In what position is a friction rub best heard during acute pericarditis?

Optimal Position for Hearing Pericardial Friction Rub in Acute Pericarditis

The pericardial friction rub is best heard with the patient sitting upright and leaning forward while briefly holding their breath. 1

Auscultation Technique

Optimal Patient Positioning

• Have the patient sit upright and lean forward while performing a brief breath hold to maximize detection of the friction rub 1
• This position brings the heart closer to the anterior chest wall and minimizes interfering lung sounds, allowing for clearer auscultation 1
• In some cases, the friction rub may be more pronounced when the patient is supine, though the sitting-leaning-forward position remains the generally optimal approach 1
• One case report noted that the sound was more pronounced in the left lateral decubitus position, though this is not the standard recommendation 2

Auscultation Location

• Listen primarily at the left lower sternal border, where the friction rub is typically most prominent 1, 3
• The rub may be audible across multiple precordial areas, so examine the entire precordium 1

Clinical Characteristics and Detection Challenges

Frequency and Nature of the Rub

• The pericardial friction rub is highly specific but only audible in approximately one-third of patients with confirmed acute pericarditis 4, 1, 5
• Reported detection rates range from 18% to 84% depending on the study, with most guidelines citing detection in less than one-third of cases 5, 6
• The rub can be mono-, bi-, or triphasic in character and has a characteristic "sandpaper-scratching" quality 1, 2

Important Caveats

• The friction rub is transient and can disappear and reappear during the course of pericarditis, making repeated examinations at different times necessary 1
• Absence of a friction rub does not exclude the diagnosis of pericarditis, as it is only one of four diagnostic criteria 1, 5
• Multiple auscultatory examinations may be required due to the intermittent nature of the rub 1

Diagnostic Context

The pericardial friction rub is one of four key diagnostic criteria for acute pericarditis, with at least two criteria required for diagnosis 1, 5, 6:

• Characteristic pleuritic chest pain that improves with sitting up or leaning forward
• Pericardial friction rub
• New widespread ST-segment elevation and PR depression on ECG
• New or worsening pericardial effusion on echocardiography

When a friction rub develops in the setting of acute myocardial infarction accompanied by persistent pain, hypotension, or nausea, urgent echocardiography is indicated to evaluate for complications 4, 1