Percussion of the heart is used to determine the position, size, configuration of the heart. Percussion can be carried out in the vertical and horizontal position of the patient. It should be borne in mind that the determined dimensions of the heart in the vertical position are smaller than in the horizontal. This phenomenon is associated with a slight mobility of the heart and the movement of the diaphragm with a change in body position.
The right border of the heart is formed from above by the superior vena cava and from below by the right atrium. Its upper left border is formed by the left part of the aortic arch, pulmonary trunk, left atrial ear and left ventricle. The front surface forms the right ventricle, the back - the left ventricle. The heart as an organ that does not contain air gives a dull sound during percussion. From the sides, it is partially covered by the lungs, due to which relative or absolute dullness is determined. The relative dullness of the heart corresponds to its real boundaries and is the projection of the front surface onto the chest, and the absolute determines only the front surface, which is not covered by the lungs.
Percussion of the heart. Definition of absolute dullness
The percussion sound over the area of relative dullness is quieter than over the area of absolute. The latter is determined by silent percussion of the heart. Normally, the right border of absolute cardiac dullness coincides with the left edge of the sternum in the area from the IV to VI ribs, the upper one with the lower edge of the cartilage of the IV left rib to the left sternal line. The left border is determined in the fifth intercostal space 10-15 mm to the right of the left midclavicular line.
An increase in absolute dullness is observed with right ventricular hypertrophy, which is observed as a result of mitral stenosis, pulmonary embolism, and pericardial effusion. With emphysema, a decrease or even complete absence of a site of absolute dullness is determined.
Percussion of the heart to determine relative dullness
Relative cardiac dullness is determined as follows. First, the upper edge of hepatic dullness is found, then, rising two ribs up, they are percussed in the fifth intercostal space, towards the sternum until a dull sound appears, which corresponds to the location of the right border of the heart. Normally, it is located along the right edge of the sternum or 5-10 mm to the right of it. Then find the upper limit. To do this, percussion from the left clavicle from top to bottom along the sternal line. On the third rib, a blunted percussion sound is normally heard, which corresponds to the location of the upper border of the heart. To determine the left border, they are percussed in the fifth intercostal space, in the direction from the front axillary line to the sternum until a dull sound appears. Normally, the left border is in the fifth intercostal space 10-15 mm to the right of the left midclavicular line.
In some diseases, the size of the heart may increase. For example, in case of hypertension, defects of the aortic valve, the left border moves to the left, with myocarditis all the cavities of the heart expand, and its borders shift left and right.
Percussion is also used to examine organs located in the abdominal cavity, although it is less informative in this case than palpation. Abdominal percussion is mainly used to determine the boundaries of individual organs, that is, the topographic form of this study is used.
Since the intestine always contains a sufficient amount of air, a high percussion sound is determined above the abdominal cavity. Percussion of the spleen, liver, kidneys makes a dull sound. These sound characteristics allow you to accurately determine the location, topographic location of the abdominal organs.