Normal X-ray anatomy of the heart

Radiation examination of the morphology of the heart and the main vessels can be performed using non-invasive and invasive techniques. Non-invasive methods include: radiography and fluoroscopy; ultrasonic research; CT scan; Magnetic resonance imaging; scintigraphy and emission tomography (one- and two-photon). Invasive procedures are: artificial contrasting of the heart by the venous route - angiocardiography; Artificial contrasting of the left cavities of the heart by the arterial route - ventriculography, coronary arteries - coronary angiography and aorta - aortography.

Radiographic methods - radiography, fluoroscopy, computed tomography - allow to determine with the greatest degree of reliability the position, shape and size of the heart and the main vessels. These organs are among the lungs, so their shadow is clearly distinguished against the background of the transparent pulmonary fields.

An experienced doctor never begins a study of the heart with an analysis of his image. First of all, he will take a look at the owner of this heart, because he knows how much the position, shape and size of the heart depend on the physique of a person. Then, he will estimate the size and shape of the chest, the state of the lungs, the level of the diaphragm dome standing from the photographs or the data of transmission. These factors also affect the character of the image of the heart. It is very important that at the same time the radiologist has the opportunity to survey the pulmonary fields. Such changes in them as arterial or venous plethora, interstitial edema, characterize the state of the small circle of blood circulation and contribute to the diagnosis of a number of heart diseases.

The heart is an organ of complex shape. On radiographs, with fluoroscopy and on computer tomograms, only a planar two-dimensional image of it is obtained. In order to get an idea of the heart as a volumetric formation, fluoroscopy resorts to constant rotations of the patient behind the screen, and in CT, 8-10 slices or more are performed. Their combination makes it possible to reconstruct a three-dimensional image of an object. Here it is appropriate to note two newly emerged circumstances that have changed the traditional approach to radiographic examination of the heart.

First, with the development of the ultrasound method, which has great opportunities to analyze the function of the heart, the need for fluoroscopy as a method for studying the activity of the heart has practically disappeared. Secondly, ultra-high-speed computer X-ray and magnetic resonance tomographs have been created, which allow carrying out a three-dimensional reconstruction of the heart. Similar, but less "advanced" features are available for some new models of ultrasonic scanners and apparatus for emission tomography. As a result, the doctor has a real, and not imaginary, as in fluoroscopy, the possibility to judge the heart as a three-dimensional object of research.

For many decades, radiographs of the heart were performed in 4 fixed projections: direct, lateral and two oblique - left and right. In connection with the development of ultrasound diagnosis, now the main projection of the radiography of the heart is one - a straight front, in which the subject is adjacent to the cassette by the breast. In order to avoid the projection increase in the heart, it is performed at a large distance from the tube-cassette (teleradiography). At the same time, to increase the sharpness of the image, the radiography time is reduced to a maximum of several milliseconds. However, in order to get an idea of the radiographic anatomy of the heart and the main vessels, a multi-projection analysis of the image of these organs is needed, especially since the clinician often has to meet with chest images.

On the roentgenogram in a direct projection, the heart gives a uniform intense shadow, located in the middle, but somewhat asymmetrically: about 1/3 of the heart is projected to the right of the median line of the body, and Vi - to the left of this line. The contour of the shadow of the heart sometimes protrudes 2-3 cm to the right of the right contour of the spine, the outline of the apex of the heart on the left does not reach the middle-clavicular line. In general, the shadow of the heart resembles a skewed oval. In persons of the hypersthenic constitution, it occupies a more horizontal position, and asthenics have a more vertical position. Cranial image of the heart passes into the shadow of the mediastinum, which at this level is represented mainly by large vessels - the aorta, the superior vena cava and the pulmonary artery. Between the contours of the vascular bundle and the heart oval, the so-called cardiovascular angles are formed - the recesses that create the waist of the heart. At the bottom of the image of the heart merges with the shadow of the abdominal organs. Angles between the contours of the heart and the diaphragm are called cardiac-diaphragmatic.

Despite the fact that on radiographs, the shadow of the heart is absolutely monotonous, it is possible to differentiate its individual chambers with a certain degree of probability, especially if the doctor has X-rays taken in several projections, i.e. At different angles of shooting. The fact is that the outlines of the cardiac shadow, which are normally even and clear, have the form of arches. Each arc represents a mapping of the outgoing on the contour of the surface of this or that part of the heart.

All the arches of the heart and vessels are distinguished by a harmonious roundness. Straightening of the arc or any part of it indicates a pathological change in the wall of the heart or adjacent tissues.

The shape and position of the heart in humans are variable. They are due to the constitutional features of the patient, its position during the study, the phase of breathing. There was a period when very fond of heart measurements on radiographs. Currently, it is usually limited to the determination of the cardiopulmonary ratio - the ratio of the diameter of the heart to the width of the chest, which normally ranges from 0.4 to 0.5 in adults (hypersthenicises are greater and asthenics are less). The main method that determines the parameters of the heart is ultrasound. With its help accurately measure not only the size of the heart chambers and vessels, but also the thickness of their walls. To measure the heart chambers, and in different phases of the cardiac cycle, can also be by means of a computerized tomography synchronized with electrocardiography, digital ventriculography or scintigraphy.

In healthy people, the shadow of the heart on the radiograph is uniform. In pathology, lime deposits in the valves and fibrous rings of the valve openings, the walls of the coronary vessels and the aorta, and the pericardium can be detected. In recent years, many patients with implanted valves and pacemakers have appeared. Note that all these dense inclusions, both natural and artificial, are clearly revealed in sonography and computed tomography.

Computed tomography is performed when the patient is in a horizontal position. The main scanning section is selected so that its plane passes through the center of the mitral valve and the apex of the heart. On the tomogram of this layer, both atriums, both ventricles, interatrial and interventricular septums appear. At the same cut, the coronal sulcus, the place of attachment of the papillary muscle and the descending aorta are differentiated. The subsequent sections are isolated both in the cranial and caudal directions. The scanner activation is synchronized with the ECG recording. In order to obtain a clear image of the cavities of the heart, the tomograms are performed after rapid automatic administration of the contrast medium. On the obtained tomograms two images are selected, made in the final phases of cardiac contraction - systolic and diastolic. Comparing them on the display screen, you can calculate the regional contractile function of the myocardium.

New prospects in the study of the morphology of the heart opened MRI, especially performed on the latest models of apparatus - ultra-high speed. In this case, one can observe cardiac contractions in real time, take pictures at specified phases of the cardiac cycle and, of course, receive parameters of heart function.

Ultrasonic scanning in different planes and at different positions of the sensor makes it possible to obtain on the display an image of the structures of the heart: ventricles and atria, valves, papillary muscles, chords; In addition, it is possible to identify additional pathological intracardiac formations. As already noted, an important advantage of sonography is the ability to evaluate with its help all parameters of cardiac structures.

Doppler echocardiography allows you to record the direction and velocity of blood in the heart cavities, identify areas of turbulent vortices at the site of the resulting obstructions to normal blood flow.

Invasive techniques for the study of the heart and blood vessels are associated with artificial contrasting of their cavities. These techniques are used both for the study of the morphology of the heart, and for the study of central hemodynamics. With angiocardiography, 20-40 ml of X-ray contrast agent is injected with an automatic syringe through a vascular catheter into one of the hollow veins or into the right atrium. Even during the introduction of a contrast medium, video recording is started on a film or a magnetic medium. Throughout the study, which lasts 5 to 7 seconds, the contrast medium sequentially fills the right heart, pulmonary artery and pulmonary veins, the left heart and the aorta. However, due to dilution of the contrast medium in the lungs, the image of the left parts of the heart and the aorta is not clear, therefore angiocardiography is used primarily for studying the right heart and small circulation. With its help, it is possible to identify a pathological message (shunt) between the chambers of the heart, an abnormality of the vessels, an acquired or congenital obstruction in the path of blood flow.

For a detailed analysis of the condition of the ventricles of the heart, contrast substance is injected directly into them. Left ventricular examination of the heart (left ventriculography) is performed in the right oblique anterior projection at an angle of 30. A 40 ml contrast medium is poured in automatically at a rate of 20 ml / s. During the introduction of the contrast medium, a series of film frames is started. End of the introduction of the contrast medium, until it is completely washed out of the ventricular cavity.Of the series of frames, two are selected, made in the finite-systolic and finely diastolic phase of the heart contraction. Taviv these frames determine not only the morphology of the ventricle, but also the contractility of the heart muscle.This method can be identified as diffuse violations of the function of the heart muscle, for example in cardiosclerosis or myocardiopathy, and the local zones of asynergia that are observed in myocardial infarction.

For the study of coronary arteries, contrast substance is injected directly into the left and right coronary arteries (selective coronary angiography). In pictures taken in different projections, the position of arteries and their main branches is studied, the shape, contours and lumen of each arterial branch, the presence of anastomoses between systems of the left and right coronary arteries. It should be noted that in the vast majority of cases, coronarography is performed not so much for diagnosis of myocardial infarction, but as the first, diagnostic stage of the intervention procedure - coronary angioplasty.

Recently, digital angiography (DSA) is increasingly being used to study the cavities of the heart and blood vessels under conditions of artificial contrast. As already noted in the previous chapter, DSA based on computer technology allows you to obtain an isolated image of the vascular bed without the shadows of bones and surrounding soft tissues. With appropriate financial capabilities, DSA will eventually completely replace conventional analog angiography.

[1], [2], [3]