Location of Pericardial Friction Rub on Auscultation
The pericardial friction rub is best heard at the left lower sternal border, with the patient sitting upright and leaning forward while briefly holding their breath. 1
Optimal Auscultation Technique
The detection of a pericardial friction rub requires proper positioning and technique to maximize sensitivity:
Position the patient sitting upright and leaning forward while they briefly hold their breath, as this brings the heart closer to the chest wall and minimizes interfering lung sounds 1
Auscultate primarily at the left lower sternal border, which is the most prominent location for detecting the friction rub 1, 2, 3
The friction rub may be audible across multiple precordial areas, though the left lower sternal border remains the optimal site 1
In some cases, the rub can be more pronounced when the patient is supine, though the sitting-leaning-forward position is generally optimal for detection 1
Clinical Characteristics and Detection Challenges
Understanding the nature of pericardial friction rubs is essential for accurate diagnosis:
The friction rub is highly specific but transient, being audible in only approximately one-third of patients with confirmed acute pericarditis 4, 1, 5
The rub can be mono-, bi-, or triphasic in character 4
Multiple auscultatory examinations may be necessary as the rub can disappear and reappear during the course of pericarditis 1
The friction rub is one of four key diagnostic criteria for acute pericarditis (along with characteristic chest pain, ECG changes, and pericardial effusion), with at least two criteria required for diagnosis 4, 5
Important Clinical Caveats
The absence of a friction rub does not exclude pericarditis, as it is only audible in less than one-third of confirmed cases 1
When a friction rub is present in the setting of acute myocardial infarction accompanied by persistent pain, hypotension, or nausea, urgent echocardiography is indicated 4
The friction rub is often accompanied by characteristic chest pain that radiates to the trapezius ridge 1
Transthoracic echocardiography should be performed in all patients with suspected pericarditis regardless of whether a friction rub is present 1