spine and the calcified aortic valve may not be visible, so it is better to determine the calcification of the valves in oblique projections. An important diagnostic value may be calcification of the pericardium.

The condition of the lungs, especially their vessels, is important in the diagnosis of heart disease. Pulmonary hypertension may be suspected when expanding large branches of the pulmonary artery, with distal pulmonary arterial sites may be normal or even reduced in size. In such patients, pulmonary blood flow is usually reduced and pulmonary veins usually have a normal value or are reduced. In contrast, with an increase in pulmonary vascular blood flow, for example, in patients with certain congenital heart defects, both proximal and distal pulmonary arteries increase and the pulmonary veins increase. A particularly pronounced increase in pulmonary blood flow is observed with a shunt (discharge of blood) from left to right, for example, with a defect of the atrial septum from the left atrium to the right.

Pulmonary venous hypertension is detected with stenosis of the mitral orifice, as well as with any left ventricular heart failure. In this case, the pulmonary veins in the upper parts of the lung are especially enlarged. As a result of exceeding the pressure in the pulmonary capillaries above the oncotic blood pressure, interstitial edema appears in these areas, which radiologically manifests itself by the erosion of the edges of the pulmonary vessels, an increase in the density of the lung tissue surrounding the bronchus. With the growth of pulmonary stagnation with the development of alveolar edema, there is a bilateral expansion of the roots of the lungs, which begin to resemble a butterfly in appearance. In contrast to the so-called cardiac pulmonary edema in their lesions associated with increased permeability of pulmonary capillaries, radiologic changes are diffuse and more pronounced.

Echocardiography

Echocardiography is a method of heart examination based on the use of ultrasound. This method is comparable with the X-ray study of its capabilities to visualize the structure of the heart, to evaluate its morphology, as well as the contractile function. Due to the possibility to use a computer, to register an image not only on paper, but also on videotape, the diagnostic value of echocardiography has increased significantly. The possibilities of this non-invasive method of investigation are now approaching the possibilities of invasive X-ray angiocardiography.

The ultrasound used in echocardiography has a much higher frequency (compared to available hearing). It reaches 1-10 million oscillations per second, or 1-10 MHz. Ultrasonic vibrations have a small wavelength and can be obtained in the form of narrow beams (similar to light rays). When the boundary of media with different resistances is reached, a part of the ultrasound is reflected, and the other part continues its way through the medium. In this case, the reflection coefficients at the boundary of different media, for example, "soft tissue-air" or "soft tissue-liquid", will differ. In addition, the degree of reflection depends on the angle of incidence of the beam on the media interface. Therefore mastering this method and its rational use require a certain skill and time.

To generate and record ultrasonic vibrations, a sensor is used that contains a piezoelectric crystal with electrodes attached to its faces. The sensor is applied to the surface of the chest in the region of the projection of the heart, and a narrow beam of ultrasound is sent to the structures studied. Ultrasonic waves are reflected from the surfaces of structural formations that differ in their density, and return to the sensor where they are recorded. There are several modes of echocardiography. With one-dimensional M-echocardiography, an image of the heart structures is obtained, with the development of their movement in time. In the M-mode, the obtained image of the heart allows you to measure the thickness of the walls and the size of the heart chambers during systole and diastole.

Two-dimensional echocardiography makes it possible to obtain a two-dimensional image of the heart in real time. In this case, sensors are used, which make it possible to obtain a two-dimensional image. Since this research is carried out in real time, the most complete method of recording its results is a video recording. Using different points in which to make a study, and changing the direction of the beam, it is possible to get a fairly detailed picture of the structure of the heart. The following sensor positions are used: apical, suprasternal, subcostal. The apical approach allows to obtain a cross section of all 4 chambers of the heart and aorta. In general, the apical section in many respects resembles an angiographic image in the anterior oblique projection.

Doppler echocardiography makes it possible to evaluate the flow of blood and the vortexes that arise during it. The Doppler effect is that the frequency of the ultrasonic signal when reflected from a moving object varies in proportion to the speed of movement of the object being polished. When the object moves (for example, blood) towards the sensor that generates ultrasonic pulses, the frequency of the reflected signal increases, and when the object is reflected from the object being removed, the frequency decreases. There are two types of Doppler studies: continuous and pulsed Doppler cardiography. With the help of this method, it is possible to measure the blood flow velocity at a particular site located at a depth of interest to the researcher, for example, the blood flow velocity in the supralvalve or sub-valvular space, which varies with different vices. Thus, the recording of blood flow at certain points and in a certain phase of the cardiac cycle allows a fairly accurate assessment of the degree of valve failure or stenosis of the hole. In addition, this method also allows you to calculate cardiac output. Currently, Doppler systems have appeared that allow real-time and color images of the Doppler echocardiogram synchronously with a two-dimensional echocardiogram. In this case, the direction and velocity of the flow are represented in different colors, which facilitates the perception and interpretation of diagnostic data. Unfortunately, not all patients can be successfully studied by echocardiography, for example, due to severe emphysema, obesity. In connection with this, a modification of echocardiography has now been developed, in which registration is performed using a sensor inserted into the esophagus.

Echocardiography allows us first of all to estimate the size of the chambers of the heart and hemodynamics. With the help of M-echocardiography, it is possible to measure the size of the left ventricle during diastole and ristola, the thickness of its posterior wall and the interventricular septum. The obtained dimensions can be converted into volume units (cm ² ). The left ventricular ejection fraction is also calculated, which normally exceeds 50% of the final diastolic volume of the left ventricle. Doppler echocardiography makes it possible to evaluate the pressure gradient through a narrowed orifice. Echocardiography is successfully used for the diagnosis of mitral stenosis, and the two-dimensional image allows us to accurately determine the size of the mitral orifice. At the same time, concomitant pulmonary hypertension and severity of right ventricular lesion, its hypertrophy are also evaluated. Doppler echocardiography is the method of choice for assessing regurgitation through valve openings. Echocardiograms are especially valuable when recognizing the cause of mitral regurgitation, in particular in the diagnosis of mitral valve prolapse. In this case, the displacement of the back of the mitral valve leaf can be seen during systole. This method also makes it possible to estimate the cause of the narrowing that occurs on the path of ejection of blood from the left ventricle into the aorta (valvular, supra-valvular and subvalvular stenosis, including obstructive cardiomyopathy). The method allows to diagnose with high accuracy hypertrophic cardiomyopathy with its different localization, both asymmetric and symmetrical. Echocardiography is the method of choice in the diagnosis of pericardial effusion. The pericardial fluid layer can be seen behind the left ventricle and in front of the right ventricle. With a large sweating, the compression of the right side of the heart is seen. It is also possible to detect a thickened pericardium and pericardial constriction. However, some structures around the heart, for example epicardial fat, can be difficult to distinguish from a thickened pericardium. In this case, methods such as computer (X-ray and nuclear magnetic resonance imaging) tomography provide a more adequate image. Echocardiography allows you to see the papillomatous growths on the valves with infective endocarditis, especially when the amount of vegetation (caused by endocarditis) is more than 2 mm in diameter. Echocardiography makes it possible to diagnose atrial myxoma and intracardiac thrombi, which are well detected in any regimen of study.

[1], [2], [3], [4], [5], [6]

Radionuclide study of the heart

The study is based on the introduction into the vein of albumin or erythrocytes with a radioactive label. Radionuclide studies allow evaluating the contractile function of the heart, perfusion and myocardial ischemia, and also to identify areas of necrosis therein. Equipment for radionuclide research includes a gamma camera in combination with a computer.

Radionuclide ventriculography is performed with intravenous injection of erythrocytes labeled with technetium-99. In this case, images of the cavity of the chambers of the heart and large vessels are obtained (to a certain extent analogous to the data of cardiac catheterization with X-ray angiocardiography). The obtained radionuclide angiocardiograms allow to evaluate the regional and general function of the left ventricular myocardium in patients with coronary heart disease, to estimate ejection fractions, to determine the function of the left ventricle in patients with heart defects, which is important for the prognosis, to study the condition of both ventricles, which is important in patients with congenital heart diseases, cardiomyopathies, arterial hypertension. The method also makes it possible to diagnose the presence of an intracardiac shunt.

Perfusion scintigraphy using radioactive thallium-201 allows one to assess the state of the coronary circulation. Thallium has a rather long half-life and is an expensive element. The thallium injected into the veins with coronary blood flow is delivered to the cells of the myocardium and penetrates through the membrane of the cardiac myocytes in the perfused part of the heart, accumulating in them. It can be recorded on a scintigram. At the same time, a weakly perfused site accumulates thallium worse, and the non-perfused part of the myocardium looks like a "cold" spot on the scintigram. Such a scintigraphy can be performed also after physical exertion. In this case, the isotope is administered intravenously during the period of maximum exercise, when the patient develops an attack of angina pectoris or changes appear on the ECG indicating ischemia. And in this case, ischemic patches are detected in connection with their worst perfusion and less accumulation of thallium in cardiac myocytes. Plots where thallium does not accumulate correspond to zones of cicatricial changes or fresh myocardial infarction. Load test scintigraphy with thallium has a sensitivity of approximately 80% and specificity of detecting myocardial ischemia 90%. Its conduct is important for assessing the prognosis in patients with ischemic heart disease. Scintigraphy with thallium is carried out in different projections. In this case, scintigrams of left ventricular myocardium are obtained, which are divided into fields. The extent of ischemia is assessed by the number of changed fields. Unlike X-ray coronary angiography, which demonstrates morphological changes in the arteries, scintigraphy with thallium allows one to evaluate the physiological significance of stenotic changes. Therefore, scintigraphy is sometimes performed after coronary angioplasty to assess the function of the shunt.

Scintigraphy after the introduction of pyrophosphate technetium-99 is performed to recognize the necrosis site in patients with acute myocardial infarction. The results of this study are evaluated qualitatively by comparison with the degree of pyrophosphate absorption by bone structures that actively accumulate it. This method is important for the diagnosis of myocardial infarction in atypical clinical course and the difficulties of electrocardiographic diagnosis in connection with violation of intraventricular conduction. In 12-14 days from the onset of an infarct, signs of pyrophosphate accumulation in the myocardium are not recorded.

MP-tomography of the heart

The study of the heart by means of nuclear magnetic resonance is based on the fact that the nuclei of some atoms, when in a strong magnetic field, themselves begin to emit electromagnetic waves that can be recorded. Using the radiation of various elements, as well as computer analysis of the obtained oscillations, it is possible to visualize well the various structures located in soft tissues, including the heart. With the help of this method, it is possible to determine well the structure of the heart at different horizontal levels, ie, to obtain tomograms, and to refine the morphological features, including the size of the chambers, the thickness of the walls of the heart, etc. Using nuclei of various elements, it is possible to detect foci of necrosis in the myocardium. Investigating the radiation spectrum of elements such as phosphorus-31, carbon-13, hydrogen-1, one can evaluate the state of phosphates rich in energy and study intracellular metabolism. Nuclear magnetic resonance in various modifications is increasingly used to obtain visible images of the heart and other organs, as well as for the study of metabolism. Although this method is still very expensive, a great prospect in its use for both scientific research and practical medicine is beyond doubt.