Pericardial fricative sound is a typical manifestation of fibrinous pericarditis, which is mainly caused by the friction between the dirty layer and the wall layer after the pericarditis becomes rough. This sound is generally rough and scraping, and sounds different from the normal heart sound, but it sounds closer to the ear than the heart sound, and is generally located between 3-4 ribs at the left edge of the sternum, and may be easier to hear when tilted forward in a sitting position, or when inhaling deeply during auscultation. The sound will also be more pronounced when the physician applies pressure to the heart button of a special stethoscope. This symptom can last for several hours, days or even weeks, but if the pericardial fluid increases and separates the dirty layer of the pericardium from the wall layer, the sound of pericardial friction will disappear.