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Apericardial friction rub, alsopericardial rub, is an audiblemedical sign used in thediagnosis ofpericarditis. Uponauscultation, this sign is an extraheart sound of to-and-fro character, typically with three components, twosystolic and onediastolic.[1] It resembles the sound of squeaky leather and often is described as grating, scratching, or rasping. The sound seems very close to the ear and may seem louder than or may even mask the other heart sounds. The sound usually is best heard between theapex andsternum but may be widespread.
Thepericardium is a double-walled sac around theheart. The inner and outer (visceral and parietal, respectively) layers are normally lubricated by a small amount of pericardial fluid, but theinflammation of pericardium causes the walls to rub against each other with audible friction. In children, rheumatic fever is often the cause of pericardial friction rub. Pericardial friction rubs can also be heard in pericarditis that is associated with uremia or post-myocardial infarction.
Pericardial friction rub is one of several, similar sounds. Adifferential diagnosis may be possible, or not, depending upon the number of components that are audible. Pericardial friction rub may have one, two, or three audible components, whereas the similarpleural friction rub ordinarily has two audible components. One- and two-component rubs are ambiguous. A three-component rub distinguishes a pericardial rub and indicates the presence of pericarditis. Also, a pleural rub can only be heard during inspiration, whereas, the pericardial rub can be heard even after cessation of breathing. Pleural rub creates pain mostly on the lateral part of the chest wall, whereas pain due to pericardial rub is always central in location. The intensity of pleural rub is increased on pressing the diaphragm of the stethoscope over the affected area, whereas there is no such change in case of a pericardial rub.