Next, we’ll listen at the lower left sternal edge. We’ll put firm pressure on the diaphragm of the stethoscope. We’ll use the cotton swab on the carotid for timing systole, and we’ll all watch respiration together. Let’s all listen together.
What we heard in our patient is a three-component friction rub. We put firm pressure on the diaphragm, we watched respiration, we timed with the carotid, and what we heard wasn’t just a systolic, very scratchy sound, but two diastolic, very scratchy sounds. We didn’t hear just [sounds]. Almost like a choo-choo train effect. And, when the patient breathed out, the sounds got louder.
There are techniques you must consider to bring out friction rubs, even though in our case, it is now obvious. Have the patient lean forward, again, using firm pressure on the diaphragm. Remember that friction rubs can come and go, so you must persist in seeking the rubbing sound, especially more than one component, to define it as a true friction rub.
We have defined a friction rub in our patient by all criteria. This is consistent with a patient who has pericarditis of an acute onset.
LLSE Oscilloscope
By viewing an oscilloscopic image and simultaneously listening we can further appreciate these auscultatory events.
Rub components
The typical pericardial friction rub has three components: a presystolic component that corresponds to atrial systole; a systolic component that corresponds to ventricular systole; and an early diastolic component that corresponds to ventricular diastole.
Occasionally, a rub may have only one or two components. A single component systolic friction rub is commonly confused with an ejection murmur.
Rub characteristics
Pericardial friction rubs may be subtle, evanescent and vary with time and respiration. When respiratory variation occurs, the commonest pattern is an increase in the intensity with inspiration. On occasion, the rub will become louder with expiration, as in our patient, or remain unchanged. Often, in order to detect a soft rub, repeated careful auscultation with the patient in different positions and with exaggerated breathing may be required.