Dr.S.Venkatesan MD

The pericarditis  of acute rheumatic fever is not a true infective pericarditis.It is more of inflammation .It is primarily  T cell mediated  reaction . Neutrophils rarely take part  in this inflammation and hence  no significant  exudation . Hence , there is less  sticky and adhesive molecules inside the pericardial space .The most inflamed layer is epicardium which a nothing but visceral  pericardium .This layer lacks the tensile strength to constrict the underlying myocardium.

For constriction to occur the fibrinous  ( thick ) layer of pericardium need to be involved . In rheumatic fever  even though it is  pancarditis ,  fibrous layer is not  involved. Further the inflammatory gradient is thought to spread from within  (Unlike tuberculosis )

Note :  In chronic tuberculous pericarditis,  diffuse inflammatory process  invade from the exterior surface . Very often ,  one can not differentiate  layers. In extreme cases even myocardium and pericardium can not be separated .

Summary

The peri-cardial effusion of acute rheumatic fever

1. Is transient ,non infective and resolving (Unlike valvular inflammation !)
2. Less of neutrophil activation  (Less adhesion)
3. It does not involve the thick , tensile  fibrous layer of pericardium hence lacks the contractile force .

Other lingering  questions

1.How common is tamponade  in acute rheumatic fever ?

2.How important is the mass of the effusion (Viz  a Viz  Intra pericardial pressure !) in causing tamponade ?

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