Three-Component Pericardial Friction Rub

The pericardial friction rub is often ephemeral and classically consists of 3 components corresponding to ventricular systole, early diastole, and atrial contraction. Attributed to the friction between the 2 inflamed layers of the pericardium, the rub has a “scratching” quality. The rub is typically loudest at the lower left sternal border and best auscultated with the patient leaning forward during either held expiration or inspiration.