BMJ Case Reports 2012; doi:10.1136/bcr.05.2011.4289
  • Unusual association of diseases/symptoms

Chiari network: a protective filter against pulmonary embolism in a case of polycythaemia

  1. John Somauroo
  1. Department of Cardiology, Countess of Chester Hospital, Chester, UK
  1. Correspondence to Professor John Somauroo, johnsomauroo{at}


The Chiari network, a net-like structure within the right atrium, has been described as an embryonic remnant of no clinical significance. Its role in facilitating paradoxical arterial embolic events and as a potential site for thrombus formation however, has been reported in the literature. This case illustrates the protective filter-effect of the Chiari network in a 79-year-old Caucasian man with an unknown diagnosis of polycythaemia rubra vera who presented with clinical signs and symptoms of deep vein thrombosis. Transoesophageal echocardiogram confirmed entrapment of a thrombus within the Chiari network, which was not visualised following treatment on repeat scanning 1 month later. Here the authors describe how the Chiari network may have prevented the occurrence of a fatal massive pulmonary embolism in a patient with a high pro-thrombotic tendency, and review the current literature regarding the action of this anatomic variant as risk factor or protector.


  • Competing interests None.

  • Patient consent Obtained.

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