title: Friction and fluid: correlating pericardial effusion and pericardial friction rub.
abstract: BACKGROUND
  In this study the relationship between pericardial friction rub (PFR) and the degree of pericardial effusion was investigated.
  
  
  METHODS
  A retrospective study was performed involving all patients for whom the diagnosis pericarditis was made on clinical grounds (type of chest pain, fever, laboratory findings and/or electrocardiographic signs) in the period 1990-1999. In this patient group (n=138) the presence of PFR was correlated against the amount of pericardial effusion measured echocardiographically.
  
  
  RESULTS
  No statistically significant correlation between the presence of PFR and the amount of pericardial effusion was observed. It is, therefore, a misconception that the presence of a PFR signifies absence or only a small volume of pericardial effusion. Our results are in line with the literature.
  
  
  CONCLUSIONS
  Based on this study and results presented in the literature, we postulate that the friction rub associated with pericarditis is not caused by friction of the 'roughened' pericardial layers, as is commonly propagated. Instead fibrin strands caused by the inflammation, connecting the two pericardial layers, may function as snares and generate, through the movements of the heart, the typical triphasic pericardial friction rub.
authors.forename: S
authors.initials: S
authors.lastname: Natan
authors.forename: E J P
authors.initials: EJ
authors.lastname: Lamfers
authors.forename: A J M Oude
authors.initials: AJ
authors.lastname: Ophuis
authors.forename: B T J
authors.initials: BT
authors.lastname: Meursing
keywords: pericardial effusion; pericardial friction rub