Topography and X-ray anatomy of the heart

The heart with the membrane surrounding it, the pericardium, is located in the chest cavity. Two or three hearts are located to the left of the median plane, and one third to the right. From the sides and partly from the front, the greater part of the heart is covered by the lungs enclosed in pleural sacs. A significantly smaller part of the heart is adjacent to the sternum and costal cartilages in front.

The upper border of the heart runs along the line connecting the upper edges of the cartilages of the right and left third ribs. The right border descends from the level of the upper edge of the cartilage of the third right rib vertically down to the cartilage of the fifth right rib (1-2 cm to the right of the edge of the sternum). The lower border is drawn along the line that runs from the cartilage of the fifth right rib to the apex of the heart. This line is projected in the left fifth intercostal space 1.0-1.5 cm inward from the midclavicular line. The left border of the heart extends from the upper edge of the cartilage of the third left rib, beginning at the level of the middle of the distance between the left edge of the sternum and the left midclavicular line, and continues to the apex of the heart. The right and left atrioventricular openings are projected onto the anterior chest wall along an oblique line following from the sternal end of the cartilage of the third left rib to the cartilage of the sixth right rib. The left atrioventricular orifice is located on this line at the level of the cartilage of the third left rib, the right one is above the place of attachment of the cartilage of the fifth right rib to the sternum. The opening of the aorta lies behind the left edge of the sternum at the level of the third costal space, the opening of the pulmonary trunk is above the place of attachment of the cartilage of the third left rib to the sternum.

In adults, the heart has different shapes depending on the body type. Thus, in people with a dolichomorphic body type, the axis of the heart is oriented vertically and the heart resembles a hanging drop ("drop heart"). In people with a brachymorphic body type, in whom the diaphragm is located relatively high, and the angle between the long axis of the heart and the median plane of the body is close to right angles, the heart occupies a horizontal position (the so-called transverse, or recumbent heart). The horizontal position of the heart is more common in women than in men. In people with a mesomorphic body type, the heart occupies an oblique position (the angle between the long axis of the heart and the median plane of the body is 43-48°).

When examined with X-rays directed from back to front (anterior survey film), the heart of a living person appears as an intense shadow located between the light pulmonary fields. This shadow has the shape of an irregular triangle, the base of which is directed toward the diaphragm. The shadows of the organs located in front of and behind the heart (sternum, organs of the posterior mediastinum and thoracic spine) are also superimposed on the shadow of the heart and its large vessels. The contours of the shadow of the heart have a number of bulges called arches. On the right contour of the heart, a smoothed upper arch is clearly visible, the upper section of which corresponds to the superior vena cava, and the lower section to the bulge of the ascending aorta, and the lower arch formed by the right atrium. Above the upper arch, there is another small arch (bulge), formed by the outer contour of the right brachiocephalic vein. The left contour of the heart forms 4 arches:

• the lower one is the largest, passing along the edge of the left ventricle;
• arch of the protruding left atrial appendage;
• the arch of the pulmonary trunk and
• the superior arch, corresponding to the aortic arch and the beginning of its descending part.

In the area of the arches formed by the left ventricle and the left auricle, the contour of the heart has a depression (interception), called the waist of the heart, separating it from the large vessels.

In an adult, the heart can normally have three different positions on an X-ray:

• oblique, inherent in most people;
• horizontal;
• vertical ("drip heart").