How do you auscultate a pericarditis friction rub using a stethoscope?

How to Auscultate a Pericardial Friction Rub

To hear a pericardial friction rub, position the patient sitting upright and leaning forward, have them briefly hold their breath after expiration, and listen with the diaphragm of your stethoscope at the left lower sternal border. 1

Optimal Patient Positioning

• Have the patient sit upright and lean forward while you auscultate—this position brings the heart closer to the anterior chest wall and minimizes interfering lung sounds 1
• Ask the patient to briefly hold their breath during auscultation to eliminate respiratory sounds that can obscure the friction rub 1
• In some cases, the friction rub may be more pronounced when the patient is supine, though the sitting-leaning-forward position is generally optimal for detection 1

Where to Listen

• Focus on the left lower sternal border, where the friction rub is typically most prominent 1
• The rub may be audible across multiple precordial areas, so scan the entire precordium if not initially detected at the left lower sternal border 1

Characteristics of the Friction Rub

• The friction rub can be mono-, bi-, or triphasic in character, corresponding to atrial systole, ventricular systole, and ventricular diastole 1
• It is a high-pitched, scratchy, or squeaky sound that has been described as similar to leather rubbing against leather 2, 3
• The sound quality is typically harsh and superficial, as if occurring very close to the stethoscope 4

Critical Clinical Caveats

• The friction rub is highly specific but transient—it is only audible in approximately 18-33% of patients with confirmed acute pericarditis 1, 2, 3
• Multiple auscultatory examinations are necessary because the rub can disappear and reappear during the course of pericarditis 1
• The absence of a friction rub does NOT exclude pericarditis—less than one-third of confirmed cases have an audible rub 1
• The rub may be present even without pericardial effusion, and conversely, large effusions may eliminate the rub by separating the pericardial layers 4

When the Friction Rub is Present

• A pericardial friction rub is one of four key diagnostic criteria for acute pericarditis (along with characteristic chest pain, ECG changes, and pericardial effusion)—at least two criteria are required for diagnosis 1, 2, 3
• When a friction rub is detected in the setting of acute myocardial infarction accompanied by persistent pain, hypotension, or nausea, urgent echocardiography is indicated to evaluate for complications 1
• Transthoracic echocardiography should be performed in all patients with suspected pericarditis to detect effusion and evaluate for complications, regardless of whether a friction rub is present 1

Special Populations

• In uremic pericarditis, the friction rub may be present but is often transient or absent entirely, even with significant effusions 5
• Uremic patients typically lack the classic features of pericarditis, with up to 70% being asymptomatic or minimally symptomatic 5