Pericardial Friction Rub

A pericardial friction rub is the sound that is generated as a result of an inflamed pericardium.
Rubs consist of one to three sounds that may be mistaken for murmurs. However, the quality of the sound(s) is different and distinctive, often scratchy or creaky.
Classically there are three components to a pericardial rub that correlate with atrial contraction (so you may hear it just before S1), during ventricular systole (between S1 and S2) and during the rapid filling phase of diastole (right after S2).

Patient 6

This is a middle-aged man with a pericardial friction rub, recorded a day after coronary artery bypass surgery.