Definition/Introduction

A pericardial rub is highly specific for acute pericarditis. It is generally heard over the left sternal border, often louder at inspiration, but sometimes can be better heard on forced expiration while the patient bends forward. The rub is often triphasic (audible in atrial, ventricular systole, and ventricular diastole phases) and is of high frequency.[1]

Issues of Concern

The prevalence of a pericardial rub in pericarditis varies widely among studies. It is anywhere between 35% and 85%,[2][3][4] likely depending on the examiner's expertise and the frequency of cardiac auscultation since the pericardial rub might variably be audible during the day.[5] It was initially thought to be due to the friction of 2 inflamed pericardiums. However, this does not explain the presence of a rub in large pericardial effusions where the pericardial layers are not in contact. Moreover, the occurrence of the pericardial rub does not seem to be related to the size of the effusion; it was found present in 31% to 54% of small effusions, 43% to 55% of moderate effusions, and 42% to 49% of large effusions (P-value greater than 0.05 in both studies).[2][6] Also, pericardial rub seems to be more detected in patients with acute pericarditis than in those with chronic pericardial disease (74.4% vs 15.2%, P <0.001).[2] Thus, the theory of friction between inflamed pericardial layers does not fully explain the occurrence of a pericardial rub. Natan et al. hypothesized that the rub might result from the movement of fibrin strands caused by inflammation.[6]

Clinical Significance

The presence and documentation of a pericardial rub are extremely important since it is one of the four criteria for diagnosing acute pericarditis. According to the 2015 European Society of Cardiology Guidelines for the diagnosis and management of pericardial diseases, acute pericarditis is diagnosable in the presence of two out of the four criteria: typical pericarditis chest pain, pericardial rub, diffuse ST-elevation or PR-depression on electrocardiogram and a new or worsening pericardial effusion.[7]

Thus, the detection of pericardial rub along with a new pericardial effusion, for example, meets the criteria, and the patient should be treated as acute pericarditis. An untreated episode of acute pericarditis increases the risk of complications, including recurrent, chronic, and constrictive pericarditis.

A pericardial rub can also indicate left ventricular dilation after acute Q-wave anterior myocardial infarction since transmural infarct can irritate the pericardium (and cause pericarditis) and cause left ventricular failure.[8] The presence of pericardial rub after Q-wave anterior myocardial infarction might also carry a worse prognosis and indicate extensive ventricular damage after coronary angioplasty.[9][10]

Nursing, Allied Health, and Interprofessional Team Interventions

Because of available technologies, medical professionals' expertise in bedside examination has declined. For every patient who presents with chest pain suspicious of acute pericarditis, the nursing and medical team should attentively try to identify a pericardial rub over the left sternal border at different times since the presence of the rub is variable during the day. Its detection modifies the patient's management since the presence of a pericardial rub is very specific for acute pericarditis.