Pericardial Friction Rub: The Characteristic Auscultatory Finding in Pericarditis
Yes, pericarditis produces a highly specific sound called a pericardial friction rub, which can be mono-, bi-, or triphasic in character, though it is only audible in approximately one-third of patients with confirmed acute pericarditis. 1
Characteristics of the Pericardial Friction Rub
The pericardial friction rub is the pathognomonic auscultatory finding in acute pericarditis, with the following features:
- The rub can be mono-, bi-, or triphasic, with the triphasic pattern being most characteristic of pericarditis 1, 2
- The sound is described as "sandpaper-scratching" or scratchy in quality, distinguishing it from cardiac murmurs 3
- The rub is highly specific but transient, meaning it can disappear and reappear during the course of the disease, necessitating multiple auscultatory examinations 1, 2
- It is only audible in approximately one-third of patients with confirmed acute pericarditis, so its absence does not exclude the diagnosis 1, 2, 4
Optimal Auscultation Technique
To maximize detection of the pericardial friction rub, use the following approach:
- Listen at the left lower sternal border, which consistently provides the highest yield for detecting the rub 2, 5, 6
- Position the patient sitting upright and leaning forward while they briefly hold their breath after end-expiration 2, 4
- This position brings the heart closer to the chest wall and minimizes lung sounds, allowing better detection of the friction rub 2
- Perform multiple examinations throughout the patient encounter, as the rub can be intermittent and transient 1, 2
Additional Auscultatory Findings
Beyond the friction rub, other sounds may be present depending on complications:
- Diminished or muffled heart sounds occur in cases of moderate to large pericardial effusions due to fluid accumulation around the heart 1, 6
- A new S3 heart sound may indicate concomitant myocardial involvement (perimyocarditis) 1
- Normal heart sounds are common in patients without hemodynamic compromise or significant effusion 1
Clinical Context and Diagnostic Implications
The pericardial friction rub is one of four key diagnostic criteria for acute pericarditis established by the European Society of Cardiology, with at least two criteria required for diagnosis (the others being characteristic chest pain, ECG changes, and pericardial effusion) 2
Important caveats to remember:
- The absence of a friction rub does not exclude pericarditis, as it is only present in less than one-third of confirmed cases 1, 2, 4
- Pericardial effusion is only detectable in about 60% of pericarditis cases, so normal echocardiography does not rule out the diagnosis 2
- When a friction rub is present in the setting of acute myocardial infarction accompanied by persistent pain, hypotension, or nausea, urgent echocardiography is indicated to evaluate for complications 2
- Transthoracic echocardiography is recommended in all patients with suspected pericarditis regardless of whether a friction rub is present, as it detects effusion and evaluates for tamponade 1, 2